2014 Vol. 39, No. 6
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2014, 39(6): 637-653.
doi: 10.3799/dqkx.2014.061
Abstract:
Though Early Paleozoic granites are widely distributed in South China, contemporary volcanic and subvolcanic rocks are rare. This study analyzed dacites from Hekou and Shangdong in Northern Guangdong Province, using detailed LA-ICPMS zircon U-Pb geochronology and Sr-Nd-Hf isotopic geochemistry. The results show that the dacite was formed in 448.7±1.7 Ma, and associated with Late Ordovician volcanism. These rocks are generally porphyritic with prophyroclastic or embayed quartz. The matrixes are normally cryptocrystalline. These features fit well with typical subvolcanic rocks. Geochemically, the dacite is high-K calc-alkaline series. They are enriched in LREE, depleted with Ta, Nb and are extremely low in Cr, Ni contents. Isotopic data show that they have ISr=0.709 0-0.714 0, εNd(t)=-8.9 to -9.3, εHf(t)=-8.06 to -3.80, consistent with the isotopic compositions of the Caledonian granitoids in South China. The model ages of two stages based on zircon Hf isotopes range from 1.67 Ga to 1.93 Ga, consistent with the whole rock Nd dating (1.91-1.94 Ga), implying that the dacite might have originated from the Paleoproterozoic crustal materials. This new finding of Hekou and Shangdong Ordovician dacite confirms the existence of Early Paleozoic subduction magmatism in this area.
Though Early Paleozoic granites are widely distributed in South China, contemporary volcanic and subvolcanic rocks are rare. This study analyzed dacites from Hekou and Shangdong in Northern Guangdong Province, using detailed LA-ICPMS zircon U-Pb geochronology and Sr-Nd-Hf isotopic geochemistry. The results show that the dacite was formed in 448.7±1.7 Ma, and associated with Late Ordovician volcanism. These rocks are generally porphyritic with prophyroclastic or embayed quartz. The matrixes are normally cryptocrystalline. These features fit well with typical subvolcanic rocks. Geochemically, the dacite is high-K calc-alkaline series. They are enriched in LREE, depleted with Ta, Nb and are extremely low in Cr, Ni contents. Isotopic data show that they have ISr=0.709 0-0.714 0, εNd(t)=-8.9 to -9.3, εHf(t)=-8.06 to -3.80, consistent with the isotopic compositions of the Caledonian granitoids in South China. The model ages of two stages based on zircon Hf isotopes range from 1.67 Ga to 1.93 Ga, consistent with the whole rock Nd dating (1.91-1.94 Ga), implying that the dacite might have originated from the Paleoproterozoic crustal materials. This new finding of Hekou and Shangdong Ordovician dacite confirms the existence of Early Paleozoic subduction magmatism in this area.
2014, 39(6): 654-670, 768.
doi: 10.3799/dqkx.2014.062
Abstract:
The Zhibula skarn-type Cu deposit is located about 2 km away from the south of Qulong super-large porphyry Cu-Mo deposit in Gangdese metallogenic belt, Tibet. The skarn and ore body are mainly distributed as layer-stratoid in the tuff and marble of Yeba Group in Lower Jurassic, which show zoning characteristics: tuff-garnert tuff-garnet skarn-pyroxene skarn-(wollastonite) marble. From early to late stages, or from tuff to marble, the colors of garnets change from dark brownish red to brownish red, followed by green(brown), and pale brownish yellow These garnets are mainly grossular and andradite. The end members of pyroxenes are dominated by diopside, with minor johannsenite. Garnets near tuff have higher Al, Ti contents, whereas those nearthe marble have relatively more enriched Fe, Mn contents. Garnets show distinctive light and dark oscillatory-zoning. Light zoning is distinctively enriched withcalcium-iron components, and dark zoning is enriched with calcium-aluminum components. These garnets generally show increasing calcium-iron components and relatively reducing calcium-aluminum components from the core to outer zones. The Zhibula layer-stratoid skarn-type ore body are developed due to thedeep buriedore-bearinghy drothermal migration with differential magmatic crystallization along the interface, or migration along fractured rock bands driven by temperature and pressure differences. In addition, selective metasomatic alteration between tuff and marble or crystalline limestone contributed to the formation of this ore deposits. Therefore, this ore deposit belongs to the magmatic hydrothermal contact metasomatic type rather than stratabound or exhalative forming layer skarn-type, and has the same forming mechanism with Qulong porphyry Cu-Mo deposit.
