Geochemistry of Late Triassic pelitic rocks in the NE part of Songpan-Ganzi Basin, western China: Implications for source weathering, provenance and tectonic setting

Geoscience Frontiers

Yan Tang¹  Yanming Yuan²  Longkang Sang²  Yunlong Yang³  Yunpeng Zhang⁴ 

[1] College of Earth Science and Resources, Chang’an University, Xi’an 710054, PR China;Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, PR China;SINOPEC Exploration Southern Company, Chengdu 610082, PR China;Xi’an Center of Geological Survey, China Geological Survey, Xi’an 710054, PR China;

关键词: Fine-grained sandstone-mudstone;    Geochemistry;    Source area weathering;    Provenance;    Tectonic setting;    Songpan-Ganzi Basin, China;   

DOI  :  10.1016/j.gsf.2012.01.006

来源: DOAJ

【 摘 要 】

Major, trace and rare earth element (REE) concentrations of Late Triassic sediments (fine-grained sandstones and mudstones) from Hongcan Well 1 in the NE part of the Songpan-Ganzi Basin, western China, are used to reveal weathering, provenance and tectonic setting of inferred source areas. The Chemical Index of Alteration (CIA) reflects a low to moderate degree of chemical weathering in a cool and somewhat dry climate, and an A-CN-K plot suggests an older upper continental crust provenance dominated by felsic to intermediate igneous rocks of average tonalite composition. Based on the various geochemical tectonic setting discrimination diagrams, the Late Triassic sediments are inferred to have been deposited in a back-arc basin situated between an active continental margin (the Kunlun-Qinling Fold Belt) and a continental island arc (the Yidun Island Arc). The Triassic sediments in the study area underwent a rapid erosion and burial in a proximal slope-basin environment by the petrographic data, while the published flow directions of Triassic turbidites in the Aba-Zoige region was not supported Yidun volcanic arc source. Therefore, we suggest that the Kunlun-Qinling terrane is most likely to have supplied source materials to the northeast part of the Songpan-Ganzi Basin during the Late Triassic.

【 授权许可】

Unknown