为进一步理解末次冰消期以来东亚夏季风(EASM)变化的时空特征,特别是中原地区全新世EASM的时空格局及其驱动机制,在AMS14C年代的支持下,本文基于荥阳盆地湖相-湿地相剖面的正构烷烃和沉积学指标(粒度和总有机碳),重建了荥阳盆地~17.8 ca...为进一步理解末次冰消期以来东亚夏季风(EASM)变化的时空特征,特别是中原地区全新世EASM的时空格局及其驱动机制,在AMS14C年代的支持下,本文基于荥阳盆地湖相-湿地相剖面的正构烷烃和沉积学指标(粒度和总有机碳),重建了荥阳盆地~17.8 cal ka BP以来的气候与环境变化历史。重建结果表明,~17.8-~11.7 cal ka BP是草原环境下的黄土状堆积阶段。~11.7-~8.5 cal ka BP为湿地沉积时段,是森林和湿地扩展的时期。~8.5-~2.8 cal ka BP为湖泊存在时段,木本植物和水生植物丰度达到最高后波动降低。~2.8-~2.4 cal ka BP为湿地存在阶段,菌藻类和/或微生物、沉水浮游植物的烷烃贡献量很大。~2.4-~1.1 cal ka BP为草原环境下的黄土沉积时段。本文进一步基于荥阳盆地长链正构烷烃的平均碳链长(ACL_(27-33),简称ACL)和C_(27+29)/C_(31+33)比值,结合渑池盆地木本花粉百分含量和禾本科/(蒿属+藜科)比值,重建了中原地区全新世以来湿度变化,并与长江中下游地区和中国北方地区(指黄河以北地区)的全新世湿度序列进行了对比。对比结果显示,全新世中期的干旱时段(~7.0-~4.0 cal ka BP或~8.0-~5.0 cal ka BP)与长江中下游地区全新世中期的干旱时段基本对应。这一时段的干旱对应于厄尔尼诺-南方涛动(ENSO)强度的较低值(即La Nino态)时段和赤道西太平洋SST较高温时段。控制上述EASM影响区的中国中部地区全新世湿度空间格局的主要机制可能是ENSO状态以及由ENSO调控的亚热带西太平洋高压(WPSH)的南北向移动。展开更多
The Early Holocene paleoclimate in Bosten Lake on the northern margin of the Tarim Basin, southern Xinjiang, is reconstructed through an analysis of a 953 cm long core （BSTC2000） taken from Bosten Lake. Multiple pro...The Early Holocene paleoclimate in Bosten Lake on the northern margin of the Tarim Basin, southern Xinjiang, is reconstructed through an analysis of a 953 cm long core （BSTC2000） taken from Bosten Lake. Multiple proxies of this core, including the mineral components of carbonate, carbonate content, stable isotopic compositions of carbonate, Ca/Sr, TOC and C/N and C/S of organic matter, are used to reconstruct the climatic change since 8500 a B.P. The chronology model is made by nine AMS 14C ages of leaves, seeds and organic matter contained in two parallel cores. The climate was cold and wet during 8500 to 8100 a B.P. Temperature increased from 8100 to 6400 a B.P., the climate was warm and humid, and the lake expanded. The lake level was highest during this stage. Then from 6400 to 5100 a B.P., the climate became cold and the lake level decreased slightly. During the late mid-Holocene, the climate was hot and dry from 5100 to 3100 a B.P., but there was a short cold period during 4400 to 3800 a B.P. At this temporal interval, a mass of ice and snow melting water supplied the lake at the early time and made the lake level rise. The second highest lake level stage occurred during 5200 to 3800 a B.P. The climate was cool and wet during 3100 to 2200 a B.P., when the lake expanded with decreasing evaporation. The lake had the last short-term high level during 3100 to 2800 a B.P. After this short high lake level period, the lake shrank because of the long-term lower temperature and reduced water supply. From 2200 to 1200 a B.P., the climate was hot and dry, and the lake shrank greatly. Although the temperature decreased somewhat from 1200 a B.P. to the present, the climate was warm and dry. The lake level began to rise a little again, but it did not reach the river bed altitude of the Konqi River, an outflow river of the Bosten Lake.展开更多
The Holocene Megathermal is divided into early, middle and late periods, each having different impacts on the Neolithic cultures due to their different climate changing trends This study is based on a comparative anal...The Holocene Megathermal is divided into early, middle and late periods, each having different impacts on the Neolithic cultures due to their different climate changing trends This study is based on a comparative analysis of the environmental evolution information recorded in the Qinghai Lake, the western edge of the Loess Plateau and Zoige and the spatial distribution of Neolithic sites of the Gansu-Qinghai region. Results show that the early and middle periods towards warm and humid promoted the development of Neolithic cultures with agriculture as the main sector in the Gansu-Qinghai region, furthermore a heyday of Yangshao Culture prosperity emerged. The Holocene entered the late period after the cold climate event at 5.9 ka BP in the Gansu-Qinghai region. Later the climate began to turn cold. However, at the 5.8-4.2 ka BP a relatively stable warm and humid climate created the conditions