The isotope composition in precipitation has been widely considered as a tracer of monsoon activity.Compared with the coastal region,the monsoon margin usually has limited precipitation with large fluctuation and is u...The isotope composition in precipitation has been widely considered as a tracer of monsoon activity.Compared with the coastal region,the monsoon margin usually has limited precipitation with large fluctuation and is usually sensitive to climate change.The water resource management in the monsoon margin should be better planned by understanding the composition of precipitation isotope and its influencing factors.In this study,the precipitation samples were collected at five sampling sites(Baiyin City,Kongtong District,Maqu County,Wudu District,and Yinchuan City)of the monsoon margin in the northwest of China in 2022 to analyze the characteristics of stable hydrogen(δD)and oxygen(δ18O)isotopes.We analyzed the impact of meteorological factors(temperature,precipitation,and relative humidity)on the composition of precipitation isotope at daily level by regression analysis,utilized the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)-based backward trajectory model to simulate the air mass trajectory of precipitation events,and adopted the potential source contribution function(PSCF)and concentration weighted trajectory(CWT)to analyze the water vapor sources.The results showed that compared with the global meteoric water line(GMWL),the slope of the local meteoric water line(LMWL;δD=7.34δ^(18)O-1.16)was lower,indicating the existence of strong regional evaporation in the study area.Temperature significantly contributed toδ18O value,while relative humidity had a significant negative effect onδ18O value.Through the backward trajectory analysis,we found eight primary locations that were responsible for the water vapor sources of precipitation in the study area,of which moisture from the Indian Ocean to South China Sea(ITSC)and the western continental(CW)had the greatest influence on precipitation in the study area.The hydrogen and oxygen isotopes in precipitation are significantly influenced by the sources and transportation paths of air mass.In addition,the results of PSCF and CWT analysis showed that the water vapor source areas were primarily distributed in the south and northwest direction of the study area.展开更多
The relationships between crustal stretching and thinning,basin structure and petroleum geology in Baiyun deep-water area were analyzed using large area 3D seismic,gravity,magnetic,ocean bottom seismic(OBS),deep-water...The relationships between crustal stretching and thinning,basin structure and petroleum geology in Baiyun deep-water area were analyzed using large area 3D seismic,gravity,magnetic,ocean bottom seismic(OBS),deep-water exploration wells and integrated ocean drilling program(IODP).During the early syn-rifting period,deep-water area was a half-graben controlled by high angle faults influenced by the brittle extension of upper crust.In the mid syn-rifting period,this area was a broad-deep fault depression controlled by detachment faults undergone brittle-ductile deformation and differentiated extension in the crust.In the late syn-rifting period,this area experienced fault-sag transition due to saucer-shaped rheology change dominated by crustal ductile deformation.A broad-deep fault depression controlled by the large detachment faults penetrating through the crust is an important feature of deep-water basin.The study suggests that the broad-deep Baiyun sag provides great accommodation space for the development of massive deltaic-lacustrine deposition system and hydrocarbon source rocks.The differentiated lithospheric thinning also resulted in the different thermal subsidence during post-rifting period,and then controlled the development of continental shelf break and deep-water reservoir sedimentary environment.The high heat flow background caused by the strong thinning of lithosphere and the rise of mantle source resulted in particularities in the reservoir diagenesis,hydrocarbon generation process and accumulation of deep-water area in northern South China Sea.展开更多
Folklore is an important carrier to show local culture and express people’s emotions in the way of oral transmission.Tradition holds that folklore loses its vitality without oral narration.However,it is difficult to ...Folklore is an important carrier to show local culture and express people’s emotions in the way of oral transmission.Tradition holds that folklore loses its vitality without oral narration.However,it is difficult to find the traditional context of telling and disseminating folklore only by word of mouth.More often,under the impetus of multiple contexts and different forces,folklore in multiple media is widely spread through mutual reference and integration.The current situation of the water Margin theory circulating in