Detrital Zircon U-Pb Ages of the Zhaojiazhuang Formation, Middle–South Section, Taihang Mountains, China and Their Geological Significance LYU Qiqi 1, 2 , LUO Shunshe 1, * , WANG Tongshan 3 , SONG Daofu 2 , TAN Cong 3 , ZHANG Yan 1 and GUAN Yulong 1 1 School of Geosciences, Yangtze University, Wuhan 430100, China 2 State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China 3 Petro China Research Institute of Petroleum Exploration & Development, Beijing 100083, China E-mail: [email protected]Objective The sedimentary Zhaojiazhuang Formation overlies the ancient Paleo-proterozoic crystalline basement in the middle–south sections of the Taihang Mountains, China. It is a complete stratigraphic sequence with clear boundaries. The formation has an angular unconformity with the underlying Paleo-proterozoic Tongyu Formation and a parallel unconformity with the overlying Changzhougou Formation from the Changcheng System, which is widely distributed throughout the Wutai–Zhongtiao–Taihang Mountains. Qiu Zhen et al. (2007) and Wang Qingchun et al. (2017) have examined its lithologic features, stratigraphic sequences, sedimentary characteristics, and trace fossils of this formation. Studies have placed the Zhaojiazhuang Formation in the Meso-proterozoic Changchengian compared with the Baicaoping Formation from the Changcheng System in the Xiong’er rift trough. Till now, the ages of detrital zircons from the Zhaojiazhuang Formation have not been reported. This study aims to provide new geochronological data for further determining the contact relation between the Changcheng System and underlying Paleo-proterozoic via detrital zircon U-Pb geochronology of the fine-grain quartz siltstone in the Zhaojiazhuang Formation. Methods Detrital zircon samples were taken from the off-white, thinly bedded fine-grain quartz siltstone in the third layer of the lower Zhaojiazhuang Formation along the Licheng profile in the middle-south sections of the Taihang Moutains. Zircon sorting was conducted at the rock and mineral analysis laboratory at the Research Institute of Regional Geological and Mineral Resources, Langfang, Hebei Province. Zircons were selected via water elutriation, high magnetic separation, and electromagnetic and heavy liquid separation. Then, the selected large, fully-formed zircon grains were observed under stereomicroscopy. Zircons were mounted onto thin sections with epoxy; then, the samples were grinded and polished sufficiently. Transmitted light, reflected light, and cathodoluminescence images were taken to observe the surface and internal zircon structure. Zircon LA-ICP-MS U-Pb dating was performed on an Agilent ICP-MS (Agilent 7900) at the isotopic laboratory within Wuhan Sample Solution Analytical Technology Co., Ltd., and the detailed analytical procedures were followed as reported previously (Duan Shigang et al., 2017). The original data were processed using the ICPMSDATACAL 10 software, and zircon age concordia diagrams were constructed using the ISOPLOT 3.0 program. For zircons older than 1000 Ma, the 207 Pb/ 206 Pb age was used, whereas for zircons less than 1000 Ma, the 206 Pb/ 238 U age was used. Results We separated 286 zircons from the siltstone sample, LC-ZJZ. The zircon grains vary in size: the majority of these were ellipsoidal, followed by short prismatic, a few were spherical, and there were occasional hexagonal dipyramidal zircons, with particle sizes varying between 50 and 130 μm and several sizes >150μm. Zircon This article is protected by copyright. All rights reserved. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/1755-6724.13785.
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Detrital Zircon U‐Pb Ages of the Zhaojiazhuang Formation ... Qiqi, LUO... · shapes are mostly semicircular and sub-angular. Majority of magmatic zircons have oscillatory zoned
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Detrital Zircon U-Pb Ages of the Zhaojiazhuang Formation, Middle–South
Section, Taihang Mountains, China and Their Geological Significance
LYU Qiqi1, 2
, LUO Shunshe1, *
, WANG Tongshan3, SONG Daofu
2, TAN Cong
3, ZHANG Yan
1 and
GUAN Yulong1
1 School of Geosciences, Yangtze University, Wuhan 430100, China
2 State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing
102249, China
3 Petro China Research Institute of Petroleum Exploration & Development, Beijing 100083, China
Qiu Zhen, Duan Xianle, Pan Zhilong, Wu Qisheng and Zhao Peng, 2007. Trace fossils from the Changchengian
Zhaojiazhuang Formation in the Taihang Mountains, Hebei. Sedimentary Geology and Tethyan Geology, 27(1): 76–78 (in
Chinese with English abstract).
Wang Qingchun, He Ping, Du Jiangmin, Liu Rongfang and Li Wei, 2017. Depositional characteristics of the Zhaojiazhuang
Formation, Changcheng System, in the middle-southern areas of the Taihang Mountains. Journal of Southwest Petroleum
University (Science & Technology Edition), 39(4): 47–56 (in Chinese with English abstract).
This article is protected by copyright. All rights reserved.
Appendix 1 LA-ICP-MS U-Pb data of zircons from the fine-grain quartz siltstone (LC-ZJZ) of the Zhaojiazhuang Formation along the Licheng profile in the middle-south sections of