地质学报2017，Vol.91Issue(12)：2623-2637,15.
拉萨地体中部上白垩统达雄组的建立及构造隆升意义
The Establishment of the Upper Cretaceous Daxiong Formation in the Central Lhasa Terrane and its Implications for Tectonic Uplifting
摘要
Abstract
An E-W-trending late Cretaceous terrestrial molasse with a thickness of 1800 m deposited in the Coqen basin,central Lhasa terrane.Detailed measurement on the well outcropped Xiagezi section near Neidaxiong village in the study area was carried out.This set of the strata can be divided into five members as follow:medium-coarse grained sandstones,massive conglemerates,medium grained sandstones interbedded with siltstones and mudstones,massive siltstones/mudstones,and homogeneous mediumgrained sandstones.The strata unconformabley overlays over the Langshan limestones and are covered by Cenozoic sediments.Analysis of lithogical facies assemblage and sedimentary structures shows that the strata formed under the alluvial fan-braided river systems.Phacinoides occurring in the interbedded volcanic rocks and the underlying Langshan limestones indicate that the strata formed at ～98～91 Ma,and this is consistent with the age of the youngest detrital zircons.Statistic results also show that conglomerate and sandstone modal compositions imply a "magmatic arc" source area.The detrital zircon U-Pb ages and Hf isotopes suggest that the widely spread Early Cretaceous Zenong volcanic rocks on the central Lhasa terrane may be the main source.Based on distribution,composition and the provenance of the Late Cretaceous terrestrial sediments,this study defined the "Daxiong Formation" and compared it with the Jingzhushan Formation in the north of the central Lhasa terrane.The study suggests that the two may represent early tectonic uplifting of the central Lhasa terrane during the early Late Cretaceous (～98～91 Ma),and this provides geological evidence for the uplifting of the Qinghai-Tibet plateau prior to the IndoAsian continental collision.关键词
晚白垩世/达雄组/拉萨地体/青藏高原/隆升Key words
Late Cretaceous/Daxiong Formation/Lhasa terrane/Tibetan Plateau/uplift引用本文复制引用
孙高远,胡修棉..拉萨地体中部上白垩统达雄组的建立及构造隆升意义[J].地质学报,2017,91(12):2623-2637,15.基金项目
本文为国家自然科学基金(批准号41602104,41472081)、江苏省自然科学青年基金(批准号BK20160858)和中央高校业务费(2015B11414)项目共同资助的成果. （批准号41602104,41472081）
