2022 Vol. 47, No. 10
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How does Big Mantle Wedge Affect Deep Mantle Processes and Evolution of the Continental Lithosphere？
2022, 47(10): 3784-3786.
doi: 10.3799/dqkx.2022.808
Abstract:
How to Reveal Mantle Magmatic and Dynamic Evolution beneath Oceanic Spreading Centers by Ophiolites?
2022, 47(10): 3804-3805.
doi: 10.3799/dqkx.2022.816
Abstract:
Does the Compositional Evolution of Earth’s Liquid Outer Core Hold the Key to the Geomagnetic Field?
2022, 47(10): 3845-3846.
doi: 10.3799/dqkx.2022.834
Abstract:
2022, 47(10): 3477-3490.
doi: 10.3799/dqkx.2022.870
Abstract:
China has a vast territory and complex geological structure, China's special geological, natural geographical pattern and biological evolution have created China's special ecological environment. Through the exploration of non-fossil energy minerals, the development of green mining, the investigation and research of agricultural geology, medical geology, disaster geology and paleoenvironment and paleoclimate, geological work can play an active role in providing clean energy and improving the quality of agricultural products. it can play an active role in dealing with the challenges of global change, optimizing the ecological environment, and ensuring people's life safety and health.
China has a vast territory and complex geological structure, China's special geological, natural geographical pattern and biological evolution have created China's special ecological environment. Through the exploration of non-fossil energy minerals, the development of green mining, the investigation and research of agricultural geology, medical geology, disaster geology and paleoenvironment and paleoclimate, geological work can play an active role in providing clean energy and improving the quality of agricultural products. it can play an active role in dealing with the challenges of global change, optimizing the ecological environment, and ensuring people's life safety and health.
2022, 47(10): 3491-3500.
doi: 10.3799/dqkx.2022.871
Abstract:
Through the three-dimensional seismic imaging of the upper mantle of the Qinghai-Tibet Plateau with a resolution of 0.5°×0.5°×10 km, it provides a new understanding for the study of the dynamic evolution of the plateau in the Cenozoic Era. The asthenosphere P-wave velocity disturbance data confirm that the Tethys Oceanic Plate only subducted to the 410 km discontinuity after its delamination, proving that not all oceanic plates were subducting to the bottom of the upper mantle. The upwelling of the thermal fluid, excited by this oceanic plate delamination in the asthenosphere and the rupture process of the continental lithosphere, caused a large-scale volcanic eruption in the middle of the plateau, which is one of the main sources of power for the uplift of the Qinghai-Tibet Plateau. According to the results of three-dimensional seismic tomography of the upper mantle, the depth of the lithosphere-asthenosphere boundary (LAB) was quantitatively calculated, revealing the upwelling locations of asthenosphere material and the sinking of lithosphere mass, indicating that the eastern part of the Qinghai-Tibet Plateau is a relatively independent continental lithosphere-mantle block in the regional dynamic process of Cenozoic dynamics.
Through the three-dimensional seismic imaging of the upper mantle of the Qinghai-Tibet Plateau with a resolution of 0.5°×0.5°×10 km, it provides a new understanding for the study of the dynamic evolution of the plateau in the Cenozoic Era. The asthenosphere P-wave velocity disturbance data confirm that the Tethys Oceanic Plate only subducted to the 410 km discontinuity after its delamination, proving that not all oceanic plates were subducting to the bottom of the upper mantle. The upwelling of the thermal fluid, excited by this oceanic plate delamination in the asthenosphere and the rupture process of the continental lithosphere, caused a large-scale volcanic eruption in the middle of the plateau, which is one of the main sources of power for the uplift of the Qinghai-Tibet Plateau. According to the results of three-dimensional seismic tomography of the upper mantle, the depth of the lithosphere-asthenosphere boundary (LAB) was quantitatively calculated, revealing the upwelling locations of asthenosphere material and the sinking of lithosphere mass, indicating that the eastern part of the Qinghai-Tibet Plateau is a relatively independent continental lithosphere-mantle block in the regional dynamic process of Cenozoic dynamics.
2022, 47(10): 3501-3510.
doi: 10.3799/dqkx.2022.872
Abstract:
Under the "dual carbon" goals, the oil & gas industry faces the dual mission of ensuring energy supply and green and low-carbon development. In this paper it analyzes the new trends and requirements faced by the oil and gas industry under the global energy transition trends, and puts forward the development path of China's oil & gas industry under the "dual carbon" goal. The first is to unswervingly continue to increase exploration and development to ensure the supply security of the country's core oil and gas needs; the second is to increase energy-saving and carbon reduction transformation in the oil and gas production process, and strive to achieve green and low-carbon development; the third is to promote the coordinated development of oil and gas and new energy such as wind and solar power, and realize the integration and mutual promotion of oil and gas and new energy; the fourth is to actively expand the symbiotic and associated resources to create new business growth poles; the fifth is to vigorously develop the CCUS industry and play its role in the implementation of the "dual carbon" goal.
Under the "dual carbon" goals, the oil & gas industry faces the dual mission of ensuring energy supply and green and low-carbon development. In this paper it analyzes the new trends and requirements faced by the oil and gas industry under the global energy transition trends, and puts forward the development path of China's oil & gas industry under the "dual carbon" goal. The first is to unswervingly continue to increase exploration and development to ensure the supply security of the country's core oil and gas needs; the second is to increase energy-saving and carbon reduction transformation in the oil and gas production process, and strive to achieve green and low-carbon development; the third is to promote the coordinated development of oil and gas and new energy such as wind and solar power, and realize the integration and mutual promotion of oil and gas and new energy; the fourth is to actively expand the symbiotic and associated resources to create new business growth poles; the fifth is to vigorously develop the CCUS industry and play its role in the implementation of the "dual carbon" goal.
