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2024, 49(4): 1189-1206.
doi: 10.3799/dqkx.2022.282
Abstract:
In order to discuss the mineralization of the Liushuwan uranium deposit in the Lushi Wulichuan area, West Henan Province, whose distinct alkali metasomatic mineralization has direct directive significance for a new round of prospecting strategic action in West Henan metallogenic belt. Therefore, it tests Huichizi pluton and exteral granitic pegmatite by petrology, petrochemistry, isotope zircon, muscovite, molybdenite incasing the granitic pegmatite by LA-ICP-MS U-Pb, Ar-Ar and Re-Os to find their linkage to uranium mineralization. It is recognized that the alkali metasomatism of mantle-derived fluids records the uranium mineralization. In Early Paleozoic, mantle derived alkaline magma invaded, melted and metasomatized the Mesoproterozoic Qinling microblocks to produce the uranium-bearing I-type Huichizi pluton (429.4±5.3 Ma) and granitic pegmatite (418.7±2 Ma), which accumulates uranium sources and served as a carrier for uranium ore. Post the formation of the granitic pegmatitte, fluid derived mantle continuously intruded and alkali metasomatised the Qingling Group, the Huichizi pluton and the pegmatite, which could alter their contents including K+Na, SiO2, REE, Zr, Hf, Ti, etc. In that case, the U-Pb, Ar-Ar and Re-Os isotopic closed systems respectively for zircon, muscovite and molybdenite would be broken. Two types of uranium-bearing hydrothermal fluids, respectively Na-Zr-Hf rich and K-Nb-Ta rich, mantle derived magma successively metasomatized the peripheral pegmatite of the Huichizi pluton to contribute the final formed Liushuwan granitic pegmatite uranium deposit. In summary, the mantle derived magma induced alkali metasomatism is the fundamental factor to contribute the spatial allocation of the Liushuwan uranium deposit, the Huichizi pluton and the granitic pegmatite. The uranium-bearing hydrothermal solution derivated from the mantle-sourced magma is the direct factor to the uranium mineralization. The alkali metasomatism destroyed the geochemical signature and isotopic system of the Huichizi pluton and the granitic pegmatite.Uranium-bearing hydrothermal solution is the direct factor of uranium mineralization in Liushuwan uranium deposit.The understanding of alkali metasomatism induced uranium mineralization in Lushi Liushuwan West Henan, not only provides a new perspective for studying the mechanism of granitic pegmatite-type uranium mineralization, but also shed insights on predicting uranium mineralization and expanding the scope for prospecting.
In order to discuss the mineralization of the Liushuwan uranium deposit in the Lushi Wulichuan area, West Henan Province, whose distinct alkali metasomatic mineralization has direct directive significance for a new round of prospecting strategic action in West Henan metallogenic belt. Therefore, it tests Huichizi pluton and exteral granitic pegmatite by petrology, petrochemistry, isotope zircon, muscovite, molybdenite incasing the granitic pegmatite by LA-ICP-MS U-Pb, Ar-Ar and Re-Os to find their linkage to uranium mineralization. It is recognized that the alkali metasomatism of mantle-derived fluids records the uranium mineralization. In Early Paleozoic, mantle derived alkaline magma invaded, melted and metasomatized the Mesoproterozoic Qinling microblocks to produce the uranium-bearing I-type Huichizi pluton (429.4±5.3 Ma) and granitic pegmatite (418.7±2 Ma), which accumulates uranium sources and served as a carrier for uranium ore. Post the formation of the granitic pegmatitte, fluid derived mantle continuously intruded and alkali metasomatised the Qingling Group, the Huichizi pluton and the pegmatite, which could alter their contents including K+Na, SiO2, REE, Zr, Hf, Ti, etc. In that case, the U-Pb, Ar-Ar and Re-Os isotopic closed systems respectively for zircon, muscovite and molybdenite would be broken. Two types of uranium-bearing hydrothermal fluids, respectively Na-Zr-Hf rich and K-Nb-Ta rich, mantle derived magma successively metasomatized the peripheral pegmatite of the Huichizi pluton to contribute the final formed Liushuwan granitic pegmatite uranium deposit. In summary, the mantle derived magma induced alkali metasomatism is the fundamental factor to contribute the spatial allocation of the Liushuwan uranium deposit, the Huichizi pluton and the granitic pegmatite. The uranium-bearing hydrothermal solution derivated from the mantle-sourced magma is the direct factor to the uranium mineralization. The alkali metasomatism destroyed the geochemical signature and isotopic system of the Huichizi pluton and the granitic pegmatite.Uranium-bearing hydrothermal solution is the direct factor of uranium mineralization in Liushuwan uranium deposit.The understanding of alkali metasomatism induced uranium mineralization in Lushi Liushuwan West Henan, not only provides a new perspective for studying the mechanism of granitic pegmatite-type uranium mineralization, but also shed insights on predicting uranium mineralization and expanding the scope for prospecting.
2024, 49(4): 1207-1223.
doi: 10.3799/dqkx.2022.447
Abstract:
The Lower Cretaceous Bayingobi Formation in the Hari sag, Bayingobi basin, Inner Mongolia, is a typical carbonate-type alkaline lake during the depositional period, and a large amount of Na-carbonate minerals developed during the salinization of the basin. In this paper, electron probe, X-diffraction, carbon and oxygen isotope and laser Raman spectroscopy were carried out to analyze the layered, speckled and vein-like Na-carbonate minerals in the trona layers of the Bayingobi Formation. The Na-carbonate minerals in the trona layer are mainly composed of trona, nahcolite, shortite, eitelite and bradleyite, with a small amount of hydrothermal minerals such as pyrite, chabazite-Na, searlesite and albite. The results of carbon and oxygen isotope testings show that the Lower Cretaceous trona layers in the Bayingobi basin were formed in a closed alkaline lake environment, the Na-carbonate minerals were formed at a temperature range of 34-80 ℃ (average 57 ℃). Under control of exhalative deposition and evaporation, silicate minerals were first formed in the trona layers, and then dolomite and calcite were formed, after Ca2+ and Mg2+ were almost consumed, trona and nacholite were precipitated. With sufficient Na+ brought by the hydrotherm, the early formed dolomite and calcite underwent metasomatism to form dawsonite and dawsonite. Based on the comprehensive analysis of mineralogy and geochemistry, the Na-carbonate sedimentary model of alkaline lake is established, which is controlled by hydrothermal exhalation and evaporative deposition, it can provide a new idea for the exploration of trona deposit.
The Lower Cretaceous Bayingobi Formation in the Hari sag, Bayingobi basin, Inner Mongolia, is a typical carbonate-type alkaline lake during the depositional period, and a large amount of Na-carbonate minerals developed during the salinization of the basin. In this paper, electron probe, X-diffraction, carbon and oxygen isotope and laser Raman spectroscopy were carried out to analyze the layered, speckled and vein-like Na-carbonate minerals in the trona layers of the Bayingobi Formation. The Na-carbonate minerals in the trona layer are mainly composed of trona, nahcolite, shortite, eitelite and bradleyite, with a small amount of hydrothermal minerals such as pyrite, chabazite-Na, searlesite and albite. The results of carbon and oxygen isotope testings show that the Lower Cretaceous trona layers in the Bayingobi basin were formed in a closed alkaline lake environment, the Na-carbonate minerals were formed at a temperature range of 34-80 ℃ (average 57 ℃). Under control of exhalative deposition and evaporation, silicate minerals were first formed in the trona layers, and then dolomite and calcite were formed, after Ca2+ and Mg2+ were almost consumed, trona and nacholite were precipitated. With sufficient Na+ brought by the hydrotherm, the early formed dolomite and calcite underwent metasomatism to form dawsonite and dawsonite. Based on the comprehensive analysis of mineralogy and geochemistry, the Na-carbonate sedimentary model of alkaline lake is established, which is controlled by hydrothermal exhalation and evaporative deposition, it can provide a new idea for the exploration of trona deposit.
2024, 49(4): 1224-1244.
doi: 10.3799/dqkx.2022.472
Abstract:
It is generally believed that it is easy to enrich oil and gas in deep-water environments such as deep lacustrine to semi-deep lacustrine in continental basins, but a large number of shale gas exploration has proved that shale gas reservoirs are generally located closer to the edge of lacustrine basins, so it is necessary to further study the law of organic matter enrichment in continental lacustrine basins. In this paper, the metallogenic conditions of shale oil, gas and coal are compared by analogy method. Combined with the primary productivity of the lake, the rate of carbon sequestration and fossil development, the paleo-geomognomy and burial history recovery means are used to put forward six evidence that shale developed in shallow water restricted environment. It is found that shale oil, gas and coal have similar metallogenic patterns, and have a symbiotic relationship with coal and evaporative salt in shallow water environment. The carbon sequestration rate in shallow water environment is much higher than that in deep water environment. The conclusion is that shale oil and gas are enriched in closed to semi-closed environment such as shallow lake bay and interbay. The condensed section of the maximum flood period should be the organic-poor section. Finally, the results are verified in Songnan area, indicating that this conclusion is universal and can guide shale oil and gas exploration better.
