IEECAS OpenIR研究单元&专题: 古环境研究室http://ir.ieecas.cn:80/handle/0/22024-03-28T12:34:51Z2024-03-28T12:34:51ZDetermination of the optimized late Pleistocene chronology of a lacustrine sedimentary core from the Heqing Basin by geomagnetic paleointensity and its paleoclimate significanceXu, XinwenQiang, XiaokeLi, XubinQiu, HaijunZhao, HuiFu, ChaofengYang, Ziyihttp://ir.ieecas.cn:80/handle/361006/177352023-12-29T07:09:10Z2023-12-29T07:09:10Z题名: Determination of the optimized late Pleistocene chronology of a lacustrine sedimentary core from the Heqing Basin by geomagnetic paleointensity and its paleoclimate significance
作者: Xu, Xinwen; Qiang, Xiaoke; Li, Xubin; Qiu, Haijun; Zhao, Hui; Fu, Chaofeng; Yang, Ziyi
摘要: Long and continuous lacustrine sedimentary sequences from SW China faithfully recorded the evolution of the Indian summer monsoon (ISM). However, the limited dating range (< 50 ka) of C-14 dating has restricted high resolution research on the last glacial cycle.We presented a relative paleointensity (RPI) record from a lacustrine sedimentary core from the Heqing Basin to optimize its AMS C-14 chronology. Detailed rock magnetic analyses indicated that SD and vortex state magnetite (and/or maghemite) was the dominant magnetic mineral of lacustrine sediments. Moderate variations in concentration-dependent (SIRM, ARM) and grain-size-dependent (ARM/SIRM) parameters satisfied the criteria for the RPI studies. Consequently, we determined the RPI by NRM20-40 mT/SIRM20-40 mT, where NRM20-40 mT denotes the NRM after demagnetization between 20 and 40 mT. Using 6 AMS C-14 dates younger than 40 ka BP as constraints, 7 age control points were determined by correlating the lows in the RPI record with those of the target paleointensity stacks PISO-1500. We established a reliable chronological framework of the upper 11.1 m of the HQ drill core by binomial fitting based on the 7 RPI age control points and the climatic transition termination II. The consistent variations in our RPI curve and other global target paleointensity curves indicated that the optimized chronology was reliable.In our optimized chronology, the visible precession cycle in ARM/SIRM indicated that the ISM was a direct response to solar insolation during the last glacial cycle. The strong ISM suggested by the high content of Mesic conifers and tropical and subtropical trees during MIS 3 shifted to MIS 5a. Thus, the "MIS 3 Mega-paleolake " hypothesis in China, which was mainly deduced by the C-14 age model, was challenged.2023-12-29T07:09:10ZPotential paleoceanographic application of cold-water bamboo coral in the South China SeaZeng, ZhiweiDang, HaowenHuang, EnqingMa, XiaolinHuang, XiangtongKong, LeYang, CeQu, XiaoliZhou, LipingJian, Zhiminhttp://ir.ieecas.cn:80/handle/361006/177112023-12-29T06:56:14Z2023-12-29T06:56:14Z题名: Potential paleoceanographic application of cold-water bamboo coral in the South China Sea
作者: Zeng, Zhiwei; Dang, Haowen; Huang, Enqing; Ma, Xiaolin; Huang, Xiangtong; Kong, Le; Yang, Ce; Qu, Xiaoli; Zhou, Liping; Jian, Zhimin2023-12-29T06:56:14ZCenozoic Uplift of Tanggula Range and Tuouohe Basin, Northern Tibet: Insights of the Anisotropy of Magnetic SusceptibilityLi, LeyiChang, HongPares, Josep M.Bradak, BalazsZhang, ZekeQiang, XiaokeGuan, ChongQuan, Chunyanhttp://ir.ieecas.cn:80/handle/361006/177052023-12-29T06:56:11Z2023-12-29T06:56:11Z题名: Cenozoic Uplift of Tanggula Range and Tuouohe Basin, Northern Tibet: Insights of the Anisotropy of Magnetic Susceptibility
作者: Li, Leyi; Chang, Hong; Pares, Josep M.; Bradak, Balazs; Zhang, Zeke; Qiang, Xiaoke; Guan, Chong; Quan, Chunyan
