In the development of sustainable lithium-ion batteries,achieving the efficient and cost-effective recycling of all components,particularly spent graphite(SG)anodes,has become a critical requirement.While considerable...In the development of sustainable lithium-ion batteries,achieving the efficient and cost-effective recycling of all components,particularly spent graphite(SG)anodes,has become a critical requirement.While considerable ef-forts have been devoted to recovering and reusing SG materials under conventional conditions,limited attention has been given to recycling under extreme conditions.This review systematically elucidates the main failure mechanisms of graphite anodes,including lithium plating and dendrite formation,solid electrolyte interface film failure,structural degradation,and current collector corrosion,with a particular focus on low-temperature and fast-charging conditions.As a contribution toward optimizing resource utilization,this review comprehensively summarizes the industrial perspective on strategies for recycling SG anodes,which aim to produce high-purity regenerated graphite(RG)powders.We also analyze current methods for modifying RG,such as structural reconstruction and surface reconditioning,to bring added value to modified RG materials.A detailed examination of the technical challenges in SG recycling and RG upgrading is presented,offering guidance for the future development of graphite upcycling technologies.This review also provides valuable insights into achieving high efficiency,intelligence,and sustainability in graphite utilization.展开更多
Fluoroethylene carbonate(FEC)is frequently added to the electrolyte in low-temperature lithium metal batteries to improve performance.However,its use results in a Li_(2)CO_(3)-rich solid electrolyte interphase(SEI)on ...Fluoroethylene carbonate(FEC)is frequently added to the electrolyte in low-temperature lithium metal batteries to improve performance.However,its use results in a Li_(2)CO_(3)-rich solid electrolyte interphase(SEI)on the lithium anode,which leads to continuous thickening of the SEI under low-temperature cycling.In this study,the local high-concentration electrolyte was utilized to optimize the solvation structure of Li^(+),thereby adjusting the composition and structure of the SEI.Consequently,the Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cell achieved over 99.5%Coulombic efficiency at-20℃ and sustained over 50 cycles at a 1 C rate at-40℃,with a specific capacity exceeding 110 mAh/g and a high Coulombic efficiency above 99%.The combined use of ethyl acetate(EA)and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether(TFTFE)promoted the formation of a layered SEI on the lithium anode,enabling efficient Li^(+)desolvation at low temperatures.This provides a novel strategy for designing lowtemperature lithium metal battery electrolytes.展开更多
Quaternary strata in China mainly comprise continental deposits in a variety of depositional settings. The continental Quaternary in temperate northern China consists mainly of eolian and fluvio-lacustrine deposits; t...Quaternary strata in China mainly comprise continental deposits in a variety of depositional settings. The continental Quaternary in temperate northern China consists mainly of eolian and fluvio-lacustrine deposits; that in subtropical southern China, mainly of vermiculated red soils, cave/fissure deposits, and fluvio-lacustrine deposits; and that in the alpine Tibetan Plateau, mainly of fluvio-lacustrine and piedmont deposits. The marine Quaternary in China consists of detrital deposits and biogenic reef deposits. The integration of biostratigraphy, magnetostratigraphy, climatostratigraphy and an astronomically calibrated chronology has led to the establishment of high-precision climatochronostratigraphic timescales for the detrital marine Quaternary in the South China Sea and the loess-paleosol sequence in the Chinese Loess Plateau. Extremely high-precision230 Th dating has provided a high-precision absolute age model for cave stalagmites over the past 640000 years as well as highresolution oxygen isotope records representing orbital-to suborbital-scale climate changes. By combining magnetic stratigraphy and biostratigraphy, robust chronostratigraphic frameworks for non-eolian continental Quaternary deposits on the scale of Quaternary geomagnetic polarities have been established. The continental Pleistocene Series consists, from oldest to youngest,of the Nihewanian Stage of the Lower Pleistocene, the Zhoukoudianian Stage of the Middle Pleistocene, and the Salawusuan Stage of the Upper Pleistocene. Stages of the continental Holocene Series have not yet been established. This review summarizes recent developments in the Quaternary chronostratigraphy of representative Quaternary strata and associated faunas, and then proposes an integrative chronostratigraphic framework and a stratigraphic correlation scheme for Quaternary continental strata in China. In the near-future, it is hoped to establish not only a Chinese continental Quaternary climatochronostratigraphic chart on the scale of glacial-interglacial cycles but also a Quaternary integrative chronostratigraphic chart including both continental and marine strata in China.展开更多
