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首页> 外文期刊>Journal of Asian earth sciences >Age and evolution of a late Archean to Paleoproterozoic upper to lower crustal section in the Wutaishan/Hengshan/Fuping terrain of northern China
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Age and evolution of a late Archean to Paleoproterozoic upper to lower crustal section in the Wutaishan/Hengshan/Fuping terrain of northern China

机译：中国北方五台山/横山/阜平地区晚太古代至古元古代地壳段的年龄和演化

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摘要

The Taihangshan-Wutaishan area forms part of the central North China Craton and consists of three main components: the Hengshan and Fuping complexes, containing predominantly ductilely deformed late Archean to Paleoproterozoic high-grade granitoid orthogneisses, intruded by mafic dykes of gabbroic composition, and the low-grade late Archean Wutai greenstone belt, developed between the high-grade terrains and consisting of bimodal volcanic rocks and metasediments, associated with coeval granitoids. Zircon dating shows that both the Hengshan and Fuping complexes were intruded by major granitoid bodies between 2.52 and 2.48 Ga, with rare occurrences of 2.7 Ga gneisses. Wutai granitoids adjacent to the Fuping complex also contain 2.7 Ga xenocrysts, all possibly reflecting the same older basement. Rare granitic gneisses in the Hengshan have emplacement ages of ～2.35 Ga and show the same structural features as the older rocks, indicating that the main deformation occurred after ～2.3 Ga. Deposition of supracrustal rocks and emplacement of mafic dykes occurred in the Paleoproterozoic, together with intrusion of granitic bodies at ～2.1 -2.0 Ga, and all underwent regional metamorphism at 1.88-1.85 Ga. We interpret the Hengshan and Fuping granitoid gneisses as the lower, plutonic, part of a late Archean to early Paleoprolerozoic Japan-type magmatic arc, with the upper, volcanic part represented by the Wutai complex. Components of this arc may have evolved at a continental margin as indicated by the 2.7 Ga zircons. Virtually all magmatic events are recorded in all three complexes. However, the 1.85 Ga metamorphic event is only recorded in the higher-grade portions of the Wutai, since low-grade and presumably high crustal level precluded metamorphic zircon growth. Shear zones in the Hengshan are interpreted as major lower crustal discontinuities post-dating the peak of high-pressure granulite metamorphism. We suggest that they formed during erogenic collapse and uplift of the Hengshan complex in the late Paleoproterozoic ( > 1800 Ma).
机译：太行山-五台山地区是华北克拉通中部地区的一部分，由三个主要部分组成：衡山和富平复合体，主要由韧性变形的太古宙晚期至古元古代的高级花岗类正长片麻岩组成，并由辉长岩成分的铁镁质岩脉侵入。低品位的太古宙五台古绿岩带，形成于高品位地形之间，由双峰火山岩和沉积物组成，与古代花岗岩相伴。锆石测年表明，衡山和富平复合体均被2.52至2.48 Ga之间的主要花岗质体侵入，很少出现2.7 Ga片麻岩。与富平情结相邻的五台花岗岩也含有2.7 Ga异种晶，它们都可能反映了相同的较旧基底。横山的稀有花岗片麻岩的沉积年龄为〜2.35 Ga，并显示出与较老的岩石相同的构造特征，表明主要变形发生在〜2.3 Ga之后。上元古代的沉积和镁铁质岩的沉积都发生在古元古代在〜2.1 -2.0 Ga处有花岗岩体侵入，并且在1.88-1.85 Ga都经历了区域变质作用。我们将横山和阜平花岗岩片麻岩解释为太古宙晚期至早古生代日本型岩浆弧的下部，深成岩的一部分。 ，以五台综合体为代表的火山上部。如2.7 Ga锆石所示，该弧的成分可能已在大陆边缘演化。几乎所有岩浆事件都记录在所有三个复合物中。但是，仅在五台山的高品位部分记录到了1.85 Ga变质事件，因为低品位和可能较高的地壳水平阻止了变质锆石的生长。横山的剪切带被解释为高压花岗岩粒变质峰之后的主要下地壳不连续性。我们建议它们是在古元古代晚期（> 1800 Ma）衡山复合体的造山运动塌陷和隆升过程中形成的。

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