摘要: The timing and intensity of deformation of the Tanggula Range and Tuotuohe Basin are in debatable but strengthening the research on them is necessary for better understanding the geodynamic models of the Tibet and the tectonic-climate connections during the Cenozoic. Here we present the anisotropy of magnetic susceptibility (AMS) records from the foreland Tuotuohe Basin to understand the tectonic uplift history of the Tanggula Range for the interval of similar to 37-19.7 Ma. Rock magnetic analyses indicate that the main magnetic carrier is paramagnetic and the minor is hematite. Thus, the AMS in the Tuotuohe Section (TS) can be used to track the tectonic strain related to tectonic processes. The distribution direction of the maximum principle susceptibility (K-max) is approximately NW-SE, which intersects at about 10 degrees with the strike of the strata and is nearly parallel to the Tanggula thrust fault system, whereas the minimum principle susceptibility (K-min) is oriented in the NE-SW direction with a girdle distribution. This is consistent with the sedimentary fabric imprinted by the NE-SW shortening direction, representing the earliest deformation stage. AMS data in the TS can be divided into two phases at 30 Ma. From similar to 37 to 30 Ma, the AMS parameters indicate an active tectonic strain and the Tanggula Range uplift induced by the India-Asia convergence, whereas between 30 and 19.7 Ma, the strain is weak compared with the earlier phase. Finally, the weak strain environment between 30 and 19.7 Ma indicated by the AMS indexes of the TS and the paleoelevation evidence from the Tuotuohe Basin all together suggest that an additional 1000-2000 m of surface uplift of the basin may have begun after 19.7 Ma.2023-12-29T06:56:11ZLate Holocene hydroclimatic changes inferred from a karst peat archive in the western Guizhou Plateau, SW ChinaZeng, MengxiuZeng, QiaoPeng, HaijunWu, YongqiuLi, YueSong, YouguiSheng, EnguoWu, YangyangWang, TianyangNi, Jianhttp://ir.ieecas.cn:80/handle/361006/177022023-12-29T06:56:10Z2023-12-29T06:56:10Z题名: Late Holocene hydroclimatic changes inferred from a karst peat archive in the western Guizhou Plateau, SW China
作者: Zeng, Mengxiu; Zeng, Qiao; Peng, Haijun; Wu, Yongqiu; Li, Yue; Song, Yougui; Sheng, Enguo; Wu, Yangyang; Wang, Tianyang; Ni, Jian
摘要: The paleoenvironmental implications of Ca-related indices of peat from karst regions are poorly understood. In this study, we analyze a 450-cm peat core drilled from a sub-alpine karst mountain in the western Guizhou Plateau, SW China. This core is analyzed for carbonate contents and loss on ignition (LOI). High-resolution X-ray fluorescence (XRF) core scanning was also performed to see the variation of chemical compositions. Based on these measurements and 12 accelerator mass spectrometry (AMS)C-14 dates, we reconstructed the history of hydroclimatic shifts in SW China and explored the significance of Ca-related indices. The reconstructed hydro climatic conditions were consistent with the stalagmite, lacustrine sediment, and peat records from the regions controlled by the Indian monsoon. Abrupt decreases in precipitation and temperature were clearly shown during the 4.2 ka and Little Ice Age (LIA) cold events. High carbonate contents in the Yejiping peat during the Medieval Warm Period (MWP) were linked to a warm and humid climate. Additionally, wavelet analysis shows that variations in Ca content have 500, 125, 103, 80, 58, 43, 20, and 12-a quasi-periods, which correspond to the Gleissberg, Pacific Decadal Oscillation (PDO), and Schwabe cycles. Our results highlight the importance of Ca related indices in peat deposits from karst depressions and provide a detailed description of the MWP and the LIA.2023-12-29T06:56:10ZEarly Oligocene-Late Miocene Wildfire History in the Northern Tibetan Plateau and Links to Temperature-Driven Precipitation ChangesMiao, YunfaChang, HongLi, LinCheng, FengGarzione, CarmalaYang, Yonghenghttp://ir.ieecas.cn:80/handle/361006/176762023-12-29T06:53:35Z2023-12-29T06:53:34Z题名: Early Oligocene-Late Miocene Wildfire History in the Northern Tibetan Plateau and Links to Temperature-Driven Precipitation Changes
作者: Miao, Yunfa; Chang, Hong; Li, Lin; Cheng, Feng; Garzione, Carmala; Yang, Yongheng