It is generally believed that it is easy to enrich oil and gas in deep-water environments such as deep lacustrine to semi-deep lacustrine in continental basins, but a large number of shale gas exploration has proved that shale gas reservoirs are generally located closer to the edge of lacustrine basins, so it is necessary to further study the law of organic matter enrichment in continental lacustrine basins. In this paper, the metallogenic conditions of shale oil, gas and coal are compared by analogy method. Combined with the primary productivity of the lake, the rate of carbon sequestration and fossil development, the paleo-geomognomy and burial history recovery means are used to put forward six evidence that shale developed in shallow water restricted environment. It is found that shale oil, gas and coal have similar metallogenic patterns, and have a symbiotic relationship with coal and evaporative salt in shallow water environment. The carbon sequestration rate in shallow water environment is much higher than that in deep water environment. The conclusion is that shale oil and gas are enriched in closed to semi-closed environment such as shallow lake bay and interbay. The condensed section of the maximum flood period should be the organic-poor section. Finally, the results are verified in Songnan area, indicating that this conclusion is universal and can guide shale oil and gas exploration better.
2024, 49(4): 1245-1260.
doi: 10.3799/dqkx.2022.280
Abstract:
The rare-metal and rare-earth mineralized alkaline-carbonatite complex was first discovered in the Dagele area of East Kunlun orogen. This discovery indicates that the East Kunlun orogen has great prospects for rare-metal mineralization. Related studies are vital for understanding the geological processes and searching for rare-metal deposits in East Kunlun orogen. This study reports the geochemistry and geochronology of baddeleyites from peridotite and carbonatite within the Dagele alkaline complex. Baddeleyites from peridotite mainly contain ZrO2 (96.48%-97.21%) with minor HfO2 (0.83%-1.17%) and Nb2O5 (0.61%-0.93%). After common Pb correction using measured 207Pb, they yield weighted average ages of 381.0±2.3 Ma and 417.5±3.4 Ma with low intercept ages of 381.1±2.3 Ma and 417.7±3.4 Ma, respectively. Baddeleyites from carbonatite are mainly composed of ZrO2 (91.1%), followed by HfO2 (4.3%), Nb2O5 (1.22%), and FeO (2.31%). They yield weighted average ages of 381.5±2.5 Ma and 416.5±4.5 Ma with low intercept ages of 381.8±1.8 Ma and 416.7±4.5 Ma, respectively. It is inferred that the carbonatite and peridotite are formed at 381.8 Ma and 417.7 Ma, respectively. There are at least two stages of enrichment of Nb in the silica-unsaturated magma. Post-collisional and post-orogenic lithosphere extension and partial melting of mantle beneath the East Kunlun collisional orogen were considered as the geodynamic mechanism for its formation. Therefore, it is suggested that the Late Silurian-Devonian is an important period of rare-metal mineralization. The area between Dagela and Nuomuhong River is one of the important regions for prospecting of rare-metal mineralization.
The rare-metal and rare-earth mineralized alkaline-carbonatite complex was first discovered in the Dagele area of East Kunlun orogen. This discovery indicates that the East Kunlun orogen has great prospects for rare-metal mineralization. Related studies are vital for understanding the geological processes and searching for rare-metal deposits in East Kunlun orogen. This study reports the geochemistry and geochronology of baddeleyites from peridotite and carbonatite within the Dagele alkaline complex. Baddeleyites from peridotite mainly contain ZrO2 (96.48%-97.21%) with minor HfO2 (0.83%-1.17%) and Nb2O5 (0.61%-0.93%). After common Pb correction using measured 207Pb, they yield weighted average ages of 381.0±2.3 Ma and 417.5±3.4 Ma with low intercept ages of 381.1±2.3 Ma and 417.7±3.4 Ma, respectively. Baddeleyites from carbonatite are mainly composed of ZrO2 (91.1%), followed by HfO2 (4.3%), Nb2O5 (1.22%), and FeO (2.31%). They yield weighted average ages of 381.5±2.5 Ma and 416.5±4.5 Ma with low intercept ages of 381.8±1.8 Ma and 416.7±4.5 Ma, respectively. It is inferred that the carbonatite and peridotite are formed at 381.8 Ma and 417.7 Ma, respectively. There are at least two stages of enrichment of Nb in the silica-unsaturated magma. Post-collisional and post-orogenic lithosphere extension and partial melting of mantle beneath the East Kunlun collisional orogen were considered as the geodynamic mechanism for its formation. Therefore, it is suggested that the Late Silurian-Devonian is an important period of rare-metal mineralization. The area between Dagela and Nuomuhong River is one of the important regions for prospecting of rare-metal mineralization.
2024, 49(4): 1261-1276.
doi: 10.3799/dqkx.2022.270
Abstract:
The timing of the closure of the A'nyemaqen ocean, which was a branch of Paleo-Tethys ocean at the East Kunlun orogenic belt (EKOB), is still a subject of debate. In this study, it presents zircon U-Pb geochronology, whole-rock elemental geochemistry and Sr-Nd isotopic data on the Haidewula diabase in the eastern section of the EKOB. Zircon LA-ICP-MS U-Pb isotope dating reveals that the Haidewula diabase formed at 238±2 Ma. The diabase is characterized by low MgO (2.76%-6.34%) contents, as well as relatively high TiO2 (1.75%-2.46%) and Fe2O3T (8.88%-12.30%) contents. The diabase shows enrichment in incompatible elements, but is relatively depleted in Nb, Ta, Sr, and Ti. All these geochemical characteristics imply that the diabase is a production of island arc magmatic activity. Additionally, the diabase displays enriched and uniform Sr-Nd isotopic compositions((87Sr/86Sr)i= 0.711 61-0.712 95, εNd(t) =-3.2 to -2.8). Based on the geochemical characteristics and isotopic compositions, it suggests that the Haidewula diabase was derived from partial melting of an enriched mantle, which had undergone metasomatism induced by the fluid released from the subducting slab, and had experienced some degree of crustal contamination during migration through continental crust. Combing our results and previous studies on Middle Permian-Triassic basic igneous rocks in the EKOB, it proposes that the northward subduction of the A'nyemaqen ocean lasted to the end of the Middle Triassic (238 Ma); the closure of the A'nyemaqen ocean happened during early Late Triassic; then, the tectonic environment of the eastern section of the EKOB transited into post-collisional extension no later than 228 Ma.
The timing of the closure of the A'nyemaqen ocean, which was a branch of Paleo-Tethys ocean at the East Kunlun orogenic belt (EKOB), is still a subject of debate. In this study, it presents zircon U-Pb geochronology, whole-rock elemental geochemistry and Sr-Nd isotopic data on the Haidewula diabase in the eastern section of the EKOB. Zircon LA-ICP-MS U-Pb isotope dating reveals that the Haidewula diabase formed at 238±2 Ma. The diabase is characterized by low MgO (2.76%-6.34%) contents, as well as relatively high TiO2 (1.75%-2.46%) and Fe2O3T (8.88%-12.30%) contents. The diabase shows enrichment in incompatible elements, but is relatively depleted in Nb, Ta, Sr, and Ti. All these geochemical characteristics imply that the diabase is a production of island arc magmatic activity. Additionally, the diabase displays enriched and uniform Sr-Nd isotopic compositions((87Sr/86Sr)i= 0.711 61-0.712 95, εNd(t) =-3.2 to -2.8). Based on the geochemical characteristics and isotopic compositions, it suggests that the Haidewula diabase was derived from partial melting of an enriched mantle, which had undergone metasomatism induced by the fluid released from the subducting slab, and had experienced some degree of crustal contamination during migration through continental crust. Combing our results and previous studies on Middle Permian-Triassic basic igneous rocks in the EKOB, it proposes that the northward subduction of the A'nyemaqen ocean lasted to the end of the Middle Triassic (238 Ma); the closure of the A'nyemaqen ocean happened during early Late Triassic; then, the tectonic environment of the eastern section of the EKOB transited into post-collisional extension no later than 228 Ma.
