中咱地块侵入岩年代学及成因探讨

发布时间：2018-06-10 21:31

本文选题：中咱地块 + 中酸性岩浆岩　；参考：《成都理工大学》2017年硕士论文

【摘要】：研究发现中咱地块是在晚古生代时期从扬子陆块西缘裂解而形成,同时伴随甘孜—理塘洋盆的逐渐发育;并在晚三叠世中期(227Ma)甘孜-理塘洋开始闭合,逐渐向中咱地块之下俯冲消减,形成中咱地块与甘孜—理塘缝合带之间的义敦岛弧褶皱带。甘孜—理塘洋盆向西俯冲消减于中咱地块的过程中,必然导致中咱地块发生相应的岩浆活动与之响应。本文选取中咱地块内的黄草坪黑云母闪长岩岩体、扎瓦拉复式岩体、亚日贡石英二长岩岩体、纳交系花岗岩岩体四个代表性的花岗质岩体进行详细的岩相学、岩石地球化学、LA-ICPMS U-Pb年代学研究。研究结果显示这些花岗质岩石为俯冲岛弧环境下形成的高钾钙碱性I型花岗岩,并且主要属于钛铁矿系列的还原型花岗质岩体;成岩年龄分别为:黄草坪黑云母闪长岩岩体—227.4±1.8 Ma;扎瓦拉石英二长岩岩体—225.15±0.96Ma,扎瓦拉钾长花岗岩岩体—218.0±1.1 Ma;亚日贡石英二长岩岩体—224.94±0.93Ma;纳交系花岗岩岩体—222.6±2.5Ma。本文所研究的四个花岗质岩体基本相同的成岩年龄预示甘孜—理塘洋盆很可能在晚三叠世早期之前(227Ma)便开始向西俯冲消减于中咱地块之下,从而引发了中咱地块内218~227Ma左右的花岗质岩浆活动。研究表明中咱地块岩浆岩与义敦岛弧带岩浆岩的形成时代和环境基本一致,都属于印支期花岗岩,并且通过对中咱地块内扎瓦拉铜金多金属矿床的研究表明,中咱地块与岩浆岩活动有关的矿床,其形成是在中咱地块从扬子地台分离以后,因此中咱地块内的找矿思路可以参照义敦岛弧带的找矿模式。
[Abstract]:It is found that the Zhongzan block was formed during the late Paleozoic from the western margin of the Yangtze block with the gradual development of the Ganzi-Litang ocean basin, and began to close in the middle of the late Triassic. It gradually subducts and subducts under the Zhongzan massif to form the Yidun island arc fold zone between the Zhongzan massif and the Ganzi-Litang suture belt. The process of subducting and subducting westward from Ganzi-Litang oceanic basin to Zhongzan block will inevitably lead to the corresponding magmatic activity and response of Zhongzan block. In this paper, four representative granitic rocks, including Huangzhuangbiotite diorite, Zawala complex, Yarigon quartz monzonite, Nanaoguitic granitoids, are selected for detailed petrographic study. A geochemistry study of LA-ICPMS U-Pb chronology. The results show that these granitic rocks are high-potassium calc-alkaline I-type granites formed in the subducted island arc environment, and mainly belong to the reduced granitic rocks of ilmenite series. The diagenetic ages are: Huangzhang biotite diorite rock body -227.4 卤1.8 Ma-225.15 卤0.96 Ma, zawala potassium feldspar granitic body -218.0 卤1.1 Ma. Yarigon quartz monosite rock body -224.94 卤0.93Ma. The diagenetic ages of the four granitic rocks studied in this paper indicate that the Ganzi-Litang ocean basin probably began to submerge westward under the Zhongzan block before the early late Triassic. Thus, the granitic magmatism of 218m 227Ma in Zhongzan block was initiated. The results show that the magmatic rocks of the Zhongzan block and the Yidun island arc belt are formed in the same age and environment and belong to the Indosinian granites. The study on the Zawala copper and gold polymetallic deposits in the Zhongzan massif shows that the formation time and environment of the magmatic rocks are basically the same as those in the Yidun island arc belt. The ore deposits related to magmatic activities in the Zhongzan massif were formed after the Zhongzan massif was separated from the Yangtze platform, so the prospecting ideas in the Zhongzan massif can refer to the prospecting model of the Yidun island arc belt.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P597.3;P588.12

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