摘要: Late Cenozoic wildfire evolution in Inner Asia has been attributed to both ice-volume modulating precipitation changes and surface uplift of the Tibetan Plateau. Whether this is the case or not requires additional research and wildfire records from older periods. In this study, 251 microcharcoal samples from the Huatugou section in the western Qaidam Basin are used to reconstruct the early Oligocene-middle Miocene wildfire history of the northern Tibetan Plateau. The results show that wildfires remained relatively frequent before similar to 26 Ma, then reduced gradually until similar to 14 Ma, and finally increased slightly but still at low level between 14 and 12 Ma. The wildfire variations can be correlated to the steppe-based dryness changes, and both of which are coincident with global temperature changes. We infer that mean annual temperature might have played a dominant role in controlling wildfire frequencies in the northern Tibetan Plateau through modulating atmospheric moisture content. This conclusion is in line with previous studies including microcharcoal-based wildfire records of 18-5 Ma successions from the Qaidam Basin as well as soot-based wildfire records from Quaternary glacial-interglacial cycles of the Chinese Loess Plateau.2023-12-29T06:53:34ZDirect Radiative Effect (DRE) of Dust Aerosols on West African and East Asian Monsoon: The Role of Ocean-Atmosphere InteractionsWang, AnqiXie, XiaoningLiu, XiaodongYin, Zhi-Yonghttp://ir.ieecas.cn:80/handle/361006/176292023-12-29T06:48:37Z2023-12-29T06:48:37Z题名: Direct Radiative Effect (DRE) of Dust Aerosols on West African and East Asian Monsoon: The Role of Ocean-Atmosphere Interactions
作者: Wang, Anqi; Xie, Xiaoning; Liu, Xiaodong; Yin, Zhi-Yong
摘要: The direct radiative effect (DRE) of dust aerosols on the West African and East Asian monsoons is analyzed using the Community Atmosphere Model version 4 containing the dust aerosol parameterization module with and without the coupling of ocean-atmosphere processes, respectively. The atmospheric model (AM) and the ocean-atmosphere coupled model (CM) can both capture the major spatial characteristics of dust aerosols and summer monsoons over West Africa and East Asia. Our results show that the DREs on the West African (WASM) and East Asian summer monsoon (EASM) are more significant in the CM simulations compared to the AM simulations, causing the strengthening of the WASM and weakening of the EASM. The DRE of dust aerosols induces a negative radiative forcing leading to a surface cooling of the downstream ocean of the dust source region when the coupled ocean feedback is added. The distinct DRE of dust aerosols on the WASM and EASM are resulted from the relative locations of the ocean cooling regions to the respective monsoon regions. This study shows the importance of the coupled ocean-atmosphere processes in the DRE and its influences on the WASM and EASM systems.2023-12-29T06:48:37ZSoil erosion and human activities over the last 60 years revealed by magnetism, particle size and minerals of check dams sediments on the Chinese Loess PlateauDong, HongmeiSong, YouguiChen, LiumeiLiu, HuifangFu, XiaofenXie, Mengpinghttp://ir.ieecas.cn:80/handle/361006/175272023-12-29T06:31:20Z2023-12-29T06:31:20Z题名: Soil erosion and human activities over the last 60 years revealed by magnetism, particle size and minerals of check dams sediments on the Chinese Loess Plateau
作者: Dong, Hongmei; Song, Yougui; Chen, Liumei; Liu, Huifang; Fu, Xiaofen; Xie, Mengping
摘要: Soil erosion has become more serious in semiarid areas around the world. However, the discrimination of the impact of concurrent climate change and human activity on soil erosion in a particular study area remains a challenge. Check dams are important engineering measures to prevent soil erosion on the Chinese Loess Plateau, and the dam sediments, as the product of soil erosion, are related to both climate change and human activities in a small watershed. The present study selected a check dams sediment profile in the upper Jinghe Basin on the Chinese Loess Plateau as a case study. Based on AMS C-14 dating and Cs-137 measurement, we established the soil erosion timescale and employed multiple methods including magnetic susceptibility, particle size, and minerals to trace the soil erosion history. We