| 脆—韧性剪切带控矿的初步探讨——对金川铜镍矿控岩控矿构造的新见解 |
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| 引用本文：.1990.A preliminary discussion on the ore-controlling effect of the brittle-ductile shear zone——a new idea on the rock- controlling and ore-controlling structure in the Jinchuan copper-nickel deposit[J].Mineral Deposits,9(4):352~362 |
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| 中文摘要:本文从构造层次的概念探讨了金川铜镍矿的控岩控矿构造，提出了一些与以往研究结果不同的看法。作者对于该矿岩体、矿体形态与分布规律、构造岩、小构造与显微构造等的研究结果表明，金川矿的超基性岩涔与矿体从形态上不是岩墙状，而是由透镜体组成的雁列脉；控岩控矿构造不是龙首山北缘深断裂F1派生的入字型构造，而是受该断裂早期演化阶段的脆—韧性剪切带所控制。文中同时探讨了该脆一韧性剪切带的特征。 |
| 中文关键词:控岩控矿构造 雁列脉 脆一韧性剪切带 |
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| A preliminary discussion on the ore-controlling effect of the brittle-ductile shear zone——a new idea on the rock- controlling and ore-controlling structure in the Jinchuan copper-nickel deposit |
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| Abstract:The Jinchuan copper-nickel deposit is the famous ”nickel capital” of China．Concerning the ore-forming structure, it has been long considered that the ultrabasic body in the ore district together with the orebodies it contains is a dyke and also a derivative “λ”shaped structure of the deep fault(F1)on the northern margin of Longshou Mountain, Which was cut at the late stage by three nearly EW-trending strike-slip faults to form the four ore districts that we see today. According to the concept of tectonic level in the development of tectonic Geology, the author has studied the shape of ultrabasic body and orebodies, their arrangement and the variation in their composition, and also made lots of observations on the tectonite representing ductile deformation of rocks-mylonite and other minor structures and microstructures. On such a basis, it is considered that the intrusive body and the copper-nickel orebodies in the Jinchuan ore district are a series of lenticular bodies in dextral en-echelon arrangement, which are here and there connected with each other, but unexceptionally form independent and closed petrofacies and ore facies, with some having been denuded into the form of a distorted funnel due to the rising of the crust. As a matter of fact, the four ore districts result from the arrangement of independent lenticular bodies formed by magma or ore fluids filling en echelon fissures which, in turn, are produced by shearing-slipping of a brittle-ductile shear zone. rather than a λ-shaped structure formed at brittle fracturing stage of fault F1. The ultrabasic body and orebodies make up an e11 echelon structure controlled by shearing-slipping of a brittle-ductile shear zone developed at the early evolution stage of fault F1. This paper discusses the behavior of the shear zone, and the data obtained are as follows: the attitude of the brittle-ductile shear zone is 290°-350°,SW<40～60°, the maximum value of shear strain(r)at the center of the shear zone reaches 3.2 or so, the estimated width of the shear zone is more than 1.8km and the total displacement is over 2.3 km, and the formation depth of the shear zone must be over 7.0 km. The author holds that this tectonic pattern also controls the distribution of all basic and ultrabasic rocks in Longshou mountain. This paper is therefore of some significance to theoretical study of ore-forming structures in such kind of ore deposits, evaluation of ore reserves and arrangement of exploration and mining work. |
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