Liangshan area is enough to illustrate this point.Water Margin has a very long history of inheritance,from government officials to ordinary people,under the influence of different media,dissemination and inheritance,become a rich local cultural capital.In the current social development context,the spread of the outlaws of the Marsh is no longer a simple word of mouth.The emergence of high-tech means such as Television and the Internet,as well as the promotion of cultural tourism,has reconstructed the legend of the contemporary water Margin figures.In the process of the reconstruction of the local legend of the water margin in Liangshan,the joint efforts of national forces and market factors have promoted the blending and exchange of three different levels of literature,such as elite literature dominated by the legend of the water margin,popular literature represented by folk quyi and folk literature spread orally by the general public,forming a communication situation of mutual learning,mutual tolerance and interaction between elegance and customs.展开更多
Searching for alternative methods for traditional irrigation is World trend at days due to a reduction in water and increased of drought due to climate changes therefore farmers need use modern methods of scheduling w...Searching for alternative methods for traditional irrigation is World trend at days due to a reduction in water and increased of drought due to climate changes therefore farmers need use modern methods of scheduling water and minimizing water losses while also increasing yield. To meet the future increasing demands water and food there is a need to utilize alternative methods to reduce evaporation, transpiration and deep percolation of water. Any countries use recycled water (drain and sewage) and desalination water from the sea or drains to irrigate crops plus computing actual crop evapotranspiration (ET<sub>c</sub>) so as to calculate the amount of water to apply to a crop. The paper aims to assess the actual evaporation and evaporation coefficient of carrots, by planting carrots in a field and the crop was exposed to several sources of water (DW and RW) and comparing ET<sub>c</sub>, K<sub>c</sub> and production among plots of three sites (A, B and C). The study used two types of irrigation water (drain water (DW) and river water (RW)). The results were to monthly rate and accumulated actual evapotranspiration to C (irrigation by RW only) more than A (67% RW and 33% DW) and B (17% RW and 83% DW) via 7% and 58%, respectively. The yield to C more than A and B by 17% and 75%, respectively. In conclusion the use of DW can cause a reduction in crop consumptive of carrot crops also causes a reduction in yield, crop length, root length, root size, canopy of crop, number of leaves and biomass of the plant therefore, the drainage water needs to treated before irrigating crops And making use of it to irrigate the fields and fill the shortfall in the amount of water from the river. The drain water helped on filling the water shortage due to climate changes and giving production of carrot crop but less than river water.展开更多
In response to the problems of unclear distribution of deep-water pre-salt carbonate reservoirs and formation conditions of large oil fields in the Santos passive continental margin basin,based on comprehensive utiliz...In response to the problems of unclear distribution of deep-water pre-salt carbonate reservoirs and formation conditions of large oil fields in the Santos passive continental margin basin,based on comprehensive utilization of geological,seismic,and core data,and reconstruction of Early Cretaceous prototype basin and lithofacies paleogeography,it is proposed for the first time that the construction of pre-salt carbonate build-ups was controlled by two types of isolated platforms:inter-depression fault-uplift and intra-depression fault-high.The inter-depression fault-uplift isolated platforms are distributed on the present-day pre-salt uplifted zones between depressions,and are built on half-and fault-horst blocks that were inherited and developed in the early intra-continental and inter-continental rift stages.The late intra-continental rift coquinas of the ITP Formation and the early inter-continental rift microbial limestones of the BVE Formation are continuously constructed;intra-depression fault-high isolated platforms are distributed in the current pre-salt depression zones,built on the uplifted zones formed by volcanic rock build-ups in the early prototype stage of intra-continental rifts,and only the BVE microbial limestones are developed.Both types of limestones formed into mound-shoal bodies,that have the characteristics of large reservoir thickness and good physical properties.Based on the dissection of large pre-salt oil fields discovered in the Santos Basin,it has been found that both types of platforms could form large-scale combined