| 花岗岩—KBF4—Na2MoO4—WO3体系的实验研究及其矿床学意义 |
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| 引用本文： | 朱永峰,曾贻善.花岗岩—KBF4—Na2MoO4—WO3体系的实验研究及其矿床学意义[J].岩石学报,1995,11(4):353-364. |
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| 作者姓名： | 朱永峰 曾贻善 |
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| 作者单位： | 北京大学地质系 |
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| 摘 要： | 为探讨长英质岩浆作用过程中金属成矿元素的地球化学行为及其成矿意义，我们进行了常压下花岗岩－ＫＢＦ３－Ｎａ２ＭｏＯ４－ＷＯ３体系的实验研究。结果表明，高温（１２５０℃）条件下呈均一状态的花岗岩－ＫＢＦ４－ＮａＭｏＯ４－ＷＯ３体系，当温度降低时发生液态不混溶，从中分离出含矿熔体的小液滴，体系中的Ｍｏ（Ｗ）几乎全部富集在这种小液滴中。含矿熔体中极富含Ｃａ、Ｍｇ和Ｐ，而贫Ｓｉ、Ａｌ和Ｋ，Ｈ２Ｏ和Ｆ富集在含矿熔体中。此实验结果表明：长英质岩浆中液态不混溶作用的发生可以使成矿元素Ｗ和Ｍｏ富集到与硅酸盐熔体不混溶的独立的非硅酸盐熔体中。这种熔体在适当的地质条件下继续演化可形成类似镁铁质岩浆演化过程中常出现的岩浆熔离型矿床。本实验结果可能为斑岩矿床的形成机理提供一种新的解释。
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| 关 键 词： | 液态不混溶，花岗岩，熔体结构，成矿作用 |
The Experimental Study of Granite-KBF_4- Na_2MoO_4 WO_3 System and its Significance in Ore-Petrology |
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| Zhu Yongfeng,Zeng Yishan and Ai Yongfu.The Experimental Study of Granite-KBF_4- Na_2MoO_4 WO_3 System and its Significance in Ore-Petrology[J].Acta Petrologica Sinica,1995,11(4):353-364. |
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| Authors: | Zhu Yongfeng Zeng Yishan and Ai Yongfu |
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| Abstract: | In order to obtain experimental evidence demonstrating the relationship between oreforming process and liquid immiscibility in felsic magma,we carried out a series of experiments at high temperature and atmospheric pressure. The experimental results show that the granite-KBF4 -Na2MoO4-WO3 system is ahomogeneous melt at high temperature. With decrease in temperature, however, the melt decomposes into twoimmiscible melts: silicate melt and ore-forming melt. The ore-forming one exists as globules in silicate melt.Mo, Ca, Na, Mg, P, Mn, F, B and OH- are concentrated in these globules. The ore forming melt is characterized with very low SiO2 and Al2O3 concentrations, and very high concentration of MoO3 and CaO; the silicatemelts are significantly enriched in SiO2 and Al2O3. The differences between the two immiscible melts exist notonly in chemical composition, but also in structure. The ore-forming melt structurally consists of MoO4],MoOF4], B(OH)4] and OH;while the silicate melt, SiO4]. Because of the difference in composition andstructure the two immiscible melts possess different physical properties. Compared to silicate melt, the ore-forming melt has a lower density and viscosity, which permit the globule to behave as bubbles in granite magma,move and concentrate in the upper part of magma chamber. This process is probably responsible for the concentration of ore-forming elements in the upper part of granite they and its immediate aureole. |
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| Keywords: | Liquid immiscibility Granite Melt structure Ore-forming process |
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