2022, 47(10): 3511-3523.
doi: 10.3799/dqkx.2022.873
Abstract:
As the most abundant field of conventional oil and gas, onshore petroliferous basins with medium and high exploration degrees in China still play the role of "ballast stone" for national energy security under the situation of "stabilizing oil and increasing gas" in the future. How to further explore the potential of mature exploration areas and expand the exploration field is a problem worthy of in-depth discussion. Based on the recent oil and gas exploration results and exploration development trends, the research shows that there are five major areas that are the most realistic directions for future onshore oil and gas exploration, including continental shale oil and gas, near source geological bodies represented by overthrust structures in the eastern oil-rich depression, deep coalbed methane in coal rich basins, large-scale strike-slip structural systems and geothermal resources. In addition, for the old oilfields in the east, it is an important direction to "develop oilfield into geothermal field". In the future exploration work, explorers should strengthen basic research, especially in the mature exploration areas in the east of China. It is urgent to strengthen the geological evaluation of the three new fields and find new resources replacement fields in the old areas. The practice shows that advanced and applicable geophysical exploration technology and engineering technology are the basic guarantee for oil and gas exploration discovery and breakthrough, and also the fundamental way to reduce the cost of oil and gas discovery. Efficient management and decision-making, taking the initiative to play a pioneering role in exploration and leading the integrated research are important ways to accelerate the promotion of resources strategy.
As the most abundant field of conventional oil and gas, onshore petroliferous basins with medium and high exploration degrees in China still play the role of "ballast stone" for national energy security under the situation of "stabilizing oil and increasing gas" in the future. How to further explore the potential of mature exploration areas and expand the exploration field is a problem worthy of in-depth discussion. Based on the recent oil and gas exploration results and exploration development trends, the research shows that there are five major areas that are the most realistic directions for future onshore oil and gas exploration, including continental shale oil and gas, near source geological bodies represented by overthrust structures in the eastern oil-rich depression, deep coalbed methane in coal rich basins, large-scale strike-slip structural systems and geothermal resources. In addition, for the old oilfields in the east, it is an important direction to "develop oilfield into geothermal field". In the future exploration work, explorers should strengthen basic research, especially in the mature exploration areas in the east of China. It is urgent to strengthen the geological evaluation of the three new fields and find new resources replacement fields in the old areas. The practice shows that advanced and applicable geophysical exploration technology and engineering technology are the basic guarantee for oil and gas exploration discovery and breakthrough, and also the fundamental way to reduce the cost of oil and gas discovery. Efficient management and decision-making, taking the initiative to play a pioneering role in exploration and leading the integrated research are important ways to accelerate the promotion of resources strategy.
2022, 47(10): 3524-3542.
doi: 10.3799/dqkx.2022.265
Abstract:
The South China Sea (SCS) is the largest marginal sea in the West Pacific, but the study of dynamic processes after the termination of the SCS seafloor spreading is not so clear. In this paper it reveals the evolution of the southern and eastern margins of the SCS during the post-SCS spreading period through systematic studies on the identification of tectonically unconformities, contemporaneous sedimentary records of fold-and-thrust belt. The results show that the southern and eastern margins of the SCS have undergone the evolution of multiple microplates from subduction to collision since the Miocene. Several collision boundaries with different characteristics were developed, including continent-continent collision, arc-continent collision and ocean-arc subduction. The southern margin of the SCS belongs to the proto-SCS slab pull tectonic zone, the Sarawak-Zengmu block in northwest Borneo took the lead in the collision, followed by the Sabah-Nansha block collision in northeast Borneo and the Palawan-Cagayan arc collision in the southwest Palawan island. Since the Middle Miocene, these tectonic events have led to the gradual extinction of the proto-SCS from west to east in a scissor-like pattern, and in the formation of a southern collisional margin characterized by microplate collisions, deep-sea trough development and thick sediments filling in the orogenic foreland. The eastern margin of the SCS is part of the Philippine subduction-collision tectonic zone. Subduction of the SCS oceanic crust to the Philippine Sea plate began in the Miocene, but the arc-continent collisions confined to the northern and southern ends of the eastern margin with further oblique subduction of the Philippine Sea plate. The interaction among the Australia-India plate, the Philippine Sea plate and the Eurasian plate controls the marginal sea closure process in the SCS. The ongoing closure process in the SCS is mainly concentrated on the southern and eastern margins, the eastern margin shows a closure process characterized by the extinction of oceanic crust, while the southern margin is a closure process characterized by the collision of microplates. Therefore, the continental margin evolution during the post-SCS spreading period can provide an excellent example for the study of marginal sea closure process, and is also important for the protection of national maritime rights and interests and the study of the dynamics of continental margins in the SCS.
