Biological records of paleoclimate and paleoenvironment changes from Guanzhong area, Shaanxi Province during the last glacial maximum

Xiangxu Xue; Weijian Zhou; Jie Zhou; J. Head; A. J.T. Jull

doi:10.1007/BF02887417

Biological records of paleoclimate and paleoenvironment changes from Guanzhong area, Shaanxi Province during the last glacial maximum

Xiangxu Xue, Weijian Zhou, Jie Zhou, J. Head, A. J.T. Jull

Geosciences

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Abstract

We have collected a suite of Paleoloxodon naumanni-Coelodonta antiquitatis fossils from a river terrace profile between Xi'an and Xianyang cities in Guanzhong Area, Shaanxi Province. A detailed examination of the fossils, together with ¹⁴C determinations and pollen analyses, have enabled us to reconstruct preliminary features of climate and environment changes and their evolutionary processes, within the last glacial maximum (LGM): about 20 ka ago, the climate was basically cool and wet, and was favourable for the existence of Paleoloxodon naumanni-Coelodonta antiquitatis fauna. This was followed by a cold, dry phase which was no longer suitable for this type of faunal suite, causing the death of a large number of mammalian assemblages. The available evidence indicates the existence of cold-dry and cool-wet climate and environment fluctuations during the LGM. The cool-wet stage within the LGM reflects a Heinrich event occurring in the high latitude areas, proving the existence of a teleconnection between polar-high latitude areas and the Loess Plateau.

Original language	English (US)
Pages (from-to)	853-857
Number of pages	5
Journal	Chinese Science Bulletin
Volume	45
Issue number	9
DOIs	https://doi.org/10.1007/BF02887417
State	Published - 2000

Keywords

Guanzhong of Shaanxi Province
Last glacial maximum
Paleoloxodon naumanni-Coelodonta antiquitatis fauna
Paleomonsoon precipitation

ASJC Scopus subject areas

General

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10.1007/BF02887417

Cite this

@article{656a6cdb0f77407cb49a9390df60b98a,

title = "Biological records of paleoclimate and paleoenvironment changes from Guanzhong area, Shaanxi Province during the last glacial maximum",

abstract = "We have collected a suite of Paleoloxodon naumanni-Coelodonta antiquitatis fossils from a river terrace profile between Xi'an and Xianyang cities in Guanzhong Area, Shaanxi Province. A detailed examination of the fossils, together with 14C determinations and pollen analyses, have enabled us to reconstruct preliminary features of climate and environment changes and their evolutionary processes, within the last glacial maximum (LGM): about 20 ka ago, the climate was basically cool and wet, and was favourable for the existence of Paleoloxodon naumanni-Coelodonta antiquitatis fauna. This was followed by a cold, dry phase which was no longer suitable for this type of faunal suite, causing the death of a large number of mammalian assemblages. The available evidence indicates the existence of cold-dry and cool-wet climate and environment fluctuations during the LGM. The cool-wet stage within the LGM reflects a Heinrich event occurring in the high latitude areas, proving the existence of a teleconnection between polar-high latitude areas and the Loess Plateau.",

keywords = "Guanzhong of Shaanxi Province, Last glacial maximum, Paleoloxodon naumanni-Coelodonta antiquitatis fauna, Paleomonsoon precipitation",

author = "Xiangxu Xue and Weijian Zhou and Jie Zhou and J. Head and Jull, {A. J.T.}",