The Zhibula skarn-type Cu deposit is located about 2 km away from the south of Qulong super-large porphyry Cu-Mo deposit in Gangdese metallogenic belt, Tibet. The skarn and ore body are mainly distributed as layer-stratoid in the tuff and marble of Yeba Group in Lower Jurassic, which show zoning characteristics: tuff-garnert tuff-garnet skarn-pyroxene skarn-(wollastonite) marble. From early to late stages, or from tuff to marble, the colors of garnets change from dark brownish red to brownish red, followed by green(brown), and pale brownish yellow These garnets are mainly grossular and andradite. The end members of pyroxenes are dominated by diopside, with minor johannsenite. Garnets near tuff have higher Al, Ti contents, whereas those nearthe marble have relatively more enriched Fe, Mn contents. Garnets show distinctive light and dark oscillatory-zoning. Light zoning is distinctively enriched withcalcium-iron components, and dark zoning is enriched with calcium-aluminum components. These garnets generally show increasing calcium-iron components and relatively reducing calcium-aluminum components from the core to outer zones. The Zhibula layer-stratoid skarn-type ore body are developed due to thedeep buriedore-bearinghy drothermal migration with differential magmatic crystallization along the interface, or migration along fractured rock bands driven by temperature and pressure differences. In addition, selective metasomatic alteration between tuff and marble or crystalline limestone contributed to the formation of this ore deposits. Therefore, this ore deposit belongs to the magmatic hydrothermal contact metasomatic type rather than stratabound or exhalative forming layer skarn-type, and has the same forming mechanism with Qulong porphyry Cu-Mo deposit.
2014, 39(6): 671-686.
doi: 10.3799/dqkx.2014.063
Abstract:
Weilasituo and Bairendaba are two large-scale silver polymetallic deposits, discovered in the western slope of the south and central sections of Great Hinggan Mountains in recent years. This study focuses on identifying and analyzing the mineral associations and occurrence of silver minerals using scanning electron microscopy-energy dispersive spectrometry and electron microprobe. The analyses suggest that mineral associations change from tungstate and oxide, to diatomic sulphide, to simple sulphide, to antimony sulfosalt mineral, to antimonide with decreasing temperature based on the microscopy observations. The silvers contained in the ore occur in several forms, including mainly visible silver minerals, followed by the lattice silver (isomorphous substitution) and sub-micron inclusion silver. The mineral sequence of visible silver's formation is Ag-bearing tetrahedrite-argentian tetrahedrite-freibergite-diaphorite-freieslebenite-pyrargyrite-dyscrasite. Ag occurs in lattice of chalcopyrite, bornite, chalcocite, pyrite and galena in isomorphism in small amount, and also as the microscopic wrappage in galena. The results, combined with the characteristics of mineral association and fluid inclusions in different mineralizing stages, indicate that W and Sn are transported as wolframic acid and tungstate at the early high-temperature meta-acid oxidizing environment, while Zn2+, Pb2+, Cu+ and other metalions are transported as chloride complexes. After wolframite's precipitation and the changes of metallogenetic fluid physical and chemical condition, the metallogenetic environment becomes slightly alkaline and reductive, and Zn2+, Cu+ and other metalions form HS- complexes. The continuous drop of temperature and water-rock interaction lead to the separation of Zn2+, Cu+ with HS- to form pyrrhotite, sphalerite etc.. In late phases, Ag+ can combine Sb3+, Cu+, Pb2+, Sb3-, S2- etc., which results in multiple silver antimony sulfide minerals, boulangerite etc..