The Mid-Miocene Climatic Optimum(MMCO;15-17 Ma)was one of the short-term climatic warm events that punctuated the Cenozoic long-term cooling trend.Because there are very few terrestrial records of this event,most of o...The Mid-Miocene Climatic Optimum(MMCO;15-17 Ma)was one of the short-term climatic warm events that punctuated the Cenozoic long-term cooling trend.Because there are very few terrestrial records of this event,most of our understanding comes from marine cores.In this report,we first present new palaeomagnetic data that revises the dating of our 400 m-thick lacustrine section in Wenshan(Yunnan),previously thought to be Late Mio-cene.These new data suggest an older age,ca.15.2-16.5 Ma,coinciding with the MMCO.We measuredδ13C on bulk organic matter(3 Corg),total organic carbon(TOC),total nitrogen(TN)and C/N ratios at a high sample resolution to:(1)reconstruct the palaeoenvironmental changes in the lake catchment area,and(2)infer mechanisms responsible for these changes.Our results show that all four geochemical parameters demonstrate that a strong environmental change occurred around the middle of the section,shortly after the C5Cn/C5Br geomagnetic reversal and the Early/Middle Miocene boundary at 15.97 Ma.We propose that the environmental shift may be due to a combination of a change in climate,which became cooler,together with a change in organic matter cycling within the lake.This study provides a new insight into the MMCO and demonstrates that although the MMCO was generally a warm event,it was also a time of climatic instability and abrupt environmental changes.展开更多
In order to provide direct evidence for the use of fire by humans at Locality 1,Zhoukoudian,we examine the burnt and unburnt sediments of newly excavated area in Layer 4 by detailed measurements of magnetic susceptibi...In order to provide direct evidence for the use of fire by humans at Locality 1,Zhoukoudian,we examine the burnt and unburnt sediments of newly excavated area in Layer 4 by detailed measurements of magnetic susceptibility,color,and diffuse reflectance spectrum.Results show that the magnetic susceptibility and redness of the burnt sediments are remarkably higher than those of other areas on the same level:up to*22 times for magnetic susceptibility and*3 times for redness of those of the adjacent unburnt sediments.Fine-grained(superparamagnetic/stable single-domain)magnetite and hematite grains make dominant contributions to the distinctly high values of magnetic susceptibility and redness in the burnt sediments.Diffuse reflectance spectroscopy results show that the burnt sediments contain more hematite than those of other areas and localities 2 and 3.High-temperature magnetic susceptibility measurements demonstrate that the burnt sediments have been heated above 700°C.Those changes in low-frequency magnetic susceptibility and redness are impossibly resulted from natural fires,thus most likely signaling the human activities of controlled use of fire.However,further work is needed to confirm whether or not these heat-affected sediments were produced in situ.展开更多
The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in u...The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM.(1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr(thousand years) periodicity, while the cave oxygen-isotope(δ18 O) records reveal periodicity in an almost pure precession band(~20 kyr periodicity)—the "Chinese 100 kyr problem".(2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation(NHSI), whereas the Asian cave δ18 O records follow NHSI without a significant lag—a discrepancy termed the "sea-land precession-phase paradox". How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the "Chinese 100 kyr problem" and "sea-land precession-phase paradox".展开更多
The Songliao Basin,northeastern China(Fig.1a),is one of the largest non-marine petroliferous basins in the world and contains a nearly complete Cretaceous terrestrial sedimentary sequences.This succession provides vit...The Songliao Basin,northeastern China(Fig.1a),is one of the largest non-marine petroliferous basins in the world and contains a nearly complete Cretaceous terrestrial sedimentary sequences.This succession provides vital information that can improve our knowledge of a series of important geodynamical,geological,and paleoenvironmental events[1,2].The lower Cretaceous Shahezi Formation,which is the main source rock strata in the basin,formed during the rifting stage of the basin and consists of gray to black lacustrine and floodplain mudstones and siltstones interbedded with gray sandstones and conglomerates.The unit overlies the Huoshiling Formation and is overlain by the Yingcheng Formation(Fig.1b).展开更多
