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Crystal Growth and Crystallization Time Scales of the Panzhihua Layered Intrusion: Constraint from Crystal Size Distribution
Author(s) -
LI Xuejun,
LUO Zhaohua,
LI Xiaowei,
WANG Yu,
YANG Zongfeng,
LI Jie,
LIU Xiao
Publication year - 2020
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.14528
Subject(s) - plagioclase , pyroxene , crystallization , geology , fractal dimension , mineralogy , crystal (programming language) , magma , texture (cosmology) , layered intrusion , materials science , fractal , geochemistry , olivine , mafic , thermodynamics , volcano , physics , mathematics , quartz , paleontology , mathematical analysis , artificial intelligence , image (mathematics) , computer science , programming language
Abstract 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.