2024, 49(4): 1277-1291.
doi: 10.3799/dqkx.2021.228
Abstract:
The unclear division of ore-bearing targets in Qianjiadian uranium deposit and its surrounding areas has become a key problem that needs to be solved urgently in current production and scientific research.In order to determine the ore-bearing strata accurately, based on the stratigraphy, sedimentology and sandstone-type metallogenic theories, the identification characteristics and classification basis are systematically researched by using lithology, well logging, paleontology and other means.Research results show that the ore bearing target layer can be identified and divided into three horizons: Quantou Formation, Qingshankou Formation and Yaojia Formation (traditional stratigraphic division classifies it as the Yaojia Formation). On this basis, the strata attribution and mineralization characteristics of different ore bodies in the region are redetermined. This study can provide a new idea and geological basis for the progress of uranium exploration in southern Songliao basin. Further study of metallogenic regularity under this new horizon system may really help to reveal the genesis of tabular uranium ore body.
The unclear division of ore-bearing targets in Qianjiadian uranium deposit and its surrounding areas has become a key problem that needs to be solved urgently in current production and scientific research.In order to determine the ore-bearing strata accurately, based on the stratigraphy, sedimentology and sandstone-type metallogenic theories, the identification characteristics and classification basis are systematically researched by using lithology, well logging, paleontology and other means.Research results show that the ore bearing target layer can be identified and divided into three horizons: Quantou Formation, Qingshankou Formation and Yaojia Formation (traditional stratigraphic division classifies it as the Yaojia Formation). On this basis, the strata attribution and mineralization characteristics of different ore bodies in the region are redetermined. This study can provide a new idea and geological basis for the progress of uranium exploration in southern Songliao basin. Further study of metallogenic regularity under this new horizon system may really help to reveal the genesis of tabular uranium ore body.
2024, 49(4): 1292-1306.
doi: 10.3799/dqkx.2022.305
Abstract:
To study the genesis of ore deposits in the Dongxiang volcanic basin, the Huxu Au-Pb-Zn deposit was selected as the research object, and a detailed study of quartz trace elements, fluid inclusions thermometry and chemical compositions of chlorite was carried out. The results indicate that the main element substitution mechanism is Al3++Li+ = Si4+.The pH of the ore-forming fluids is fluctuated episodically. The fluid inclusions are mainly gas-liquid type. The chlorite formed in an environment with relatively high sulfur fugacity and low oxygen fugacity. The ore-forming temperature is estimated to be 210-280 ℃.Combined with previous studies, it suggests that the Huxu deposit evolved with varying mixing ratio of magmatic fluids and meteoric water, accompanied by fluid-rock interaction, leading to the precipitation of ore veins in the opening fractures. The Huxu deposit is considered as epithermal deposit, with buried porphyry body.
To study the genesis of ore deposits in the Dongxiang volcanic basin, the Huxu Au-Pb-Zn deposit was selected as the research object, and a detailed study of quartz trace elements, fluid inclusions thermometry and chemical compositions of chlorite was carried out. The results indicate that the main element substitution mechanism is Al3++Li+ = Si4+.The pH of the ore-forming fluids is fluctuated episodically. The fluid inclusions are mainly gas-liquid type. The chlorite formed in an environment with relatively high sulfur fugacity and low oxygen fugacity. The ore-forming temperature is estimated to be 210-280 ℃.Combined with previous studies, it suggests that the Huxu deposit evolved with varying mixing ratio of magmatic fluids and meteoric water, accompanied by fluid-rock interaction, leading to the precipitation of ore veins in the opening fractures. The Huxu deposit is considered as epithermal deposit, with buried porphyry body.
2024, 49(4): 1307-1323.
doi: 10.3799/dqkx.2022.467
Abstract:
To better determine the precise mineralization age and examine the genesis of the Xincun uranium deposit in Motianling granite, North Guangxi, it carried out detailed mineralogical observation, in-situ U-Pb isotope and chemical composition analysis on the pitchblende of U-silicified type mineralization from the Xincun deposit using scanning electron microscopy (SEM), electron probe (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The chemical age of pitchblende obtained by the electron probe gives a very wide range and thus cannot represent the true formation age of the Xincun uranium mineralization. The results of LA-ICP-MS U-Pb isotope indicate that the pitchblende of the Xincun deposit contains a certain amount of common Pb, and the Tera-Wasserburg diagram yields a lower intercept age of 57.61±0.34 Ma (MSWD=0.97), which can represent the exact timing of Xincun deposit. The major and trace element results show that the pitchblende of the Xincun deposit has high WO3 and CaO contents but extremely low ThO content, indicating that the ore fluid may be enriched in U and W and has medium-low temperature. The chondrite-normalized patterns of rare earth elements in pitchblende are slightly rich in light-REE, and similar to the rare earth partition of the ore-hosting granite. It is thus speculated that the uranium is probably derived from the granitoid itself. The newly obtained mineralization age is consistent with the main metallogenic period (70-50 Ma) of the hydrothermal uranium deposits in northern Guangxi. Similar to most of the Mesozoic and Cenozoic hydrothermal uranium deposits in South China, the Xincun deposit was formed due to the extension and thinning of the Cretaceous-Paleogene lithosphere in South China.
To better determine the precise mineralization age and examine the genesis of the Xincun uranium deposit in Motianling granite, North Guangxi, it carried out detailed mineralogical observation, in-situ U-Pb isotope and chemical composition analysis on the pitchblende of U-silicified type mineralization from the Xincun deposit using scanning electron microscopy (SEM), electron probe (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The chemical age of pitchblende obtained by the electron probe gives a very wide range and thus cannot represent the true formation age of the Xincun uranium mineralization. The results of LA-ICP-MS U-Pb isotope indicate that the pitchblende of the Xincun deposit contains a certain amount of common Pb, and the Tera-Wasserburg diagram yields a lower intercept age of 57.61±0.34 Ma (MSWD=0.97), which can represent the exact timing of Xincun deposit. The major and trace element results show that the pitchblende of the Xincun deposit has high WO3 and CaO contents but extremely low ThO content, indicating that the ore fluid may be enriched in U and W and has medium-low temperature. The chondrite-normalized patterns of rare earth elements in pitchblende are slightly rich in light-REE, and similar to the rare earth partition of the ore-hosting granite. It is thus speculated that the uranium is probably derived from the granitoid itself. The newly obtained mineralization age is consistent with the main metallogenic period (70-50 Ma) of the hydrothermal uranium deposits in northern Guangxi. Similar to most of the Mesozoic and Cenozoic hydrothermal uranium deposits in South China, the Xincun deposit was formed due to the extension and thinning of the Cretaceous-Paleogene lithosphere in South China.
2024, 49(4): 1324-1338.
doi: 10.3799/dqkx.2023.177
Abstract:
To decipher the petrogenesis of the newly discovered alkaline rhyolite in the Baerzhe giant rare metal deposit in Inner Mongolia, and its genetic relationship with the ore⁃related peralkaline granite and Aliwula alkaline rhyolite from the adjacent area, in this research it carried out high spatial resolution LA-SF-ICP-MS zircon U-Pb dating, mineralogical and whole⁃rock geochemical studies. The results show that the eruption age of the Baerzhe alkaline rhyolite is 124.4±1.6 Ma, which is obviously younger than that of the Aliwula alkaline rhyolite(141 Ma), which represents a new stage of alkaline volcanic activity in the middle-southern section of the Great Xing'an Range during the Early Cretaceous. The Baerzhe and Aliwula alkaline rhyolites have high SiO2, alkali metals, TFe2O3, F and low Al2O3 contents, and belong to comendites. Both are rich in light rare earth elements (LREE) and high field strength elements (HFSE) such as Nb, Ta, Zr, and Hf, and contain high Rb, Th, U and extremely low Ba and Sr contents. In addition, both have the same whole-rock Nd isotopic composition, with εNd(t) values of 1.6 and 1.7-1.8, respectively. Therefore, both Baerzhe and Aliwula alkaline rhyolites are the products of partial melting of the juvenile lower crust. The Baerzhe alkaline rhyolite and ore⁃related peralkaline granite have the same formation age and isotope composition, and are different products of same, evolving magmatic system. Given the wider exposure range of volcanic rocks, alkaline volcanic rocks can be used as an important geological prospecting indicator for the underlying rare metal deposits, and it is pointed out that Aliwula area has a good prospecting potential for such deposits.
