The Pingshan low-angle shear zone and its implications for the late Paleoproterozoic extension of the Trans-North China Orogen

IF 3.2 2区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Precambrian Research Pub Date : 2025-04-26 DOI:10.1016/j.precamres.2025.107797

Wangbin Gong , Duwei Qiu , Yuanfang Zhao , Jianmin Hu , Xia Liang

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引用次数: 0

Abstract

The Trans-North China Orogen (TNCO) records the amalgamation of the Eastern and Western blocks to form the North China Craton (NCC) at ∼1.85 Ga. A series of geologic events related to regional extension occurred in the TNCO, represented by the ∼1.80–1.60 Ga Taihang-Lüliang mafic dyke swarms, the Yanliao rift, and the Xiong’er rift. However, the tectonic process and initial time of the extension remain unclear. The Pingshan ductile shear zone (PSSZ), located in the central part of the TNCO, has been interpreted as a Paleoproterozoic normal fault. In this study, we present the results of detailed field observations, and analyses of the microstructure, quartz c-axis fabrics, and geochronology of the PSSZ. The results show that the PSSZ underwent low-angle top-to-the-SE shearing at ∼1.84–1.83 Ga, with deformation temperatures ranging from 400 ℃ to 500 ℃. The nearly synchronous PSSZ and low-angle deformation zone developed on the northwestern margin of the Fuping Complex constitute an extensional structural system. These structures resulted in the rapid uplift of the Fuping Complex. The extensional structures in the central part, combined with the scattered anorogenic granite plutons developed along the orogen from north to south, indicated that the TNCO was dominated by post-orogenic extension during ∼1.84–1.80 Ga.

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平山低角剪切带及其对晚古元古代跨华北造山带伸展的指示意义

跨华北造山带（TNCO）记录了东、西地块在~ 1.85 Ga的融合形成华北克拉通（NCC）。TNCO发生了一系列与区域伸展有关的地质事件，代表为~ 1.80 ~ 1.60 Ga太行—l良基性岩脉群、燕辽裂谷和熊耳裂谷。然而，构造过程和伸展的起始时间仍不清楚。平山韧性剪切带（PSSZ）位于TNCO中段，是一条古元古代正断层。在这项研究中，我们介绍了详细的野外观测结果，并分析了PSSZ的微观结构，石英c轴结构和地质年代学。结果表明：PSSZ在~ 1.84 ~ 1.83 Ga发生了低角度从顶部到东南方向的剪切，变形温度为400 ~ 500℃；富平杂岩西北缘发育的近同步PSSZ和低角度变形带构成了一个伸展构造体系。这些构造导致富平杂岩的快速隆起。中部的伸展构造，结合沿造山带由北向南发育的散在造山带花岗岩岩体，表明在~ 1.84 ~ 1.80 Ga期间，TNCO以造山后伸展为主。

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来源期刊

Precambrian Research 地学-地球科学综合

CiteScore

7.20

自引率

28.90%

发文量

325

审稿时长

12 months

期刊介绍： Precambrian Research publishes studies on all aspects of the early stages of the composition, structure and evolution of the Earth and its planetary neighbours. With a focus on process-oriented and comparative studies, it covers, but is not restricted to, subjects such as: (1) Chemical, biological, biochemical and cosmochemical evolution; the origin of life; the evolution of the oceans and atmosphere; the early fossil record; palaeobiology; (2) Geochronology and isotope and elemental geochemistry; (3) Precambrian mineral deposits; (4) Geophysical aspects of the early Earth and Precambrian terrains; (5) Nature, formation and evolution of the Precambrian lithosphere and mantle including magmatic, depositional, metamorphic and tectonic processes. In addition, the editors particularly welcome integrated process-oriented studies that involve a combination of the above fields and comparative studies that demonstrate the effect of Precambrian evolution on Phanerozoic earth system processes. Regional and localised studies of Precambrian phenomena are considered appropriate only when the detail and quality allow illustration of a wider process, or when significant gaps in basic knowledge of a particular area can be filled.