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关于南岭花岗岩及其成矿作用问题的思考——与吴福元教授等商榷

花匠小妙招
2024-11-10 20:22

基金项目:

本文为国家自然科学基金资助项目（编号：41872047）的成果

Thoughts on granite and its mineralization in Nanling Range——A discussion with Prof. WU Fuyuan et al

Author:

WANG Xiang

School of Earth Sciences and Engineering，Nanjing University，Nanjing，210023
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单位:

南京大学地球科学与工程学院，南京,210023 School of Earth Sciences and Engineering，Nanjing University，Nanjing，210023 摘要 | | 访问统计 | | | || 文章评论

摘要:

本文针对吴福元等（2023）“南岭高分异花岗岩成岩与成矿”一文（后简称“吴文”）提出两个不同认识：① 南岭地区广泛出露的燕山早期花岗岩，常构成复式花岗岩体的主体。吴文依靠三个幔源物质（玄武岩、微粒包体和基性岩脉）的证据，认为这些花岗岩是壳幔相互作用的产物。笔者认为这些“幔源物质”的存在不足以作为“壳幔相互作用”的证据，南岭燕山早期花岗岩实际上为沿着地壳剪压断裂主动侵位的同造山花岗岩(主体花岗岩)。② 吴文认为，这些复式花岗岩体中的补体花岗岩（小岩体）也是燕山早期的，为“同源岩浆”的高分异演化的产物。本文对前半句持否定性的看法，但认同后半句的结论，并以完全不同的方式表明，初始花岗岩浆是在重力和热量对流下的深部岩浆房中经历20 Ma以上的分离结晶作用，才可能在岩浆房上部形成含巨量成矿物质的残余花岗岩浆。这些残余花岗岩浆在早白垩世的拉张环境中，快速地被动上侵而溶离成两部分 (流体和熔体)，分别形成岩浆热液矿床和造山后花岗岩(补体花岗岩）。

Abstract:

This paper put forward two questions about “Petrogenesis of the highly fractionated granites and their mineralization in Nanling Range” by WU Fuyuan et al.（2023）published in Acta Petrologica Sinica，volume 39，issue 1：(1) Extensive early Yanshanian granites in the Nanling Range constitute the main intrusive phase of granitic complexes. Based on the evidence of three mantle- derived materials（basalt, microgranular enclave and basic vein），WU Fuyuan et al.（2023）believes that these granites are the products of crust—mantle interaction. This paper argues over these lines of mantle- derived evidence, and proposes that the early Yanshanian granites in the Nanling Range are syn- orogenic granites (main intrusive phase) that were emplaced along crustal shearing—compressive fault in the forceful mechanisms. (2) WU Fuyuan et al.（2023）believes that the subsequent intrusive phase（small stock）in these granitic complexes is also the early Yanshanian，and should be the highly differentiated product of the main intrusive phase with the same origin. This paper emphasizes that the initial granite magma must undergo more than 20 Ma of fractional crystallization in the deep magma chamber under the gravity and heat convections，and then it is possible to form residual magma with huge amount of ore- forming minerals in the upper part of the magma chamber. In the early Cretaceous extensional environment, these residual magmas rapidly intruded in the permissive mechanisms，and would split into two portions：one forming magmatic—hydrothermal deposit and another forming the subsequent intrusive phase（i.e.，post- orogenic granite）respectively.

引用本文

汪相.2023.关于南岭花岗岩及其成矿作用问题的思考——与吴福元教授等商榷[J].地质论评,69(3):2023030022,[DOI].
WANG Xiang.2023. Thoughts on granite and its mineralization in Nanling Range——A discussion with Prof. WU Fuyuan et al[J]. Geological Review,69(3):2023030022.

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