structural-stratigraphic traps,surrounded by high-quality lacustrine and lagoon source rocks at the periphery,and efficiently sealed by thick high-quality evaporite rocks above,forming the optimal combination of source,reservoir and cap in the form of“lower generation,middle storage,and upper cap”,with a high degree of oil and gas enrichment.It has been found that the large oil fields are all bottom water massive oil fields with a unified pressure system,and they are all filled to the spill-point.The future exploration is recommended to focus on the inter-depression fault-uplift isolated platforms in the western uplift zone and the southern section of eastern uplift zones,as well as intra-depression fault-high isolated platforms in the central depression zone.The result not only provides an important basis for the advanced selection of potential play fairways,bidding of new blocks,and deployment of awarded exploration blocks in the Santos Basin,but also provides a reference for the global selection of deep-water exploration blocks in passive continental margin basins.展开更多
Marginal water east of the Hainan Island is where internal waves occur frequently. Few studies have been conducted on these internal waves so far, and their formation mechanism remains unclear. In this study, the auth...Marginal water east of the Hainan Island is where internal waves occur frequently. Few studies have been conducted on these internal waves so far, and their formation mechanism remains unclear. In this study, the author uses the China-Brazil Earth Resources Satellite data (CBERS) to detect and calculate the distribution, direction, wavelength and amplitude of internal waves in this area. The results show that the direction of these internal waves is offshore and their wavelength is about 150-200 m. The internal waves can be postulated as formed by upwelling or reversed tide.展开更多
The goal of the study was to model water quality impacts of growing perennial grasses on marginal soils. The GLEAMS-NAPRA and RUSLE models were used to simulate long-term surface runoff, percolation, erosion, total ph...The goal of the study was to model water quality impacts of growing perennial grasses on marginal soils. The GLEAMS-NAPRA and RUSLE models were used to simulate long-term surface runoff, percolation, erosion, total phosphorus (TP), and nitrate (NO3-N) losses associated with the production of corn-based bioenergy systems (i.e. conventional tillage corn and corn grain plus stover removal), switchgrass and Miscanthus on three marginal quality soils and one good quality soil in Indiana. Simulations showed that switchgrass and Miscanthus had no effect on annual runoff, but decreased percolation by at least 17%. Results also suggested a potential for reduction in erosion for Miscanthus across the soil types examined when compared to corn-based bioenergy production. The production of switchgrass and Miscanthus did not have significant effects on the simulated TP and NO3-N losses in runoff compared to corn production systems. Nitrates leached from fertilized Miscanthus production were approximately 90% lower than NO3-N leached from the production of fertilized switchgrass and corn systems. Additional studies are needed to better understand the hydrology, erosion and nutrient responses of Miscanthus and switchgrass production to meet bioenergy demands.展开更多
The tectonic cycle of the marginal sea basins in South China Sea(SCS)includes two cycles,i.e.,the formation and contraction of Palaeo-SCS and Neo-SCS.The northern part of SCS is a rift basin on a passive continental m...The tectonic cycle of the marginal sea basins in South China Sea(SCS)includes two cycles,i.e.,the formation and contraction of Palaeo-SCS and Neo-SCS.The northern part of SCS is a rift basin on a passive continental margin,while the the Nansha Block is a drifting rift basin.The southern part is a compound compressional basin on an active continental margin;the western part is a shear-extensional basin on a transform continental margin;the eastern part is an accretionary wedge basin on a subduction continental margin.The deep-water basins are mainly distributed on the continental slope and the the Nansha Block.There are three sets of source rocks in the deep-water areas of the northern continental margin in SCS,i.e.,Eocene terrestrial facies,early Oligocene transitional facies and late Oligocene marine facies.A set of Late Cretaceous-Early Oligocene terrestrial marine facies source rocks are developed in the drift-rift basin of SCS.Three sets of Oligocene,early Miocene and Mid-Miocene marine-terrestrial transitional facies source rocks are developed in the deep-water areas of both the southern and western continental margins of SCS.Four sets of reservoirs developed in the northern deep waters of SCS are dominated by deep sea fans.Two sets of reservoirs developed in the the Nansha Block are dominated