Organic-rich sediments represent vital components of Earth's geochemical cycles, acting both as potential hydrocarbon and coal reservoirs and as unconventional archives for critical metals such as rare earth eleme...Organic-rich sediments represent vital components of Earth's geochemical cycles, acting both as potential hydrocarbon and coal reservoirs and as unconventional archives for critical metals such as rare earth elements(REEs). With the growing emphasis on clean energy technologies, the Cenozoic organic deposits of India have gained renewed significance;however, those from the southern state of Kerala remain understudied. This study investigates lignite and associated carbonaceous sediments from the Cheruvathur and Warkalli Formations using a multi-proxy approach integrating organic petrography,infrared spectroscopy, stable carbon isotopes, and REE geochemistry. The lignite exhibits huminite dominance with Type Ⅲ kerogen, deposited in a wet, mesotropic bog forest swamp under anoxic conditions. The mineral assemblage, dominated by kaolinite, quartz, illite, montmorillonite, feldspar,and pyrite/marcasite, reflects strong chemical alteration in a reducing environment. The δ^(13)C values(-25.1 to-27.3) indicate a C_(3) angiosperm source and deposition in tropical to subtropical swamp settings. REE patterns reveal LREE enrichment in carbonaceous shales and HREE enrichment in lignite,with distinct Ce, Eu, and Gd anomalies associated with provenance and redox conditions. The findings provide new insights into the paleoenvironmental evolution of Kerala's Cenozoic basins and highlight their potential as unconventional REE-bearing resources in the context of the global energy transition.展开更多
本文基于固城湖湖相沉积物中的元素地球化学、磁化率和粒度指标,高分辨率重建苏皖沿江平原全新世以来的水文气候变化;进而结合先秦时期考古遗址的时空分布特征,探讨研究区人地关系的演变历程。结果表明,11.5—7.0 cal ka BP期间,经历新...本文基于固城湖湖相沉积物中的元素地球化学、磁化率和粒度指标,高分辨率重建苏皖沿江平原全新世以来的水文气候变化;进而结合先秦时期考古遗址的时空分布特征,探讨研究区人地关系的演变历程。结果表明,11.5—7.0 cal ka BP期间,经历新仙女木(YD)冷干事件后,气候迅速转为最温暖湿润期,但波动频繁;7.0—5.0 cal ka BP前期气候有向冷干转变的趋势,后期气候暖湿,湖泊水位稳定;5.0—4.0 cal ka BP气候逐渐变干;4.0—1.5 cal ka BP气候波动频繁,经历“湿润—干旱—湿润”的转变过程。1.5 cal ka BP以来人类对环境的影响显著加强。上述水文气候演变过程影响了遗址的空间分布、农业发展和文化兴衰。新石器早期气候波动频繁,人类过于依赖环境,文明发展缓慢;新石器中晚期稳定的水文气候条件为农业发展奠定了生境基础,促进人口扩张;夏时期气候急剧恶化失衡,遗址数量骤减、文化衰退;商周时期水文气候恶劣,人类通过改变生产战略和技术革新以谋求自身生存和发展。随着生产力水平的提高,人地关系演变的主导因子由自然因素逐渐向人为因素倾斜,在一定限度内冷干或暖湿的气候都能推动人类文明的发展。人类从被动顺应到主动适应自然环境,体现了人类与自然环境之间的博弈过程。展开更多
[目的]探究中晚全新世环境演化与人类活动之间的相互作用.[方法]针对南海北部泥质陆架区B1047和B1104站位沉积物系统开展粒度、主微量元素、稀土元素、黏土矿物及AMS 14 C等测年综合分析,揭示该地区5.2 ka BP以来的陆源碎屑来源以及环...[目的]探究中晚全新世环境演化与人类活动之间的相互作用.[方法]针对南海北部泥质陆架区B1047和B1104站位沉积物系统开展粒度、主微量元素、稀土元素、黏土矿物及AMS 14 C等测年综合分析,揭示该地区5.2 ka BP以来的陆源碎屑来源以及环境对人类活动的响应机制.[结果]物源分析表明,两站位沉积物主要来源于珠江沿岸流和海南岛碎屑物质,还有少量物质来源于琼州海峡.粒度端元模拟识别出3个端元,EM1/EM3比值对应于南海沿岸流体系中冬季风驱动的华南沿岸流的强弱,反映出东亚季风强弱变化;CIA、Rb/Sr以及黏土矿物比值指示化学风化强度变化.结果显示,化学风化指标与黏土矿物比值的变化呈现频繁波动并持续增强的趋势,重金属富集因子在2.2 ka BP以后与化学风化指标同步增强.[结论]结合粒度、黏土矿物分析以及地球化学元素分析表明,琼州海峡东5.2 ka BP以来的环境-人类活动变化大致可分为3个阶段:5.2~4.5 ka BP期间,南海北部的环境演化过程受气候变冷引发的海平面下降控制;4.5~2.2 ka BP期间,化学风化指标的增强与人类活动的初始增强阶段有关,是人类活动成为主导地质活动开始的时间;2.2 ka BP以来,重金属元素排放强度与化学风化指标呈同步升高特征,人类活动的增强逐渐超过了自然气候对华南大陆的控制,而人类活动反过来又受到东亚季风变化的影响.这些研究结果印证了人类文明发展与自然环境变化相互制约与依存的人地关系,为理解华南地区史前人地关系的演变提供了新的证据.展开更多