To decipher the petrogenesis of the newly discovered alkaline rhyolite in the Baerzhe giant rare metal deposit in Inner Mongolia, and its genetic relationship with the ore⁃related peralkaline granite and Aliwula alkaline rhyolite from the adjacent area, in this research it carried out high spatial resolution LA-SF-ICP-MS zircon U-Pb dating, mineralogical and whole⁃rock geochemical studies. The results show that the eruption age of the Baerzhe alkaline rhyolite is 124.4±1.6 Ma, which is obviously younger than that of the Aliwula alkaline rhyolite(141 Ma), which represents a new stage of alkaline volcanic activity in the middle-southern section of the Great Xing'an Range during the Early Cretaceous. The Baerzhe and Aliwula alkaline rhyolites have high SiO2, alkali metals, TFe2O3, F and low Al2O3 contents, and belong to comendites. Both are rich in light rare earth elements (LREE) and high field strength elements (HFSE) such as Nb, Ta, Zr, and Hf, and contain high Rb, Th, U and extremely low Ba and Sr contents. In addition, both have the same whole-rock Nd isotopic composition, with εNd(t) values of 1.6 and 1.7-1.8, respectively. Therefore, both Baerzhe and Aliwula alkaline rhyolites are the products of partial melting of the juvenile lower crust. The Baerzhe alkaline rhyolite and ore⁃related peralkaline granite have the same formation age and isotope composition, and are different products of same, evolving magmatic system. Given the wider exposure range of volcanic rocks, alkaline volcanic rocks can be used as an important geological prospecting indicator for the underlying rare metal deposits, and it is pointed out that Aliwula area has a good prospecting potential for such deposits.
2024, 49(4): 1339-1351.
doi: 10.3799/dqkx.2022.506
Abstract:
Yueguifeng Formation is the main source rock in Lishui-Jiaojiang depression, but it's poor research on provenance which brings great difficulties to oil and gas exploration. Based on zircon U-Pb dating and heavy mineral analysis, it was systematically analyzed and compared for the provenance characteristics, differences and geological significance of the Yueguifeng Formation. The results show that the provenance is mainly medium-acid igneous rocks main ages of which are 130-100 Ma with a small amount of metamorphic rocks, mainly containing stable heavy minerals such as zircon, hematite and magnetite. The provenance of Jiaojiang depression and east Lishui sub-depression mainly came from Yandang uplift, and the provenance of west Lishui sub-depression mainly came from Fujian-Zhejiang uplift. A small amount of igneous and metamorphic rocks came from the basement near the study area. Zircon roundness preference and ZTR values are higher, indicating that the provenance was transported over medium and long distances, which is conducive to the enrichment of quartz and feldspar minerals in medium-acid magmatic rocks, forming quartz sandstone reservoirs with good compaction resistance.
Yueguifeng Formation is the main source rock in Lishui-Jiaojiang depression, but it's poor research on provenance which brings great difficulties to oil and gas exploration. Based on zircon U-Pb dating and heavy mineral analysis, it was systematically analyzed and compared for the provenance characteristics, differences and geological significance of the Yueguifeng Formation. The results show that the provenance is mainly medium-acid igneous rocks main ages of which are 130-100 Ma with a small amount of metamorphic rocks, mainly containing stable heavy minerals such as zircon, hematite and magnetite. The provenance of Jiaojiang depression and east Lishui sub-depression mainly came from Yandang uplift, and the provenance of west Lishui sub-depression mainly came from Fujian-Zhejiang uplift. A small amount of igneous and metamorphic rocks came from the basement near the study area. Zircon roundness preference and ZTR values are higher, indicating that the provenance was transported over medium and long distances, which is conducive to the enrichment of quartz and feldspar minerals in medium-acid magmatic rocks, forming quartz sandstone reservoirs with good compaction resistance.
2024, 49(4): 1352-1366.
doi: 10.3799/dqkx.2022.294
Abstract:
The Laohushan monogenic volcano is located in Dakouqin area, southern Jilin Province. In order to explore the geochemistry characteristics and genesis of the Miocene tephrite in this volcanic area, together with the coupling between it and the evolution of regional fault structure, the whole rock geochemistry and Pb isotope study on it were carried out. Na2O/K2O values of the tephrites are range from 1.30 to 1.38, with low A/CNK (0.97-1.09) and high Mg# (58.05-61.11) values. The tephrites are enriched in high field strength elements (HFSEs), such as Th, U and Nb, and relatively weakly enriched in large ion lithophile elements (LILEs), such as Rb, Ba and K, with LREE/HREE=10.66-11.32. The values of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb are range from 17.661 to 17.675, 15.451 to 15.457 and 37.652 to 37.692, respectively. The parental magma is mainly from the asthenosphere mantle, with a small amount of subducted oceanic crust components, which shows the attribute characteristics of OIB (oceanic island basalt) or intraplate metasomatic enriched mantle source. The depth range of magma formation is about 93-105 km, and the existence of the Yitong-Shulan fault provides conduit and space for magma upwelling and fissure eruption. In addition, the formation of basaltic magma and its associated volcanic activity occurred in an extensional tectonic environment.
The Laohushan monogenic volcano is located in Dakouqin area, southern Jilin Province. In order to explore the geochemistry characteristics and genesis of the Miocene tephrite in this volcanic area, together with the coupling between it and the evolution of regional fault structure, the whole rock geochemistry and Pb isotope study on it were carried out. Na2O/K2O values of the tephrites are range from 1.30 to 1.38, with low A/CNK (0.97-1.09) and high Mg# (58.05-61.11) values. The tephrites are enriched in high field strength elements (HFSEs), such as Th, U and Nb, and relatively weakly enriched in large ion lithophile elements (LILEs), such as Rb, Ba and K, with LREE/HREE=10.66-11.32. The values of 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb are range from 17.661 to 17.675, 15.451 to 15.457 and 37.652 to 37.692, respectively. The parental magma is mainly from the asthenosphere mantle, with a small amount of subducted oceanic crust components, which shows the attribute characteristics of OIB (oceanic island basalt) or intraplate metasomatic enriched mantle source. The depth range of magma formation is about 93-105 km, and the existence of the Yitong-Shulan fault provides conduit and space for magma upwelling and fissure eruption. In addition, the formation of basaltic magma and its associated volcanic activity occurred in an extensional tectonic environment.
2024, 49(4): 1367-1384.
doi: 10.3799/dqkx.2022.260
Abstract:
To identify the formation background of oil shale and the enrichment mechanism of high-quality intervals are the fundamental works for in-situ upgrading of oil shale reservoir. In this paper, geochemical methods, e.g., TOC, major and trace element, rare earth element and biomarkers, were carried out to restore paleosedimentary environment as well as discuss organic matter accumulation mechanism. The results suggest that oil shale within the entire interval of Youganwo Formation is rich in organic matter, and the bottom is composed of thin carbonaceous shale, sandstone and lignite. Mo content, Ba/Al, Babio and biomarkers all reflect that Youganwo Formation has high primary productivity, with intermittent "algal bloom" phenomenon. V/(V+Ni), Ceanom, Th/U, pyrite framboids and Pr/nC17-Ph/nC18 crossplot indicate that Youganwo Formation was anoxic environment. Sr/Cu, Rb/Sr and climate index C identify that the climate of Youganwo Formation was warm and humid. Sr/Ba, Ba/Ga, Ca/(Fe+Ca), Al2O3/MgO and gammacerane feature suggest that water of ancient lake is fresh. The ancient lake of Youganwo Formation was semi-deep to deep, proved by Zr/Al, Rb/K and MnO content. Through the correlations between paleo-environmental parameters with TOC content, it is deemed that the warm and humid climate and freshwater environment can provide good conditions for the flourishing of algae, forming high quality productivity, and therefore it determines the quality and development characteristics of Youganwo Formation oil shale. High primary productivity with abundant organic matter sources is the main condition for oil shale formation, and anoxic semi-deep to deep lake environment, as a promoting factor, is conducive to organic matter accumulation and preservation. To sum up, in this paper it proposes the accumulation model of organic matter in high-quality oil shale of Youganwo Formation in the Maoming Basin.
To identify the formation background of oil shale and the enrichment mechanism of high-quality intervals are the fundamental works for in-situ upgrading of oil shale reservoir. In this paper, geochemical methods, e.g., TOC, major and trace element, rare earth element and biomarkers, were carried out to restore paleosedimentary environment as well as discuss organic matter accumulation mechanism. The results suggest that oil shale within the entire interval of Youganwo Formation is rich in organic matter, and the bottom is composed of thin carbonaceous shale, sandstone and lignite. Mo content, Ba/Al, Babio and biomarkers all reflect that Youganwo Formation has high primary productivity, with intermittent "algal bloom" phenomenon. V/(V+Ni), Ceanom, Th/U, pyrite framboids and Pr/nC17-Ph/nC18 crossplot indicate that Youganwo Formation was anoxic environment. Sr/Cu, Rb/Sr and climate index C identify that the climate of Youganwo Formation was warm and humid. Sr/Ba, Ba/Ga, Ca/(Fe+Ca), Al2O3/MgO and gammacerane feature suggest that water of ancient lake is fresh. The ancient lake of Youganwo Formation was semi-deep to deep, proved by Zr/Al, Rb/K and MnO content. Through the correlations between paleo-environmental parameters with TOC content, it is deemed that the warm and humid climate and freshwater environment can provide good conditions for the flourishing of algae, forming high quality productivity, and therefore it determines the quality and development characteristics of Youganwo Formation oil shale. High primary productivity with abundant organic matter sources is the main condition for oil shale formation, and anoxic semi-deep to deep lake environment, as a promoting factor, is conducive to organic matter accumulation and preservation. To sum up, in this paper it proposes the accumulation model of organic matter in high-quality oil shale of Youganwo Formation in the Maoming Basin.
