| 安徽月山地区闪长岩类岩浆动力学及其与成矿作用的联系 |
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| 引用本文：.1995.Magmatic dynamics and its relations to metallization of diorites in Yueshan, Anhui Province[J].Mineral Deposits,14(4):303~313 |
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| 基金项目:国家教委高等学校博士点科研基金 |
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| 中文摘要:基于火成岩石学、流体动力学、流变学及传热学和热力学等的研究，计算和分析了安徽月山地区闪长岩类岩浆的分凝、上升、对流、定位和结晶等岩浆过程的速度与机理，并探讨了岩浆的某些物理性质和动力学行为如熔体的含水量、水的运动特征、岩浆上升速度和对流状态等与成矿作用的联系。 |
| 中文关键词:闪长岩类 岩浆物理学 岩浆动力学 成矿作用 月山地区 |
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| Magmatic dynamics and its relations to metallization of diorites in Yueshan, Anhui Province |
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| Abstract:Yueshan area of Anhui Province is one of the most important parts of the copper, iron (sulfur) and gold metallogenic belt of the Middle and Lower Yangtze Valley. On the basis of studies on petrology, fluid dynamics, theology, thermal conductivity and thermodynamics, the authors have calculated and analysed the physical properties of magma and the dynamic mechanism of magmatic ascending, emplacement and crystallization for the formation of Yueshan, Zongpu and Wuhen diorite intrusives in Yueshan area and also investigated the relationships between physics and dynamics of magma (such as H2O content of melt, migration character of magmatic water, and ascending velocity and convection state of magma) and metallization. The main results obtained are as follows: The diortic magma of Yueshan, Zongpu and Wuhen intrusives has moderate H2O content (3.64% ~ 4.10% )and comparatively low viscosity as compared with ordinary granitic magma in the world. The ascending magma contains some 5%～10% suspended phenocrysts and displays behaviors of Bingham body. The magma ascends rapidly in the form of dike extension along the NE- and nearly EW-trending faults and at their intersects, and is then emplaced hypabyssally at a high temperature (>800℃). The convection resulting from emplacement of magma leads to relatively rapid cooling. Compared with other intrusives, the metallogenic Yueshan dioritic body has a relatively high H20 content and a magmatic growth system, consisting of a shallow ore-bearing stock, a medium-depth magmatic (or rock) pillar and a deep batholith (i.e. a "three-layer-structure"), which is favorable for the accumulation of magmatic water, ore-forming elements and carrier elements in the fluid phases during the melt-fluid partitioning processes and the continuous activity and mineralization of the ore-bearing hydrothermal system. The magma ascends more rapidly than magma of the diapiric Hongzheng granite, suggesting that besides being related to the emplacement mechanism, the ascending velocity of magma is mainly restricted by multiple factors such as properties (composition, water content, viscosity and density)of magma itself, ascending pathway of magma, physical behaviors of wall rocks and tectonic stress field. This also implies that there might exist a good channelway connecting the shallow stock with the deep magmatic chamber, which is favorable for the upward migration and mineralization of magmatic hydrothermal solution. At high temperature (≥1000℃) the convection velocity of the Yueshan magma is relatively low, and at the temperature approaching solid-liquid phase (800℃±), the velocity is relatively high, which is even more favorable for the steady and thorough partitioning of melts as well as their further accumulation at the late stage of crystallization. The cooling of Yueshan rock body lasts much longer than that of Zongpu rock body and Wuhen rock body, and the slow cooling of magma is very favorable for the formation of ore-bearing hydrothermal system in magma of Yueshan rock body and certain degrees of skarnization and mineralization through water-rock interaction under specific structural conditions. It is thus concluded that Yueshan intrusive body has more favorable ore potentiality than Zongpu and Wuhen in a series of physical and dynamic behaviors of magma. |
| keywords:diorites, magmatic physics, metallization, Yueshan area |
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