Detrital Zircon U-Pb Age and Hf Isotopic Composition, and Detrital Apatite (U-Th)/He Age from the Paleogene Sediments of Changsha-Gongma Basin, the Songpan-Ganzi Block and Their Geological Significance
详细信息
- 责任者：Dai Jingen (State Key Laboratory of Biogeology and Environmental Geology ; School of Earth Sciences and Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Li Yalin
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(3)
- 关键词：碎屑岩 ; clastic rocks ; 铀—铅计时 ; U-Pb dating ; 青藏高原 ; Qinghai-Tibetan Plateau
- 页码：p.1003-1016
- 图表：illus., 2 tables, 71 refs.
- 分类号：0803
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The surface uplift and erosion of Tibetan Plateau is critical for many Cenozoic geological events ranging from continental lithosphere deformation to global cooling.Previous studies of this topic are mostly focused on Lhasa and Qiangtang blocks,central Tibetan Plateau.However,the Songpan-Ganzi block has received much less attention,resulting in the elusive understanding of its uplift history.Here we report results from sedimentology,detrital zircon U-Pb ages and Hf isotopic compositions,and detrital apatite(U-Th)/He ages from the Paleogene sediments of Changsha-Gongma Basin,western-central Songpan-Ganzi block.Sediments in the Changsha-Gongma Basin are characterized by poorly sorted conglomerate,lithic sandstone,and massive mudstone,indicating they were fast accumulations and closed to provenance area.Sample SD02 possesses four significant peak zircon ages at 200～500Ma,760～1040Ma,1800～2000Ma,and 2300～2600Ma,which are comparable with those of Triassic sandstones in the Songpan-Ganzi block,suggesting that they were all derived from the the Songpan-Ganzi block.The Songpan-Ganzi underwent one period of uplift and erosion during Late Cretaceous-Early Paleogene on the basis of the onset of Changsha-Gongma Basin sedimentation.This stage of uplift was coeval with those of central Tibetan Plateau,strongly implying that the proto-Tibetan Plateau also involved the Songpan-Ganzi block.Apatite(U-Th)/He ages from sample SD02 indicate that the Changsha-Gongma Basin experienced another stage of uplift and erosion during Late Oligocene and Early Miocene,as well as most of the Songpan-Ganzi block.Detrital zircon Hf model ages from sample SD02 are clustered at 0.77～2.5Ga,suggesting that the crustal growth of their preliminary provenance area largely occurred during Proterozoic.
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