by delta and biogenic reef.The southern part of SCS is dominated by deep sea fan and biogenic reef.Reservoirs of large channels and other clastic facies were developed in front of the estuaries,while biogenic reef bank was formed in the uplift zone.The hydrocarbon accumulation assemblages are mainly presented as Oligocene-Pliocene in the deep waters on the northern continental margin of SCS,Eocene-Lower Oligocene in the the Nansha Block,Oligocene-Pliocene and Oligocene-Miocene in the deep waters on the southern and western continental margin of SCS,respectively.The major hydrocarbon reservoir types in the deep waters of SCS are related to structural traps,deep water fans and biogenic reefs.The formation of basin,hydrocarbon and reservoir in the deep waters of SCS are controlled by the tectonic cycles of the marginal sea basins,revealing a great potential for hydrocarbon exploration.展开更多
Marginalization and abandonment of paddy terraces are widespread,but their effects on the sustainability of subsequent agricultural production are still unknown.Hani Paddy Terraces,included in Globally Important Agric...Marginalization and abandonment of paddy terraces are widespread,but their effects on the sustainability of subsequent agricultural production are still unknown.Hani Paddy Terraces,included in Globally Important Agriculture Heritage Systems,are threatened by paddy fields drainage.Here,changes in terrace structure,the productivity of topsoil(0-20 cm),and soil water holding capacity at 0-70 cm depth were determined in a case study of Hani Paddy Terraces in Amengkong River Basin in Yuanyang County in Southwestern China,which had been converted into dryland terraces for 2-14 years.Our results showed that:(1)The degree of terrace structures degradation exhibited a U-shaped curve with increasing time since draining,with those drained for 5-9 years having the best structure;(2)Soil productivity index decreased first and then increased with time after conversion;(3)Maximum water holding capacity at 0-70 cm soil depth dramatically decreased after conversion and such trend became increasingly obvious with increasing time since conversion.Our study revealed that drainage of paddy terraces along with associated changes in crop and field management led to an increase in soil productivity,but degradation of terrace structures and a decrease in water holding capacity will inhibit restoration to paddy terraces.These findings enhance the understanding of the biophysical changes due to marginalization in paddy terraces.展开更多
基金supported by the National Natural Science Foundation of China(42161007)the Scientific Research Program for Higher Education Institutions of Gansu Province(2021B-081)the Natural Science Foundation of Gansu Province(22JR5RA074).
文摘The isotope composition in precipitation has been widely considered as a tracer of monsoon activity.Compared with the coastal region,the monsoon margin usually has limited precipitation with large fluctuation and is usually sensitive to climate change.The water resource management in the monsoon margin should be better planned by understanding the composition of precipitation isotope and its influencing factors.In this study,the precipitation samples were collected at five sampling sites(Baiyin City,Kongtong District,Maqu County,Wudu District,and Yinchuan City)of the monsoon margin in the northwest of China in 2022 to analyze the characteristics of stable hydrogen(δD)and oxygen(δ18O)isotopes.We analyzed the impact of meteorological factors(temperature,precipitation,and relative humidity)on the composition of precipitation isotope at daily level by regression analysis,utilized the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)-based backward trajectory model to simulate the air mass trajectory of precipitation events,and adopted the potential source contribution function(PSCF)and concentration weighted trajectory(CWT)to analyze the water vapor sources.The results showed that compared with the global meteoric water line(GMWL),the slope of the local meteoric water line(LMWL;δD=7.34δ^(18)O-1.16)was lower,indicating the existence of strong regional evaporation in the study area.Temperature significantly contributed toδ18O value,while relative humidity had a significant negative effect onδ18O value.Through the backward trajectory analysis,we found eight primary locations that were responsible for the water vapor sources of precipitation in the study area,of which moisture from the Indian Ocean to South China Sea(ITSC)and the western continental(CW)had the greatest influence on precipitation in the study area.The hydrogen and oxygen isotopes in precipitation are significantly influenced by the sources and transportation paths of air mass.In addition,the results of PSCF and CWT analysis showed that the water vapor source areas were primarily distributed in the south and northwest direction of the study area.