for the development of Majiayao Culture of the Neolithic Age in this region, thus the distribution of its cultural heritage sites expanded towards high altitudes and high latitudes. From 4.2 ka BP onwards, the climate became cold and dry, which had a significant influence on the Neolithic cultures of the Gansu-Qinghai region, leading to a dramatic change in the cultural characters and spatial distribution of Qijia Culture around 4.2 ka BP. After a nearly 300 years of cold and dry period, the unified Neolithic farming culture completely collapsed. Afterwards an industrial division of animal husbandry and farming and regional multiple cultures formed, and ultimately led to the end of primitive society and the starting of a civilized society.展开更多
Pollen records from the Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes during the last 13.0 ka BP. Before 12.1 ka BP, steppe or desert-steppe vegetation domina...Pollen records from the Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes during the last 13.0 ka BP. Before 12.1 ka BP, steppe or desert-steppe vegetation dominated landscape then was replaced by a coniferous forest under a generally wet climate （12.1-11.0 ka BP）. The vegetation was deteriorated into steppe landscape and further into a desert-steppe landscape between 11.0 and 9.8 ka BP. After a brief episode of a cool and wet climate （9.8-9.6 ka BP）, a relatively mild and dry condition prevailed during the early Holocene （9.6-7.6 ka BP）. The most favourable climate of warm and humid period occurred during mid-Holocene （7.6-4.0 ka BP） marked by forest-steppe landscape and vegetation alternatively changed between steppe and desert-steppe from -4.0 to -1.0 ka BP.展开更多
A pollen record from Haiyuan section in the southern part of Ningxia revealed a detailed history of vegetation variation and associated climate changes during the period from^13.0 to^7.0 14 C ka BP.A steppe landscape ...A pollen record from Haiyuan section in the southern part of Ningxia revealed a detailed history of vegetation variation and associated climate changes during the period from^13.0 to^7.0 14 C ka BP.A steppe landscape under a moderately dry(and probably cool)condition(~12.7-~12.1 14 C ka BP)was replaced by a coniferous forest dominating the landscape under a generally wet climate from^12.1 to ~11.01 4C ka BP.This generally wet period,corresponding to the European B?lling/All?rod period,can be divided into three stages:a cool and wet stage between^12.1 and^11.4 14 C ka BP,a mild and rela- tively dry stage between^11.4 and^11.2 14 C ka BP,and a mild and wet stage between^11.2 and^11.0 14 C ka BP.The coniferous forest-dominated landscape was then deteriorated into steppe landscape (~11.0-~10.6 14 C ka BP)and further into a desert steppe landscape from^10.6 to^9.8 14 C ka BP,being correspondent to the European Younger Dryas period.After a brief episode of a cool and wet climate (~9.8-~9.6 14 C ka BP),a relatively mild and dry condition prevailed during the early Holocene(~9.6- ~7.6 14 C ka BP)and then a warm and humid climate started the mid-Holocene(~7.6-~7.2 14 C ka BP).展开更多
Based on modern pollen studies and reliable chronology of nine AMS 14C dates, a detailed history of vegetation and climate changes during the past 8660 cal. a BP was reconstructed by a high-resolution pollen record fr...Based on modern pollen studies and reliable chronology of nine AMS 14C dates, a detailed history of vegetation and climate changes during the past 8660 cal. a BP was reconstructed by a high-resolution pollen record from Ugii Nuur in central Mongolia. Poaceae-steppe dominated the study area and the climate was mild and semi-humid before 7800 cal. a BP with a noticeable cool and humid interval at 8350―8250 cal. a BP. Xerophytic plant increased and the climate became warm and dry gradually since 7800 cal. a BP. From 6860 to 3170 cal. a BP, semi-desert steppe expanded, suggesting a prolonged warm and dry climate. Between 3170 and 2340 cal. a BP, regional forest steppe expanded whereas semi-desert steppe