note = "Funding Information: Mammalian assemblages from the Xianyang sand pit, together with Late Pleistocene fauna from Shalawusu and Huanxian-Qingyang areas, belong to the Paleoloxodon-Coelodonta faunal suite. However, Xianyang fauna contains Cewus nippon hortulorum, which prefers a warm-wet forest or grassland with forest margin environment, together with Bubalus youngi, that was also discovered at Mengxian County, Henan Province. The examples mentioned above reflect a cool and wet living environment with more water and forest, corresponding to relatively warm and wet or cool and wet conditions within the glacial period. 3 Discussion From climate and environment reconstructions aided by Xianyang faunal data, we postulate a dominant summer monsoon precipitation increase event within a background of global cooling in East Asia during the LGM (20 000 ka). The climate would have been favorable to the existence of Paleoloxodon-Coelodonta fauna. This concept is further substantiated by pollen data from Layer 9. Abies and Picea are 7.0%-24.2% and 3.0%-5.4% respectively. If the sum of Abies and Picea became more than 20%, it would be expected that sparse Abies and Picea forests existed in the area during that timec3'.T he timing of the precipitation increase event can be correlated with the Heinrich 2 (H2) eventrs1.A fter this period, the climate returned to cold and dry winter monsoon dominance typical of the LGM. Because of the severe cold and dry conditions, a large number of mammalian fauna were not able to withstand the environment change and died out. Because of the degree of preservation of fossils, we can presume that water energy conditions at that time were relatively weak, hence the faunal remains stayed within the river course. From a geomorphological point of view, we suggest that the sand gravel layer containing mud boulder was produced by a cold and dry climate and environment. Frost weathering and arid disintegration were strong, and vegetation cover was scattered under the cold and dry conditions. Both banks of the river would have been susceptible to collapse thus providing clastic materials caused by small water volume and a large river loading. This would happen particularly in small rivers (for example, the Weihe River and its tributary) which are susceptible to overload or overload saturation. Downcutting would have decreased and accretion accumulation occurred. Trimming and widening of the river valley occurred, causing a collapse of mud from the river bank, producing boulder clay via short distance transportation. The Early Holocene climate recorded in the profile is representative of cold and dry conditions, with grassland together with deposition of sand gravel containing boulder clay. The Late Holocene is characterized by the resumption of river downcutting and deposition of eolian sediments; at the same time, water and temperature conditions were favorable to blackloam development. Wood pollen occupied 63.4% of the total pollen, reflecting warm and wet climate conditions. However, there were periodic cold and dry fluctuations within the warm-humid Late Holocene climate. Various geological and biological records from inland China indicate that during the LGM, there was desert expansion, rapid deposition of loess, shrinkage of arid-semi arid lakes, mountain glacial advance, and permafrost conditions. The tundra and steppe belt advanced southeastward 8{"} further in latitude than the present and the coastline retreated eastward 800-1 000 km compared with the present position. Annual temperatures in central and eastern China were 10-12°C lower than those of the present day'''. Paleobiological records for this study suggest that the LGM was not a continuous cold and dry period, but was punctuated by cool and wet periods, similar to those indicated for Heinrich events, discussed in recent studies, and characterized by global precipitation trends. For example, humid events reflected by Pinus pollen from Lake Tulane in Florida, USA correlate well with HI-H~'~', because the Gulf of Mexico region is influenced by trade winds, producing a wet environment with high precipitation. Cold and wet events found in the Chinese Zhujiang River outlet and the South China Sea provide a good correlation with the H1 event[71.Y ao Tandong suggested that the temperature change of last glacial maximum ranges from 3 to 7°C from Guliya ice core, reflecting the frequent fluctuations of glacial climate[81. Porter and An proposed the correlation of winter monsoon strengthening events with H1-H6 on the basis of grain size analysis of Luochuan sequences from Loess ~lateau'~B'.a sed on the above evidence, global climates have not completely followed the cold and dry pattern indicated by Heinrich events. Because of the interaction between south and north polar cold sources, ocean thermal circulation and the atmosphere, some places reflect cold and dry, others reflect wet-cool, and still others reflect an interalteration of cold-dry with cool-wet conditions. A spacial variation study of the same global event can only be carried out when more reliably dated material becomes available. The cool-wet fluctuation from the Xianyang profile within the LGM sequence correlates with H2, indicating a fingerprint of the high latitude Heinrich event in the southern Loess Plateau. The precipitation increase of east Asian monsoon during the LGM may be related to an interaction of the cold airmass from high latitudes with warm moist air from the low latitude tropical ocean^{"}^'. We believe that our understanding will be improved with more data available. Acknowledgements The authors would like to thank Pro. Di Shixiang for field work and data analysis; Prof. Li Wenhou and Mr. Zhao Jufa for sample collection and field work; Prof. An Zhisheng for his constructive advice. This work was supported by the State Science & Technology Commission (SSTC 95-40), the Education Commission of Shaanxi Province, the National Natural Science Foundation of China (Grant Nos. 49725308 and 49894170), and the Chinese Academy of Sciences (Grant No. KZ952-S 1-4 19). References 1. An, Z. S., Wu, X. H., Lu ,Y. C. et al., The preliminary study of pleoenvironment change in China since the last 20 ka, in Loess, Quaternary Research, Global Change (in Chinese), Part I1 (ed. Liu Tungshen), Beijing: Science Press, 1990, 1-26. 2. Sun, X. J., A restudy of the latest Pleistocene paleovegetation at Beizhuangcun, Shaanxi province, northern China, Quaternary Sciences (in Chinese), 1989(2): 177. 3. Zhou, W. J., An, Z. S., Jull, A. J. T. et al., Reappraisal of Chinese Loess Plateau stratigraphic sequences over the last 30 000 years, Radiocarbon, 1998,40(2): 905. 4. Kahlke, R. D., Die Entstehungs-, Entwicklungs-und Verbreitungschichte des oberpleistozanen Mammuthus-Coelodota-Faunenkomploxes in Eurasien (Gropsaauger) (ed. Herausgegeben von Prof. Dr. Willi Ziegler), Frankfurt Am Main, Verlag Waldemar Kramer, 1994. 5. Broecher, W. S., Massive iceberg discharges as triggers for global climate change, Nature,1994, 373: 421. 6. Grivmn, E. C., A 500 000-year record of climate oscillation from Florid and its temporal correlation with the Heinrich events, Science, 1993,261: 198. 7. Kudrass, H. R., Global nature of the Younger Dryas cooling event inferred from oxygen isotope data from Sulu Sea Cores, Nature, 1991,394: 406. 8. Yao, T. D., Abrupt climate change of Tibetan Plateau in the last glaciation, Science in China (in Chinese), Ser. D, 1999,",