Weilasituo and Bairendaba are two large-scale silver polymetallic deposits, discovered in the western slope of the south and central sections of Great Hinggan Mountains in recent years. This study focuses on identifying and analyzing the mineral associations and occurrence of silver minerals using scanning electron microscopy-energy dispersive spectrometry and electron microprobe. The analyses suggest that mineral associations change from tungstate and oxide, to diatomic sulphide, to simple sulphide, to antimony sulfosalt mineral, to antimonide with decreasing temperature based on the microscopy observations. The silvers contained in the ore occur in several forms, including mainly visible silver minerals, followed by the lattice silver (isomorphous substitution) and sub-micron inclusion silver. The mineral sequence of visible silver's formation is Ag-bearing tetrahedrite-argentian tetrahedrite-freibergite-diaphorite-freieslebenite-pyrargyrite-dyscrasite. Ag occurs in lattice of chalcopyrite, bornite, chalcocite, pyrite and galena in isomorphism in small amount, and also as the microscopic wrappage in galena. The results, combined with the characteristics of mineral association and fluid inclusions in different mineralizing stages, indicate that W and Sn are transported as wolframic acid and tungstate at the early high-temperature meta-acid oxidizing environment, while Zn2+, Pb2+, Cu+ and other metalions are transported as chloride complexes. After wolframite's precipitation and the changes of metallogenetic fluid physical and chemical condition, the metallogenetic environment becomes slightly alkaline and reductive, and Zn2+, Cu+ and other metalions form HS- complexes. The continuous drop of temperature and water-rock interaction lead to the separation of Zn2+, Cu+ with HS- to form pyrrhotite, sphalerite etc.. In late phases, Ag+ can combine Sb3+, Cu+, Pb2+, Sb3-, S2- etc., which results in multiple silver antimony sulfide minerals, boulangerite etc..
2014, 39(6): 687-695.
doi: 10.3799/dqkx.2014.064
Abstract:
Hongling lead-zinc polymetallic deposit share many similarities with others from the southern Daxinganling polymetallic metallogenic belt. There are two types of molybdenum mineralization in the mining area, including porphyry and skarn. The former, displaying spot-disseminated feature, occurs in granite porphyry, whereas the latter, displaying film like feature, occurs in quartz. The metallogenic age of Hongling deposit can be constrained from Re-Os isotopic dating of the two kinds of molybdenite. Five samples of spot-disseminated molybdenite yield model ages varying from 139.9±2.3 Ma to 141.5±3.2 Ma, with an isochron age of 140.3±3.4 Ma (MSWD=0.082), and a weighted average of 140.10±1.80 Ma. The isochron age and weighted average model age are consistent with one another, implying that molybdenum mineralization in Hongling deposit occurred in Late Jurassic. A film-like molybdenite sample yielded a model age of 143.7±3.6 Ma, representing the initial stage of lead-zinc mineralization. The Re-187Os contents of the film-like molybdenite are higher than that of spot-disseminated molybdeniteby one order of magnitude, which hints that they have different origins and there are two phases of molybdenum mineralization. The characteristics of Re content of the 6 molybdenite samples suggest that the ore-forming elements had a shallow source, and was mainly derived from the crust. The extremely low content of Re might be du to the low Re content within its parent magma as well as its paragenetic mineral assemblage. Combined with the results of previous study, it is concluded that (a) both rock- and ore-forming materials of Hongling deposit came from hyperplasia crust; and (b) the deposit formed in a dynamical environment of continental crust extension post Mongolia-Okhotsk collisional orogeny.