In addition to its well-known fossils,the Upper Miocene Baogeda Ula Formation is coupled with multiple basaltic lava flows,creating an ideal setting for studying its depositional history,geochronology,and associated v...In addition to its well-known fossils,the Upper Miocene Baogeda Ula Formation is coupled with multiple basaltic lava flows,creating an ideal setting for studying its depositional history,geochronology,and associated vertebrate fossils.This paper,in honor of Prof.Qiu Zhanxiang for his widely admired emphasis on the geological contexts of vertebrate fossils,attempts to synthesize known contact relationships,existing K-Ar dates,and capping basalt elevations to reframe our concept of the lithostratigraphy,magnetostratigraphy,and lateral distribution of the Baogeda Ula Formation.Within this new framework,the Baogeda Ula Formation is defined by unconformable contact with the underlying Tunggur Formation at the lower boundary and a capping basalt at the upper boundary.In many sections,two or three layers of basalts are interbedded within sedimentary strata,with the capping basalts typically belonging to the top two basalts.The newly defined Baogeda Ula Formation includes a lower member as exemplified by Halajin Hushu section and Ulan Hushuyin Nur section,and an upper member at Baogeda Ula section.This expanded concept of the Baogeda Ula Formation includes two major faunas,i.e.,the Bahean Halajin Hushu Fauna and Baodean Baogeda Ula Fauna,both falling within the Upper Miocene.We also describe rare fossil skunks(Promephitis)found in recent years that support the age assessments presented herein.展开更多
Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(AC...Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(ACA)region.However,debate persists regarding whether dryland lakes in this region exhibited aridification or humidification during the Holocene.Lopnur serves as the terminal lake of Tarim rivers during the Holocene,which offers an ideal natural laboratory to address the questions.In this study,a high-resolution chronological framework was established through precise radiocarbon dating.Multi-proxy analyses,including geochemical composition,grain size distributions,MS,LOI,and C/N ratios were conducted from a lacustrine profile in the core area of“Great ear”in the southern part of Lopnur catchment.These analyses enabled the reconstruction of hydrological dynamics and facilitated the disentanglement of independent signals linked to climate variability,runoff fluctuations,and lake-level changes.The results demonstrate that the MidHolocene(7800–4000 cal yr B.P.)was characterized by cold and humid conditions,resulting in elevated surface runoff and lake level.The Late Holocene(4000–1300 cal yr B.P.)experienced intensified aridification,characterized by reduced runoff and declining lake level.These evidences suggested a climatic regime of a distinctive alternation between“cold-wet”and“warm-dry”climatic regimes during the Mid-to-Late Holocene.Compared with the previous studies from adjacent regions,we speculate that the hydroclimatic evolution of Lopnur catchment possibly influenced by a complex interplay of large spatial scale forcings,including variations in annual insolation,greenhouse gas concentrations,and ice sheets,as well as the localized controls such as topographic features,vegetation cover,and cloud-radiative feedbacks.Our findings enhance the understanding of past climatic complexity and provide valuable insights for future water resource management strategies in drylands.展开更多
