论文部分内容阅读
报道了阿尔金东段北缘的古元古代晚期壳源火成碳酸岩全岩地球化学和锆石SHRIMP定年结果.它们明显切割围岩,以岩株状、岩脉状产出,包裹不同类型围岩包体.岩石主要由方解石、透辉石组成,含石英、长石等长英质矿物.岩石高CaO(20.56%～39.80%),SiO2含量变化较大(23.33%～54.06%),稀土总量低(TREE=28.36×10-6～63.01×10-6)、弱负铕异常(Eu/Eu*=0.69～0.83)、轻重稀土分离不强((La/Yb)N=9.20～16.85),相对富集大离子亲石元素Sr、Rb、Ba、Th,亏损高场强元素Nb、Ti、P.锆石具核-边结构,边部锆石普遍存在不明显的环带,具变质深熔锆石的结构特征,其207Pb/206Pb加权平均年龄为1931±18Ma.它们是高级变质作用条件下米兰岩群不纯大理岩深熔作用的产物.
Reported the whole Paleoproterozoic eclogite carbonatite geochemistry and zircon SHRIMP dating results in the northern margin of the eastern part of the Altun.They clearly cut the surrounding rock and are produced in rock-like and dyke-like patterns and wrapped in different types The rocks are mainly composed of calcite and diopside and contain quartz minerals such as quartz and feldspar.The rocks have high contents of CaO (20.56% ~ 39.80%) and SiO2 (23.33% ~ 54.06%), (TREE = 28.36 × 10-6 ~ 63.01 × 10-6), weakly negative Eu (Eu / Eu * = 0.69-0.83), and the separation of light and heavy rare earths is not strong (La / Yb) N = 9.20 ~ 16.85). Relatively enriched in large ion lithophile elements Sr, Rb, Ba, Th, depleted high field strength elements Nb, Ti and P. The zircons with core-edge structures and marginal zircons are not obvious, The structural characteristics of the metamorphosed zircon are 207Pb / 206Pb with a weighted mean age of 1931 ± 18Ma, which are the products of impure marble diagenesis in the Milanese rock mass under the metamorphic conditions.