Euryale （Nymphaeaceae） is a monotypic genus distributed in eastern Asia, but fossils in its native distribu- tion are sparse as compared to Europe where the genus has disappeared. Here, we describe a new fossil spec...Euryale （Nymphaeaceae） is a monotypic genus distributed in eastern Asia, but fossils in its native distribu- tion are sparse as compared to Europe where the genus has disappeared. Here, we describe a new fossil species, Euryale yunnanensis sp. nov., from the late Miocene Zhaotong Basin in southwestern China on the basis of seed remains. Char- acteristics including an ellipsoidal to almost spherical shape, a smooth surface, a germination cap that covers the micro- pyle, the separation of the hilum and germination cap （mi- cropyle）, elliptic testa surface cells with undulate margins and thickened cell walls collectively indicate a close affinity with the genus Euryale in Nymphaeaceae. Comparisons of seed morphology and anatomy demonstrate that the newly described fossil species differs from modem and other fossil species of Euryale and thus verify the assignment to a new fossil species. As the modem Euryale is an aquatic plant, preferably living in swamps and lakes with shallow and stable water, we hypothesize that a lake and/or swamp environment with shallow water was present near Shui- tangba in the Zhaotong Basin, where the Shuitangba homi- noid lived during the late Miocene. This inference is generally consistent with paleoenvironmental data extracted from avian, fish, frog, turtle and crocodile fossils, as well as from aquatic pollen. The fossil history suggests a compara- tively recent （Miocene） emergence of Euryale, which is roughly in agreement with the divergence time inferred from the molecular information.展开更多
A new occurrence of buckthorn fossil leaves is reported from the upper Eocene strata of Markam Basin,southeastern Tibet,China.The leaf margin is either entire or slightly sinuous.Secondary veins are regularly spaced,f...A new occurrence of buckthorn fossil leaves is reported from the upper Eocene strata of Markam Basin,southeastern Tibet,China.The leaf margin is either entire or slightly sinuous.Secondary veins are regularly spaced,forming eucamptodromous venation.These secondaries exist as straight lines from midvein to near margin and then arch abruptly upward and enter into a margin vein.The tertiary veins are densely spaced and parallel,and are percurrent to secondary veins.This leaf architecture conforms with Berhamniphyllum Jones and Dilcher,an extinct fossil genus reported from America.Our fossils are characterized by their dense secondaries,with secondary veins on the upper half portion of the blade accounting for over 40%of all secondaries.A new species,Berhamniphyllum junrongiae Z.K.Zhou,T.X.Wang et J.Huang sp.nov.,is proposed.Further analysis shows that confident assignment among Rhamnidium,Berchemia,and Karwinskia cannot be made based on leaf characters alone.Berhamniphyllum might represent an extinct common ancestor of these genera.In this study,several fossil Berchemia from Yunnan and Shandong are emended and reassigned to Berhamniphyllum.A new complex,namely the Berchemia Complex,is proposed based on morphology,molecular evidence,and the fossil record.This complex contains the fossil leaves of Rhamnidium,Karwinskia,Berchemia,and Berhamniphyllum.The historical biogeography of the Berchemia Complex is also discussed in this paper.This complex might have originated in the late Cretaceous in Colombia,South America,and dispersed to North America via Central America during the Eocene.Subsequently,the complex moved from North America to East Asia via the Bering Land Bridge no later than the late Eocene.Besides,the complex migrated from North America to Europe via the North Atlantic Land Bridge and then migrated further to Africa.In East Asia,it first appeared in Markam on the Qinghai-Tibetan Plateau,and then dispersed to other regions of Asia.展开更多
The tropical reef ecosystems are created by living organisms,such as corals and algae,and provide important habitats for millions of people and a variety of marine life,which have been severely threatened by climate c...The tropical reef ecosystems are created by living organisms,such as corals and algae,and provide important habitats for millions of people and a variety of marine life,which have been severely threatened by climate changes over the past decades[1].These biogenic reefs account for a quarter of global CaCO_(3)production and thus are critical to global carbon cycling[2,3].展开更多
