煎茶岭地区同位素地质年龄数据及其地质意义

ISOTOPIC GEOCHRONOLOGICAL DATA AND THEIR GEOLOGICAL SIGNIFICANCE IN JIANCHALING REGION,SHAANXI PROVINCE

采用Sm—Nd同位素地质年代学方法测得超基性岩体的形成年龄为927×10~6a左右.岩体属于晚元古代产物;侵位其中的有花岗斑岩,其Rb—Sr法全岩等时线年龄为400×10~6a左右,属加东期岩浆活动产物;后期辉长岩等岩脉K—Ar法年龄为206×10~6a左右;结合铅同位素资料,还讨论了煎茶岭地区岩浆演化史、岩石变质文以及镍矿床的主要成矿时代.为研究煎茶岭地区变质超基性岩体地质提供了同位素地质年龄资料.

The forming age of 927 × 106a in Jianchaling ultrabasic rocks is got by using Sm-Nd isotope chronological method, being belong to late Proterozoic Era. The granite-porphyry intruding in the ultrabasic rocks has a Rb-Sr whole rock isochron age at about 400×106a,being products of Caledonian Period in age. K-Ar age of the later stage gabbro dykes is about 206×106a. In the light of the Pb isotopic data ,the history of magmatic evolution,of metamorphism and the main metalloge-netic epoch of Ni deposit in Jianchaling region are discussed and the isotopic geochronologic data of the meta-ultrabasics in Jianchaling region are presented.