摘要
岩浆的分离结晶作用和地壳同化混染作用是造成硫饱和的重要因素。本文以金平-Song Da地区二叠纪低钛苦橄岩为原生岩浆,使用MELTS程序模拟了岩浆在分离结晶和围岩同化混染作用的控制下达到硫饱和,发生硫化物熔体的熔离。模拟结果表明,低钛苦橄质岩浆从源区上升到浅部岩浆房的过程中发生了约10%的橄榄石的分离结晶,形成高镁的玄武质岩浆。高镁玄武质岩浆在浅部岩浆房内同化混染>18%的围岩,并经历约27%硅酸盐矿物的分离结晶后达到硫饱和。熔离的硫化物熔体在岩浆通道内聚集形成了白马寨铜镍硫化物矿。经历硫化物熔体熔离后的残余岩浆喷出地表形成了金平地区亏损Ni和Cu并具有强烈地壳混染特征的低钛玄武岩。
Fractional crystallization and crustal contamination are important factors to trigger magma over S-saturation. In this study, we chose the Permian low-Ti picrite in Jinping-Song Da area as a primary magma to simulate fractional crystallization and crustal contamination which may trigger the magma over S-saturation to form Baimazhai Ni-Cu sulfide deposit based on MELTS program. The simulation shows that 10% olivine had crystallized from the low-Ti picritic magma and then the residue magma would become to high Mg basaltic. In the upper crust chamber, the high-Mg basaltic magma had contaminated more than 18% wall rocks and 27% silicate minerals have crystallized, then the magma would reach S-saturation. The segregated sulfide was concentrated to middle of magma channel by flow differentiation, and consequently, formed Baimazhai concentric Ni-Cu sulfide deposit. The magma which underwent sulfide segregation erupted to form the Ni- and Cu-depleted low-Ti basalt with significant crustal contamination characters in Jinping Song Da area.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第10期3581-3591,共11页
Acta Petrologica Sinica
基金
国家自然科学基金面上项目(41172064)
科技部973项目(2011CB808903)联合资助
关键词
白马寨硫化物矿
峨眉山大火成岩省
MELTS程序
分离结晶
Baimazhai sulfide deposit
Emeishan large igneous province
MELTS program
Fractional crystallization