The timing and mechanisms of the human occupation of the demanding high-altitude Tibetan Plateau environment are of great interest.Here,we report on our reinvestigations and dating of the Nwya Devu site,located nearly...The timing and mechanisms of the human occupation of the demanding high-altitude Tibetan Plateau environment are of great interest.Here,we report on our reinvestigations and dating of the Nwya Devu site,located nearly 4600 meters above sea level on the central Tibetan Plateau.A new microblade techno-complex was identified on a lower lake shore at this site,distinct from the previously reported blade tool assemblage.These two lithic assemblages were dated to 45.6±2.6 and10.3±0.5 ka using optically stimulated luminescence and accelerator mass spectrometry^(14)C methods.They represent,respectively,the earliest known Paleolithic and microlithic sites on the interior Tibetan Plateau,indicating multiple occupation episodes of hunter-gatherers during the past 45 ka.Our studies reveal that relatively stable depositional conditions and a paleoenvironment characterized by a comparatively warm climate facilitated these multiple occupations at Nwya Devu.The contemporaneous occurrence of the Upper Paleolithic blade technology on the Tibetan Plateau and most of Eurasia between 50 and 40 ka indicates rapid,large-scale dispersals of humans that profoundly affected human demography on a large scale.Combining new archaeological evidence and previously reported genetic data,we conclude that the Tibetan Plateau provided a relatively stable habitat for Upper Paleolithic hunter-gatherers,which may have contributed to the complex and multiple-origin gene pool of present-day Tibetans.展开更多
Biogenic reefs are one of two major depositional types in the South China Sea, and are constructed by coral, algae and bryozoa. The West Pacific is a major area of biogenic reef development and plays a critical role i...Biogenic reefs are one of two major depositional types in the South China Sea, and are constructed by coral, algae and bryozoa. The West Pacific is a major area of biogenic reef development and plays a critical role in the global carbon cycle. However, the lack of geochronological studies in previous works inhibits our understanding of their contributions. Herein, we conduct a cyclostratigraphic and magnetostratigraphic study on Neogene biogenic reefs using the XK–1 core that was drilled at the Shidao Island,Xisha(Paracel) Islands. The main findings of this study are:(1) the establishment of reliable magentostratigraphy for Ledong, Huangliu, Meishan and Sanya Formations;(2) the magnetic susceptibility variation can be inferred as growth index and tuned to the 405–ka long eccentricity cycle;(3) the astronomical geochronology suggests that the bottom ages for Ledong, Yinggehai, Huangliu, Meishan,and Sanya Formations are 2.2 Ma, 5.7 Ma, 10.4 Ma, 16.6 Ma, and 24.3 Ma, respectively; and (4) Earth's eccentricity and obliquity played predominant roles in biogenic reef establishment on orbital to tectonic timescales. Thus, the reported geochronology offers an opportunity to test the contributions of various factors and hypothesize their roles in the global carbon cycle in future.展开更多
Volcanic arc degassing contributes significantly to atmospheric CO_(2)levels and therefore has a pivotal impact on paleoclimate changes.The Neo-Tethyan decarbonation subduction is thought to have played a major role in...Volcanic arc degassing contributes significantly to atmospheric CO_(2)levels and therefore has a pivotal impact on paleoclimate changes.The Neo-Tethyan decarbonation subduction is thought to have played a major role in Cenozoic climate changes,although there are still no quantifiable restrictions.Here we build past subduction scenarios using an improved seismic tomography reconstruction method and cal-culate the subducted slabflux in the India-Eurasia collision region.Wefind remarkable synchronicity between calculated slabflux and paleoclimate parameters in the Cenozoic,indicating a causal link between these processes.The closure of the Neo-Tethyan intra-oceanic subduction resulted in more carbon-rich sediments subducting along the Eurasia margin,as well as continental arc volcanoes,which further triggered global warming up to the Early Eocene Climatic Optimum.The abrupt termination of the Neo-Tethyan subduction due to the India-Eurasia collision could be the primary tectonic cause of the~50-40 Ma CO_(2)drop.The gradual decrease in atmospheric CO_(2)concentration after 40 Ma may be attributed to enhance continental weathering due to the growth of the Tibetan Plateau.Our results con-tribute to a better understanding of the dynamic implications of Neo-Tethyan Ocean evolution and may provide new constraints for future carbon cycle models.展开更多
基金supported by the National Natural Science Foundation of China(grant numbers 52374410,22209006)the Natural Science Foundation of Shandong Province(grant numbers ZR2022QE009)+3 种基金Beijing Natural Science Foundation(grant numbers Z220021)the National Key R&D Program of China(grant numbers 2022YFB3305400)the Joint Funds of the National Natural Science Foundation of China(grant numbers U2130204)Beijing Outstanding Young Scientists Program(grant numbers BJJWZYJH01201910007023).