Hongling lead-zinc polymetallic deposit share many similarities with others from the southern Daxinganling polymetallic metallogenic belt. There are two types of molybdenum mineralization in the mining area, including porphyry and skarn. The former, displaying spot-disseminated feature, occurs in granite porphyry, whereas the latter, displaying film like feature, occurs in quartz. The metallogenic age of Hongling deposit can be constrained from Re-Os isotopic dating of the two kinds of molybdenite. Five samples of spot-disseminated molybdenite yield model ages varying from 139.9±2.3 Ma to 141.5±3.2 Ma, with an isochron age of 140.3±3.4 Ma (MSWD=0.082), and a weighted average of 140.10±1.80 Ma. The isochron age and weighted average model age are consistent with one another, implying that molybdenum mineralization in Hongling deposit occurred in Late Jurassic. A film-like molybdenite sample yielded a model age of 143.7±3.6 Ma, representing the initial stage of lead-zinc mineralization. The Re-187Os contents of the film-like molybdenite are higher than that of spot-disseminated molybdeniteby one order of magnitude, which hints that they have different origins and there are two phases of molybdenum mineralization. The characteristics of Re content of the 6 molybdenite samples suggest that the ore-forming elements had a shallow source, and was mainly derived from the crust. The extremely low content of Re might be du to the low Re content within its parent magma as well as its paragenetic mineral assemblage. Combined with the results of previous study, it is concluded that (a) both rock- and ore-forming materials of Hongling deposit came from hyperplasia crust; and (b) the deposit formed in a dynamical environment of continental crust extension post Mongolia-Okhotsk collisional orogeny.
2014, 39(6): 696-704.
doi: 10.3799/dqkx.2014.065
Abstract:
About 600 surface sediment samples were collected in the Qiongzhou Strait and the surrounding marine environment, and were analyzed particle-size distribution. Results show that the sediments are dominated by sand and gravel sandsinside the Qiongzhou Strait, and the sediments change gradually from coarser to finer particles, mostly silt and clay sized, away from the inner strait areas to the outside areas. The boundaries of sand sediments spread arched in the east mouth, whereas they spread in the shape of fingers in the west. The distribution of grain size frequency curve can be divided into 5 categories, (a) single kurtosis to the east strait, (b) east strait double kurtosis, (c) single and double kurtosis in the strait, (d) west strait single kurtosis, and (e) west strait double kurtosis. The sediment transport trends was analyzed by the GSTA model, which shows that the sediment mainly moved from the north and south sides to the middle into the strait, whereas in the east area the sediments moved obviously from the strait to the outside sea, and there was a northward trend in the west area. Both the distribution of grain size and the transport trend of the sediments show that the sediments mainly originated from the bottom and side of the strait which were eroded by the tides. Based on interpretation of the modern depositional environment in the Qiongzhou Strait, combined with the grain size characters and the AMS-14C data of 4 core samples which were obtained by the gravity corer, it is concluded that the final formation of the Qiongzhou Strait began about 8 000 a ago due to the rise of sea level, and the initial landform was shaped by the tides. In addition, about 5 000 to 4 600 a ago, the Qiongzhou Strait has been in a stage of rapid development, and the tidal deltas spread most widely until the end of the warm period when the sea level dropped and the tide power weakened, which led to the stabilization and formation of the present Qiongzhou Strait.
About 600 surface sediment samples were collected in the Qiongzhou Strait and the surrounding marine environment, and were analyzed particle-size distribution. Results show that the sediments are dominated by sand and gravel sandsinside the Qiongzhou Strait, and the sediments change gradually from coarser to finer particles, mostly silt and clay sized, away from the inner strait areas to the outside areas. The boundaries of sand sediments spread arched in the east mouth, whereas they spread in the shape of fingers in the west. The distribution of grain size frequency curve can be divided into 5 categories, (a) single kurtosis to the east strait, (b) east strait double kurtosis, (c) single and double kurtosis in the strait, (d) west strait single kurtosis, and (e) west strait double kurtosis. The sediment transport trends was analyzed by the GSTA model, which shows that the sediment mainly moved from the north and south sides to the middle into the strait, whereas in the east area the sediments moved obviously from the strait to the outside sea, and there was a northward trend in the west area. Both the distribution of grain size and the transport trend of the sediments show that the sediments mainly originated from the bottom and side of the strait which were eroded by the tides. Based on interpretation of the modern depositional environment in the Qiongzhou Strait, combined with the grain size characters and the AMS-14C data of 4 core samples which were obtained by the gravity corer, it is concluded that the final formation of the Qiongzhou Strait began about 8 000 a ago due to the rise of sea level, and the initial landform was shaped by the tides. In addition, about 5 000 to 4 600 a ago, the Qiongzhou Strait has been in a stage of rapid development, and the tidal deltas spread most widely until the end of the warm period when the sea level dropped and the tide power weakened, which led to the stabilization and formation of the present Qiongzhou Strait.
