Provenance of the Late Permian Xuanwei Formation in the Upper Yangtze Block: Constraints from the Sedimentary Record and Tectonic Implications

论文摘要

Xuanwei Formation is composed of mudstone, siltstone, and sandstone, with local conglomerate. However, its provenance and tectonic setting have been scarcely studied. In this paper, we use sedimentology, electron probe microanalysis（EPMA）, and detrital zircon dating to investigate its source area and depositional tectonic setting. The facies assemblages indicate that it formed in alluvial fan and fluvial river sedimentary environments. The strata thicknesses and facies distribution indicate that the sediment supply was from the west. The results of EPMA show that chromian spinels within the sediments are characterized by high Cr# and varying Mg#. Discrimination plots suggest that these spinels were sourced from large igneous province（LIP） magmatic rocks. The laser ablation inductively coupled plasma mass spectrometry（LA-ICP-MS） U–Pb chronology of detrital zircons suggests that the sediments were derived from intermediate–acid igneous rocks dating back to 251–260? Ma. We could, therefore, conclude that the provenance of the Xuanwei Formation is from Emeishan basalt and synchronous felsic igneous rocks, which is consistent with the composition of the detrital framework. The detrital zircon dates also suggest that felsic magmatism occurred during the Late Permian, not after the eruption of the Emeishan basalt. Based on the sedimentary successions and provenance analysis, the tectonic setting for Xuanwei Formation deposition was a volcanic rifted margin.

论文目录

• 1 Introduction
• 2 Geological Background
• 3 Sedimentology
•   3.1 Facies description and interpretation
•   3.2 Section description and interpretation
•   3.3 Sedimentary facies
•   3.4 Petrology
• 4 Sampling and Analytical Methods
•   4.1 Sampling
•   4.2 EPMA
•   4.3 Detrital zircon U-Pb dating
• 5 Analytical Results
•   5.1 EPMA
•   5.2 Detrital zircon geochronology
• 6 Discussions
•   6.1 Provenance
•   6.2 Implications for ELIP felsic volcanism
•   6.3 Tectonic setting
• 7 Conclusions

文章来源

类型: 期刊论文

作者: ZHANG Yingli,JIA Xiaotong,WANG Zongqi

来源: Acta Geologica Sinica(English Edition) 2019年06期

年度: 2019

分类: 基础科学

专业: 地质学

单位: MNR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences,Engineering Seismology Institute of Zhejiang Province

基金: supported by the National Science Foundation of China (No. 41302080),the fundamental research funds for central public welfare research institutes(No:K1613),Chinese Geological Survey (No. DD20190099,DD20190437)

分类号: P534.46;P512.2;P597.3

页码: 1673-1686

总页数: 14

文件大小: 1246K

下载量: 8