文摘In the development of sustainable lithium-ion batteries,achieving the efficient and cost-effective recycling of all components,particularly spent graphite(SG)anodes,has become a critical requirement.While considerable ef-forts have been devoted to recovering and reusing SG materials under conventional conditions,limited attention has been given to recycling under extreme conditions.This review systematically elucidates the main failure mechanisms of graphite anodes,including lithium plating and dendrite formation,solid electrolyte interface film failure,structural degradation,and current collector corrosion,with a particular focus on low-temperature and fast-charging conditions.As a contribution toward optimizing resource utilization,this review comprehensively summarizes the industrial perspective on strategies for recycling SG anodes,which aim to produce high-purity regenerated graphite(RG)powders.We also analyze current methods for modifying RG,such as structural reconstruction and surface reconditioning,to bring added value to modified RG materials.A detailed examination of the technical challenges in SG recycling and RG upgrading is presented,offering guidance for the future development of graphite upcycling technologies.This review also provides valuable insights into achieving high efficiency,intelligence,and sustainability in graphite utilization.
基金supported by the Key Research and Development Program of Shandong Province,China(2021CXGC010401)the National Key Research and Development Program of China(2022YFB2502102)+1 种基金the National Natural Science Foundation of China(52272185)the Beijing Outstanding Young Scientists Program(BJJWZYJH01201910007023).
文摘Fluoroethylene carbonate(FEC)is frequently added to the electrolyte in low-temperature lithium metal batteries to improve performance.However,its use results in a Li_(2)CO_(3)-rich solid electrolyte interphase(SEI)on the lithium anode,which leads to continuous thickening of the SEI under low-temperature cycling.In this study,the local high-concentration electrolyte was utilized to optimize the solvation structure of Li^(+),thereby adjusting the composition and structure of the SEI.Consequently,the Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cell achieved over 99.5%Coulombic efficiency at-20℃ and sustained over 50 cycles at a 1 C rate at-40℃,with a specific capacity exceeding 110 mAh/g and a high Coulombic efficiency above 99%.The combined use of ethyl acetate(EA)and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether(TFTFE)promoted the formation of a layered SEI on the lithium anode,enabling efficient Li^(+)desolvation at low temperatures.This provides a novel strategy for designing lowtemperature lithium metal battery electrolytes.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41690110, 41621004 and L152401)
文摘Quaternary strata in China mainly comprise continental deposits in a variety of depositional settings. The continental Quaternary in temperate northern China consists mainly of eolian and fluvio-lacustrine deposits; that in subtropical southern China, mainly of vermiculated red soils, cave/fissure deposits, and fluvio-lacustrine deposits; and that in the alpine Tibetan Plateau, mainly of fluvio-lacustrine and piedmont deposits. The marine Quaternary in China consists of detrital deposits and biogenic reef deposits. The integration of biostratigraphy, magnetostratigraphy, climatostratigraphy and an astronomically calibrated chronology has led to the establishment of high-precision climatochronostratigraphic timescales for the detrital marine Quaternary in the South China Sea and the loess-paleosol sequence in the Chinese Loess Plateau. Extremely high-precision230 Th dating has provided a high-precision absolute age model for cave stalagmites over the past 640000 years as well as highresolution oxygen isotope records representing orbital-to suborbital-scale climate changes. By combining magnetic stratigraphy and biostratigraphy, robust chronostratigraphic frameworks for non-eolian continental Quaternary deposits on the scale of Quaternary geomagnetic polarities have been established. The continental Pleistocene Series consists, from oldest to youngest,of the Nihewanian Stage of the Lower Pleistocene, the Zhoukoudianian Stage of the Middle Pleistocene, and the Salawusuan Stage of the Upper Pleistocene. Stages of the continental Holocene Series have not yet been established. This review summarizes recent developments in the Quaternary chronostratigraphy of representative Quaternary strata and associated faunas, and then proposes an integrative chronostratigraphic framework and a stratigraphic correlation scheme for Quaternary continental strata in China. In the near-future, it is hoped to establish not only a Chinese continental Quaternary climatochronostratigraphic chart on the scale of glacial-interglacial cycles but also a Quaternary integrative chronostratigraphic chart including both continental and marine strata in China.