文摘Organic-rich sediments represent vital components of Earth's geochemical cycles, acting both as potential hydrocarbon and coal reservoirs and as unconventional archives for critical metals such as rare earth elements(REEs). With the growing emphasis on clean energy technologies, the Cenozoic organic deposits of India have gained renewed significance;however, those from the southern state of Kerala remain understudied. This study investigates lignite and associated carbonaceous sediments from the Cheruvathur and Warkalli Formations using a multi-proxy approach integrating organic petrography,infrared spectroscopy, stable carbon isotopes, and REE geochemistry. The lignite exhibits huminite dominance with Type Ⅲ kerogen, deposited in a wet, mesotropic bog forest swamp under anoxic conditions. The mineral assemblage, dominated by kaolinite, quartz, illite, montmorillonite, feldspar,and pyrite/marcasite, reflects strong chemical alteration in a reducing environment. The δ^(13)C values(-25.1 to-27.3) indicate a C_(3) angiosperm source and deposition in tropical to subtropical swamp settings. REE patterns reveal LREE enrichment in carbonaceous shales and HREE enrichment in lignite,with distinct Ce, Eu, and Gd anomalies associated with provenance and redox conditions. The findings provide new insights into the paleoenvironmental evolution of Kerala's Cenozoic basins and highlight their potential as unconventional REE-bearing resources in the context of the global energy transition.
文摘本文基于固城湖湖相沉积物中的元素地球化学、磁化率和粒度指标,高分辨率重建苏皖沿江平原全新世以来的水文气候变化;进而结合先秦时期考古遗址的时空分布特征,探讨研究区人地关系的演变历程。结果表明,11.5—7.0 cal ka BP期间,经历新仙女木(YD)冷干事件后,气候迅速转为最温暖湿润期,但波动频繁;7.0—5.0 cal ka BP前期气候有向冷干转变的趋势,后期气候暖湿,湖泊水位稳定;5.0—4.0 cal ka BP气候逐渐变干;4.0—1.5 cal ka BP气候波动频繁,经历“湿润—干旱—湿润”的转变过程。1.5 cal ka BP以来人类对环境的影响显著加强。上述水文气候演变过程影响了遗址的空间分布、农业发展和文化兴衰。新石器早期气候波动频繁,人类过于依赖环境,文明发展缓慢;新石器中晚期稳定的水文气候条件为农业发展奠定了生境基础,促进人口扩张;夏时期气候急剧恶化失衡,遗址数量骤减、文化衰退;商周时期水文气候恶劣,人类通过改变生产战略和技术革新以谋求自身生存和发展。随着生产力水平的提高,人地关系演变的主导因子由自然因素逐渐向人为因素倾斜,在一定限度内冷干或暖湿的气候都能推动人类文明的发展。人类从被动顺应到主动适应自然环境,体现了人类与自然环境之间的博弈过程。
文摘[目的]探究中晚全新世环境演化与人类活动之间的相互作用.[方法]针对南海北部泥质陆架区B1047和B1104站位沉积物系统开展粒度、主微量元素、稀土元素、黏土矿物及AMS 14 C等测年综合分析,揭示该地区5.2 ka BP以来的陆源碎屑来源以及环境对人类活动的响应机制.[结果]物源分析表明,两站位沉积物主要来源于珠江沿岸流和海南岛碎屑物质,还有少量物质来源于琼州海峡.粒度端元模拟识别出3个端元,EM1/EM3比值对应于南海沿岸流体系中冬季风驱动的华南沿岸流的强弱,反映出东亚季风强弱变化;CIA、Rb/Sr以及黏土矿物比值指示化学风化强度变化.结果显示,化学风化指标与黏土矿物比值的变化呈现频繁波动并持续增强的趋势,重金属富集因子在2.2 ka BP以后与化学风化指标同步增强.[结论]结合粒度、黏土矿物分析以及地球化学元素分析表明,琼州海峡东5.2 ka BP以来的环境-人类活动变化大致可分为3个阶段:5.2~4.5 ka BP期间,南海北部的环境演化过程受气候变冷引发的海平面下降控制;4.5~2.2 ka BP期间,化学风化指标的增强与人类活动的初始增强阶段有关,是人类活动成为主导地质活动开始的时间;2.2 ka BP以来,重金属元素排放强度与化学风化指标呈同步升高特征,人类活动的增强逐渐超过了自然气候对华南大陆的控制,而人类活动反过来又受到东亚季风变化的影响.这些研究结果印证了人类文明发展与自然环境变化相互制约与依存的人地关系,为理解华南地区史前人地关系的演变提供了新的证据.