year = "2000",

doi = "10.1007/BF02887417",

language = "English (US)",

volume = "45",

pages = "853--857",

journal = "Chinese Science Bulletin",

issn = "1001-6538",

publisher = "Elsevier B.V.",

number = "9",

}

TY - JOUR

T1 - Biological records of paleoclimate and paleoenvironment changes from Guanzhong area, Shaanxi Province during the last glacial maximum

AU - Xue, Xiangxu

AU - Zhou, Weijian

AU - Zhou, Jie

AU - Head, J.

AU - Jull, A. J.T.

N1 - Funding Information: Mammalian assemblages from the Xianyang sand pit, together with Late Pleistocene fauna from Shalawusu and Huanxian-Qingyang areas, belong to the Paleoloxodon-Coelodonta faunal suite. However, Xianyang fauna contains Cewus nippon hortulorum, which prefers a warm-wet forest or grassland with forest margin environment, together with Bubalus youngi, that was also discovered at Mengxian County, Henan Province. The examples mentioned above reflect a cool and wet living environment with more water and forest, corresponding to relatively warm and wet or cool and wet conditions within the glacial period. 3 Discussion From climate and environment reconstructions aided by Xianyang faunal data, we postulate a dominant summer monsoon precipitation increase event within a background of global cooling in East Asia during the LGM (20 000 ka). The climate would have been favorable to the existence of Paleoloxodon-Coelodonta fauna. This concept is further substantiated by pollen data from Layer 9. Abies and Picea are 7.0%-24.2% and 3.0%-5.4% respectively. If the sum of Abies and Picea became more than 20%, it would be expected that sparse Abies and Picea forests existed in the area during that timec3'.T he timing of the precipitation increase event can be correlated with the Heinrich 2 (H2) eventrs1.A fter this period, the climate returned to cold and dry winter monsoon dominance typical of the LGM. Because of the severe cold and dry conditions, a large number of mammalian fauna were not able to withstand the environment change and died out. Because of the degree of preservation of fossils, we can presume that water energy conditions at that time were relatively weak, hence the faunal remains stayed within the river course. From a geomorphological point of view, we suggest that the sand gravel layer containing mud boulder was produced by a cold and dry climate and environment. Frost weathering and arid disintegration were strong, and vegetation cover was scattered under the cold and dry conditions. Both banks of the river would have been susceptible to collapse thus providing clastic materials caused by small water volume and a large river loading. This would happen particularly in small rivers (for example, the Weihe River and its tributary) which are susceptible to overload or overload saturation. Downcutting would have decreased and accretion accumulation occurred. Trimming and widening of the river valley occurred, causing a collapse of mud from the river bank, producing boulder clay via short distance transportation. The Early Holocene climate recorded in the profile is representative of cold and dry conditions, with grassland together with deposition of sand gravel containing boulder clay. The Late Holocene is characterized by the resumption of river downcutting and deposition of eolian sediments; at the same time, water and temperature conditions were favorable to blackloam development. Wood pollen occupied 63.4% of the total pollen, reflecting warm and wet climate conditions. However, there were periodic cold and dry fluctuations within the warm-humid Late Holocene climate. Various geological and biological records from inland China indicate that during the LGM, there was desert expansion, rapid deposition of loess, shrinkage of arid-semi arid lakes, mountain glacial advance, and permafrost conditions. The tundra and steppe belt advanced southeastward 8" further in latitude than the present and the coastline retreated eastward 800-1 000 km