The South China Sea (SCS) is the largest marginal sea in the West Pacific, but the study of dynamic processes after the termination of the SCS seafloor spreading is not so clear. In this paper it reveals the evolution of the southern and eastern margins of the SCS during the post-SCS spreading period through systematic studies on the identification of tectonically unconformities, contemporaneous sedimentary records of fold-and-thrust belt. The results show that the southern and eastern margins of the SCS have undergone the evolution of multiple microplates from subduction to collision since the Miocene. Several collision boundaries with different characteristics were developed, including continent-continent collision, arc-continent collision and ocean-arc subduction. The southern margin of the SCS belongs to the proto-SCS slab pull tectonic zone, the Sarawak-Zengmu block in northwest Borneo took the lead in the collision, followed by the Sabah-Nansha block collision in northeast Borneo and the Palawan-Cagayan arc collision in the southwest Palawan island. Since the Middle Miocene, these tectonic events have led to the gradual extinction of the proto-SCS from west to east in a scissor-like pattern, and in the formation of a southern collisional margin characterized by microplate collisions, deep-sea trough development and thick sediments filling in the orogenic foreland. The eastern margin of the SCS is part of the Philippine subduction-collision tectonic zone. Subduction of the SCS oceanic crust to the Philippine Sea plate began in the Miocene, but the arc-continent collisions confined to the northern and southern ends of the eastern margin with further oblique subduction of the Philippine Sea plate. The interaction among the Australia-India plate, the Philippine Sea plate and the Eurasian plate controls the marginal sea closure process in the SCS. The ongoing closure process in the SCS is mainly concentrated on the southern and eastern margins, the eastern margin shows a closure process characterized by the extinction of oceanic crust, while the southern margin is a closure process characterized by the collision of microplates. Therefore, the continental margin evolution during the post-SCS spreading period can provide an excellent example for the study of marginal sea closure process, and is also important for the protection of national maritime rights and interests and the study of the dynamics of continental margins in the SCS.
2022, 47(10): 3543-3568.
doi: 10.3799/dqkx.2022.248
Abstract:
The 405 ka eccentricity cycle characterizes the variability of monsoon precipitation and marine carbon cycle over a long geological history, which has been revealed by continental and marine sedimentary records from the Precambrian to the Cenozoic. As a fundamental tempo of hydrological and carbon cycle over the Earth's surface, particularly in low-latitude areas, the 405 ka eccentricity cycle is used as a metronome for astronomically calibrated timescale. This eccentricity cycle, however, could be obscured during some specific periods, caused by massive volcanic-sourced CO2 emission, the revolution of biosphere, and the expansion of the polar ice sheets. The obscuring of eccentricity cycles, in fact, provides a novel perspective to study significant evolution of the Earth's surface system, and to unveil mechanisms of climate changes across the greenhouse to the icehouse period. At the end of this paper, we give some suggestions on how to conduct future studies of the astronomical forcing of climate change in China. It is highly prospective that Chinese scientist community can put forward this academic topic to a cutting-edge level.
The 405 ka eccentricity cycle characterizes the variability of monsoon precipitation and marine carbon cycle over a long geological history, which has been revealed by continental and marine sedimentary records from the Precambrian to the Cenozoic. As a fundamental tempo of hydrological and carbon cycle over the Earth's surface, particularly in low-latitude areas, the 405 ka eccentricity cycle is used as a metronome for astronomically calibrated timescale. This eccentricity cycle, however, could be obscured during some specific periods, caused by massive volcanic-sourced CO2 emission, the revolution of biosphere, and the expansion of the polar ice sheets. The obscuring of eccentricity cycles, in fact, provides a novel perspective to study significant evolution of the Earth's surface system, and to unveil mechanisms of climate changes across the greenhouse to the icehouse period. At the end of this paper, we give some suggestions on how to conduct future studies of the astronomical forcing of climate change in China. It is highly prospective that Chinese scientist community can put forward this academic topic to a cutting-edge level.
2022, 47(10): 3569-3579.
doi: 10.3799/dqkx.2022.350
Abstract:
With the rise of a new-round scientific and technological revolution, the era of Earth System Science is coming. Crossing the disciplines between geology and atmospheric science will inevitably bring new developments in Earth science. Atmospheric science has undergone three development stages in the past four centuries, including collecting data, creating theories, and building models. However, geology requires more prolonged data accumulation due to the more profound spatio-temporal complexity. At present, geology is facing a shift in the research paradigm from collecting data to creating theories and building models. Crossing the disciplines between geology and atmospheric science will provide experiences and inspirations for this shift. Here, two scientific questions are essential in crossing the fields. First, how does the solar forcing influence atmospheric and oceanic circulation? Second, how does the solid Earth surface, including topography and bathymetry, modify the Earth climate system? Answering these two questions will help to create new theories on multi-time scales and develop Earth system models in a new generation. The department of atmospheric science at China University of Geosciences (Wuhan) has become a pioneer in promoting this disciplinary cross in China but still has a long way to go.
With the rise of a new-round scientific and technological revolution, the era of Earth System Science is coming. Crossing the disciplines between geology and atmospheric science will inevitably bring new developments in Earth science. Atmospheric science has undergone three development stages in the past four centuries, including collecting data, creating theories, and building models. However, geology requires more prolonged data accumulation due to the more profound spatio-temporal complexity. At present, geology is facing a shift in the research paradigm from collecting data to creating theories and building models. Crossing the disciplines between geology and atmospheric science will provide experiences and inspirations for this shift. Here, two scientific questions are essential in crossing the fields. First, how does the solar forcing influence atmospheric and oceanic circulation? Second, how does the solid Earth surface, including topography and bathymetry, modify the Earth climate system? Answering these two questions will help to create new theories on multi-time scales and develop Earth system models in a new generation. The department of atmospheric science at China University of Geosciences (Wuhan) has become a pioneer in promoting this disciplinary cross in China but still has a long way to go.