2024, 49(4): 1385-1399.
doi: 10.3799/dqkx.2023.068
Abstract:
In deep water area of the northern continental margin of the South China Sea, unidirectional detachment faults were mostly developed in the Eocene, and the middle part of the Zhu Ⅱ depression was located in the intersection area of the south dip single detachment fault and the north dip multistage detachment fault system in the junction zone of Zhu-2 and Zhu-1 and Zhu-3 depressions of the Pearl River Mouth basin, forming a unique "opposite detachment type composite sag". However, its structural characteristics and cause of formation need to be further studied. Based on the latest high-precision 3D seismic data and the complete Eocene drilling data, the tectonic geomorphology of the T80/T83 depression in the key geological period of Eocene is restored to be a narrow and deep separated type to a wide and shallow converging type. The depositional center migrated from the near source steep slope to the central zone on both sides, and the uplift fault block in the intersection area of the opposite faults distributed along the east-west long axis. The tectonic evolution sequence reveals that the opposite detachment fault system started in the key tectonic transformation period of Eocene (T83-43 Ma). In response to the change of the subduction direction of the remote Pacific plate, the crust in the region was detached and thinned under the action of extensional stress. The fault block tilting and differential uplift occurred on the detachment section, and thus became a dynamic source region receiving denuding. At the same time, strong magmatic activity was generated. The dustpan-like fault depression with opposite distribution was reconstructed and the long-axis dynamic supply model in the opposite detachment area was formed. The determination of the spatio-temporal configuration of the long-axis dynamic source area and depositional center of the opposite detachment type composite depression is helpful to serve the prediction of high-quality hydrocarbon reservoir assemblage during the Eocene rift in the deepwater area.
In deep water area of the northern continental margin of the South China Sea, unidirectional detachment faults were mostly developed in the Eocene, and the middle part of the Zhu Ⅱ depression was located in the intersection area of the south dip single detachment fault and the north dip multistage detachment fault system in the junction zone of Zhu-2 and Zhu-1 and Zhu-3 depressions of the Pearl River Mouth basin, forming a unique "opposite detachment type composite sag". However, its structural characteristics and cause of formation need to be further studied. Based on the latest high-precision 3D seismic data and the complete Eocene drilling data, the tectonic geomorphology of the T80/T83 depression in the key geological period of Eocene is restored to be a narrow and deep separated type to a wide and shallow converging type. The depositional center migrated from the near source steep slope to the central zone on both sides, and the uplift fault block in the intersection area of the opposite faults distributed along the east-west long axis. The tectonic evolution sequence reveals that the opposite detachment fault system started in the key tectonic transformation period of Eocene (T83-43 Ma). In response to the change of the subduction direction of the remote Pacific plate, the crust in the region was detached and thinned under the action of extensional stress. The fault block tilting and differential uplift occurred on the detachment section, and thus became a dynamic source region receiving denuding. At the same time, strong magmatic activity was generated. The dustpan-like fault depression with opposite distribution was reconstructed and the long-axis dynamic supply model in the opposite detachment area was formed. The determination of the spatio-temporal configuration of the long-axis dynamic source area and depositional center of the opposite detachment type composite depression is helpful to serve the prediction of high-quality hydrocarbon reservoir assemblage during the Eocene rift in the deepwater area.
2024, 49(4): 1400-1410.
doi: 10.3799/dqkx.2022.246
Abstract:
Flow direction, dynamic and chemical properties change frequently in fluvial and tidal sedimentary environment, the reservoir mineral foundation and diagenetic process are complex and changeable, and the physical property is strong heterogeneity, which has always been the difficulty restricting its exploration and development. In this paper, Pinghu Formation in Xihu Depression of East Sea, China was taken as an example. Material basis, materiality pattern and main controlling factors were investigated in two high-energy sedimentary microphases, namely tidal channel and submerged divergent river channel. Methods include core observation, pore penetration test, light microscopy, isotope and inclusions. The results show follows. (1) The upper/middle part of tidal channel possessed good physical properties with an average porosity of 18% and permeability of 120 mD, while the bottom of tidal channel was dense with an average porosity of 4% and permeability of 0.05 mD. The main reason for the inhomogeneity is that the bottom is dense due to carbonate cementation. (2) The upper part of submerged diversion channel had good physical properties with an average porosity of 5% and permeability of 70 mD, while the bottom of submerged diversion channel was dense with an average porosity of 1% and permeability of 0.05 mD. The main reason for the inhomogeneity is that the bottom is dense due to kaolinite filling. The above analysis has important theoretical guiding significance to deepen the law and formation mechanism of reservoir heterogeneity under fluvial and tidal background. The technical methods and research results can be applied to the oil and gas exploration of low permeability sandstone reservoirs in the East China Sea basin, and have important reference significance for the oil and gas exploration of deep clastic reservoirs in offshore China and foreign blocks.
Flow direction, dynamic and chemical properties change frequently in fluvial and tidal sedimentary environment, the reservoir mineral foundation and diagenetic process are complex and changeable, and the physical property is strong heterogeneity, which has always been the difficulty restricting its exploration and development. In this paper, Pinghu Formation in Xihu Depression of East Sea, China was taken as an example. Material basis, materiality pattern and main controlling factors were investigated in two high-energy sedimentary microphases, namely tidal channel and submerged divergent river channel. Methods include core observation, pore penetration test, light microscopy, isotope and inclusions. The results show follows. (1) The upper/middle part of tidal channel possessed good physical properties with an average porosity of 18% and permeability of 120 mD, while the bottom of tidal channel was dense with an average porosity of 4% and permeability of 0.05 mD. The main reason for the inhomogeneity is that the bottom is dense due to carbonate cementation. (2) The upper part of submerged diversion channel had good physical properties with an average porosity of 5% and permeability of 70 mD, while the bottom of submerged diversion channel was dense with an average porosity of 1% and permeability of 0.05 mD. The main reason for the inhomogeneity is that the bottom is dense due to kaolinite filling. The above analysis has important theoretical guiding significance to deepen the law and formation mechanism of reservoir heterogeneity under fluvial and tidal background. The technical methods and research results can be applied to the oil and gas exploration of low permeability sandstone reservoirs in the East China Sea basin, and have important reference significance for the oil and gas exploration of deep clastic reservoirs in offshore China and foreign blocks.
2024, 49(4): 1411-1420.
doi: 10.3799/dqkx.2022.452
Abstract:
In the three-dimensional geological modeling, many works focus on the simulation of the fault itself, ignoring the influence of the fault sequence on the stratum structure. However, it is very necessary and critical to consider the fault sequence and the deformation caused by it. To solve this problem, based on the theory of fault recovery and evolution influence region, in this paper it proposes a fault vector field modeling method for 3D geological modeling with complex fault network. First, the fault vector field displacement operator is used to recover the stratum and fault data within the influence region in the reverse order of fault structure evolution, and then the stratum and fault data affected by the fault are calculated step by step in the positive order of evolution to obtain a 3D geological model with complex fault network. Through modeling experiments and comparative experiments, it is verified that the method has a higher utilization rate of data and the ability to deal with fracture contact, and all displacements caused by fracture will be automatically calculated in the modeling process, which improves the rationality and efficiency of modeling. The model constructed by this method takes full account of the influence of the time sequence of fault structure, and is more able to solve the problem of fault network model construction with complex contact relationship than the general method.
In the three-dimensional geological modeling, many works focus on the simulation of the fault itself, ignoring the influence of the fault sequence on the stratum structure. However, it is very necessary and critical to consider the fault sequence and the deformation caused by it. To solve this problem, based on the theory of fault recovery and evolution influence region, in this paper it proposes a fault vector field modeling method for 3D geological modeling with complex fault network. First, the fault vector field displacement operator is used to recover the stratum and fault data within the influence region in the reverse order of fault structure evolution, and then the stratum and fault data affected by the fault are calculated step by step in the positive order of evolution to obtain a 3D geological model with complex fault network. Through modeling experiments and comparative experiments, it is verified that the method has a higher utilization rate of data and the ability to deal with fracture contact, and all displacements caused by fracture will be automatically calculated in the modeling process, which improves the rationality and efficiency of modeling. The model constructed by this method takes full account of the influence of the time sequence of fault structure, and is more able to solve the problem of fault network model construction with complex contact relationship than the general method.