文摘In addition to its well-known fossils,the Upper Miocene Baogeda Ula Formation is coupled with multiple basaltic lava flows,creating an ideal setting for studying its depositional history,geochronology,and associated vertebrate fossils.This paper,in honor of Prof.Qiu Zhanxiang for his widely admired emphasis on the geological contexts of vertebrate fossils,attempts to synthesize known contact relationships,existing K-Ar dates,and capping basalt elevations to reframe our concept of the lithostratigraphy,magnetostratigraphy,and lateral distribution of the Baogeda Ula Formation.Within this new framework,the Baogeda Ula Formation is defined by unconformable contact with the underlying Tunggur Formation at the lower boundary and a capping basalt at the upper boundary.In many sections,two or three layers of basalts are interbedded within sedimentary strata,with the capping basalts typically belonging to the top two basalts.The newly defined Baogeda Ula Formation includes a lower member as exemplified by Halajin Hushu section and Ulan Hushuyin Nur section,and an upper member at Baogeda Ula section.This expanded concept of the Baogeda Ula Formation includes two major faunas,i.e.,the Bahean Halajin Hushu Fauna and Baodean Baogeda Ula Fauna,both falling within the Upper Miocene.We also describe rare fossil skunks(Promephitis)found in recent years that support the age assessments presented herein.
基金supported by the National Natural Science Foundation of China(No.42001084)the Major Science and Technology Projects of Xinjiang Uygur Autonomous Region(Nos.2022A03009-2,2022A03009)the Third Xinjiang Scientific Expedition Program(No.2022xjkk1303)。
文摘Exploring hydroclimatic variability and its driving mechanisms during the Holocene is essential for comprehending both historical and prospective responses of water resources to climatic shifts in Arid Central Asia(ACA)region.However,debate persists regarding whether dryland lakes in this region exhibited aridification or humidification during the Holocene.Lopnur serves as the terminal lake of Tarim rivers during the Holocene,which offers an ideal natural laboratory to address the questions.In this study,a high-resolution chronological framework was established through precise radiocarbon dating.Multi-proxy analyses,including geochemical composition,grain size distributions,MS,LOI,and C/N ratios were conducted from a lacustrine profile in the core area of“Great ear”in the southern part of Lopnur catchment.These analyses enabled the reconstruction of hydrological dynamics and facilitated the disentanglement of independent signals linked to climate variability,runoff fluctuations,and lake-level changes.The results demonstrate that the MidHolocene(7800–4000 cal yr B.P.)was characterized by cold and humid conditions,resulting in elevated surface runoff and lake level.The Late Holocene(4000–1300 cal yr B.P.)experienced intensified aridification,characterized by reduced runoff and declining lake level.These evidences suggested a climatic regime of a distinctive alternation between“cold-wet”and“warm-dry”climatic regimes during the Mid-to-Late Holocene.Compared with the previous studies from adjacent regions,we speculate that the hydroclimatic evolution of Lopnur catchment possibly influenced by a complex interplay of large spatial scale forcings,including variations in annual insolation,greenhouse gas concentrations,and ice sheets,as well as the localized controls such as topographic features,vegetation cover,and cloud-radiative feedbacks.Our findings enhance the understanding of past climatic complexity and provide valuable insights for future water resource management strategies in drylands.
