CAJ | 학술논문

二红洼岩体位于新疆东天山黄山镁铁-超镁铁岩带的西段，地表由南、北两个小岩体组成，北岩体出露面积约1．42km2，呈北东-南西向展布；南岩体在呈椭圆形，出露面积约为6．25km2。岩体可分为两个侵入期次：第一侵入期次岩性为（含长）二辉橄榄岩和橄榄辉长岩，第二侵入期次岩性为辉长苏长岩和淡色辉长岩，辉长苏长岩侵入于第一期次形成的含长二辉橄榄岩和橄榄辉长岩中。岩体橄榄石 Fo 值在80．9～89．7之间，为贵橄榄石；Ni含量变化范围较大，主要集中在102．19×10-6～4319．66×10-6之间。岩体母岩浆 MgO 含量为10．3％， FeO含量为10．8％；回归计算结果显示二红洼岩体的原始岩浆中 MgO 含量为15．73％，FeO 含量为10．71％。在橄榄石的结晶过程中母岩浆达到硫饱和，并发生有硫化物的熔离作用；橄榄石与硫化物的晶出质量比（橄榄石：硫化物）为50～100∶1。通过岩石学、矿物学特征以及模拟计算结果表明，二红洼岩体具有形成铜镍矿床的基本条件，但是岩体在深部岩浆房已经达到硫饱和并发生了硫化物的熔离作用，导致母岩浆中亏损Ni、Cu等成矿元素，未能形成工业矿体；在以后找矿勘探中，需要寻找早期硫化物熔离所形成的那部分硫化物熔体，并进一步寻找成矿富集的有利地段。
이홍와암체위우신강동천산황산미철-초미철암대적서단，지표유남、북량개소암체조성，북암체출로면적약1．42km2，정북동-남서향전포；남암체재정타원형，출로면적약위6．25km2。암체가분위량개침입기차：제일침입기차암성위（함장）이휘감람암화감람휘장암，제이침입기차암성위휘장소장암화담색휘장암，휘장소장암침입우제일기차형성적함장이휘감람암화감람휘장암중。암체감람석 Fo 치재80．9～89．7지간，위귀감람석；Ni함량변화범위교대，주요집중재102．19×10-6～4319．66×10-6지간。암체모암장 MgO 함량위10．3％， FeO함량위10．8％；회귀계산결과현시이홍와암체적원시암장중 MgO 함량위15．73％，FeO 함량위10．71％。재감람석적결정과정중모암장체도류포화，병발생유류화물적용리작용；감람석여류화물적정출질량비（감람석：류화물）위50～100∶1。통과암석학、광물학특정이급모의계산결과표명，이홍와암체구유형성동얼광상적기본조건，단시암체재심부암장방이경체도류포화병발생료류화물적용리작용，도치모암장중우손Ni、Cu등성광원소，미능형성공업광체；재이후조광감탐중，수요심조조기류화물용리소형성적나부분류화물용체，병진일보심조성광부집적유리지단。
The Chinese Tianshan orogenic belt is located in the southern part of the Central Asian Orogenic Belt (CAOB)in north Xinjiang,NW China.The Erhongwa mafic-ultramafic intrusion is at the western part of the Huangshan mafic-ultramafic rock belt which is located at the eastern part of the north Tianshan orogenic belt,can be divided into two small intrusions which named north and south intrusion,the area in the surface is 1. 42km2 and 6. 25km2 ,respectively.The Erhongwa intrusion is a multiple intrusion and composed of two intrusive rocks units,the first period have plagioclase-bearing lherzolite and olivine gabbro,and the second period which is composed of gabbronorite and gabbroic rocks.Olivine crystals enclosed in large clinopyroxene and plagioclase crystals from the plagioclase-bearing lherzolite and olivine gabbro have Fo contents between 80. 9~89. 7 mole %,and the contents of Ni in the olivine crystals between 102. 19~4319. 66 ppm,which decrease rapidly with Fo contents indicating sulfide segregation from magma during olivine crystallization. Numerical modeling using bulk sulfide compositions and constraints from olivine-liquid relation reveals that the parental magma of the Erhongwa mafic-ultramafic intrusion was a high-MgO theolitic magma containing 10. 3 wt. % MgO and 10. 8 wt. % FeO.The estimated MgO content in the primitive magma is up to 15. 73 wt. %.At 2 kb total pressure and the oxidation state of QFM-1,olivine start to crystallize at 1368℃according the MELTS program,the sulfide segregation and olivine fractional crystallization occurred almost at the same time during the magma evolution,and the sulfide:olivine is 1:50~100.The petrology and mineralogy characteristics and the modeling calculation results suggest that the Erhongwa intrusion have the basic conditions for form the Ni-Cu deposit,but the previous sulfide segregation in a staging chamber lead to the depletion of the ore-forming elements (e. g. ,Ni,Cu)in the parental magma.We need to find the sulfide melt which is formed by the previous sulfide segregation in the staging chamber and the favourable areas of metallogenic enrichment.