岩石矿物学杂志2012，Vol.31Issue(2)：212-224,13.
新疆北山地区坡北镁铁-超镁铁岩体单斜辉石的矿物学特征及其地质意义
Mineralogy of clinopyroxene from Pobei mafic-ultramafic complex in Beishan area, Xinjiang, and its geological significance
摘要
Abstract
As the major rock-forming mineral in Pobei mafic-ultramafic complex, clinopyroxene is distributed in almost every rock phase. In order to find out the nature, evolution and tectonic setting of magma, the authors analyzed chemical compositions of clinopyroxene by means of EPMA and LA-ICPMS. The results demonstrate that cliopyroxene is characterized by SiO2(51.05%~54.00%), MgO (13.95%～17.64%), CaO (19.87%～ 23.56%), FeO (3.44%～6.58%), TiQ2(0.13%～1.36%), Al2Q3(2.17%~4.21%), Na2O(0.17%~ 0.50%), and &2O3(0.01%~1.27%). The clinopyroxene discrimination diagrams show that the parent magma was sub-alkaline tholeiite and probably formed in an island arc setting. Clinopyroxene thermobarometer calculation shows that the crystallization temperature was from 1 141℃ to 1 22℃. ΣREE and (Ce/Yb)N valuessuggests that magma crystallization was intensified from wehrlite and olivine pyroxenite to olivine gabbro and hornblende gabbro. Combined with other data available, the authors believe that the magma was assimilated when it experienced fractional crystallization. Wehrlite and olivine pyroxenite have more SiO2 and Na2O, which might have come from biotite quartz schist, whereas olivine gabbro and hornblende gabbro have more CaO, which probably came from marble. Wehrlite and olivine pyroxenite have lower FeO and were assimilated by biotite quartz schist, which might have led to sulfide segregation.关键词
坡北镁铁-超镁铁杂岩体/单斜辉石/岩浆系列/构造背景/同化混染Key words
Pobei mafic-ultramafic complex/ clinopyroxene/ igneous series/ tectonic setting/ assimilation分类
天文与地球科学引用本文复制引用
刘艳荣,吕新彪,梅微,代玉才..新疆北山地区坡北镁铁-超镁铁岩体单斜辉石的矿物学特征及其地质意义[J].岩石矿物学杂志,2012,31(2):212-224,13.基金项目
“十二五”国家科技支撑计划项目(2011BAB06B04-05) （2011BAB06B04-05）