retreated, indicating the climate became cool and wet gradually and the humidity reached the maximum at the end of this stage. From 2340 to 1600 cal. a BP, a general cool and wet climate prevailed. And the climatic instability increased after 1600 cal. a BP. Review of regional pub-lished palaeoclimatic records implies that the mid-Holocene dry climate might have prevailed in vast areas from central Mongolia to arid areas of northwest China. Pollen-based climate reconstruction for UG04 core was well correlated with the result of climate model on Central Asia by Bush. In addition, several abrupt climatic events (cool and wet) were found and some could be broadly compared with the cool events in Atlantic.展开更多
The ratio of Zirconium to Rubidium (Zr/Rb) is suggested to be a better proxy for the East Asian winter monsoon strength than the widely-used grain size distribution. The rationale for the Zr/Rb proxy relies on the fol...The ratio of Zirconium to Rubidium (Zr/Rb) is suggested to be a better proxy for the East Asian winter monsoon strength than the widely-used grain size distribution. The rationale for the Zr/Rb proxy relies on the following assumptions: (1) Grain size fractionating characteristics during eolian dust transport should be archived in the Zr/Rb ratio records and this assumption is based on the premise that Zr is preferentially enriched in coarser grain size fraction while Rb tend to be enriched in finer grain size fraction; and (2) post-depositional weathering does not change the Zr/Rb ratio due to the immobility of these two elements. To examine these two assumptions, three last interglacial paleosols (S1) from Dingxi, Tianshui and Lantian, along a NW-SE transect across the Chinese Loess Plateau, were geo- chemically investigated. Our results show that the Rb concentration exhibits an increasing trend along the NW-SE transect both in the paleosol (S1) and the measured portions of the loess units (L1 and L2), being supportive to the assumption that Rb is enriched in the fine particles. But we also found that Rb loss did occur to some extent in the three profiles, contradicting to the presumption of Rb immobility during pedogenic processes. The Zr concentration exhibits an expected decreasing trend in the measured portions of the loess units and an unexpected increasing trend in the paleosol along the NW-SE transect. Moreover, the ratios of Zirconium to Hafnium (Zr/Hf) show different variation patterns between interglacial and glacial, implying that Zr-bearing minerals and their resident grain size frac- tions are probably not identical during interglacial and glacial. Thus, the assumption that Zr is enriched in coarse grain size fraction can no longer hold. We conclude that the final Zr/Rb value is not only de- pendent on grain size sorting processes but also on post-depositional alteration and source prove- nance. Under enhanced chemical weathering, especially when chemical index of alteration (CIA) is greater than 65, the Zr/Rb value loses its validity to be a reliable proxy for the winter monsoon strength. In addition, all the Zr/Rb value is constrained above 1.7, a minimum which is definitely modulated by all the three aforementioned factors.展开更多
The magnetic susceptibility in the Chinese loess is considered to have recorded thehistory of pedogenesis or land-surface stability, and has thus been used as an acute proxy of thesummer monsoon intensity. With regard...The magnetic susceptibility in the Chinese loess is considered to have recorded thehistory of pedogenesis or land-surface stability, and has thus been used as an acute proxy of thesummer monsoon intensity. With regard to pedogenesis, most authors failed to appreciate thecomplexity of weathering processes. Specifically, not acknowledged are local redox conditions,carbonate concentration and leaching. Pre-depositional pedogenesis may be another factorundermining the legitimacy of using the susceptibility as an acute proxy of the summer monsoonintensity. These factors may not necessarily reflect the degree of pedogenesis