基金supported by National Nat-ural Science Foundation of China(U1502231)the CAS 135 Program(XTBG-F01)+3 种基金a grant from the China Scholarship Council to J.Lebreton Anberr6e(2013GCX606)the National Natural Science Foundation of China(41404056)the State Key Laboratory of Lithospheric Evolution(11431780the State Key Laboratory of Paleobiology and Stratigraphy,Nanjing Institute of Geology and Paleontology,CAS(15310)
文摘The Mid-Miocene Climatic Optimum(MMCO;15-17 Ma)was one of the short-term climatic warm events that punctuated the Cenozoic long-term cooling trend.Because there are very few terrestrial records of this event,most of our understanding comes from marine cores.In this report,we first present new palaeomagnetic data that revises the dating of our 400 m-thick lacustrine section in Wenshan(Yunnan),previously thought to be Late Mio-cene.These new data suggest an older age,ca.15.2-16.5 Ma,coinciding with the MMCO.We measuredδ13C on bulk organic matter(3 Corg),total organic carbon(TOC),total nitrogen(TN)and C/N ratios at a high sample resolution to:(1)reconstruct the palaeoenvironmental changes in the lake catchment area,and(2)infer mechanisms responsible for these changes.Our results show that all four geochemical parameters demonstrate that a strong environmental change occurred around the middle of the section,shortly after the C5Cn/C5Br geomagnetic reversal and the Early/Middle Miocene boundary at 15.97 Ma.We propose that the environmental shift may be due to a combination of a change in climate,which became cooler,together with a change in organic matter cycling within the lake.This study provides a new insight into the MMCO and demonstrates that although the MMCO was generally a warm event,it was also a time of climatic instability and abrupt environmental changes.
基金supported by the Ministry of Science and Technology of China(2007FY110200)
文摘In order to provide direct evidence for the use of fire by humans at Locality 1,Zhoukoudian,we examine the burnt and unburnt sediments of newly excavated area in Layer 4 by detailed measurements of magnetic susceptibility,color,and diffuse reflectance spectrum.Results show that the magnetic susceptibility and redness of the burnt sediments are remarkably higher than those of other areas on the same level:up to*22 times for magnetic susceptibility and*3 times for redness of those of the adjacent unburnt sediments.Fine-grained(superparamagnetic/stable single-domain)magnetite and hematite grains make dominant contributions to the distinctly high values of magnetic susceptibility and redness in the burnt sediments.Diffuse reflectance spectroscopy results show that the burnt sediments contain more hematite than those of other areas and localities 2 and 3.High-temperature magnetic susceptibility measurements demonstrate that the burnt sediments have been heated above 700°C.Those changes in low-frequency magnetic susceptibility and redness are impossibly resulted from natural fires,thus most likely signaling the human activities of controlled use of fire.However,further work is needed to confirm whether or not these heat-affected sediments were produced in situ.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41888101 & 41731174)。
文摘The Asian summer monsoon(ASM) is a vast climate system, whose variability is critical to the livelihoods of billions of people across the Asian continent. During the past half-century, much progress has been made in understanding variations on a wide range of timescales, yet several significant issues remain unresolved. Of note are two long-standing problems concerning orbital-scale variations of the ASM.(1) Chinese loess magnetic susceptibility records show a persistent glacial-interglacial dominated ~100 kyr(thousand years) periodicity, while the cave oxygen-isotope(δ18 O) records reveal periodicity in an almost pure precession band(~20 kyr periodicity)—the "Chinese 100 kyr problem".(2) ASM records from the Arabian Sea and other oceans surrounding the Asian continent show a significant lag of 8–10 kyr to Northern Hemisphere summer insolation(NHSI), whereas the Asian cave δ18 O records follow NHSI without a significant lag—a discrepancy termed the "sea-land precession-phase paradox". How can we reconcile these differences? Recent and more refined model simulations now provide spatial patterns of rainfall and wind across the precession cycle, revealing distinct regional divergences in the ASM domain, which can well explain a large portion of the disparities between the loess, marine, and cave proxy records. Overall, we also find that the loess, marine, and cave records are indeed complementary rather than incompatible, with each record preferentially describing a certain aspect of ASM dynamics. Our study provides new insight into the understanding of different hydroclimatic proxies and largely reconciles the "Chinese 100 kyr problem" and "sea-land precession-phase paradox".
基金supported by the National Natural Science Foundation of China(41688103 and 41425013)the Strategic Priority Program of Chinese Academy of Sciences(XDB18030505)a contribution to the Project 679 of the Council of the International Geoscience Programme。
文摘The Songliao Basin,northeastern China(Fig.1a),is one of the largest non-marine petroliferous basins in the world and contains a nearly complete Cretaceous terrestrial sedimentary sequences.This succession provides vital information that can improve our knowledge of a series of important geodynamical,geological,and paleoenvironmental events[1,2].The lower Cretaceous Shahezi Formation,which is the main source rock strata in the basin,formed during the rifting stage of the basin and consists of gray to black lacustrine and floodplain mudstones and siltstones interbedded with gray sandstones and conglomerates.The unit overlies the Huoshiling Formation and is overlain by the Yingcheng Formation(Fig.1b).