2014, 39(6): 705-715.
doi: 10.3799/dqkx.2014.066
Abstract:
The utilization of MC-ICP-MS on thallium isotope is an important development in nontraditional stable isotopic geochemistry. This paper presents the advances in analytical methods and geological applications of Tl isotope in recent years, including element geochemical behavior, analytical techniques of Tl isotope, isotopic fractionation mechanism, the variability in various geological reservoirs, and its applications. Tl isotopes, compared to other isotopes, offer distinctive implications in the fields of planetary science, paleoceanography, mantle geochemistry, petrology, and mineral deposits. Therefore, Tl isotopes can have a great prospect in the further applications in geological and environmental sciences.
The utilization of MC-ICP-MS on thallium isotope is an important development in nontraditional stable isotopic geochemistry. This paper presents the advances in analytical methods and geological applications of Tl isotope in recent years, including element geochemical behavior, analytical techniques of Tl isotope, isotopic fractionation mechanism, the variability in various geological reservoirs, and its applications. Tl isotopes, compared to other isotopes, offer distinctive implications in the fields of planetary science, paleoceanography, mantle geochemistry, petrology, and mineral deposits. Therefore, Tl isotopes can have a great prospect in the further applications in geological and environmental sciences.
2014, 39(6): 716-732.
doi: 10.3799/dqkx.2014.067
Abstract:
To understand the characteristics and evolution of REE during the process of the ultramafic laterization under different climate conditions, two outcrops Kolonodale in Indonesia and Yuanjiang in China are chosen for comparision. It is found that the contents of REE from the laterite crusts are higher than those from the bed rocks in both places (enrichment factor being 44.21 and 236.19 respectively).The indices of differentiation between the LREE and HREE decrease with profile downward toward, and the indice of Ce anomaly shows a shift from the positive Ce anomaly in the upper segment to negative Ce anomaly in the lower part. The difference between the two profiles lies in the distribution of the highest REE enriched segment. The laterite layer represent the most REE enriched for the Yuanjiang, whereas the saprolite layer for the Kolonodale. The evaluation of the mass balance shows remarkable migration and differentiation of REE in the ultramafic laterization process, which were constrained effectively by the pH environmentand organic matter (O.M.). The results indicate that climate have had great influence on the geochemical evolution of REE during the ultramafic laterization. Under the rainforest climate condition, the REE from the Kolonodale originates mainly from the basal rocks and has experienced intensive redistribution during the laterization; whereas the REE from the Yuanjiang has a mixed source stemming from both the parent rock and aeolian sediment, and it has been through only slight redistribution during the laterization.
To understand the characteristics and evolution of REE during the process of the ultramafic laterization under different climate conditions, two outcrops Kolonodale in Indonesia and Yuanjiang in China are chosen for comparision. It is found that the contents of REE from the laterite crusts are higher than those from the bed rocks in both places (enrichment factor being 44.21 and 236.19 respectively).The indices of differentiation between the LREE and HREE decrease with profile downward toward, and the indice of Ce anomaly shows a shift from the positive Ce anomaly in the upper segment to negative Ce anomaly in the lower part. The difference between the two profiles lies in the distribution of the highest REE enriched segment. The laterite layer represent the most REE enriched for the Yuanjiang, whereas the saprolite layer for the Kolonodale. The evaluation of the mass balance shows remarkable migration and differentiation of REE in the ultramafic laterization process, which were constrained effectively by the pH environmentand organic matter (O.M.). The results indicate that climate have had great influence on the geochemical evolution of REE during the ultramafic laterization. Under the rainforest climate condition, the REE from the Kolonodale originates mainly from the basal rocks and has experienced intensive redistribution during the laterization; whereas the REE from the Yuanjiang has a mixed source stemming from both the parent rock and aeolian sediment, and it has been through only slight redistribution during the laterization.