compared them with a local hydrometeorological record in the Jinghe Basin to explore the relationship between soil erosion and human activities. AMS C-14 and Cs-137 results indicated that the profile was deposited since 1953. The results of magnetic susceptibility, particle size, and minerals revealed 3 soil erosion phases during the last 60 years. Soil erosion in this region is not only related to precipitation changes, but also closely related to human activities. Prior to the Reform and Opening-up in China in 1978, climatic change played a leading role in check dams sedimentation and hydrological changes. Subsequently, despite accelerated soil erosion associated with the family contract responsibility system, the check dams, afforestation and a warmer climate mitigated the soil erosion to some extent, runoff and sediment load continued to decrease. Since 1999, China's Grain for Green project has greatly reduced the runoff and sediment load. However, the policy of filling gullies and creating land since 2010 should be reconsidered carefully in terms of all aspects, including the eco-environment, hydrological cycle, and economics.2023-12-29T06:31:20ZLake eutrophication in northeast China induced by the recession of the East Asian summer monsoonChen, LinZhao, JiajuZhang, ZhipingShen, ZhongweiDong, WeimiaoMa, RuiChen, JieNiu, LiliChen, ShengqianWu, DuoLiu, JianbaoZhou, Aifenghttp://ir.ieecas.cn:80/handle/361006/175212023-12-29T06:31:18Z2023-12-29T06:31:18Z题名: Lake eutrophication in northeast China induced by the recession of the East Asian summer monsoon
作者: Chen, Lin; Zhao, Jiaju; Zhang, Zhiping; Shen, Zhongwei; Dong, Weimiao; Ma, Rui; Chen, Jie; Niu, Lili; Chen, Shengqian; Wu, Duo; Liu, Jianbao; Zhou, Aifeng
摘要: Lakes are one of the most important freshwater resources on Earth and they provide a wide range of ecosystem services. However, due to rapid economic development and the intensification of human activities, many lakes have become eutrophic, which may threaten their status as water resources. Human activities have played a significant role in lake eutrophication, but whether this role is independent of, or coupled with, natural climate change requires further study. We selected Dali Lake, a large lake affected by human activity within the ancient warfare borders, to clarify the ecological response of a lake to climate change and human activity. We used analyses of sedimentary n-alkanes and AMS C-14 dating to reconstruct the paleolimnological evolution of Dali Lake since 15 cal kyr BP, and specifically to assess the timing and causes of eutrophication. The results show that the short-chain n-alkanes (C17-19-alkanes) in Dali Lake are mainly produced by bacteria and algae within the lake, and that the sedimentary absolute abundance of short-chain n-alkanes (A(17-19)-alkanes) can be used as a proxy for assessing the ecological status of the lake. The ecological status of Dali Lake was the most stable during the early to middle Holocene, when the East Asian summer monsoon was strong, but bacterial and algal outbreaks occurred during three episodes of a weakened summer monsoon-the Older Dryas, Younger Dryas, and the Common Era-when the lake experienced different degrees of eutrophication. During the recession of the East Asian summer monsoon, the weakening of precipitation recharge of the lake led to a reduction in lake area and an increase in nutrient concentrations in the lake water, while aeolian dust input was an additional nutrient source, leading to bacterial and algal outbreaks. During the Common Era, lake eutrophication occurred in the context of both summer monsoon recession and enhanced human activities, but their combined effects did not lead to more intense lake eutrophication than was caused by monsoon recession during the Younger Dryas. We conclude that, although human activities have enhanced the eutrophication of Dali Lake, the reduction in lake size due to monsoon recession and the resulting increase in the salinity and nutrient concentration of the lake water, combined with increased aeolian inputs, were a more important trigger of lake eutrophication. (C) 2022 Elsevier Ltd. All rights reserved.2023-12-29T06:31:18ZLipid biomarkers in Lake Wudalianchi record abrupt environmental changes from the volcanic eruption in 1776Yao, YuanHuang, YongsongZhao, JiajuWang, LiCheng, Haihttp://ir.ieecas.cn:80/handle/361006/175092023-12-29T06:31:13Z2023-12-29T06:31:13Z题名: Lipid biomarkers in Lake Wudalianchi record abrupt environmental changes from the volcanic eruption in 1776
