- 责任者：Deng YuFeng(School of Resources and Environmental Engineenng ; Hefei University of Technology ; Heifei 230009 ; China) ; Song XieYan
- 刊名：Acta Petrologica Sinica
- 出版年：2012
- 卷期：28(7)
- 关键词：侵入体 ; intrusions ; 橄榄石 ; olivine ; 天山 ; Tianshan Mountains
- 页码：p.2224-2234
- 图表：illus.,1 table,41 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
The Huangshandong mafic-ultramafic intrusion is located in middle of eastern Tianshan orogenic belt, Xinjiang. Four stages of magma intrusion have been identified. The first magmatic emplacement is comprised of olivine gabbro, hornblende gabbro and diorite, formed the upper part and the main portion of the intrusion. The resultant of the second stage emplacement formed gabbronorite dykes in the western and northwestern of the intrusion. Plagioclase lherzolite, lies in the lower part and regarded as the main host rock for the Cu-Ni ores, represents the products of the third magma intrusion. The last stage emplacement formed bottom hornblende gabbro. The olivine occurs mainly in the first stage olivine gabbro, and in the third stage plagioclase lherzolite. The forsterite number(Fo)of olivine ranges from 68.5 to 82.5. The olivine from sulfide-bearing plagioclase lherzolite has highest Fo(79.7～82.5); the Fo of olivine in the plagioclase lherzolite range from 78.3 to 79.9; the olivine from fractionated olivine gabbro has lower Fo(68.5～72.2). The Mg# (atomic Mg/(Mg+Fe))of parental
magma estimated by using the compositions of most Fo-rich olivine crystals is 0.59 and indicates the parental magma was formed by fractional crystallization of primary basaltic magma. The model calculation results display the data of olivine from the ore-free rocks are explicable if the magma became saturated with sulfide after 2% olivine crystallization, and then simultaneously separated olivine and sulfide in a ratio of 50︰1. Scatter to the lower right side of olivine crystallization and sulfide segregation line is explicable as result of the olivine interacting with trapped intercumulus liquid. The negative Fo-Ni relationship of olivine from the sulfide-bearing plagioclase lherzolite is apparently related to local equilibration of the olivine with trapped sulfide liquids.