| 东昆仑东段哈拉尕吐花岗岩基岩浆混合作用:来自岩石学和矿物学约束 |
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| 引用本文： | 陈国超,裴先治,李瑞保,李佐臣,裴磊,刘成军,陈有炘,王盟,张玉,李小兵.东昆仑东段哈拉尕吐花岗岩基岩浆混合作用:来自岩石学和矿物学约束[J].地球科学,2018,43(9):3200-3217. |
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| 作者姓名： | 陈国超 裴先治 李瑞保 李佐臣 裴磊 刘成军 陈有炘 王盟 张玉 李小兵 |
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| 作者单位： | 1.长安大学地球科学与资源学院, 西部矿产资源与地质工程教育部重点实验室, 陕西西安 710054 |
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| 基金项目： | 国家自然科学基金项目41472191中央高校基本科研业务费专项资金项目310827161002中央高校基本科研业务费专项资金项目310827161006国家自然科学基金项目41172186国家自然科学基金项目41502191国家自然科学基金项目40972136 |
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| 摘 要： | 哈拉尕吐花岗岩基位于东昆仑东段，其中花岗闪长岩岩浆混合作用明显，是研究岩浆混合作用的良好对象.从岩石学、岩相学和矿物化学等方面对哈拉尕吐花岗岩基进行了详细研究.电子探针结果显示:寄主岩斜长石的An值同相对应包体中斜长石捕掳晶近似；包体中基质斜长石大部分具核边结构，核部和边部An值存在间断；部分包体中浅色基质斜长石的An值与具核边结构斜长石的边部近似；辉长闪长岩中斜长石具较高的An值.寄主岩角闪石同相对应包体中角闪石捕掳晶的结晶温度、压力和氧逸度较为接近；包体中基质角闪石的结晶温度和压力低于寄主岩角闪石，氧逸度稍高于寄主岩角闪石；辉长闪长岩角闪石具有最高的结晶温度和压力及最低的氧逸度.哈图沟剖面和德福胜剖面寄主岩中的斜长石和角闪石的成分具有一定差别.岩浆不同期次侵入结晶和岩浆自身演化，使不同地点斜长石和角闪石的成分和物理化学特征具有一定变化.镁铁质岩浆位于地壳深部，氧逸度较低，使结晶的角闪石具有较高的形成压力和较低的氧逸度，斜长石具较高An值；随着镁铁质岩浆注入寄主岩，由于环境突变，使斜长石受到熔蚀；由于岩浆上侵以及两种岩浆物理化学性质差别较大，导致温度、压力和水饱和度降低，氧逸度升高，使包体中残留岩浆快速结晶，形成具核边结构、浅色均一的斜长石，以及结晶程度较差、较高氧逸度的角闪石.
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| 关 键 词： | 东昆仑造山带 哈拉尕吐花岗岩基 矿物化学 岩浆演化 岩浆混合 地球化学 |
| 收稿时间： | 2018-02-13 |
Magma Mixing in Halagatu Granitic Batholith from Eastern Part of the East Kunlun Orogenic Belt: Constraints from Lithology and Mineralogy |
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| Abstract: | Magma mixing events occurred widely and fiercely in Halagatu granitic batholith in eastern part of the East Kunlun orogenic belt, one of the ideal natural labs for magma mixing and mingling studies. We study through electron microprobe (EPMA) the lithology, petrography and mineral chemistry from the granitic batholith. The results reveal that plagioclases in the host rocks and those in the xenocrystals in MMEs have similar mineral features of anorthite-albite component value (An value). And most plagioclases in matrix of MMEs have core-rim structures with an An value discontinuity. An values of the light-colored matrix plagioclase in some MMEs are similar to those with core-rim structures. The plagioclases in gabbro diorite have a higher An value. The crystallization temperature, pressure and oxygen fugacity of the hornblendes of the host rocks are similar to those of the hornblende xenocrystals in MMEs. The crystallization temperature and pressure of the matrix hornblende in the MMEs are lower than those in the host rocks, and the oxygen fugacity is slightly higher than that in the host rocks. The hornblendes in gabbro diorite have the highest crystallization temperature and pressure and the lowest oxygen fugacity. The compositions of the plagioclase and hornblende in the host rocks of the Hatugou section and Defusheng section are different. Intermittent magma intrusions and crystallizations, together with their evolution resulted in differences in composition, physical and chemical features varying with places. The mafic magma stayed in deep the Crust with lower oxygen fugacity, providing a condition of high pressure and low oxygen fugacity for hornblende crystallization and high An value for plagioclases. With the injection of mafic magma into the host rocks, due to environmental changes, plagioclases are subject to erosion. The temperature, pressure and water saturation reduced, whilst oxygen fugacity increased because of magma intrusion and physical and chemical differences for the two magmas. Thus the residual magma in MMEs crystallized quickly to form plagioclases with core-rim structures and uniformly light color, and hornblendes with non-crystal shape and high value of oxygen fugacity. |
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