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引用本文:朱大岗1 孟宪刚1 邵兆刚1 杨朝斌2 韩建恩1 余 佳1 孟庆伟1 吕荣平1. 西藏阿里札达盆地早更新世早期沉积及其古气候与古环境变化[J]. 中国地质, 2006, 33(6): 1276-1284.
ZHU Da-gang1, MENG Xian-gang1, SHAO Zhao-gang1, YANG Chao-bin2, HAN Jian-en1, YU Jia1, MENG Qing-wei1, LV Rong-ping1. Early Pleistocene deposits and paleoclimatic and paleoenvironmental changes in the Zanda basin, Ngari area, Tibet[J]. Geology in China, 2006, 33(6): 1276-1284(in Chinese with English abstract).
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西藏阿里札达盆地早更新世早期沉积及其古气候与古环境变化
朱大岗1 孟宪刚1 邵兆刚1 杨朝斌2 韩建恩1 余 佳1 孟庆伟1 吕荣平11,2
1.中国地质科学院地质力学研究所,北京 100081;2.西藏自治区国土资源厅,西藏 拉萨 850000
摘要:
提要:综合分析了西藏阿里札达盆地早更新世早期的多种与气候环境变化密切相关的地质记录,结果表明该区早更新世早期的沉积可划分为3种不同的沉积相和4个岩性段;古气候与古环境变化可划分为4个阶段:(1)2.68~2.45 Ma,为冲洪积相沉积,冻融褶皱开始出现,植被以乔木为主,主要为松、藜、蒿,属山地寒温气候;(2)2.45~2.11 Ma,为冲洪积相,地层中冻融褶皱多呈扭曲状,草本植物迅速上升,显示出灌木草原气候特征,气候变得凉爽干燥;(3)2.11~1.49 Ma,沉积相为冲洪积相—冰缘沉积相,以冰缘沉积相为主,冻融褶皱层开始增多,出现了喜凉的介形类化石,草本植物数量和种类达到最大,灌木也相对增加,显示气候进一步趋于干旱;(4)1.49~1.36 Ma,为冰湖沉积相,地层中普遍出现冻融褶皱,喜凉的介形类化石丰度很高,草本植物有小幅下降,但蕨类植物增加幅度较大,显示了干冷草原气候特征,气候干旱寒冷。
关键词:  西藏札达  早更新世早期  孢粉记录  冻融褶皱  气候与环境变化
DOI:
分类号:
基金项目:国家自然科学基金项目(40572134)和中国地质调查局项目(1212010511902)共同资助。
Early Pleistocene deposits and paleoclimatic and paleoenvironmental changes in the Zanda basin, Ngari area, Tibet
ZHU Da-gang1, MENG Xian-gang1, SHAO Zhao-gang1, YANG Chao-bin2, HAN Jian-en1, YU Jia1, MENG Qing-wei1, LV Rong-ping11,2
1.Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China;2.Department of Land and Resources of the Tibet Autonomous Region, Lhasa 850000, China
Abstract:
Abstract:The paper analyzes various geological records closely related to the earliest Pleistocene climatic and environmental changes in the Zanda basin, Ngari, Tibet. The analytic results indicate that the earliest Pleistocene deposits in the study area may be divided into three sedimentary facies and four lithozones and that the paleoclimatic and paleoenvironmental changes may be divided into four stages: ① the 2.68-2.45 Ma stage, which is marked by alluvial and diluvial deposits, when freeze-and-thaw folds started to appear and the vegetations were dominated by arbores, mainly including Pinus, Chenopodiaceae and Artemisia, indicating a cool-temperate alpine climate; ② the 2.45-2.11 Ma stage, which is also marked by alluvial and diluvial deposits, when most freeze-and-thaw folds in strata were contorted, herbaceous plants increased rapidly, showing the features of the shrub-grassland climate, and the climate became cool and dry; ③ the 2.11-1.49 Ma stage, which is marked by alluvial-diluvial and periglacial deposits (mainly periglacial deposits), when the freeze-and-thaw folds increased, there appeared cryophilic ostracods, and the quantity and varieties of herbaceous plants reached a maximum and the shrubs also increased relatively, showing that the climate became more and more arid; and ④ the 1.49-1.36 Ma stage, which is marked by glaciolacustrine deposits, when the freeze-and-thaw folds appeared extensively in the strata, the abundance of cryophilic ostracods was very high and the herbaceous plants decreased slightly but pteridophytes increased significantly, showing the features of the cold-dry grassland climate.
Key words:  Zanda, Tibet  earliest Pleistocene  sporopollen record, freeze-and-thaw fold  climatic and environmental change