摘要
系统研究白云鄂博含矿围岩的岩性,发现含矿白云岩中具有火山碎屑结构、杏仁状及角砾状构造,在西矿带白云岩中夹有黑云母片岩,而东矿带则与富钠火山岩共生。其岩石化学成分与世界其他岩浆成因的碳酸岩相似,白云岩的一系列岩石化学、稀土元素地球化学图解均判别其为岩浆成因特征。根据魏菊英等的研究表明,碳、氧同位素受海水混合作用的影响,由喷发中心到正常沉积碳酸盐呈现规律性升高的变化趋势,因此含矿白云岩及近矿白云岩是白云质火山岩。白云岩中含钾长石、萤石等热液矿物,高度富集F、Sr、Ba等元素,平均w(F)为13 5849%,w(Sr)为0 1588%,w(Ba)为0 8537%。白云岩中磷灰石构成主要矿物,P2O5高度富集,平均w(P2O5)为7 79%。这些特征均表明了白云岩为岩浆成因,是裂谷早期裂陷阶段岩浆活动的产物,故将白云鄂博矿区的白云岩定名为白云质火山岩。
This article studies the lithologic characters and its genesis of the country rock in Baiyun'ebo mine, and discovers that volcanic texture in orebearing dololithite is of pyroclastic structure, amygdaloidalor brecciola texture, and interlays with biotites schist in the west of the deposit, but is paragenous with Narich volcanic rock in the east. Its chemical compositions are similar to those of carbonatite formed by magma; a series of lithologic chemistry and REE's geochemical diagrams of dololithite all characterize its magmatic genesis.Based on the research done by Wei Juying, the isotopes of carbon and oxygen, affected by seawater, show gradually increasing trend from the center of eruption to normal sedimentary deposit. Hence,the Composition of carbonatite in Baiyun'ebo is close to dolomitic volcanic rock. The dolomite contains hydrothermal mineral such as Kfeldspar and fluorite, and high concentration in the elements of F, Sr, and B, averaged out 13584 9%,0158 8%,0853 7%,respectively. But apatite is the main mineral in the dolomite, and resulted in high concentration of P2O5 with average content of 779%. All these characters show the dolomite in Baiyun'ebo mine belongs to magmatogene rock and it is the product of early rift process. Thus,the country rock in Baiyun'ebo mine is defined as dolomitic volcanic rock.
出处
《现代地质》
CAS
CSCD
2003年第3期287-293,共7页
Geoscience
基金
国家自然科学基金项目(40073013)
国土资源部国际合作与科技司自由探索项目(2000440)。
关键词
白云鄂博
白云质火山岩
岩石化学
微量元素
稀土元素
Baiyun'ebo
dolomitic volcanic rock
lithologic chemistry
trace elements
rare earth element