2024, 49(4): 1421-1430.
doi: 10.3799/dqkx.2023.123
Abstract:
Gas hydrate is an important development of marine new energy, and the Qiongdongnan basin of the South China Sea is a hydrate enrichment and hot research area. In order to further understand hydrate reservoir characteristics of the Qiongdongnan area, thermal insulation and pressuring coring sampled by domestic technical equipment were selected for analysis and first-hand data were obtained. By comprehensive analysis of grain size, rock and mineral analysis (including electron microscope scanning), LWD, thermal imaging, chloride ion saturation method, etc., it is measured that the reservoir is mainly composed of siliceous and aluminous clay deposits composed of quartz (23% content), plagioclase (17% content), sericite (15% content), albite (14% content), etc., and the median grain size of reservoir is 15.1 μm to 34.1μm and the saturation distribution is 3% to 54%. It reveals six characteristics of hydrate reservoir: "fine-grained, unconsolidated, easily disintegrate and disperse, high resistance, high acoustic velocity, and strong heterogeneity". Combined with gas source, reservoir analysis and exploration knowledge, a reservoir formation model of "off-site thermogenic gas injection, local microbial gas supplement, accumulation at top of gas chimney, and horizontal formation in the submarine fan reservoir" has been established. Focusing on the X-ray and CT scanning of 123 mbsf and 153 mbsf in-situ pressure-retaining cores, two main types of reservoirs are identified: argillaceous silt pore-type reservoir (submarine fan) and argillaceous silt micro-fractured reservoir (gas chimney fluid reconstruction), a new discovered type of hydrate reservoirs in the South China Sea. Exploration inspirations are put forward, "study the occurrence and resource potential of shallow scaled sand-bodies of geological events in the Zhujiangkou and Qiongdongnan sea, and strengthen research on heat and mass transfer of reservoir formation mechanism and resource evaluation".The research will provide important scientific reference for hydrate research and production test of the South China Sea.
Gas hydrate is an important development of marine new energy, and the Qiongdongnan basin of the South China Sea is a hydrate enrichment and hot research area. In order to further understand hydrate reservoir characteristics of the Qiongdongnan area, thermal insulation and pressuring coring sampled by domestic technical equipment were selected for analysis and first-hand data were obtained. By comprehensive analysis of grain size, rock and mineral analysis (including electron microscope scanning), LWD, thermal imaging, chloride ion saturation method, etc., it is measured that the reservoir is mainly composed of siliceous and aluminous clay deposits composed of quartz (23% content), plagioclase (17% content), sericite (15% content), albite (14% content), etc., and the median grain size of reservoir is 15.1 μm to 34.1μm and the saturation distribution is 3% to 54%. It reveals six characteristics of hydrate reservoir: "fine-grained, unconsolidated, easily disintegrate and disperse, high resistance, high acoustic velocity, and strong heterogeneity". Combined with gas source, reservoir analysis and exploration knowledge, a reservoir formation model of "off-site thermogenic gas injection, local microbial gas supplement, accumulation at top of gas chimney, and horizontal formation in the submarine fan reservoir" has been established. Focusing on the X-ray and CT scanning of 123 mbsf and 153 mbsf in-situ pressure-retaining cores, two main types of reservoirs are identified: argillaceous silt pore-type reservoir (submarine fan) and argillaceous silt micro-fractured reservoir (gas chimney fluid reconstruction), a new discovered type of hydrate reservoirs in the South China Sea. Exploration inspirations are put forward, "study the occurrence and resource potential of shallow scaled sand-bodies of geological events in the Zhujiangkou and Qiongdongnan sea, and strengthen research on heat and mass transfer of reservoir formation mechanism and resource evaluation".The research will provide important scientific reference for hydrate research and production test of the South China Sea.
2024, 49(4): 1431-1447.
doi: 10.3799/dqkx.2022.292
Abstract:
Marine sediment is not only a critical burial area of organic carbon from various sources but also a very active biogeochemical reactor, which plays a vital role in the global marine carbon cycle. Compared with the geochemical testing and qualitative description methods, the numerical model can break through the limitations of time and space and quantitatively obtain the reaction rate and flux of each carbon cycle process in marine sediments. Therefore, it has been paid more and more attention by the academic community. The degradation of organic matter in marine sediments is the most critical biogeochemical process driving the carbon cycle. Part of the dissolved inorganic carbon released into the surrounding pore water can diffuse to the overlying water column. The other part can form authigenic carbonate minerals with calcium and magnesium plasma precipitation. In this paper it firstly reviews the modeling process of three main types of sediment organic matter degradation models (discrete model, reactive continuum model, and Power model) and their applications in the global marine sediment organic matter degradation process. Then, starting from the primary and secondary reactions related to the degradation of organic matter, the description method of the reaction rate model of geochemical processes related to the degradation of organic matter in sediments is introduced, and the influence of the degradation of organic matter on the formation of authigenic carbonates and their carbon isotopes is discussed from the perspective of carbonate equilibrium system and isotope mass balance model. Finally, the problems and shortcomings of the current mathematical model in describing the degradation process of organic matter and the formation of authigenic carbonate are analyzed, and on this basis, the research points that need to be strengthened in the future are prospected. It is hoped that in this paper it will provide useful scientific support for understanding the mutual feedback between the ocean carbon cycle and global climate change and establishing a reliable prediction system for ocean carbon cycle and biogeochemistry.
Marine sediment is not only a critical burial area of organic carbon from various sources but also a very active biogeochemical reactor, which plays a vital role in the global marine carbon cycle. Compared with the geochemical testing and qualitative description methods, the numerical model can break through the limitations of time and space and quantitatively obtain the reaction rate and flux of each carbon cycle process in marine sediments. Therefore, it has been paid more and more attention by the academic community. The degradation of organic matter in marine sediments is the most critical biogeochemical process driving the carbon cycle. Part of the dissolved inorganic carbon released into the surrounding pore water can diffuse to the overlying water column. The other part can form authigenic carbonate minerals with calcium and magnesium plasma precipitation. In this paper it firstly reviews the modeling process of three main types of sediment organic matter degradation models (discrete model, reactive continuum model, and Power model) and their applications in the global marine sediment organic matter degradation process. Then, starting from the primary and secondary reactions related to the degradation of organic matter, the description method of the reaction rate model of geochemical processes related to the degradation of organic matter in sediments is introduced, and the influence of the degradation of organic matter on the formation of authigenic carbonates and their carbon isotopes is discussed from the perspective of carbonate equilibrium system and isotope mass balance model. Finally, the problems and shortcomings of the current mathematical model in describing the degradation process of organic matter and the formation of authigenic carbonate are analyzed, and on this basis, the research points that need to be strengthened in the future are prospected. It is hoped that in this paper it will provide useful scientific support for understanding the mutual feedback between the ocean carbon cycle and global climate change and establishing a reliable prediction system for ocean carbon cycle and biogeochemistry.
2024, 49(4): 1448-1458.
doi: 10.3799/dqkx.2022.266
Abstract:
The interaction between groundwater and rivers is critical to maintaining the health of river ecosystems, but the quantitative research on the groundwater discharge to large rivers in humid regions is currently weak. In response to this problem, in this paper it takes the Jingjiang Section of the middle reach of the Yangtze River as the study area, and uses the 222Rn mass balance model to estimate the groundwater discharge in the Jingjiang Section of the middle reach of the Yangtze River through field sampling and hydrometeorological data collection, and uses the EC mass balance model and water balance model to verify the result of 222Rn mass balance. The results show that the average groundwater discharge rate of the Jingjiang Section in the middle reach of the Yangtze River is 133 mm/d, the total discharge volume is 1.06×108 m3/d, and the contribution to the water balance is about 10.99%. Among different sub-sections, the groundwater discharge rate from Zhicheng to Shashi is the highest, and the groundwater discharge rate from Jianli to Luoshan is the lowest. Aquifer richness and groundwater table may be key factors controlling the rate of groundwater discharge. This research is of great significance for the local eco-environmental protection and the control and management of water resources, and can also provide a theoretical basis for the better development and utilization of water resources in the middle reach of the Yangtze River and eco-environmental protection in the future.