基金supported by the National Natural Science Foundation of China(31300187,31300188)the Natural Science Foundation of Yunnan Province(2010CC010)
文摘Euryale （Nymphaeaceae） is a monotypic genus distributed in eastern Asia, but fossils in its native distribu- tion are sparse as compared to Europe where the genus has disappeared. Here, we describe a new fossil species, Euryale yunnanensis sp. nov., from the late Miocene Zhaotong Basin in southwestern China on the basis of seed remains. Char- acteristics including an ellipsoidal to almost spherical shape, a smooth surface, a germination cap that covers the micro- pyle, the separation of the hilum and germination cap （mi- cropyle）, elliptic testa surface cells with undulate margins and thickened cell walls collectively indicate a close affinity with the genus Euryale in Nymphaeaceae. Comparisons of seed morphology and anatomy demonstrate that the newly described fossil species differs from modem and other fossil species of Euryale and thus verify the assignment to a new fossil species. As the modem Euryale is an aquatic plant, preferably living in swamps and lakes with shallow and stable water, we hypothesize that a lake and/or swamp environment with shallow water was present near Shui- tangba in the Zhaotong Basin, where the Shuitangba homi- noid lived during the late Miocene. This inference is generally consistent with paleoenvironmental data extracted from avian, fish, frog, turtle and crocodile fossils, as well as from aquatic pollen. The fossil history suggests a compara- tively recent （Miocene） emergence of Euryale, which is roughly in agreement with the divergence time inferred from the molecular information.
基金supported by the Strategic Priority Research Program of CAS (Grant Nos. XDA2007030102 & XDB26000000)the NSFC (the National Natural Science Foundation of China)-NERC (Natural Environment Research Council of the United Kingdom) joint research program (Grant Nos. 41661134049 & NE/P013805/1)+2 种基金The Second Tibetan Plateau Scientific Expedition and Research Program (STEP), CAS (Grant No. 2019QZKK0705)Youth Innovation Promotion Association, CAS (Grant No. 2017439)Key Research Program of Frontier Sciences, CAS (Grant No. QYZDB-SSW-SMC016)
文摘A new occurrence of buckthorn fossil leaves is reported from the upper Eocene strata of Markam Basin,southeastern Tibet,China.The leaf margin is either entire or slightly sinuous.Secondary veins are regularly spaced,forming eucamptodromous venation.These secondaries exist as straight lines from midvein to near margin and then arch abruptly upward and enter into a margin vein.The tertiary veins are densely spaced and parallel,and are percurrent to secondary veins.This leaf architecture conforms with Berhamniphyllum Jones and Dilcher,an extinct fossil genus reported from America.Our fossils are characterized by their dense secondaries,with secondary veins on the upper half portion of the blade accounting for over 40%of all secondaries.A new species,Berhamniphyllum junrongiae Z.K.Zhou,T.X.Wang et J.Huang sp.nov.,is proposed.Further analysis shows that confident assignment among Rhamnidium,Berchemia,and Karwinskia cannot be made based on leaf characters alone.Berhamniphyllum might represent an extinct common ancestor of these genera.In this study,several fossil Berchemia from Yunnan and Shandong are emended and reassigned to Berhamniphyllum.A new complex,namely the Berchemia Complex,is proposed based on morphology,molecular evidence,and the fossil record.This complex contains the fossil leaves of Rhamnidium,Karwinskia,Berchemia,and Berhamniphyllum.The historical biogeography of the Berchemia Complex is also discussed in this paper.This complex might have originated in the late Cretaceous in Colombia,South America,and dispersed to North America via Central America during the Eocene.Subsequently,the complex moved from North America to East Asia via the Bering Land Bridge no later than the late Eocene.Besides,the complex migrated from North America to Europe via the North Atlantic Land Bridge and then migrated further to Africa.In East Asia,it first appeared in Markam on the Qinghai-Tibetan Plateau,and then dispersed to other regions of Asia.
基金the Strategic Priority Research Programme of Chinese Academy of Sciences(XDA13010106,XDA13010102)the National Natural Science Foundation of China(41888101,41976063,41690110)。
文摘The tropical reef ecosystems are created by living organisms,such as corals and algae,and provide important habitats for millions of people and a variety of marine life,which have been severely threatened by climate changes over the past decades[1].These biogenic reefs account for a quarter of global CaCO_(3)production and thus are critical to global carbon cycling[2,3].
