长白山天池火山的岩石矿物学特征——对结晶分异过程和岩浆混合作用的启示

发布时间：2018-04-15 10:43

本文选题：长白山 + 天池火山　；参考：《地球学报》2017年02期

【摘要】：本文对天池火山玄武岩盾,粗面质-碱流质层状锥体以及顶部的粗面质-碱流质碎屑岩类及熔岩的岩石矿物成分做了系统分析,发现在玄武岩类中的主要矿物组合为斜长石、富钙辉石以及富镁橄榄石,而粗面岩-碱流岩类的主要矿物组合为碱性长石、富铁的辉石及橄榄石,并开始出现石英、独居石以及大量的铁钛氧化物,符合结晶分异的演化趋势。同时在玄武岩类及粗面-碱流岩类中均存在不平衡矿物,再结合矿物环带的成分变化、矿物的熔蚀现象及不同特征的岩石条带等,认为天池火山在黑石沟玄武岩、第一、三造锥阶段粗面岩以及千年大喷发的浮岩中均存在岩浆混合作用。根据岩石学及年代学等特征,认为不同时期的玄武质岩浆来自同一地幔源区,经不同程度的结晶分异作用形成,前造锥阶段及造锥阶段的岩石由不同阶段的玄武岩演化而来,全新世的碱流岩类则由造锥阶段粗面岩类演化而来。
[Abstract]:In this paper, the rock mineral composition of basalt shield, coarse surface alkaline fluid stratiform pyramidal body, coarse surface alkaline fluid clastic rock and lava in Tianchi volcano are systematically analyzed. It is found that the main mineral assemblages in basalts are plagioclase, plagioclase and plagioclase.Ca-rich pyroxene and magnesium rich olivine, while the main mineral assemblages of coarse-alkali feldspar are alkaline feldspar, iron-rich pyroxene and olivine, and quartz, monazite and a large amount of iron-titanium oxides are beginning to appear.It accords with the evolution trend of crystallization differentiation.At the same time, there are unbalanced minerals in basalts and coarse-alkali-feldspar rocks. Combined with the composition changes of the mineral belt, the phenomenon of mineral erosion and the rock bands with different characteristics, it is considered that Tianchi volcano is located in the basalt of the Heishigou basalt.Magmatic mixing occurs in the trachyte and the magmatic magma in the magmatic rocks of the millennia eruption.According to the characteristics of petrology and geochronology, it is considered that the Black Tortoise magma of different periods came from the same mantle source region, and formed through different degrees of crystallization differentiation. The rocks of pre-coning stage and coning stage evolved from different stages of basalt.In the Holocene, the alkali-feldspar rocks evolved from the coarse-faced rocks in the coning stage.
【作者单位】：中国地质博物馆;中国地震局活动构造与火山重点实验室;
【基金】：国家自然科学基金(编号:41172304) 国土资源部公益性行业科研专项经费(编号:201011003)联合资助~~
【分类号】：P57;P317

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