基金Supported by the Science and Technology Project of CNOOC Ltd.(YXKY-2012-SHENHAI-01)China National Science and Technology Major Project(2011ZX05025-003+1 种基金 2016ZX05026-003)the National Natural Science Foundation of China(91128207)
文摘The relationships between crustal stretching and thinning,basin structure and petroleum geology in Baiyun deep-water area were analyzed using large area 3D seismic,gravity,magnetic,ocean bottom seismic(OBS),deep-water exploration wells and integrated ocean drilling program(IODP).During the early syn-rifting period,deep-water area was a half-graben controlled by high angle faults influenced by the brittle extension of upper crust.In the mid syn-rifting period,this area was a broad-deep fault depression controlled by detachment faults undergone brittle-ductile deformation and differentiated extension in the crust.In the late syn-rifting period,this area experienced fault-sag transition due to saucer-shaped rheology change dominated by crustal ductile deformation.A broad-deep fault depression controlled by the large detachment faults penetrating through the crust is an important feature of deep-water basin.The study suggests that the broad-deep Baiyun sag provides great accommodation space for the development of massive deltaic-lacustrine deposition system and hydrocarbon source rocks.The differentiated lithospheric thinning also resulted in the different thermal subsidence during post-rifting period,and then controlled the development of continental shelf break and deep-water reservoir sedimentary environment.The high heat flow background caused by the strong thinning of lithosphere and the rise of mantle source resulted in particularities in the reservoir diagenesis,hydrocarbon generation process and accumulation of deep-water area in northern South China Sea.
文摘Folklore is an important carrier to show local culture and express people’s emotions in the way of oral transmission.Tradition holds that folklore loses its vitality without oral narration.However,it is difficult to find the traditional context of telling and disseminating folklore only by word of mouth.More often,under the impetus of multiple contexts and different forces,folklore in multiple media is widely spread through mutual reference and integration.The current situation of the water Margin theory circulating in Liangshan area is enough to illustrate this point.Water Margin has a very long history of inheritance,from government officials to ordinary people,under the influence of different media,dissemination and inheritance,become a rich local cultural capital.In the current social development context,the spread of the outlaws of the Marsh is no longer a simple word of mouth.The emergence of high-tech means such as Television and the Internet,as well as the promotion of cultural tourism,has reconstructed the legend of the contemporary water Margin figures.In the process of the reconstruction of the local legend of the water margin in Liangshan,the joint efforts of national forces and market factors have promoted the blending and exchange of three different levels of literature,such as elite literature dominated by the legend of the water margin,popular literature represented by folk quyi and folk literature spread orally by the general public,forming a communication situation of mutual learning,mutual tolerance and interaction between elegance and customs.
文摘Searching for alternative methods for traditional irrigation is World trend at days due to a reduction in water and increased of drought due to climate changes therefore farmers need use modern methods of scheduling water and minimizing water losses while also increasing yield. To meet the future increasing demands water and food there is a need to utilize alternative methods to reduce evaporation, transpiration and deep percolation of water. Any countries use recycled water (drain and sewage) and desalination water from the sea or drains to irrigate crops plus computing actual crop evapotranspiration (ET<sub>c</sub>) so as to calculate the amount of water to apply to a crop. The paper aims to assess the actual evaporation and evaporation coefficient of carrots, by planting carrots in a field and the crop was exposed to several sources of water (DW and RW) and comparing ET<sub>c</sub>, K<sub>c</sub> and production among plots of three sites (A, B and C). The study used two types of irrigation water (drain water (DW) and river water (RW)). The results were to monthly rate and accumulated actual evapotranspiration to C (irrigation by RW only) more than A (67% RW and 33% DW) and B (17% RW and 83% DW) via 7% and 58%, respectively. The yield to C more than A and B by 17% and 75%, respectively. In conclusion the use of DW can cause a reduction in crop consumptive of carrot crops also causes a reduction in yield, crop length, root length, root size, canopy of crop, number of leaves and biomass of the plant therefore, the drainage water needs to treated before irrigating crops And making use of it to irrigate the fields and fill the shortfall in the amount of water from the river. The drain water helped on filling the water shortage due to climate changes and giving production of carrot crop but less than river water.