2014, 39(6): 733-740.
doi: 10.3799/dqkx.2014.068
Abstract:
REE biogeochemistry is important in understanding the occurrence, migration and fractionation of REE and its ecologically environmental effects. In order to explore the REE biogeochemistry of soil-vegetation system in mining affected region, Dabaoshan mine, a typical polymetallic mine, was chosen as a study area. Soils and leaves of dominant Dicranopteris Pedata and Pinus massoniana, from and outside the mine, were collected. Then REE contents were measured by using the ICP-MS. REE distribution patterns, ∑REE, δEu and δCe were analyzed. Results show that mining area, with the mean ∑REE 284.99 mg/kg, has significantly higher REE contents than outside areas., In addition, REE contents in epipedon are much higher than those in subsoil due to the effects of mining activity. What's more, the fractional degree of HREE and LREE of both soil and plant is much weaker in mining area compared with that outside the mine. The soils and plants collected are all characterized by Eu deficiency and Ce enrichment. And the accumulator Dicranopteris Pedatahas lower REE enrichment coefficient than Pinus massoniana by the presence of heavy metal. Therefore, the mining environment has negative effect on the normal migration and fractionation of REE in soil-vegetation system and growth of plants.
REE biogeochemistry is important in understanding the occurrence, migration and fractionation of REE and its ecologically environmental effects. In order to explore the REE biogeochemistry of soil-vegetation system in mining affected region, Dabaoshan mine, a typical polymetallic mine, was chosen as a study area. Soils and leaves of dominant Dicranopteris Pedata and Pinus massoniana, from and outside the mine, were collected. Then REE contents were measured by using the ICP-MS. REE distribution patterns, ∑REE, δEu and δCe were analyzed. Results show that mining area, with the mean ∑REE 284.99 mg/kg, has significantly higher REE contents than outside areas., In addition, REE contents in epipedon are much higher than those in subsoil due to the effects of mining activity. What's more, the fractional degree of HREE and LREE of both soil and plant is much weaker in mining area compared with that outside the mine. The soils and plants collected are all characterized by Eu deficiency and Ce enrichment. And the accumulator Dicranopteris Pedatahas lower REE enrichment coefficient than Pinus massoniana by the presence of heavy metal. Therefore, the mining environment has negative effect on the normal migration and fractionation of REE in soil-vegetation system and growth of plants.
2014, 39(6): 741-750.
doi: 10.3799/dqkx.2014.069
Abstract:
Based on the analyses of petroleum systems in the Chaluhe sag, hydrocarbon secondary migration in thesource-reservoir assemblage (E2s-E2s) was evaluated by using 2D basin modeling technique. This study aims to investigate the individual hydrocarbon migration-accumulation units, analyze different conditions for the hydrocarbon accumulation, and locate possible favorable areas as exploration targets. The following conclusions are drawn: (1) Key geologic elements of the petroleum systems are well integrated in the Chaluhe, three events of hydrocarbon accumulation can be identified, and the E2s-E2s (!) is recognized as the most significant petroleum system in the study area. (2) Secondary migration direction and intensity were mainly controlled by the fluid potential energy field. Hydrocarbon accumulation during the main period of hydrocarbon migration was characterized by wide distribution and high density. Hydrocarbon fluids mainly charged two areas with lower fluid potential, namely along the northwest basin-marginal fault and the eastern Wanchang, Liangjia uplifts, respectively. (3) The Chaluhe sag consists off our hydrocarbon migration-accumulation units, including units Ⅰ, Ⅱ, Ⅲ, and Ⅳ. Unit Ⅱ has the best potential for hydrocarbon migration and accumulation, followed by unit Ⅰ. The periclinal area in the Wanchang uplift ranks to be the most favorable area for oil and gas exploration in the Chaluhe sag.