compared with the present position. Annual temperatures in central and eastern China were 10-12°C lower than those of the present day'''. Paleobiological records for this study suggest that the LGM was not a continuous cold and dry period, but was punctuated by cool and wet periods, similar to those indicated for Heinrich events, discussed in recent studies, and characterized by global precipitation trends. For example, humid events reflected by Pinus pollen from Lake Tulane in Florida, USA correlate well with HI-H~'~', because the Gulf of Mexico region is influenced by trade winds, producing a wet environment with high precipitation. Cold and wet events found in the Chinese Zhujiang River outlet and the South China Sea provide a good correlation with the H1 event[71.Y ao Tandong suggested that the temperature change of last glacial maximum ranges from 3 to 7°C from Guliya ice core, reflecting the frequent fluctuations of glacial climate[81. Porter and An proposed the correlation of winter monsoon strengthening events with H1-H6 on the basis of grain size analysis of Luochuan sequences from Loess ~lateau'~B'.a sed on the above evidence, global climates have not completely followed the cold and dry pattern indicated by Heinrich events. Because of the interaction between south and north polar cold sources, ocean thermal circulation and the atmosphere, some places reflect cold and dry, others reflect wet-cool, and still others reflect an interalteration of cold-dry with cool-wet conditions. A spacial variation study of the same global event can only be carried out when more reliably dated material becomes available. The cool-wet fluctuation from the Xianyang profile within the LGM sequence correlates with H2, indicating a fingerprint of the high latitude Heinrich event in the southern Loess Plateau. The precipitation increase of east Asian monsoon during the LGM may be related to an interaction of the cold airmass from high latitudes with warm moist air from the low latitude tropical ocean^"^'. We believe that our understanding will be improved with more data available. Acknowledgements The authors would like to thank Pro. Di Shixiang for field work and data analysis; Prof. Li Wenhou and Mr. Zhao Jufa for sample collection and field work; Prof. An Zhisheng for his constructive advice. This work was supported by the State Science & Technology Commission (SSTC 95-40), the Education Commission of Shaanxi Province, the National Natural Science Foundation of China (Grant Nos. 49725308 and 49894170), and the Chinese Academy of Sciences (Grant No. KZ952-S 1-4 19). References 1. An, Z. S., Wu, X. H., Lu ,Y. C. et al., The preliminary study of pleoenvironment change in China since the last 20 ka, in Loess, Quaternary Research, Global Change (in Chinese), Part I1 (ed. Liu Tungshen), Beijing: Science Press, 1990, 1-26. 2. Sun, X. J., A restudy of the latest Pleistocene paleovegetation at Beizhuangcun, Shaanxi province, northern China, Quaternary Sciences (in Chinese), 1989(2): 177. 3. Zhou, W. J., An, Z. S., Jull, A. J. T. et al., Reappraisal of Chinese Loess Plateau stratigraphic sequences over the last 30 000 years, Radiocarbon, 1998,40(2): 905. 4. Kahlke, R. D., Die Entstehungs-, Entwicklungs-und Verbreitungschichte des oberpleistozanen Mammuthus-Coelodota-Faunenkomploxes in Eurasien (Gropsaauger) (ed. Herausgegeben von Prof. Dr. Willi Ziegler), Frankfurt Am Main, Verlag Waldemar Kramer, 1994. 5. Broecher, W. S., Massive iceberg discharges as triggers for global climate change, Nature,1994, 373: 421. 6. Grivmn, E. C., A 500 000-year record of climate oscillation from Florid and its temporal correlation with the Heinrich events, Science, 1993,261: 198. 7. Kudrass, H. R., Global nature of the Younger Dryas cooling event inferred from oxygen isotope data from Sulu Sea Cores, Nature, 1991,394: 406. 8. Yao, T. D., Abrupt climate change of Tibetan Plateau in the last glaciation, Science in China (in Chinese), Ser. D, 1999,