The interaction between groundwater and rivers is critical to maintaining the health of river ecosystems, but the quantitative research on the groundwater discharge to large rivers in humid regions is currently weak. In response to this problem, in this paper it takes the Jingjiang Section of the middle reach of the Yangtze River as the study area, and uses the 222Rn mass balance model to estimate the groundwater discharge in the Jingjiang Section of the middle reach of the Yangtze River through field sampling and hydrometeorological data collection, and uses the EC mass balance model and water balance model to verify the result of 222Rn mass balance. The results show that the average groundwater discharge rate of the Jingjiang Section in the middle reach of the Yangtze River is 133 mm/d, the total discharge volume is 1.06×108 m3/d, and the contribution to the water balance is about 10.99%. Among different sub-sections, the groundwater discharge rate from Zhicheng to Shashi is the highest, and the groundwater discharge rate from Jianli to Luoshan is the lowest. Aquifer richness and groundwater table may be key factors controlling the rate of groundwater discharge. This research is of great significance for the local eco-environmental protection and the control and management of water resources, and can also provide a theoretical basis for the better development and utilization of water resources in the middle reach of the Yangtze River and eco-environmental protection in the future.
2024, 49(4): 1459-1469.
doi: 10.3799/dqkx.2022.316
Abstract:
To understand the influence of groundwater velocity and medium particles on As(Ⅲ) migration in the riparian zone, natural river sand is selected as the medium, and groundwater solutions containing As(Ⅲ) as commonly seen in some riparian zones are prepared to carry out batch experiments and dynamic column experiments. Combing with the characterization analysis, the influence and mechanism of velocity and medium particle size on As(Ⅲ) migration are discussed. The results show follows: (1) The adsorption equilibrium time of As(Ⅲ) is longer for the smaller particle size of river sand. The equilibrium adsorption capacity (Qe) of As (Ⅲ) on the river sand decreases with the increase of its particle sizes (except for river sand with a particle size of 0.15-0.18 mm), and the maximum amount (Qm) of monolayer adsorption shows a decreasing trend with the increase of particle size. (2) As(Ⅲ) migration in the column filled with river sand is significantly affected by the particle size and velocity. On one hand, the river sand of the smaller particle size has a larger specific surface area, which usually leads to longer interaction time between aqueous solutions and solid medium, thus limiting the groundwater flushing rate. This is not conducive to the migration of As(Ⅲ) in river sand. On the other hand, the higher flowing velocity leads to a stronger hydraulic shear force in the void channel. Meanwhile, the increase of turbulence intensity reduces the thickness of the retained boundary layer, which is conducive to the migration of As(Ⅲ) in river sand.
To understand the influence of groundwater velocity and medium particles on As(Ⅲ) migration in the riparian zone, natural river sand is selected as the medium, and groundwater solutions containing As(Ⅲ) as commonly seen in some riparian zones are prepared to carry out batch experiments and dynamic column experiments. Combing with the characterization analysis, the influence and mechanism of velocity and medium particle size on As(Ⅲ) migration are discussed. The results show follows: (1) The adsorption equilibrium time of As(Ⅲ) is longer for the smaller particle size of river sand. The equilibrium adsorption capacity (Qe) of As (Ⅲ) on the river sand decreases with the increase of its particle sizes (except for river sand with a particle size of 0.15-0.18 mm), and the maximum amount (Qm) of monolayer adsorption shows a decreasing trend with the increase of particle size. (2) As(Ⅲ) migration in the column filled with river sand is significantly affected by the particle size and velocity. On one hand, the river sand of the smaller particle size has a larger specific surface area, which usually leads to longer interaction time between aqueous solutions and solid medium, thus limiting the groundwater flushing rate. This is not conducive to the migration of As(Ⅲ) in river sand. On the other hand, the higher flowing velocity leads to a stronger hydraulic shear force in the void channel. Meanwhile, the increase of turbulence intensity reduces the thickness of the retained boundary layer, which is conducive to the migration of As(Ⅲ) in river sand.
2024, 49(4): 1470-1486.
doi: 10.3799/dqkx.2022.449
Abstract:
North China area is rich in geothermal resources. The newly discovered Gaoyuzhuang geothermal reservoir in the Jixian System has even greater potential for development and utilization. However, there are issues such as high fracture in homogeneity and low productivity in Gaoyuzhuang Formation. Two typical geothermal wells in the Gaoyuzhuang Formation of the North China plain were selected for experimental study and in-situ application of two reconstruction techniques, acid and sand fracturing. The efficiency is evaluated by analyzing the pressure curves at different stages. An integrated technical approach to geothermal reservoir evaluation-plan design-effect evaluation is presented. The water output increased from 4.72 m3/h to 44.10 m3/h after acid fracturing of the Gaoyuzhuang geothermal reservoir in Xiong'an New Area, and the unit water surge increased from 0.024 m3/h·m to 0.745 m3/h·m. The sand fracturing of the Gaoyuzhuang reservoir in the Cangxian uplift has doubled the unit gushing water from 3.009 m3/h·m to 6.158 m3/h·m. Both methods show significant productivity gains.
North China area is rich in geothermal resources. The newly discovered Gaoyuzhuang geothermal reservoir in the Jixian System has even greater potential for development and utilization. However, there are issues such as high fracture in homogeneity and low productivity in Gaoyuzhuang Formation. Two typical geothermal wells in the Gaoyuzhuang Formation of the North China plain were selected for experimental study and in-situ application of two reconstruction techniques, acid and sand fracturing. The efficiency is evaluated by analyzing the pressure curves at different stages. An integrated technical approach to geothermal reservoir evaluation-plan design-effect evaluation is presented. The water output increased from 4.72 m3/h to 44.10 m3/h after acid fracturing of the Gaoyuzhuang geothermal reservoir in Xiong'an New Area, and the unit water surge increased from 0.024 m3/h·m to 0.745 m3/h·m. The sand fracturing of the Gaoyuzhuang reservoir in the Cangxian uplift has doubled the unit gushing water from 3.009 m3/h·m to 6.158 m3/h·m. Both methods show significant productivity gains.
2024, 49(4): 1487-1497.
doi: 10.3799/dqkx.2022.261
Abstract:
In order to determine the composition and stability of soil organic carbon pool in alpine areas, different grassland types (alpine meadow, alpine steppe and alpine swamp meadow) in Qilian Mountain area were selected as the research objects, the heavy and light components in 0-50 cm soil were separated and extracted by layer, and the contents of heavy fraction organic carbon (HFOC) and light fraction organic carbon (LFOC) were determined and analyzed. The results show that the effects of different grassland types on the content and distribution of soil HFOC and LFOC were different, the contents of HFOC and LFOC had obvious vertical changes among soil layers, show the trend of high and low, and there were obvious differences among different regions. The order of LFOC content in different grassland types is alpine swamp meadow > alpine steppe > alpine meadow, The order of soil organic carbon pool stability in different grassland types is alpine meadow > alpine steppe > alpine swamp meadow. Soil pH, moisture content, TC, SOC, TN content and C/N value were significantly correlated with soil HFOC and LFOC content(p < 0.01).In summary, the composition and stability of soil organic carbon pool in Qilian grassland ecosystem were affected by grassland types, soil physical and chemical properties and environmental variables.
In order to determine the composition and stability of soil organic carbon pool in alpine areas, different grassland types (alpine meadow, alpine steppe and alpine swamp meadow) in Qilian Mountain area were selected as the research objects, the heavy and light components in 0-50 cm soil were separated and extracted by layer, and the contents of heavy fraction organic carbon (HFOC) and light fraction organic carbon (LFOC) were determined and analyzed. The results show that the effects of different grassland types on the content and distribution of soil HFOC and LFOC were different, the contents of HFOC and LFOC had obvious vertical changes among soil layers, show the trend of high and low, and there were obvious differences among different regions. The order of LFOC content in different grassland types is alpine swamp meadow > alpine steppe > alpine meadow, The order of soil organic carbon pool stability in different grassland types is alpine meadow > alpine steppe > alpine swamp meadow. Soil pH, moisture content, TC, SOC, TN content and C/N value were significantly correlated with soil HFOC and LFOC content(p < 0.01).In summary, the composition and stability of soil organic carbon pool in Qilian grassland ecosystem were affected by grassland types, soil physical and chemical properties and environmental variables.
2024, 49(4): 1498-1514.
doi: 10.3799/dqkx.2022.283
Abstract:
A large number of ancient landslides with double or multi sliding zones exist in the Three Gorge Reservoir (TGR) area. However, there are few studies on the deformation characteristics and stability changes characteristics of the reservoir landslide with double sliding zones under the action of reservoir water level (RWL) fluctuation. In this paper, the deformation characteristics of Taping landslide were obtained by filed investigation and the in-situ monitoring data. Furthermore, numerical simulation was carried out to investigate seepage filed and stability characteristics of the Taping landslide under RWL fluctuation and precipitation. Then the responses of the two different sliding zones in the Taping landslide to RWL fluctuation and precipitation were revealed. The result indicates that the Taping landslide shows a significant retrogressive failure pattern. Precipitation mainly has a greater influence on the shallow sliding zone, and the influence of precipitation on the deep sliding zone is low. As the RWL rises, the stability of the shallow sliding zone decreases and the stability of the deep sliding zone increases. As the RWL drops, the stability of the shallow sliding zone increases and the stability of the deep sliding zone decreases.
