敦煌盆地早更新世沉积物粒度分析、^(36)Cl定年及其构造隆升意义

Grain Size Analysis and ^(36)Cl Dating of Early Pleistocene Sediments of Dunhuang Basin,Tectonic Uplift Implication

青藏高原早更新世末期的快速隆升对全球气候变化、中国西部盆山地貌形成与荒漠化的发展有着重大影响。高原东北缘敦煌盆地早更新世河湖相沉积物粒度分析和红色泥岩36 Cl断代法定年结果表明:早更新世晚期(1.164～1.087Ma B.P.),青藏高原北部党金山快速隆升,砾石层和粗砂层发育,沉积速率加快;1.087～0.809Ma B.P.,山脉隆升速度变缓,沉积速率降低;0.809Ma B.P.以来,受山脉隆升的影响,敦煌盆地气候逐渐变得干旱,沙漠形成。区域分析表明,沉积速率所反映的中国中西部山脉隆升最新的年代存在差别,不同时期高原的隆升产生不同的气候效应。因此,构造隆升和气候变化的细节尚待进一步研究。

The Early Pleistocene rapid uplift of the Tibet plateau plays an important role to global climate change,formation of basin-range geography and appearance of desertification in Western China.Detailed grain size analysis and 36Cl dating have been carried out on the Early Pleistocene fluvio-lacustrine sediments of the Dunhuang basin in northeastern Tibet plateau.Results show that the Dangjinshan Mountains rose rapidly at the end of the Early Pleistocene（1.164-1.087 Ma B.P.）,and gravels and coarse sandstones were deposited with high sedimentation rate.From 1.087 Ma B.P.to 0.809 Ma B.P.,mountain uplift speed became slower with lower sedimentation rate.Since 0.809 Ma B.P.,climate in the Dunhuang basin area became arid,and desert was formed possibly affected by mountain uplift.The regional analysis results suggest that the last uplifting time of Mountains in the Middle-West China was distinction,which generated various climate effects.Therefore,the relationship between tectonic uplift of the Tibet plateau and climate change is needed to further study.