基金Supported by the National Science and Technology Major Project(2016ZX05029001)CNPC Science and Technology Project(2019D-4310)。
文摘In response to the problems of unclear distribution of deep-water pre-salt carbonate reservoirs and formation conditions of large oil fields in the Santos passive continental margin basin,based on comprehensive utilization of geological,seismic,and core data,and reconstruction of Early Cretaceous prototype basin and lithofacies paleogeography,it is proposed for the first time that the construction of pre-salt carbonate build-ups was controlled by two types of isolated platforms:inter-depression fault-uplift and intra-depression fault-high.The inter-depression fault-uplift isolated platforms are distributed on the present-day pre-salt uplifted zones between depressions,and are built on half-and fault-horst blocks that were inherited and developed in the early intra-continental and inter-continental rift stages.The late intra-continental rift coquinas of the ITP Formation and the early inter-continental rift microbial limestones of the BVE Formation are continuously constructed;intra-depression fault-high isolated platforms are distributed in the current pre-salt depression zones,built on the uplifted zones formed by volcanic rock build-ups in the early prototype stage of intra-continental rifts,and only the BVE microbial limestones are developed.Both types of limestones formed into mound-shoal bodies,that have the characteristics of large reservoir thickness and good physical properties.Based on the dissection of large pre-salt oil fields discovered in the Santos Basin,it has been found that both types of platforms could form large-scale combined structural-stratigraphic traps,surrounded by high-quality lacustrine and lagoon source rocks at the periphery,and efficiently sealed by thick high-quality evaporite rocks above,forming the optimal combination of source,reservoir and cap in the form of“lower generation,middle storage,and upper cap”,with a high degree of oil and gas enrichment.It has been found that the large oil fields are all bottom water massive oil fields with a unified pressure system,and they are all filled to the spill-point.The future exploration is recommended to focus on the inter-depression fault-uplift isolated platforms in the western uplift zone and the southern section of eastern uplift zones,as well as intra-depression fault-high isolated platforms in the central depression zone.The result not only provides an important basis for the advanced selection of potential play fairways,bidding of new blocks,and deployment of awarded exploration blocks in the Santos Basin,but also provides a reference for the global selection of deep-water exploration blocks in passive continental margin basins.
基金supported by the Project of Knowledge Innovation of Chinese Academy of Sciences (KZCX1-YW-12-01)863(2008AA09Z112)+3 种基金National Natural Sciences Foundation of China(40876092)Program of Guangdong Provincial Science &Technology(2008B030303026)Natural Sciences Foundation of Guangdong Province(8351030101000002)Project of Knowledge Innovation of South China Sea Institute of Oceanology(LYQY200701)
文摘Marginal water east of the Hainan Island is where internal waves occur frequently. Few studies have been conducted on these internal waves so far, and their formation mechanism remains unclear. In this study, the author uses the China-Brazil Earth Resources Satellite data (CBERS) to detect and calculate the distribution, direction, wavelength and amplitude of internal waves in this area. The results show that the direction of these internal waves is offshore and their wavelength is about 150-200 m. The internal waves can be postulated as formed by upwelling or reversed tide.
文摘The goal of the study was to model water quality impacts of growing perennial grasses on marginal soils. The GLEAMS-NAPRA and RUSLE models were used to simulate long-term surface runoff, percolation, erosion, total phosphorus (TP), and nitrate (NO3-N) losses associated with the production of corn-based bioenergy systems (i.e. conventional tillage corn and corn grain plus stover removal), switchgrass and Miscanthus on three marginal quality soils and one good quality soil in Indiana. Simulations showed that switchgrass and Miscanthus had no effect on annual runoff, but decreased percolation by at least 17%. Results also suggested a potential for reduction in erosion for Miscanthus across the soil types examined when compared to corn-based bioenergy production. The production of switchgrass and Miscanthus did not have significant effects on the simulated TP and NO3-N losses in runoff compared to corn production systems. Nitrates leached from fertilized Miscanthus production were approximately 90% lower than NO3-N leached from the production of fertilized switchgrass and corn systems. Additional studies are needed to better understand the hydrology, erosion and nutrient responses of Miscanthus and switchgrass production to meet bioenergy demands.