A large number of ancient landslides with double or multi sliding zones exist in the Three Gorge Reservoir (TGR) area. However, there are few studies on the deformation characteristics and stability changes characteristics of the reservoir landslide with double sliding zones under the action of reservoir water level (RWL) fluctuation. In this paper, the deformation characteristics of Taping landslide were obtained by filed investigation and the in-situ monitoring data. Furthermore, numerical simulation was carried out to investigate seepage filed and stability characteristics of the Taping landslide under RWL fluctuation and precipitation. Then the responses of the two different sliding zones in the Taping landslide to RWL fluctuation and precipitation were revealed. The result indicates that the Taping landslide shows a significant retrogressive failure pattern. Precipitation mainly has a greater influence on the shallow sliding zone, and the influence of precipitation on the deep sliding zone is low. As the RWL rises, the stability of the shallow sliding zone decreases and the stability of the deep sliding zone increases. As the RWL drops, the stability of the shallow sliding zone increases and the stability of the deep sliding zone decreases.
2024, 49(4): 1515-1523.
doi: 10.3799/dqkx.2023.182
Abstract:
The Middle-Late Triassic was a critical period for the construction of modern ecosystems, and a systematic study of the co-evolution of organisms and the environment during this period is significant for revealing the mechanisms of biological recovery and the reconstruction of ecosystems. Amber is important for discussing the evolution of plants and paleoclimate in the Middle to Late Triassic. Here, it reports for the first time the finding of amber in an Anisian marine succession in Qingyan Section, South China, which was located in the north-eastern Tethys. Ammonoid biostratigraphy gives a Pelsonian age for the layers bearing amber. Amber has been recovered in close association with plant remains identified as Voltzia sp., indicating that this plant has likely exuded the resin. The fact that fossil resin is restricted only within humid events strongly indicates a climatic control on resin production during the Triassic.
The Middle-Late Triassic was a critical period for the construction of modern ecosystems, and a systematic study of the co-evolution of organisms and the environment during this period is significant for revealing the mechanisms of biological recovery and the reconstruction of ecosystems. Amber is important for discussing the evolution of plants and paleoclimate in the Middle to Late Triassic. Here, it reports for the first time the finding of amber in an Anisian marine succession in Qingyan Section, South China, which was located in the north-eastern Tethys. Ammonoid biostratigraphy gives a Pelsonian age for the layers bearing amber. Amber has been recovered in close association with plant remains identified as Voltzia sp., indicating that this plant has likely exuded the resin. The fact that fossil resin is restricted only within humid events strongly indicates a climatic control on resin production during the Triassic.
2024, 49(4): 1524-1540.
doi: 10.3799/dqkx.2022.062
Abstract:
Wuchiapingian is a key interval as a fast ecosystem recovery period between two mass extinctions, the End-Guadalupian crisis and the End-Permian mass extinction. Carbonate platforms were widely distributed in the middle of Yangtze platform and the Dian-Qian-Gui area during this interval. Among them, the Leye carbonate platform is one of the typically isolated carbonate platforms within the Nanpanjiang basin. The continuous Wuchiapingian marine carbonate (Heshan Formation) was deposited above the disconformity surface on the top of Guadalupian Maokou Formation. The traditional Middle-Late Permian stratigraphic frame scale in this area mainly relies on the fusulinids biozones, while only a few Wuchiapingian conodonts have been reported. Here, conodonts from the base of Heshan Formation at the Shuabacun Section and the Liuwei Section in the Leye platform have been obtained and studied. Eight conodont species (including one new species) belonging to two genera in total were identified, and they are Clarkina asymmetrica, C. aff. asymmetrica, C. daxianensis, C. dukouensis, C. leveni, Hindeodus julfensis, H. typicalis and Hindeodus praechangxingensis sp. nov.. In ascending order, two conodont zones, the C. asymmetrica Zone and the C. leveni Zone can be identified at the Shuabacun Section. And one conodont zone, the C. asymmetrica Zone is also identified at the Liuwei Section. Based on this, we surmise that the beginning of the early Wuchiapingian carbonate deposition occurs in the C. asymmetrica Zone at Leye carbonate platform, after the global end-Guadalupian regression. It can provide important data for studying the local carbonate platform and basin evolution and also regional stratigraphic correlation.
Wuchiapingian is a key interval as a fast ecosystem recovery period between two mass extinctions, the End-Guadalupian crisis and the End-Permian mass extinction. Carbonate platforms were widely distributed in the middle of Yangtze platform and the Dian-Qian-Gui area during this interval. Among them, the Leye carbonate platform is one of the typically isolated carbonate platforms within the Nanpanjiang basin. The continuous Wuchiapingian marine carbonate (Heshan Formation) was deposited above the disconformity surface on the top of Guadalupian Maokou Formation. The traditional Middle-Late Permian stratigraphic frame scale in this area mainly relies on the fusulinids biozones, while only a few Wuchiapingian conodonts have been reported. Here, conodonts from the base of Heshan Formation at the Shuabacun Section and the Liuwei Section in the Leye platform have been obtained and studied. Eight conodont species (including one new species) belonging to two genera in total were identified, and they are Clarkina asymmetrica, C. aff. asymmetrica, C. daxianensis, C. dukouensis, C. leveni, Hindeodus julfensis, H. typicalis and Hindeodus praechangxingensis sp. nov.. In ascending order, two conodont zones, the C. asymmetrica Zone and the C. leveni Zone can be identified at the Shuabacun Section. And one conodont zone, the C. asymmetrica Zone is also identified at the Liuwei Section. Based on this, we surmise that the beginning of the early Wuchiapingian carbonate deposition occurs in the C. asymmetrica Zone at Leye carbonate platform, after the global end-Guadalupian regression. It can provide important data for studying the local carbonate platform and basin evolution and also regional stratigraphic correlation.
2024, 49(4): 1541-1554.
doi: 10.3799/dqkx.2022.252
Abstract:
In order to extract accurately and efficiently the bare rock from high-resolution remote sensing image, in this study it used Chinese Gaofen-2 (GF-2) satellite imagery as data source, the slope difference bare rock index (SDBRI) and bare rock shadow index (BRSI) for the extraction of bare rock and bare rock shadow were created, respectively. Based on the two index models, it proposed a strategy for sub-meter-level high-resolution image bare rock extraction in the open-pit mining area. Then the southern mountainous area of Qingzhou City, Shandong Province was selected as the test area. The results show follows: In the SDBRI index image, the values of the bare rock can be easily distinguished from the surrounding vegetation. And the separability of bare rock and other objectives is significantly higher than that of other index models such as NDVI, CRI1, and CRI2. The visual interpretation results from the Google Earth high resolution images are used as verification data for accuracy evaluation, and the IoU index reaches about 91%. The method proposed in this paper can meet the needs of large-scale open rock mapping in mining areas based on Chinese high-resolution image data, and can provide technical support for remote sensing monitoring of mine environment, which has strong practical value.
In order to extract accurately and efficiently the bare rock from high-resolution remote sensing image, in this study it used Chinese Gaofen-2 (GF-2) satellite imagery as data source, the slope difference bare rock index (SDBRI) and bare rock shadow index (BRSI) for the extraction of bare rock and bare rock shadow were created, respectively. Based on the two index models, it proposed a strategy for sub-meter-level high-resolution image bare rock extraction in the open-pit mining area. Then the southern mountainous area of Qingzhou City, Shandong Province was selected as the test area. The results show follows: In the SDBRI index image, the values of the bare rock can be easily distinguished from the surrounding vegetation. And the separability of bare rock and other objectives is significantly higher than that of other index models such as NDVI, CRI1, and CRI2. The visual interpretation results from the Google Earth high resolution images are used as verification data for accuracy evaluation, and the IoU index reaches about 91%. The method proposed in this paper can meet the needs of large-scale open rock mapping in mining areas based on Chinese high-resolution image data, and can provide technical support for remote sensing monitoring of mine environment, which has strong practical value.
2013, 38(3): 454-460.
doi: 10.3799/dqkx.2013.045
2014, 39(3): 261-270.
doi: 10.3799/dqkx.2014.025
2014, 39(3): 283-292.
doi: 10.3799/dqkx.2014.027
2013, 38(6): 1327-1330.
doi: 10.3799/dqkx.2013.000
2013, 38(5): 963-974.
doi: 10.3799/dqkx.2013.094
