对流干扰下的重力分异——基性岩侧向分带及矿化的主要机制

发布时间：2018-06-10 21:22

本文选题：基性—超基性岩 + 侧向分带　；参考：《地质论评》2017年04期

【摘要】：在基性—超基性岩中,特别是那些含矿岩体,常常发育有原生的侧向分带,传统的重力分异理论无法用原地分异机制对这一现象进行合理解释;新的硫化物成矿模型同样不能令人信服。我们在对重力结晶分异的研究中发现,对流干扰下的重力结晶分异可以形成侧向分带。研究采用动力学分析的方法,深入了解对流干扰下岩浆重力分异作用中的颗粒行为。在动力学分析中,考虑了前人研究中普遍忽略的伯努利效应。研究表明,伴随着快速对流干扰的岩浆重力结晶分异可以产生侧向分离效应,使颗粒趋于在侧壁附近快速堆积。侧分离效应和侧壁冷却效应一起迫使循环向热流上升中心方向后退,形成侧向分带岩石。由于对流通常只发生在岩浆侵位后结晶分异的早期高温阶段,与铜镍硫化物熔离的阶段相吻合,因此,铜镍硫化物的矿化通常与对流干扰下的重力分异密切相关。最后以一个实例解释侧向分带和成矿作用的形成机制。研究成果突破了传统关于重力分异的认识,为深入认识岩浆演化及指导找矿提供新的思路。
[Abstract]:In basic ultrabasic rocks, especially those containing ore bodies, the primary lateral zoning is often developed, and the traditional theory of gravity separation can not be reasonably explained by the mechanism of ground differentiation; the new sulfide metallogenic model is not convincing. We found in the study of the fractionation of gravity crystallization and convective interference. The gravitational crystallization differentiation can form the lateral zoning. The dynamic analysis method is used to study the granular behavior in the magmatic gravity differentiation under the convective interference. In the dynamic analysis, the Bernoulli effect, which is generally neglected in previous studies, is considered. The study shows that the magmatic crystallization differentiation with the rapid convection interference is accompanied by the rapid convection. The lateral separation effect can lead to rapid accumulation of particles near the side wall. Side separation effect and side wall cooling effect compel the cycle to retreat to the direction of the central heat flow and form lateral zoning rocks. Because convection usually occurs only at the early stage of high temperature after magma emplacement, it is in the phase of melting with copper and nickel sulfide. Therefore, the mineralization of copper and nickel sulfide is closely related to the gravity differentiation under the convective interference. Finally, an example is made to explain the formation mechanism of lateral zoning and mineralization. The research results break through the traditional understanding of gravity differentiation, and provide a new way of thinking for deep understanding of magma evolution and guiding the prospecting.
【作者单位】：中国有色桂林矿产地质研究院有限公司;中国地质科学院岩溶地质研究所国土资源部/广西壮族自治区岩溶动力学重点实验室;
【基金】：广西区大规模地质找矿项目“广西恭城县五福锡钽铌矿普查”(编号:[2010]604)的资助~~
【分类号】：P588.124;P611

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