although they havedefinitely affected the susceptibility signature. Some contributors to the susceptibility aredemonstrated to be inorganic iron and other organically complexed iron. The organic ironassociated with decomposed plant litter is proven to be the most important contributor to thesusceptibility in modern loess. But, magnetotactic bacteria are believed to be the major generatorsof the ultrafine ferromagnetic particles responsible for the susceptibility signature in theQuaternary loess and paleosols. The factors affecting susceptibility signature may well be site- andtime-dependent even within the Chinese Loess Plateau. Therefore, a more comprehensive modeland a more comprehensive approach are needed to address the relationship between thepaleoclimate and the proxy.展开更多
文摘为进一步理解末次冰消期以来东亚夏季风(EASM)变化的时空特征,特别是中原地区全新世EASM的时空格局及其驱动机制,在AMS14C年代的支持下,本文基于荥阳盆地湖相-湿地相剖面的正构烷烃和沉积学指标(粒度和总有机碳),重建了荥阳盆地~17.8 cal ka BP以来的气候与环境变化历史。重建结果表明,~17.8-~11.7 cal ka BP是草原环境下的黄土状堆积阶段。~11.7-~8.5 cal ka BP为湿地沉积时段,是森林和湿地扩展的时期。~8.5-~2.8 cal ka BP为湖泊存在时段,木本植物和水生植物丰度达到最高后波动降低。~2.8-~2.4 cal ka BP为湿地存在阶段,菌藻类和/或微生物、沉水浮游植物的烷烃贡献量很大。~2.4-~1.1 cal ka BP为草原环境下的黄土沉积时段。本文进一步基于荥阳盆地长链正构烷烃的平均碳链长(ACL_(27-33),简称ACL)和C_(27+29)/C_(31+33)比值,结合渑池盆地木本花粉百分含量和禾本科/(蒿属+藜科)比值,重建了中原地区全新世以来湿度变化,并与长江中下游地区和中国北方地区(指黄河以北地区)的全新世湿度序列进行了对比。对比结果显示,全新世中期的干旱时段(~7.0-~4.0 cal ka BP或~8.0-~5.0 cal ka BP)与长江中下游地区全新世中期的干旱时段基本对应。这一时段的干旱对应于厄尔尼诺-南方涛动(ENSO)强度的较低值(即La Nino态)时段和赤道西太平洋SST较高温时段。控制上述EASM影响区的中国中部地区全新世湿度空间格局的主要机制可能是ENSO状态以及由ENSO调控的亚热带西太平洋高压(WPSH)的南北向移动。
基金co-supported by the National Natural Science Foundation of China (grant Nos.40773064,40331012 and 40041004)"973" Program of China (No.G1999043501)
文摘The Early Holocene paleoclimate in Bosten Lake on the northern margin of the Tarim Basin, southern Xinjiang, is reconstructed through an analysis of a 953 cm long core （BSTC2000） taken from Bosten Lake. Multiple proxies of this core, including the mineral components of carbonate, carbonate content, stable isotopic compositions of carbonate, Ca/Sr, TOC and C/N and C/S of organic matter, are used to reconstruct the climatic change since 8500 a B.P. The chronology model is made by nine AMS 14C ages of leaves, seeds and organic matter contained in two parallel cores. The climate was cold and wet during 8500 to 8100 a B.P. Temperature increased from 8100 to 6400 a B.P., the climate was warm and humid, and the lake expanded. The lake level was highest during this stage. Then from 6400 to 5100 a B.P., the climate became cold and the lake level decreased slightly. During the late mid-Holocene, the climate was hot and dry from 5100 to 3100 a B.P., but there was a short cold period during 4400 to 3800 a B.P. At this temporal interval, a mass of ice and snow melting water supplied the lake at the early time and made the lake level rise. The second highest lake level stage occurred during 5200 to 3800 a B.P. The climate was cool and wet during 3100 to 2200 a B.P., when the lake expanded with decreasing evaporation. The lake had the last short-term high level during 3100 to 2800 a B.P. After this short high lake level period, the lake shrank because of the long-term lower temperature and reduced water supply. From 2200 to 1200 a B.P., the climate was hot and dry, and the lake shrank greatly. Although the temperature decreased somewhat from 1200 a B.P. to the present, the climate was warm and dry. The lake level began to rise a little again, but it did not reach the river bed altitude of the Konqi River, an outflow river of the Bosten Lake.
基金National Natural Science Foundation of China, No.40771211 No.40261003 National Key Technology Research and Development Program, No.2007BAC03A11 The authors would like to express their sincere thanks to Prof. Fang Xiuqi from Beijing Normal University for his constructive suggestions that greatly improved this manuscript, as well as Dr. Ran Min from Lanzhou University for providing some information, and Yang Yuhan, a master from Qinghai Normal University, for collecting the materials, in the prepa- ration of this paper.