2022, 47(10): 3580-3602.
doi: 10.3799/dqkx.2022.284
Abstract:
In the 21th century, China has made brilliant achievements in the exploration of sandstone-type uranium deposits. Sandstone-type uranium deposits are located in sedimentary basins. The formation of uranium deposits must go through two important evolutionary stages from sedimentary burial stage to uplift metallogenic stage. The participation and restriction of atmospheric precipitation and oxidation-reduction are the most significant metallogenic characteristics in the uplift metallogenic stage. Obviously, this is the product of a typical supergene diagenesis, an important link in the complex diagenetic sequence of uranium reservoirs, and belongs to the category of "exogenetic mineralization". Although the mineralization of sandstone-type uranium deposit follows the general mechanism of oxidation-reduction and uranium valence change, the special sedimentary background leads to the diversity and regional specificity of uranium mineralization. Some key ore controlling elements created by sedimentation, sedimentary environment and paleoclimate can directly affect uranium mineralization in epigenetic rock stage from "gene". From sedimentation, diagenesis to uranium mineralization is a geological process with genetic connection, and the basin-mountain coupling mechanism is always the most fundamental original driving force. With the in-depth study of the detailed behavior of uranium mineralization, some innovative discoveries continue to impact the previous inherent understanding, such as the interaction between carbonaceous debris and uranium mineralization, the complex and orderly evolution habit of pyrite, the symbiosis and superposition of carbonate cement and uranium mineralization, the fluid tracing of sensitive minerals, the uranium mineralization mechanism restricted by the heterogeneity of uranium reservoir, the ore making model of double reducing medium, and compound geochemical barrier of uranium mineralization, etc. Other studies have posed cognitive challenges to traditional geological theories, such as the "carbonization mechanism" of carbonaceous debris in the open diagenetic environment of uranium reservoir, the chemical dynamic mechanism of uranium precipitation on the dissolution or growth interfaces of pyrite, the uranium metallogenic mechanism in arid sedimentary background, etc. At the same time, the study of uranium metallogenic mechanism and general law has also laid a good geological foundation for the study of geological effects of sandstone-type uranium deposit decay and the systematic exploration of basin uranium resources. It is believed that the systematic study on the metallogenic mechanism and genetic relationship of the whole sedimentary basin will release the huge basin uranium resource potential and deposit productivity, and help to achieve the "double carbon goal" while further enriching the uranium metallogenic theory.
In the 21th century, China has made brilliant achievements in the exploration of sandstone-type uranium deposits. Sandstone-type uranium deposits are located in sedimentary basins. The formation of uranium deposits must go through two important evolutionary stages from sedimentary burial stage to uplift metallogenic stage. The participation and restriction of atmospheric precipitation and oxidation-reduction are the most significant metallogenic characteristics in the uplift metallogenic stage. Obviously, this is the product of a typical supergene diagenesis, an important link in the complex diagenetic sequence of uranium reservoirs, and belongs to the category of "exogenetic mineralization". Although the mineralization of sandstone-type uranium deposit follows the general mechanism of oxidation-reduction and uranium valence change, the special sedimentary background leads to the diversity and regional specificity of uranium mineralization. Some key ore controlling elements created by sedimentation, sedimentary environment and paleoclimate can directly affect uranium mineralization in epigenetic rock stage from "gene". From sedimentation, diagenesis to uranium mineralization is a geological process with genetic connection, and the basin-mountain coupling mechanism is always the most fundamental original driving force. With the in-depth study of the detailed behavior of uranium mineralization, some innovative discoveries continue to impact the previous inherent understanding, such as the interaction between carbonaceous debris and uranium mineralization, the complex and orderly evolution habit of pyrite, the symbiosis and superposition of carbonate cement and uranium mineralization, the fluid tracing of sensitive minerals, the uranium mineralization mechanism restricted by the heterogeneity of uranium reservoir, the ore making model of double reducing medium, and compound geochemical barrier of uranium mineralization, etc. Other studies have posed cognitive challenges to traditional geological theories, such as the "carbonization mechanism" of carbonaceous debris in the open diagenetic environment of uranium reservoir, the chemical dynamic mechanism of uranium precipitation on the dissolution or growth interfaces of pyrite, the uranium metallogenic mechanism in arid sedimentary background, etc. At the same time, the study of uranium metallogenic mechanism and general law has also laid a good geological foundation for the study of geological effects of sandstone-type uranium deposit decay and the systematic exploration of basin uranium resources. It is believed that the systematic study on the metallogenic mechanism and genetic relationship of the whole sedimentary basin will release the huge basin uranium resource potential and deposit productivity, and help to achieve the "double carbon goal" while further enriching the uranium metallogenic theory.
2022, 47(10): 3603-3615.
doi: 10.3799/dqkx.2022.295
Abstract:
Large-scale mapping of the hydrothermal deposits refers to the geological mapping with the scales of 1∶1 000 and the larger scales, which is mainly used to record various geological phenomena that can be directly observed with the naked eye, such as outcrops, flat tunnels, boreholes and hand specimens in the mining area. The purpose of large-scale mapping is to identify the metallogenic characteristics, spatial distribution and temporal evolution of the hydrothermal deposits, which are useful for accurately constraining the genetic type and metallogenic process of hydrothermal deposits, as well as assisting further prospecting and exploration. In the field survey, the beginners do not know how to describe and record the complex phenomena of the hydrothermal deposits, and they are also not very clear about what to fill and how to map. To address these issues, we try to weaken the genetic type of the ore deposit from the basic principle, focusing on the formation process of the structure, fluid, alteration and mineralization of the hydrothermal deposit, and propose "ore-forming fluid + fresh wall rock → wall rock alteration + ore" as a universal formula for the formation of hydrothermal deposits, and puts forward the analogies of "structure → skeleton" and "alteration → flesh". In addition, we focus on some long-ignored aspects in the process of large-scale mapping of hydrothermal deposits, such as identification of metallogenic environment, ore-forming fluid channels and traps, hydrothermal filling and metasomatism, and identification of vein cross-cutting, etc. Furthermore, we eventual focus is on explaining the hidden genetic inspiration behind these geological phenomena.