Based on the analyses of petroleum systems in the Chaluhe sag, hydrocarbon secondary migration in thesource-reservoir assemblage (E2s-E2s) was evaluated by using 2D basin modeling technique. This study aims to investigate the individual hydrocarbon migration-accumulation units, analyze different conditions for the hydrocarbon accumulation, and locate possible favorable areas as exploration targets. The following conclusions are drawn: (1) Key geologic elements of the petroleum systems are well integrated in the Chaluhe, three events of hydrocarbon accumulation can be identified, and the E2s-E2s (!) is recognized as the most significant petroleum system in the study area. (2) Secondary migration direction and intensity were mainly controlled by the fluid potential energy field. Hydrocarbon accumulation during the main period of hydrocarbon migration was characterized by wide distribution and high density. Hydrocarbon fluids mainly charged two areas with lower fluid potential, namely along the northwest basin-marginal fault and the eastern Wanchang, Liangjia uplifts, respectively. (3) The Chaluhe sag consists off our hydrocarbon migration-accumulation units, including units Ⅰ, Ⅱ, Ⅲ, and Ⅳ. Unit Ⅱ has the best potential for hydrocarbon migration and accumulation, followed by unit Ⅰ. The periclinal area in the Wanchang uplift ranks to be the most favorable area for oil and gas exploration in the Chaluhe sag.
2014, 39(6): 751-759.
doi: 10.3799/dqkx.2014.070
Abstract:
Irrigation with brackish water has a long history throughout the world. Irrational use of brackish or saline waters, however, may lead to soil salinization and reduction of crop yields. In order to promote reasonable applications of brackish water and fertilizer irrigation, a series of experiments of mulched drip-irrigation with brackish and fresh waters were carried out at Bazhou Irrigation Experimental Station (Korla, Xinjiang, China). Plant and soil samples were collected at every growth stage. Cotton yields were measured at boll opening stage. Nine elements (Ca, Na, Mg, K, Cu, Fe, Mn, Zn and B) of each sample were tested in triplicate by ICP-OES (ICAP6300) after pretreated. The influence of water quality on the element compositions of soil and cotton and cotton yield were discussed based on the experiment. The results show that growth rate of Na+ in narrow rows and interspace of mulches was lower than that in wide rows because of higher content of Cu, Fe, Zn. The ratios of K+/Na+ and Ca2+/Na+, however, in most cotton organs show no significant differences between the two treatments. From buds to boll stages, brackish water irrigation enhanced the accumulation of above ground dry matters, which was favorable for vegetative development. From boll to boll opening stages, root and reproductive growth under brackish water were superior to that for fresh water. Furthermore, dry matters, boll weight, numbers of boll per unit area and cotton yield under brackish water were higher than those for fresh water. According to the correlations analyses, relationship between most trace and macro elements was weak. High correlations, however, were found among manganese, boron, and calcium. Within a certain threshold, boron, manganese promoted the absorption of calcium in cotton. It has been proved that a rational use of brackish water will not lead to the growth stress. On the contrary, it would not only lower the growth rate of Na+ in the soil effectively, but also strengthen cotton's resistibility to salt stress and increase cotton yields as well.
Irrigation with brackish water has a long history throughout the world. Irrational use of brackish or saline waters, however, may lead to soil salinization and reduction of crop yields. In order to promote reasonable applications of brackish water and fertilizer irrigation, a series of experiments of mulched drip-irrigation with brackish and fresh waters were carried out at Bazhou Irrigation Experimental Station (Korla, Xinjiang, China). Plant and soil samples were collected at every growth stage. Cotton yields were measured at boll opening stage. Nine elements (Ca, Na, Mg, K, Cu, Fe, Mn, Zn and B) of each sample were tested in triplicate by ICP-OES (ICAP6300) after pretreated. The influence of water quality on the element compositions of soil and cotton and cotton yield were discussed based on the experiment. The results show that growth rate of Na+ in narrow rows and interspace of mulches was lower than that in wide rows because of higher content of Cu, Fe, Zn. The ratios of K+/Na+ and Ca2+/Na+, however, in most cotton organs show no significant differences between the two treatments. From buds to boll stages, brackish water irrigation enhanced the accumulation of above ground dry matters, which was favorable for vegetative development. From boll to boll opening stages, root and reproductive growth under brackish water were superior to that for fresh water. Furthermore, dry matters, boll weight, numbers of boll per unit area and cotton yield under brackish water were higher than those for fresh water. According to the correlations analyses, relationship between most trace and macro elements was weak. High correlations, however, were found among manganese, boron, and calcium. Within a certain threshold, boron, manganese promoted the absorption of calcium in cotton. It has been proved that a rational use of brackish water will not lead to the growth stress. On the contrary, it would not only lower the growth rate of Na+ in the soil effectively, but also strengthen cotton's resistibility to salt stress and increase cotton yields as well.
