藏南错那洞穹隆高分异淡色花岗岩的矿物学特征
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P588.12+1;P575.3

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国家重点研发计划项目(2017YFC0601505);国家自然科学基金项目(41302066);西藏华钰矿业股份有限公司博士后基金项目(80303-SHX070);成都理工大学中青年骨干教师培养计划项目(KYGG201402)


Mineralogical characteristics of highly fractionated leucogranite in Cuonadong dome, southern Tibet
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    摘要:

    藏南特提斯喜马拉雅东部的错那洞淡色花岗岩产出有白云母、石榴子石、电气石等特征性矿物,显示具有高度分异岩浆岩的特征。从二云母花岗岩到电气石花岗岩到石榴子石花岗岩,碱性长石均为正长石,斜长石从更长石演变为钠长石,白云母Al2O3、Na2O含量逐渐升高,反映花岗岩逐渐向富Al富Na演化的趋势。二云母花岗岩中黑云母XFe值、Al逐渐升高,表明二云母花岗岩之间存在结晶分异演化。电气石Xvac值、Al、Mg和Fe含量之间的变化,反映电气石花岗岩到花岗伟晶岩岩浆结晶环境中Na含量的增加,表明花岗伟晶岩结晶分异演化程度高于电气石花岗岩。石榴子石高XFeXMn值的特征,也是高分异花岗岩的标志。上述矿物学研究结果表明,错那洞二云母花岗岩是由岩浆早期结晶矿物与残余的母岩浆组成的糊状物经过长期结晶形成的,而电气石花岗岩和石榴子石花岗岩由从晶粥体中分离出来的衍生熔体形成。

    Abstract:

    Leucogranitics rocks, crop out in the eastern Tethys Himalaya Cuonadong dome, southern Tibet, have characteristic minerals such as muscovite, garnet and tourmaline, and show the characteristics of highly differentiated magmatic rocks. From two-mica granite, tourmaline granite to garnet granite, alkaline feldspar is orthoclase, plagioclase evolved from oligoclase to albite, the content of Al2O3 and Na2O in muscovite increased gradually, reflecting the evolution trend of granite towards aluminum-rich and sodium-rich. In the two-mica granite, the XFe and Al of biotite increase gradually, which indicates that there is crystallization differentiation evolution in the two-mica granites. The variation of the contents of Xvac, Al, Mg and Fe in tourmaline reflects the increase of Na content in the magmatic crystallization environment from tourmaline granite to granite pegmatite, indicating that the degree of crystallization differentiation of granite pegmatite is higher than that of tourmaline granite. The characteristics of garnet with high XFe and XMn values are also the marks of highly fractionated granites. The Cuonadong two-mica granite was formed by long-term crystallization of a crystal mush composed of early magmatic crystalline minerals and residual parent magma, while tourmaline granite and garnet granite are formed by derivative melts separated from crystal mush.

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张丁川,张刚阳,陈曦,杨宾,2021,藏南错那洞穹隆高分异淡色花岗岩的矿物学特征[J].岩石矿物学杂志,40(6):1093~1115.

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  • 收稿日期:2020-12-25
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  • 在线发布日期: 2021-11-15
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