Large-scale mapping of the hydrothermal deposits refers to the geological mapping with the scales of 1∶1 000 and the larger scales, which is mainly used to record various geological phenomena that can be directly observed with the naked eye, such as outcrops, flat tunnels, boreholes and hand specimens in the mining area. The purpose of large-scale mapping is to identify the metallogenic characteristics, spatial distribution and temporal evolution of the hydrothermal deposits, which are useful for accurately constraining the genetic type and metallogenic process of hydrothermal deposits, as well as assisting further prospecting and exploration. In the field survey, the beginners do not know how to describe and record the complex phenomena of the hydrothermal deposits, and they are also not very clear about what to fill and how to map. To address these issues, we try to weaken the genetic type of the ore deposit from the basic principle, focusing on the formation process of the structure, fluid, alteration and mineralization of the hydrothermal deposit, and propose "ore-forming fluid + fresh wall rock → wall rock alteration + ore" as a universal formula for the formation of hydrothermal deposits, and puts forward the analogies of "structure → skeleton" and "alteration → flesh". In addition, we focus on some long-ignored aspects in the process of large-scale mapping of hydrothermal deposits, such as identification of metallogenic environment, ore-forming fluid channels and traps, hydrothermal filling and metasomatism, and identification of vein cross-cutting, etc. Furthermore, we eventual focus is on explaining the hidden genetic inspiration behind these geological phenomena.
2022, 47(10): 3616-3632.
doi: 10.3799/dqkx.2022.236
Abstract:
Water, the primary volatile constituent in anatectic melt and terrestrial magma, has a significant effect on the physical and chemical properties of the melt. Due to limitations in analytical techniques and the fugitive nature of anatectic melts, it is extremely difficult to quantitatively determine water concentration and water speciation, resulting in a very limited understanding of the formation mechanism and evolution process for partial melting in subduction zone. Confocal micro-Raman spectroscopy, which has the advantages of high spatial resolution, fast, nondestructive analysis and simple sample preparation, severs the purpose of detecting small melt inclusions. Additionally, based on the principle that there is a good linear relationship between the height/intensity of Raman spectrum peak and the content of corresponding groups, the internal calibration and external calibration are established for the quantitative analysis of water content and water speciation in silicate melt inclusions with synthesized silicate glass as the standard sample. As a newly developed technique and method, more and more geologists pay attention to it. However, a large number of researches are still focused on the deduction and correction of the analytical method itself, while the research on natural samples is relatively lacking. Limited research indicates that the method can be widely used in magmatites and high-grade metamorphic rocks. It achieves quantitatively determining the water content of matrix or melt inclusion in porphyry, thereby effectively tracing the rheological behavior of magma during magma intrusion or eruption. Water content and speciation of the anatectic melt in the continental subduction zone provides tight constraints for continental crust differentiation and melt metasomatites at the slab-wedge interface.
Water, the primary volatile constituent in anatectic melt and terrestrial magma, has a significant effect on the physical and chemical properties of the melt. Due to limitations in analytical techniques and the fugitive nature of anatectic melts, it is extremely difficult to quantitatively determine water concentration and water speciation, resulting in a very limited understanding of the formation mechanism and evolution process for partial melting in subduction zone. Confocal micro-Raman spectroscopy, which has the advantages of high spatial resolution, fast, nondestructive analysis and simple sample preparation, severs the purpose of detecting small melt inclusions. Additionally, based on the principle that there is a good linear relationship between the height/intensity of Raman spectrum peak and the content of corresponding groups, the internal calibration and external calibration are established for the quantitative analysis of water content and water speciation in silicate melt inclusions with synthesized silicate glass as the standard sample. As a newly developed technique and method, more and more geologists pay attention to it. However, a large number of researches are still focused on the deduction and correction of the analytical method itself, while the research on natural samples is relatively lacking. Limited research indicates that the method can be widely used in magmatites and high-grade metamorphic rocks. It achieves quantitatively determining the water content of matrix or melt inclusion in porphyry, thereby effectively tracing the rheological behavior of magma during magma intrusion or eruption. Water content and speciation of the anatectic melt in the continental subduction zone provides tight constraints for continental crust differentiation and melt metasomatites at the slab-wedge interface.
2022, 47(10): 3633-3647.
doi: 10.3799/dqkx.2022.206
Abstract:
There are large areas of desert/sandy land located in the interior of Northwest China. To determine their material origin is crucial to understand the formation and development of these deserts. Especially, it is controversial whether the detrital materials in Tengger, Hedong, Mu Us, Ulan Buhe and Kubuqi deserts and sand lands come from the distant Yellow River or the near source area. In view of this, it carried out in-situ Pb isotopic analyses of detrital K-feldspar grains (n=554) widely found in these deserts to determine whether there is a provenance relationship with the upper reaches of the Yellow River. Combined with the published Pb isotopic compositions of detrital K-feldspar from the upper Yellow River and provenance tracing results in the region, the results show that the detrital material from the upper Yellow River mainly affected the Tengger Desert in a limited local area, but did not penetrate into the desert hinterland. The material in the upper reach of the Yellow River is not related to Hedong sand land, Mu Us sand land, Ulan Buhe desert and Kubuqi desert. The material of these deserts/sandy lands in Northwest China was mainly derived from near source area, which is a sedimentary process response to the uplift of the Tibetan plateau and climatic drought since the Early Pleistocene.