作者: Yao, Yuan; Huang, Yongsong; Zhao, Jiaju; Wang, Li; Cheng, Hai
摘要: Volcanic eruptions can cause abrupt changes in surrounding environments, but detailed sediment records of such changes are rare. The very high sediment accumulation rate in Lake Wudalianchi, a volcanic-dammed freshwater lake in northeastern China, provides an excellent opportunity for reconstructing volcanic-induced environmental change. Here we use multiple lipid biomarkers to reconstruct changes in aquatic ecosystems, hydrology, and methane cycling before and after a regional explosive volcanic eruption in 1776. Our results indicate that the Wudalianchi catchment was a shallow organic-rich marsh environment with abundant aquatic emergent macrophytes and an intense microbial methane cycle before the volcanic eruption. Following the volcanic eruption, the marsh was rapidly transformed into an oligohaline lake environment due to river channel damming by lava. Associated with the abrupt environmental change, we observe corresponding changes of cyclisation ratios of branched glycerol dialkyl glycerol tetraethers or brGDGTs (CBT and CBT ' indices), and the inferred pH displays an abrupt increase of -1.3. Group 1 alkenones emerge abruptly after the eruption when the inferred pH exceeds 8. Our results provide the first high-resolution reconstruction of environmental change induced by volcanic eruption and demonstrate the high efficacy of the lipid biomarkers in recording aquatic and terrestrial changes.2023-12-29T06:31:13ZNovel methods of resolving daily growth patterns in giant clam (Tridacna spp.) shellsLiu, ChengchengZhao, LiqiangZhao, NanyuYang, WeiHao, JialongQu, XiaoliLiu, ShanDodson, JohnYan, Honghttp://ir.ieecas.cn:80/handle/361006/175062023-12-29T06:31:12Z2023-12-29T06:31:12Z题名: Novel methods of resolving daily growth patterns in giant clam (Tridacna spp.) shells
作者: Liu, Chengcheng; Zhao, Liqiang; Zhao, Nanyu; Yang, Wei; Hao, Jialong; Qu, Xiaoli; Liu, Shan; Dodson, John; Yan, Hong
摘要: Sclerochronology is a powerful tool for high resolution paleoclimate and paleoenvironment reconstruction. However, we can only observe annual growth bands using traditional technology for most marine bivalves, hampering the ability to establish daily resolution chronology in order to reconstruct past weather changes. Giant clams (Tridacna spp.) are the largest bivalves in the world. Their hard and dense aragonite shells have clear annual and even daily growth bands, creating the potential for daily resolution chronology establishment and paleoweather reconstruction. In this study, we present two new and reliable methods that resolve daily growth patterns in giant clam shells: (1) Fluorescence image method. Measuring the width between two bright fluo-rescent bands of the Tridacna shell with the help of CooRecorder 9.0 software based on the clear daily growth bands obtained by laser scanning confocal microscope (LSCM). (2) Ultrahigh resolution Sr/Ca method. Counting the amount of Sr/Ca ratio data in each daily cycle derived from Tridacna shell, and then calculating the daily growth increment based on the spatial resolution of Sr/Ca data. The results show the variation of daily growth increments profiles obtained by the two methods synchronize, and the chronology uncertainty is statistically acceptable over a long-term record, indicating that both methods can estimate the daily growth increment of Tridacna shell reliably. The methods developed here lay the foundation for paleoweather reconstruction using daily growth increments of Tridacna spp.2023-12-29T06:31:12Z