基金supported by the National Natural Science Foundation of China(Grant Nos.41888101,41977380 and 42072033)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB26000000 and XDA2004010102)+3 种基金the Second Tibetan Plateau Scientific Expedition and Research(Grant No.2019QZKK0601)the National Social Science Foundation of China(Grant No.21@WTK001)supported by the Chinese Academy of Sciences President’s International Fellowship Initiative Award(Grant No.2018VCA0016)the Je Tsongkhapa Endowment for Central and Inner Asian Archaeology at the University of Arizona。
文摘The timing and mechanisms of the human occupation of the demanding high-altitude Tibetan Plateau environment are of great interest.Here,we report on our reinvestigations and dating of the Nwya Devu site,located nearly 4600 meters above sea level on the central Tibetan Plateau.A new microblade techno-complex was identified on a lower lake shore at this site,distinct from the previously reported blade tool assemblage.These two lithic assemblages were dated to 45.6±2.6 and10.3±0.5 ka using optically stimulated luminescence and accelerator mass spectrometry^(14)C methods.They represent,respectively,the earliest known Paleolithic and microlithic sites on the interior Tibetan Plateau,indicating multiple occupation episodes of hunter-gatherers during the past 45 ka.Our studies reveal that relatively stable depositional conditions and a paleoenvironment characterized by a comparatively warm climate facilitated these multiple occupations at Nwya Devu.The contemporaneous occurrence of the Upper Paleolithic blade technology on the Tibetan Plateau and most of Eurasia between 50 and 40 ka indicates rapid,large-scale dispersals of humans that profoundly affected human demography on a large scale.Combining new archaeological evidence and previously reported genetic data,we conclude that the Tibetan Plateau provided a relatively stable habitat for Upper Paleolithic hunter-gatherers,which may have contributed to the complex and multiple-origin gene pool of present-day Tibetans.
基金supported by the National Natural Science Foundation of China(41630965,41690112 and 41621004)the National Programme on Global Change and Air–Sea Interaction of China(GASI–GEOGE–04)the Fundamental Research Funds for the Central Universities
文摘Biogenic reefs are one of two major depositional types in the South China Sea, and are constructed by coral, algae and bryozoa. The West Pacific is a major area of biogenic reef development and plays a critical role in the global carbon cycle. However, the lack of geochronological studies in previous works inhibits our understanding of their contributions. Herein, we conduct a cyclostratigraphic and magnetostratigraphic study on Neogene biogenic reefs using the XK–1 core that was drilled at the Shidao Island,Xisha(Paracel) Islands. The main findings of this study are:(1) the establishment of reliable magentostratigraphy for Ledong, Huangliu, Meishan and Sanya Formations;(2) the magnetic susceptibility variation can be inferred as growth index and tuned to the 405–ka long eccentricity cycle;(3) the astronomical geochronology suggests that the bottom ages for Ledong, Yinggehai, Huangliu, Meishan,and Sanya Formations are 2.2 Ma, 5.7 Ma, 10.4 Ma, 16.6 Ma, and 24.3 Ma, respectively; and (4) Earth's eccentricity and obliquity played predominant roles in biogenic reef establishment on orbital to tectonic timescales. Thus, the reported geochronology offers an opportunity to test the contributions of various factors and hypothesize their roles in the global carbon cycle in future.
基金supported by the National Natural Science Foundation of China(41888101 and 41625016)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(311021003)the National Key Research and Development Program of China(2022YFF0802800)。
文摘Volcanic arc degassing contributes significantly to atmospheric CO_(2)levels and therefore has a pivotal impact on paleoclimate changes.The Neo-Tethyan decarbonation subduction is thought to have played a major role in Cenozoic climate changes,although there are still no quantifiable restrictions.Here we build past subduction scenarios using an improved seismic tomography reconstruction method and cal-culate the subducted slabflux in the India-Eurasia collision region.Wefind remarkable synchronicity between calculated slabflux and paleoclimate parameters in the Cenozoic,indicating a causal link between these processes.The closure of the Neo-Tethyan intra-oceanic subduction resulted in more carbon-rich sediments subducting along the Eurasia margin,as well as continental arc volcanoes,which further triggered global warming up to the Early Eocene Climatic Optimum.The abrupt termination of the Neo-Tethyan subduction due to the India-Eurasia collision could be the primary tectonic cause of the~50-40 Ma CO_(2)drop.The gradual decrease in atmospheric CO_(2)concentration after 40 Ma may be attributed to enhance continental weathering due to the growth of the Tibetan Plateau.Our results con-tribute to a better understanding of the dynamic implications of Neo-Tethyan Ocean evolution and may provide new constraints for future carbon cycle models.