There are large areas of desert/sandy land located in the interior of Northwest China. To determine their material origin is crucial to understand the formation and development of these deserts. Especially, it is controversial whether the detrital materials in Tengger, Hedong, Mu Us, Ulan Buhe and Kubuqi deserts and sand lands come from the distant Yellow River or the near source area. In view of this, it carried out in-situ Pb isotopic analyses of detrital K-feldspar grains (n=554) widely found in these deserts to determine whether there is a provenance relationship with the upper reaches of the Yellow River. Combined with the published Pb isotopic compositions of detrital K-feldspar from the upper Yellow River and provenance tracing results in the region, the results show that the detrital material from the upper Yellow River mainly affected the Tengger Desert in a limited local area, but did not penetrate into the desert hinterland. The material in the upper reach of the Yellow River is not related to Hedong sand land, Mu Us sand land, Ulan Buhe desert and Kubuqi desert. The material of these deserts/sandy lands in Northwest China was mainly derived from near source area, which is a sedimentary process response to the uplift of the Tibetan plateau and climatic drought since the Early Pleistocene.
2022, 47(10): 3648-3664.
doi: 10.3799/dqkx.2022.332
Abstract:
The knowledge how land plants originated and diversified during the Paleozoic (the plant terrestrialization for short) and how they induced impacts on Earth's surface environments is of great significance for a better understanding of the evolution of Earth System. Devonian is a key interval of vascular plant radiation, when extant clades such as lycopsids, ferns, sphenopsids, and seed plants originated, innovative organ systems such as roots, leaves, wood, and seeds evolved, and forests became an important component of terrestrial landscape. Recent advances concerning interactions between early plants and Earth's environments include: how Paleozoic vegetation forced the evolution of fluvial landscapes; how early land plants enhanced chemical weathering; and how terrestrial organic carbon buried during the Paleozoic; etc. Future studies aim to, on one side, reveal more details about the process and mechanisms of plant terrestrialization, based on evidence varying from genes to terrestrial ecosystems, and on the other side, learn more about the effects of Earth's environments by such a transformative event at multiple spatial scales, such as microscopic-, habitat-, regional-, and global scales.
The knowledge how land plants originated and diversified during the Paleozoic (the plant terrestrialization for short) and how they induced impacts on Earth's surface environments is of great significance for a better understanding of the evolution of Earth System. Devonian is a key interval of vascular plant radiation, when extant clades such as lycopsids, ferns, sphenopsids, and seed plants originated, innovative organ systems such as roots, leaves, wood, and seeds evolved, and forests became an important component of terrestrial landscape. Recent advances concerning interactions between early plants and Earth's environments include: how Paleozoic vegetation forced the evolution of fluvial landscapes; how early land plants enhanced chemical weathering; and how terrestrial organic carbon buried during the Paleozoic; etc. Future studies aim to, on one side, reveal more details about the process and mechanisms of plant terrestrialization, based on evidence varying from genes to terrestrial ecosystems, and on the other side, learn more about the effects of Earth's environments by such a transformative event at multiple spatial scales, such as microscopic-, habitat-, regional-, and global scales.
2022, 47(10): 3665-3676.
doi: 10.3799/dqkx.2022.184
Abstract:
Heavy rainfall is a main factor for reactivating the deformation of large deep-seated landslides. Understanding the infiltration mechanism is of great significance to obtaining the rainfall thresholds for landslide reactivation and hence facilitating early warning. Tanjiawan landslide is a well-studied large-scale and deep-seated reactivated landslide in Zigui County of the Three Gorges Reservoir Area. It is therefore considered as a typical example in this study, and the spatiotemporal distribution of surface cracks with time series were described and analyzed herein. 15 years of manual monitoring data and 2 years of real-time monitoring data were employed to analyze the deformation process of the landslide. By exploring the correlation between the displacement and the cumulative as well as antecedent rainfall in the stepping stage, a dynamic mechanism of infiltration was proposed for the reactivated deformation evolution in the deep-seated landslide. It is demonstrated that the 7 stages of step-like deformation were related to the heavy rainfall of the Tanjiawan landslides, but the cumulative horizontal displacement increment had no obvious positive correlation with the cumulative rainfall. Moreover, even when the increment of horizontal displacement is similar, the accumulate rainfall can still be quite different. The cumulative rainfall and maximum daily rainfall that caused the first step deformation were much greater than those in the subsequent stages, and the analysis indicated that it may be controlled by the dynamic mechanism of infiltration. Furthermore, the infiltration has transformed from pore seepage to coupled pore seepage with larger permeability and crack preferential flow. It has a theoretical significance and reference value for further study of the mechanism and early warning of deep-stead landslide reactivation induced by heavy rainfall.
Heavy rainfall is a main factor for reactivating the deformation of large deep-seated landslides. Understanding the infiltration mechanism is of great significance to obtaining the rainfall thresholds for landslide reactivation and hence facilitating early warning. Tanjiawan landslide is a well-studied large-scale and deep-seated reactivated landslide in Zigui County of the Three Gorges Reservoir Area. It is therefore considered as a typical example in this study, and the spatiotemporal distribution of surface cracks with time series were described and analyzed herein. 15 years of manual monitoring data and 2 years of real-time monitoring data were employed to analyze the deformation process of the landslide. By exploring the correlation between the displacement and the cumulative as well as antecedent rainfall in the stepping stage, a dynamic mechanism of infiltration was proposed for the reactivated deformation evolution in the deep-seated landslide. It is demonstrated that the 7 stages of step-like deformation were related to the heavy rainfall of the Tanjiawan landslides, but the cumulative horizontal displacement increment had no obvious positive correlation with the cumulative rainfall. Moreover, even when the increment of horizontal displacement is similar, the accumulate rainfall can still be quite different. The cumulative rainfall and maximum daily rainfall that caused the first step deformation were much greater than those in the subsequent stages, and the analysis indicated that it may be controlled by the dynamic mechanism of infiltration. Furthermore, the infiltration has transformed from pore seepage to coupled pore seepage with larger permeability and crack preferential flow. It has a theoretical significance and reference value for further study of the mechanism and early warning of deep-stead landslide reactivation induced by heavy rainfall.
