安徽铜陵天鹅抱蛋山石英闪长岩岩石学和矿物学特征及其地质意义  

MINERALOGICAL CHARACTERISTICS OF THE TIAN′EBAODANSHAN IN THE TONGLING AREA,ANHUI QUARTZ DIORITE PROVINCE AND ITS GEOLOGICAL SIGNIFICANCE

作　　者：杨彦超[1,2] 杜杨松[2] 李名松[1] 李明轩[2] 曹秋义[1] 

机构地区：[1]核工业航测遥感中心,河北石家庄050002 [2]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《矿物岩石》2015年第4期51-58,共8页Mineralogy and Petrology

基　　金：国家自然科学基金项目(40672045)

摘　　要：天鹅抱蛋山石英闪长岩与天马山矽卡岩型硫金矿床具有密切的成因关系,通过对闪长岩进行岩相学观察和详细的矿物化学分析来探讨岩体的形成条件及其地质意义。本区闪长岩中斜长石主要为更长石(An=23~30)和中长石(An=31~38),具有正环带结构,指示岩体在形成过程中经历快速抬升的地质作用。早期角闪石为浅闪石,结晶压力为301 MPa^504 MPa,对应的岩体侵位深度为9.9km^16.6km,结晶温度为721℃~761℃;晚期角闪石为镁角闪石,结晶压力为128 MPa^167 MPa,对应的岩体侵位深度为4.2km^5.5km,结晶温度为632℃~692℃。黑云母为镁质黑云母,镁质率为0.45~0.70,说明岩体属于深源系列,其成分特征指示岩体具有壳幔混源的成因特点,结晶温度为650℃~700℃。结合岩体的稀土元素、同位素地球化学数据分析表明:来自与上地幔的岩浆上侵至中下地壳(约14.7km),并发生同化混染作用和结晶分异演化,随后快速的上侵至近地表(约4.8km),最后冷凝固结为天鹅抱蛋山闪长岩。The Tian＇ebaodanshan quartz diorite is closely related with the Tianmashan gold deposit. The forming conditions of the rock body and its geological significance with the petrographic and mineralogical characteristics of the Tianrebaodanshan quartz diorite are studied. Plagioclases in the rocks consist of oligoclase with An ranging from 23 to 30 and andesine with An ranging from 31 to 38. Normal oscillatory zoning indicates that the rock body experienced rapid uplift in the process of formation. The early stage hornblendes are edenite formed at pressure of 301 MPa -504 MPa,at depth of 9.9 km-16.6 km and at temperature of 721 ℃ -761 ℃. The late stage hornblendes are magnesiohornhlende formed at pressure of I28 MPa- 167 MPa, at depth of 4.2 km-5.5 km and at temperature of 650 ℃ -700 ℃. Biotites in the rocks belong to Mg-biotites with the ratios of Mg/（Mg＋Fe2＋ Mn） ranging from 0.45 to 0. 70 , indicating that the rocks belong to deep-source series. Analysis of chemical composition of the biotites reveals that it is resulted from a mixed source of mantle and crust and the crystallization temperature ranges from 650 ℃ to 700 ℃. Comprehensive analysis of the geochemical data of isotope and REE and mineralogical characteristics indicates that magma emplaeed from upper mantle to middle-lower crust （about 14.7 km） and accompanied by fractionation crystallization znd assimilation. Subsequently, the magma rapidly emplaced to the shallow part of earthrs surface （about 4.8 km） and eventually formed the Tiantebaodanshan quartz diorite.

关 键 词：天鹅抱蛋山岩体 石英闪长岩 岩相学 矿物学 温压条件 安徽铜陵 

分 类 号：P584[天文地球—岩石学] P579[天文地球—地质学]