2014, 39(6): 760-768.
doi: 10.3799/dqkx.2014.071
Abstract:
Ten undisturbed soil samples were collected from deep vadose zone (8.0-21.0 m) at Zhengding, Hebei, and analyzed to study how thickening vadose zone impacts the infiltration recharge processes. These samples were measured by Pressure Plate Extractor to gain the soil retention curves, which were fitted by Mualem-van Genuchten Model using RETC software. Unsaturated hydraulic conductivity and the relation curves were obtained through the curve-fitting processes. The impact on the infiltration recharge processes at the thickening vadose zone is discussed according the Darcy's equation. It is concluded that the unsaturated hydraulic conductivities at sampling time were 25-240 mm/a at the depth of 8.0-21.0 m. If the velocity of water table decline was fast at a certain depth historically, the unsaturated conductivities with same water content should also have large values, which shows the soil has large infiltration capacity. Soil hydraulic parameters and infiltration capacities would change because of water table fluctuated-declining and drainage consolidation, which would impact vertical infiltration recharge.
Ten undisturbed soil samples were collected from deep vadose zone (8.0-21.0 m) at Zhengding, Hebei, and analyzed to study how thickening vadose zone impacts the infiltration recharge processes. These samples were measured by Pressure Plate Extractor to gain the soil retention curves, which were fitted by Mualem-van Genuchten Model using RETC software. Unsaturated hydraulic conductivity and the relation curves were obtained through the curve-fitting processes. The impact on the infiltration recharge processes at the thickening vadose zone is discussed according the Darcy's equation. It is concluded that the unsaturated hydraulic conductivities at sampling time were 25-240 mm/a at the depth of 8.0-21.0 m. If the velocity of water table decline was fast at a certain depth historically, the unsaturated conductivities with same water content should also have large values, which shows the soil has large infiltration capacity. Soil hydraulic parameters and infiltration capacities would change because of water table fluctuated-declining and drainage consolidation, which would impact vertical infiltration recharge.
2014, 39(6): 769-774.
doi: 10.3799/dqkx.2014.072
Abstract:
In order to investigate the efects of cementation on elastic properties and permeability of reservoir rocks, a 3D digital model of core was constructed. Then this model was simulated using the process-based method and finite element lattice Boltzmann method. The results show that cementation influences the rock stiffness and pore connectivity, controlling elastic modulus and rock permeability, respectively. Given same porosity, rocks with cement occurring in the pore throats have high elastic modulus and low permeability; whereas rocks with cement precipitating within pores have low elastic modulus and high permeability. Among the simulated three cementation scenarios, the rock elastic modulus increases with increasing amount of cement, and there is a linear relationship between them, Rock permeability, however, deceases with increasing amount of cement, because permeability is more sensitive to where cements precipitate than rock elastic parameters.
In order to investigate the efects of cementation on elastic properties and permeability of reservoir rocks, a 3D digital model of core was constructed. Then this model was simulated using the process-based method and finite element lattice Boltzmann method. The results show that cementation influences the rock stiffness and pore connectivity, controlling elastic modulus and rock permeability, respectively. Given same porosity, rocks with cement occurring in the pore throats have high elastic modulus and low permeability; whereas rocks with cement precipitating within pores have low elastic modulus and high permeability. Among the simulated three cementation scenarios, the rock elastic modulus increases with increasing amount of cement, and there is a linear relationship between them, Rock permeability, however, deceases with increasing amount of cement, because permeability is more sensitive to where cements precipitate than rock elastic parameters.