2022, 47(10): 3677-3700.
doi: 10.3799/dqkx.2022.249
Abstract:
The large deep-seated landslides are extremely developed in the Tibetan Plateau with extremely complex topography and geological structures, such as the Nujiang River, Lancang River, Jinsha River and Minjiang River.The large deep-seated creeping landslides are characterized with large scale and volume, deep-buried sliding belt, and obvious progressive deformation characteristics, which are often manifested as long-term creeping-intermittent resurrection-overall sliding. According to the spatial structure of landslides, there are mainly three types: the trailing edge-pond creeping landslide, bedding rock creeping landslide, thick layer deposit creeping landslide. In this paper it analyzes the spatial structure and influencing factors of large-scale deep creeping landslides, the engineering geomechanical properties of landslide zone soils, the characteristics of groundwater seepage field and the hysteresis of rainfall-induced landslides, as well as the progressive deformation failure mechanism and dynamic stability. The research progress of large deep-seated creeping landslides has been analyzed, 3 key scientific issues and 4 main research contents are put forward. It is recommended to strengthen the study of deep sliding zone mechanical strength under the multi-field coupling periodic action of the seepage-consolidation-creep-slip, the analysis of the heterogeneous permeability characteristics of landslide rock and soil and groundwater distribution characteristics, the effective rainfall infiltration mechanism and gradual deformation and failure hysteresis law. It is necessary to study and put out a landslide stability evaluation method based on progressive deformation mechanism, which could provide an important theoretical basis for the geo-hazard early identification and comprehensive prevention.
The large deep-seated landslides are extremely developed in the Tibetan Plateau with extremely complex topography and geological structures, such as the Nujiang River, Lancang River, Jinsha River and Minjiang River.The large deep-seated creeping landslides are characterized with large scale and volume, deep-buried sliding belt, and obvious progressive deformation characteristics, which are often manifested as long-term creeping-intermittent resurrection-overall sliding. According to the spatial structure of landslides, there are mainly three types: the trailing edge-pond creeping landslide, bedding rock creeping landslide, thick layer deposit creeping landslide. In this paper it analyzes the spatial structure and influencing factors of large-scale deep creeping landslides, the engineering geomechanical properties of landslide zone soils, the characteristics of groundwater seepage field and the hysteresis of rainfall-induced landslides, as well as the progressive deformation failure mechanism and dynamic stability. The research progress of large deep-seated creeping landslides has been analyzed, 3 key scientific issues and 4 main research contents are put forward. It is recommended to strengthen the study of deep sliding zone mechanical strength under the multi-field coupling periodic action of the seepage-consolidation-creep-slip, the analysis of the heterogeneous permeability characteristics of landslide rock and soil and groundwater distribution characteristics, the effective rainfall infiltration mechanism and gradual deformation and failure hysteresis law. It is necessary to study and put out a landslide stability evaluation method based on progressive deformation mechanism, which could provide an important theoretical basis for the geo-hazard early identification and comprehensive prevention.
2022, 47(10): 3701-3722.
doi: 10.3799/dqkx.2022.275
Abstract:
Soil-atmosphere interaction refers to the complex process of material exchange and energy transfer between the surface shallow of soil and the atmosphere, and this process is driven by a variety of meteorological factors. Due to global climate change, extreme climate events have occurred frequently in recent years. The engineering properties of soil have changed dramatically in the process of increasingly severe climate environment. The change of soil leads to a large number of landslide disasters, which brings many new challenges to the field of geotechnical and geological engineering. In this paper it systematically summarizes the mechanism of rainfall, air temperature, air humidity, wind and solar radiation affecting slope stability, and analyzes the correlation effect among soil cracking, surface vegetation and soil-atmosphere interaction. The mainly conclusions are as follows. (1) There are various ways of slope instability and failure caused by rainfall, including the instability and sliding of slope directly caused by rainfall infiltration, the erosion of rainfall destroys the slope surface, and the swelling and shrinkage failure of expansive soil slope caused by raining and drying cycle. (2) Under the condition of rainfall, the damage degree of soil slope is regulated by both rainfall threshold and soil permeability. (3) The increase of temperature accelerates the process of soil evaporation and shrinkage cracking. High temperature environment has an adverse impact on the stability of frozen soil slope. (4) High wind speed, low air humidity and strong solar radiation increase the evaporation rate of soil mass and indirectly enhance the stability of soil slope. (5) The cracks formed by soil cracking become a new channel for water exchange between soil and atmosphere. Cracks increase the evaporation area of soil and increase the evaporation rate of soil. At the same time, cracks provide a priority path for rainfall infiltration, which makes rainfall infiltrates the slope faster and deeper, and destroys the stability of the slope. (6) Through the transpiration of leaves, plants release the water absorbed by roots into the atmosphere and reduce the soil moisture content. Plant roots enhance the water holding capacity of soil and reduce the permeability of soil. At the same time, the root system strengthens the soil in the form of reinforcement, which improves the stability of the slope. In view of the research status of this subject, it puts forward the research direction and focus in the future, including the theoretical model of soil-vegetation-atmosphere interaction, the instability mechanism of frozen soil slope under climate influence, and the ecological regulation measures of extreme climate engineering geology.