文摘The tectonic cycle of the marginal sea basins in South China Sea(SCS)includes two cycles,i.e.,the formation and contraction of Palaeo-SCS and Neo-SCS.The northern part of SCS is a rift basin on a passive continental margin,while the the Nansha Block is a drifting rift basin.The southern part is a compound compressional basin on an active continental margin;the western part is a shear-extensional basin on a transform continental margin;the eastern part is an accretionary wedge basin on a subduction continental margin.The deep-water basins are mainly distributed on the continental slope and the the Nansha Block.There are three sets of source rocks in the deep-water areas of the northern continental margin in SCS,i.e.,Eocene terrestrial facies,early Oligocene transitional facies and late Oligocene marine facies.A set of Late Cretaceous-Early Oligocene terrestrial marine facies source rocks are developed in the drift-rift basin of SCS.Three sets of Oligocene,early Miocene and Mid-Miocene marine-terrestrial transitional facies source rocks are developed in the deep-water areas of both the southern and western continental margins of SCS.Four sets of reservoirs developed in the northern deep waters of SCS are dominated by deep sea fans.Two sets of reservoirs developed in the the Nansha Block are dominated by delta and biogenic reef.The southern part of SCS is dominated by deep sea fan and biogenic reef.Reservoirs of large channels and other clastic facies were developed in front of the estuaries,while biogenic reef bank was formed in the uplift zone.The hydrocarbon accumulation assemblages are mainly presented as Oligocene-Pliocene in the deep waters on the northern continental margin of SCS,Eocene-Lower Oligocene in the the Nansha Block,Oligocene-Pliocene and Oligocene-Miocene in the deep waters on the southern and western continental margin of SCS,respectively.The major hydrocarbon reservoir types in the deep waters of SCS are related to structural traps,deep water fans and biogenic reefs.The formation of basin,hydrocarbon and reservoir in the deep waters of SCS are controlled by the tectonic cycles of the marginal sea basins,revealing a great potential for hydrocarbon exploration.
基金This work was supported by the National Natural Science Foundation of China[grant numbers 41501592,42061044,42061074].The authors would like to thank Professor Xingwu Duan of Yunnan University for suggestions for experimental design and Jiancheng Deng of Yunnan University and the villagers of Amengkong for their assistance in fieldwork.
文摘Marginalization and abandonment of paddy terraces are widespread,but their effects on the sustainability of subsequent agricultural production are still unknown.Hani Paddy Terraces,included in Globally Important Agriculture Heritage Systems,are threatened by paddy fields drainage.Here,changes in terrace structure,the productivity of topsoil(0-20 cm),and soil water holding capacity at 0-70 cm depth were determined in a case study of Hani Paddy Terraces in Amengkong River Basin in Yuanyang County in Southwestern China,which had been converted into dryland terraces for 2-14 years.Our results showed that:(1)The degree of terrace structures degradation exhibited a U-shaped curve with increasing time since draining,with those drained for 5-9 years having the best structure;(2)Soil productivity index decreased first and then increased with time after conversion;(3)Maximum water holding capacity at 0-70 cm soil depth dramatically decreased after conversion and such trend became increasingly obvious with increasing time since conversion.Our study revealed that drainage of paddy terraces along with associated changes in crop and field management led to an increase in soil productivity,but degradation of terrace structures and a decrease in water holding capacity will inhibit restoration to paddy terraces.These findings enhance the understanding of the biophysical changes due to marginalization in paddy terraces.