Palynological evidence for Late Miocene–Pliocene vegetation evolution recorded in the red clay sequence of the central Chinese Loess Plateau and implication for palaeoenvironmental change
Palynological evidence for Late Miocene–Pliocene vegetation evolution recorded in the red clay sequence of the central Chinese Loess Plateau and implication for palaeoenvironmental change
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DOI：
10.1016/j.palaeo.2006.06.012
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发表时间：
2006-11
期刊：
影响因子：
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通讯作者：
Luo Wang;Houyuan Lu;N. Wu;Jingjing Li;Y. Pei;G. Tong;Shuzhen Peng
中科院分区：
文献类型：
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作者：
Luo Wang;Houyuan Lu;N. Wu;Jingjing Li;Y. Pei;G. Tong;Shuzhen Peng
在中国北部，黄土高原东部晚中新世-上新世红粘土填补了2.6万Ma以来众所周知的黄土-土层序与黄土高原西部中新世黄土-土层序之间的气候记录空白。前人的研究表明，红粘土也是风吹成因，时间跨度为∼7-8~∼2.6亿Ma。因此，红粘土为重建古生态演替和古气候变化提供了很好的档案。本文对黄土高原中部西峰晚中新世-上新世红粘土序列进行了孢粉学研究，对∼6.2~∼2.4 Ma以来植被演化和气候变化的本质提供了新的认识。结果表明，在此期间，黄土高原中部地区主要被草原植被覆盖，表明气候条件持续干旱。在此期间，共识别出三个植被带。A区(∼6.2~∼5.8 Ma)以草原生态系统为特征；B区(∼5.8~∼4.2 Ma)以温带森林植物明显增多为特征，表明区域气候相对湿润；C区(∼4.2~∼2.4 Ma)为典型的草原生态系统。植被漂移约4.5~3.7 Ma，当温带森林植物减少时，植被逐渐向典型草原甚至荒漠草原转变。这被解释为表示干燥事件。青藏高原在4.5 Ma左右的隆升导致季风逆转的加剧，被认为在这一重大的生态变化中发挥了重要作用。高纬度降温可能是黄土高原地区∼4.5Ma至∼3.7亿Ma期间气候变化的部分原因，也可能是3.7亿Ma左右生态变化的驱动力。
In northern China, the Late Miocene–Pliocene red clay in the eastern Loess Plateau fills a gap of climate records between the well-known loess-soil sequences of the last 2.6 Ma and the Miocene loess-soil sequences from the western Loess Plateau. Previous studies indicate that the red clay is also of wind-blown origin, covering the period from ∼7–8 to ∼2.6 Ma. The red clay therefore provides a good archive to reconstruct paleoecological succession and paleoclimate change. In this study, a palynological investigation was conducted on the late Miocene–Pliocene red clay sequence at Xifeng, central Loess Plateau, which provides new insights into the nature of the evolution of vegetation and climate change from ∼6.2 to ∼2.4 Ma. Our results show that during this period the central Loess Plateau region was covered mainly by a steppe vegetation, indicating long lasting dry climatic condition. Three vegetational zones were recognized during this period. Zone A (∼6.2 to ∼5.8 Ma) is characterized by a steppe ecosystem; Zone B (∼5.8 to ∼4.2 Ma) is characterized by a significant increase of temperate forest plants, indicating a relatively humid regional climate; Zone C (∼4.2 to ∼2.4 Ma) indicates a typical steppe ecosystem. The vegetation shift at about 4.5–3.7 Ma, when the temperate forest plants decrease, the vegetation gradually changed to typical grassland and even to desert steppe. This is interpreted to represent a drying event. The uplift of the Tibetan Plateau at about 4.5 Ma that resulted in the intensification of the monsoon reversal is thought to have played an important role in this significant ecological change. High-latitude cooling may have partially contributed to the climate shift during ∼4.5 to ∼3.7 Ma in the Loess Plateau region, and most likely was the driving force for the ecological shift at about 3.7 Ma.