Soil-atmosphere interaction refers to the complex process of material exchange and energy transfer between the surface shallow of soil and the atmosphere, and this process is driven by a variety of meteorological factors. Due to global climate change, extreme climate events have occurred frequently in recent years. The engineering properties of soil have changed dramatically in the process of increasingly severe climate environment. The change of soil leads to a large number of landslide disasters, which brings many new challenges to the field of geotechnical and geological engineering. In this paper it systematically summarizes the mechanism of rainfall, air temperature, air humidity, wind and solar radiation affecting slope stability, and analyzes the correlation effect among soil cracking, surface vegetation and soil-atmosphere interaction. The mainly conclusions are as follows. (1) There are various ways of slope instability and failure caused by rainfall, including the instability and sliding of slope directly caused by rainfall infiltration, the erosion of rainfall destroys the slope surface, and the swelling and shrinkage failure of expansive soil slope caused by raining and drying cycle. (2) Under the condition of rainfall, the damage degree of soil slope is regulated by both rainfall threshold and soil permeability. (3) The increase of temperature accelerates the process of soil evaporation and shrinkage cracking. High temperature environment has an adverse impact on the stability of frozen soil slope. (4) High wind speed, low air humidity and strong solar radiation increase the evaporation rate of soil mass and indirectly enhance the stability of soil slope. (5) The cracks formed by soil cracking become a new channel for water exchange between soil and atmosphere. Cracks increase the evaporation area of soil and increase the evaporation rate of soil. At the same time, cracks provide a priority path for rainfall infiltration, which makes rainfall infiltrates the slope faster and deeper, and destroys the stability of the slope. (6) Through the transpiration of leaves, plants release the water absorbed by roots into the atmosphere and reduce the soil moisture content. Plant roots enhance the water holding capacity of soil and reduce the permeability of soil. At the same time, the root system strengthens the soil in the form of reinforcement, which improves the stability of the slope. In view of the research status of this subject, it puts forward the research direction and focus in the future, including the theoretical model of soil-vegetation-atmosphere interaction, the instability mechanism of frozen soil slope under climate influence, and the ecological regulation measures of extreme climate engineering geology.
2022, 47(10): 3723-3735.
doi: 10.3799/dqkx.2022.058
Abstract:
In order to study the genetic mechanism of hot dry rock (HDR), the formation background, thermal control structure system and scale of HDR are comprehensively analyzed in this paper.The distribution of HDR in the earth is not ubiquitous, but has its special tectonic background.The thermal controlling structure system plays a very important role in the transmission and accumulation of heat energy of HDR and causes different anomalies in the lithosphere.The thermal controlling structures can be further divided into four basic types: heat generating structure, heat conducting structure, heat storage structure and heat releasing structure.Heat generating structures include mantle asthenosphere diapir, magma chamber with large amount of high radioactive elements, active deep faults and so on.The brittle-ductile transitional zone in the middle and lower crust and the active ductile shear zone are thermal conductive structures.The ductile shear rheological layer is the heat conduction layer and the heat storage structure.Volcanoes, earthquakes, shallow active faults are heat releasing structures.The types of thermal control structure are limited by structural scale and tectonic setting.Due to the great differences in the distribution and development characteristics of heat controlling structures in the crust, the buried depth, scale, capacity and distribution state of geothermal energy such as hot dry rocks in the crust are also quite different.
In order to study the genetic mechanism of hot dry rock (HDR), the formation background, thermal control structure system and scale of HDR are comprehensively analyzed in this paper.The distribution of HDR in the earth is not ubiquitous, but has its special tectonic background.The thermal controlling structure system plays a very important role in the transmission and accumulation of heat energy of HDR and causes different anomalies in the lithosphere.The thermal controlling structures can be further divided into four basic types: heat generating structure, heat conducting structure, heat storage structure and heat releasing structure.Heat generating structures include mantle asthenosphere diapir, magma chamber with large amount of high radioactive elements, active deep faults and so on.The brittle-ductile transitional zone in the middle and lower crust and the active ductile shear zone are thermal conductive structures.The ductile shear rheological layer is the heat conduction layer and the heat storage structure.Volcanoes, earthquakes, shallow active faults are heat releasing structures.The types of thermal control structure are limited by structural scale and tectonic setting.Due to the great differences in the distribution and development characteristics of heat controlling structures in the crust, the buried depth, scale, capacity and distribution state of geothermal energy such as hot dry rocks in the crust are also quite different.
2022, 47(10): 3736-3764.
doi: 10.3799/dqkx.2022.288
Abstract:
Paleomagnetism involves in interdisciplinary studies including geology, geophysics, and environmental science, etc..It focuses on geomagnetic field evolution, geodynamic process, paleoenvironment and paleoclimate evolution by analyzing magnetic information in natural samples.Since the mid-20th century, paleomagnetism has developed rapidly in various research fields, and many new research branches have been derived by integrating with other disciplines.In this paper, it firstly reviews the history and basic research fields of paleomagnetism.Then, it introduces the high-precision satellite magnetic survey and its related research fields, as well as new progress in the moon and mars magnetism.It further discusses the integrated applications of paleomagnetism, high-precision magnetic survey, and other methods in geomagnetic field evolution, plate tectonics, deep earth structure, Lunar and Martian magnetic field and environmental evolution.Finally, it proposes some potential research directions of paleomagnetism.
Paleomagnetism involves in interdisciplinary studies including geology, geophysics, and environmental science, etc..It focuses on geomagnetic field evolution, geodynamic process, paleoenvironment and paleoclimate evolution by analyzing magnetic information in natural samples.Since the mid-20th century, paleomagnetism has developed rapidly in various research fields, and many new research branches have been derived by integrating with other disciplines.In this paper, it firstly reviews the history and basic research fields of paleomagnetism.Then, it introduces the high-precision satellite magnetic survey and its related research fields, as well as new progress in the moon and mars magnetism.It further discusses the integrated applications of paleomagnetism, high-precision magnetic survey, and other methods in geomagnetic field evolution, plate tectonics, deep earth structure, Lunar and Martian magnetic field and environmental evolution.Finally, it proposes some potential research directions of paleomagnetism.