PY - 2000

Y1 - 2000

N2 - We have collected a suite of Paleoloxodon naumanni-Coelodonta antiquitatis fossils from a river terrace profile between Xi'an and Xianyang cities in Guanzhong Area, Shaanxi Province. A detailed examination of the fossils, together with 14C determinations and pollen analyses, have enabled us to reconstruct preliminary features of climate and environment changes and their evolutionary processes, within the last glacial maximum (LGM): about 20 ka ago, the climate was basically cool and wet, and was favourable for the existence of Paleoloxodon naumanni-Coelodonta antiquitatis fauna. This was followed by a cold, dry phase which was no longer suitable for this type of faunal suite, causing the death of a large number of mammalian assemblages. The available evidence indicates the existence of cold-dry and cool-wet climate and environment fluctuations during the LGM. The cool-wet stage within the LGM reflects a Heinrich event occurring in the high latitude areas, proving the existence of a teleconnection between polar-high latitude areas and the Loess Plateau.

AB - We have collected a suite of Paleoloxodon naumanni-Coelodonta antiquitatis fossils from a river terrace profile between Xi'an and Xianyang cities in Guanzhong Area, Shaanxi Province. A detailed examination of the fossils, together with 14C determinations and pollen analyses, have enabled us to reconstruct preliminary features of climate and environment changes and their evolutionary processes, within the last glacial maximum (LGM): about 20 ka ago, the climate was basically cool and wet, and was favourable for the existence of Paleoloxodon naumanni-Coelodonta antiquitatis fauna. This was followed by a cold, dry phase which was no longer suitable for this type of faunal suite, causing the death of a large number of mammalian assemblages. The available evidence indicates the existence of cold-dry and cool-wet climate and environment fluctuations during the LGM. The cool-wet stage within the LGM reflects a Heinrich event occurring in the high latitude areas, proving the existence of a teleconnection between polar-high latitude areas and the Loess Plateau.

KW - Guanzhong of Shaanxi Province

KW - Last glacial maximum

KW - Paleoloxodon naumanni-Coelodonta antiquitatis fauna

KW - Paleomonsoon precipitation

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SN - 1001-6538

VL - 45

SP - 853

EP - 857

JO - Chinese Science Bulletin

JF - Chinese Science Bulletin

IS - 9

ER -

Biological records of paleoclimate and paleoenvironment changes from Guanzhong area, Shaanxi Province during the last glacial maximum

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