摘要
新疆东天山香山地区镁铁-超镁铁杂岩体中产有香山中中型铜镍矿床和香山西大型铜镍-钛铁矿床。通过对这套镁铁-超镁铁岩进行系统的野外研究和采样,对各类岩石进行详细的岩石学和岩石地球化学研究,识别出该区两个具有不同成矿专属性的岩石系列。(1)早期与钒钛磁铁矿矿化有关的岩石系列(简称'钛铁系列'),岩石组合为细晶辉长岩-钛铁辉长岩(钛铁矿石)-含钛(角闪)辉长岩-淡色辉长岩。从钛铁矿石-含钛辉长岩-淡色辉长岩连续演化,矿物组成和岩石结构逐渐过渡,岩石相对偏酸性,化学成分以富碱、富铁、高钛、硅、铝、钙,钙碱指数(ealk/m)高而镁铁指数(m/f)低为特征,稀土和微量元素方面斜长石堆积作用和分离结晶作用特征明显;(2)晚期与铜镍硫化物矿化有关的岩石系列(简称'铜镍系列'),岩石组合为超镁铁岩-韵律状橄榄辉长岩-蚀变角闪辉长岩,与前一系列呈侵入关系。该系列岩石组合偏基性,化学成分上明显富镁,贫铁、钛,具相对较低的硅、铝和钾、钠含量,稀土和微量元素配分曲线平缓,与原始地幔/亏损地幔特征相近。此外,本区发育的浅成-超浅成脉岩(辉绿岩类)多为辉长岩类的晚期补充岩相,其岩石化学特征位于两个演化系列的末端,可能是两个演化系列残余岩浆混合-再侵位的产物。
The mafic-ultramafic complex in the Xiangshan area of the eastern Tianshan Mts. , Xinjiang, produce a medium-sized Middle-Xiangshan Cu-Ni deposit and a large-scale western-Xiangshan Cu-Ni-( V-) Ti-Fe deposit. Through systematical field investigation and sampling for the suit of mafic-ultramafic rocks, a detailed petrology and geochemistry research was carried out and two rock series with different metallogenetic specialization in study area have been identified. 1) Early stage rock series related to (V)-Ti- Fe mineralization with rock association of aplitic gabbro, Ti-Fe gabbro (Ti-Fe ore) , Ti-bearing (hornblende) gabbro and leucogabbro, shortly called as '( V-) Ti-Fe rock series'. The three rock types of Ti-Fe ore, Ti-bearing gabbro and leucogabbro have continued evolution and gradual transition in mineral assemblage and rock texture. This series is characterized by alkali, Fe, Ti, Si, Al and Carich, high calc-alkaline enrichment index (calk/m) and low mafic index (m/f) in chemical composition, and by distinct plagioclase cumulation and magma fractional crystallization in geochemistry of REE and trace elements. 2) Later stage rock series that can intrude in the Ti-Fe series rocks related to Cu-Ni sulfide mineralization with rock association of ultramafic rocks, rhythmic olive gabbro and altered hornblende gabbro, shortly called as 'Cu-Ni rock series'. This series is characterized by Mg-rich and relatively lower Fe, Ti, Si, Al, K and Na contents in chemical composition, and by gently REE and trace patterns that reflect a characteristics of primary mantle or depleted mantle. The other hypabyssal dykes ( diabase) in the ore district, mainly as later additional facies of gabbro, display an end evolution of the two rock series, i. e. , product of magma mixing of two residual magma series.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2009年第4期888-900,共13页
Acta Petrologica Sinica
基金
国家重点基础研究项目(2007CB411304和2001 CB409806)资助
关键词
镁铁-超镁铁杂岩
铜镍系列
(钒)钛铁系列
香山
新疆
Mafic-ultramafic complex
Cu-Ni rock series
(V-) Ti-Fe rock series
Xiangshan
Xinjiang
