地幔交代作用的微区微量元素证据——云南双沟蛇绿岩的质子探针研究

CONSTRANTS ON TRACE ELEMENT IN MICRO AREA FOR MANTLE METASOMATISM: STUDY OF PROTON MICROPROBE FOR THE SHUANGGOU OPHIOLITE, YUNNAN PROVINCE

用质子探针技术对双沟地幔交代熔融物的微区微量元素进行了测定。研究表明,地幔橄榄岩中的残留矿物橄榄石和斜方辉石仅含Ni和Zn,而Ga、Ge、Sr、Rb、Zr、Y、As、Pb等微量元素主要集中在地幔部分熔融所产生的矿物(尤其是尖晶石和绿泥石)中。微区范围内微量元素的分布表明,尖晶石二辉橄榄岩地幔不均一性的尺度可达微米级,通常解释为尖晶石二辉橄榄岩在开放系统下地幔交代作用的结果。

This paper reported the result of trace dement composition and distribution at micro area of melt from mantle metasomatism of peridotite in the Shuanggou ophiolite. Both olivine and orthopyroxene which belong to the mantle residual minerals only contant in Ni and Zn. The trace elements, such as Ga, Ge, Sr, Rb, Zr, Y, As, Pb etc. are mainly concentrated at products from mantle partial melting, especially spinel and chlorite. The distribution of trace elements at micro area is distinct variated, showing mantle inhomogeneity in few ten micrometer scale, and commonly illustrated as a result of mantle metasomatism at open system for peridotite.