文摘The Holocene Megathermal is divided into early, middle and late periods, each having different impacts on the Neolithic cultures due to their different climate changing trends This study is based on a comparative analysis of the environmental evolution information recorded in the Qinghai Lake, the western edge of the Loess Plateau and Zoige and the spatial distribution of Neolithic sites of the Gansu-Qinghai region. Results show that the early and middle periods towards warm and humid promoted the development of Neolithic cultures with agriculture as the main sector in the Gansu-Qinghai region, furthermore a heyday of Yangshao Culture prosperity emerged. The Holocene entered the late period after the cold climate event at 5.9 ka BP in the Gansu-Qinghai region. Later the climate began to turn cold. However, at the 5.8-4.2 ka BP a relatively stable warm and humid climate created the conditions for the development of Majiayao Culture of the Neolithic Age in this region, thus the distribution of its cultural heritage sites expanded towards high altitudes and high latitudes. From 4.2 ka BP onwards, the climate became cold and dry, which had a significant influence on the Neolithic cultures of the Gansu-Qinghai region, leading to a dramatic change in the cultural characters and spatial distribution of Qijia Culture around 4.2 ka BP. After a nearly 300 years of cold and dry period, the unified Neolithic farming culture completely collapsed. Afterwards an industrial division of animal husbandry and farming and regional multiple cultures formed, and ultimately led to the end of primitive society and the starting of a civilized society.
基金National Science Fund for Distinguished Young Scholars, 40025105 National Natural Science Foundation of China, No. 40331012+3 种基金 NSF Project, No.EAR 0402509 No.BCS 00-78557 Doctoral Fund from Southwest University, No. 104220-20710904 CSTC, No.2009BB7112
文摘Pollen records from the Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes during the last 13.0 ka BP. Before 12.1 ka BP, steppe or desert-steppe vegetation dominated landscape then was replaced by a coniferous forest under a generally wet climate （12.1-11.0 ka BP）. The vegetation was deteriorated into steppe landscape and further into a desert-steppe landscape between 11.0 and 9.8 ka BP. After a brief episode of a cool and wet climate （9.8-9.6 ka BP）, a relatively mild and dry condition prevailed during the early Holocene （9.6-7.6 ka BP）. The most favourable climate of warm and humid period occurred during mid-Holocene （7.6-4.0 ka BP） marked by forest-steppe landscape and vegetation alternatively changed between steppe and desert-steppe from -4.0 to -1.0 ka BP.
基金Supported by the National Natural Science Foundation of China(Grant Nos.40331012 and 40421101)and NSF(Grant Nos.EAR 04-02509 and BCS 06-23478)
文摘A pollen record from Haiyuan section in the southern part of Ningxia revealed a detailed history of vegetation variation and associated climate changes during the period from^13.0 to^7.0 14 C ka BP.A steppe landscape under a moderately dry(and probably cool)condition(~12.7-~12.1 14 C ka BP)was replaced by a coniferous forest dominating the landscape under a generally wet climate from^12.1 to ~11.01 4C ka BP.This generally wet period,corresponding to the European B?lling/All?rod period,can be divided into three stages:a cool and wet stage between^12.1 and^11.4 14 C ka BP,a mild and rela- tively dry stage between^11.4 and^11.2 14 C ka BP,and a mild and wet stage between^11.2 and^11.0 14 C ka BP.The coniferous forest-dominated landscape was then deteriorated into steppe landscape (~11.0-~10.6 14 C ka BP)and further into a desert steppe landscape from^10.6 to^9.8 14 C ka BP,being correspondent to the European Younger Dryas period.After a brief episode of a cool and wet climate (~9.8-~9.6 14 C ka BP),a relatively mild and dry condition prevailed during the early Holocene(~9.6- ~7.6 14 C ka BP)and then a warm and humid climate started the mid-Holocene(~7.6-~7.2 14 C ka BP).
