Crystal Growth and Crystallization Time Scales of the Panzhihua Layered Intrusion:Constraint from Crystal Size Distribution  

作　　者：LI Xuejun LUO Zhaohua LI Xiaowei WANG Yu YANG Zongfeng LI Jie LIU Xiao 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China

出　　处：《Acta Geologica Sinica(English Edition)》2020年第5期1428-1439,共12页地质学报（英文版）

基　　金：funded by National Basic Research Program of China(Grant No.2011CB808901);the Geological Survey Program of the China Geological Survey(Grant No.1212011220921)。

摘　　要：The Panzhihua layered intrusions is generated closely related to the Emeishan LIPs.This paper analyzes the spatial distribution of plagioclase and pyroxene.The quantitative texture analysis of 2209 plagioclase shows that the characteristic length of plagioclase is 0.54 to 0.96 mm,the intercept variation range is large,from-0.67 to 0.96,and the slope is-1.85 to-1.04,the Aspect Ratio shows from 1.84 to 2.59 and fractal dimension D is 1.908–1.933.The quantitative texture analysis of 2342 pyroxene shows that the characteristic length of pyroxene is 0.38–0.64 mm,the intercept shows from 0.46 to 2.26,The slope ranges from-2.6 to-1.47,the Aspect Ratio value varies from 1.53 to 1.71,the fractal dimension D is 0.93 to 1.13.All the CSDs results of the Panzhihua intrusions indicate that plagioclase and pyroxene form in an open magma system and undergo four replenishment of magma injection.The plagioclase crystals do not grow as the lathlike shape,and the fractal growth leads to complex crystal surface.The plagioclase undergoes deformation compaction during the crystal process,and then is oriented.The pyroxene crystals grow along an approximately triaxial ratio and undergo texture adjustment and small crystal dissolution reabsorption.When all crystals in magma system grows up to 2 mm,the pyroxene undergoes cumulation in the Panzhihua layered intrusions.The plagioclase crystallization time scale is 171.23–304.41 years,representing that the crystallization is the more uniform in central part of the melt.The nucleation density continuously increases during the crystallization process of the magma system.The time scale to reach the final maximum crystal nucleation density is 15.28–58.98 years.

关 键 词：crystal size distribution crystallization time scales layered intrusions Emeishan large igneous province Panzhihua 

分 类 号：P588.1[天文地球—岩石学]