基金Supported by National Natural Science Foundation of China (Grant Nos. 40331012, 40671190, 40421101)U.S. National Science Foundation (Grant Nos. NSF-ESH-04-02509, NSF-BCS-06-23478, NSF-BCS00-78557)
文摘Based on modern pollen studies and reliable chronology of nine AMS 14C dates, a detailed history of vegetation and climate changes during the past 8660 cal. a BP was reconstructed by a high-resolution pollen record from Ugii Nuur in central Mongolia. Poaceae-steppe dominated the study area and the climate was mild and semi-humid before 7800 cal. a BP with a noticeable cool and humid interval at 8350―8250 cal. a BP. Xerophytic plant increased and the climate became warm and dry gradually since 7800 cal. a BP. From 6860 to 3170 cal. a BP, semi-desert steppe expanded, suggesting a prolonged warm and dry climate. Between 3170 and 2340 cal. a BP, regional forest steppe expanded whereas semi-desert steppe retreated, indicating the climate became cool and wet gradually and the humidity reached the maximum at the end of this stage. From 2340 to 1600 cal. a BP, a general cool and wet climate prevailed. And the climatic instability increased after 1600 cal. a BP. Review of regional pub-lished palaeoclimatic records implies that the mid-Holocene dry climate might have prevailed in vast areas from central Mongolia to arid areas of northwest China. Pollen-based climate reconstruction for UG04 core was well correlated with the result of climate model on Central Asia by Bush. In addition, several abrupt climatic events (cool and wet) were found and some could be broadly compared with the cool events in Atlantic.
基金Supported by Chinese Ministry of Education (Grant No. 2000-65)the U.S. National Science Foundation (Grant No. BCS-0078557)
文摘The ratio of Zirconium to Rubidium (Zr/Rb) is suggested to be a better proxy for the East Asian winter monsoon strength than the widely-used grain size distribution. The rationale for the Zr/Rb proxy relies on the following assumptions: (1) Grain size fractionating characteristics during eolian dust transport should be archived in the Zr/Rb ratio records and this assumption is based on the premise that Zr is preferentially enriched in coarser grain size fraction while Rb tend to be enriched in finer grain size fraction; and (2) post-depositional weathering does not change the Zr/Rb ratio due to the immobility of these two elements. To examine these two assumptions, three last interglacial paleosols (S1) from Dingxi, Tianshui and Lantian, along a NW-SE transect across the Chinese Loess Plateau, were geo- chemically investigated. Our results show that the Rb concentration exhibits an increasing trend along the NW-SE transect both in the paleosol (S1) and the measured portions of the loess units (L1 and L2), being supportive to the assumption that Rb is enriched in the fine particles. But we also found that Rb loss did occur to some extent in the three profiles, contradicting to the presumption of Rb immobility during pedogenic processes. The Zr concentration exhibits an expected decreasing trend in the measured portions of the loess units and an unexpected increasing trend in the paleosol along the NW-SE transect. Moreover, the ratios of Zirconium to Hafnium (Zr/Hf) show different variation patterns between interglacial and glacial, implying that Zr-bearing minerals and their resident grain size frac- tions are probably not identical during interglacial and glacial. Thus, the assumption that Zr is enriched in coarse grain size fraction can no longer hold. We conclude that the final Zr/Rb value is not only de- pendent on grain size sorting processes but also on post-depositional alteration and source prove- nance. Under enhanced chemical weathering, especially when chemical index of alteration (CIA) is greater than 65, the Zr/Rb value loses its validity to be a reliable proxy for the winter monsoon strength. In addition, all the Zr/Rb value is constrained above 1.7, a minimum which is definitely modulated by all the three aforementioned factors.
文摘The magnetic susceptibility in the Chinese loess is considered to have recorded thehistory of pedogenesis or land-surface stability, and has thus been used as an acute proxy of thesummer monsoon intensity. With regard to pedogenesis, most authors failed to appreciate thecomplexity of weathering processes. Specifically, not acknowledged are local redox conditions,carbonate concentration and leaching. Pre-depositional pedogenesis may be another factorundermining the legitimacy of using the susceptibility as an acute proxy of the summer monsoonintensity. These factors may not necessarily reflect the degree of pedogenesis although they havedefinitely affected the susceptibility signature. Some contributors to the susceptibility aredemonstrated to be inorganic iron and other organically complexed iron. The organic ironassociated with decomposed plant litter is proven to be the most important contributor to thesusceptibility in modern loess. But, magnetotactic bacteria are believed to be the major generatorsof the ultrafine ferromagnetic particles responsible for the susceptibility signature in theQuaternary loess and paleosols. The factors affecting susceptibility signature may well be site- andtime-dependent even within the Chinese Loess Plateau. Therefore, a more comprehensive modeland a more comprehensive approach are needed to address the relationship between thepaleoclimate and the proxy.
