鲁西栗杭地区新太古代地质剖面的解剖:野外研究和SHRIMP U-Pb锆石定年  

Anatomy of a Neoarchean Geological Section in the Lihang Area, Western Shandong: Field Observation and SHRIMP U-Pb Zircon Dating

作　　者：李源[1,2] 任鹏 颉颃强[1] 谢士稳[1] 王世进[4] 宋志勇[4] 万渝生[1] Li Yuan;Ren Peng;Xie Hangqiang;Xie Shiwen;Wang Shijin;Song Zhiyong;Wan Yusheng(Beijing SHRIMP Center Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;School of Resources and Environmental Engineering,Hefei University of Technology,Hefei 230009,China;School of Earth Science and Resources,Chang'an University,Xi'an 710064,China;Shandong Geological Suruey Institute,Jinan 250013,China)

机构地区：[1]中国地质科学院地质研究所北京离子探针中心,北京100037 [2]合肥工业大学资源与环境工程学院,安徽合肥230009 [3]长安大学地球科学与资源学院,陕西西安710064 [4]山东省地质调查院,山东济南250013

出　　处：《地球科学》2020年第9期3341-3352,共12页Earth Science

基　　金：中国地质调查局地质调查项目(Nos.DD20190009,D20190358,DD20190370,DD20190003)。

摘　　要：以往对鲁西新太古代地质研究主要是区域性的,对于露头尺度上的深入研究还不多见.本文对鲁西泰山栗杭地区的地质剖面进行了详细的野外地质和锆石SHRIMP年代学研究.岩石十分新鲜,类型多种多样,现象丰富且复杂.条带状英云闪长质片麻岩和细粒英云闪长质片麻岩的岩浆锆石年龄分别为2.62 Ga和2.63 Ga,可解释为岩石的形成时代.另一条带状英云闪长质片麻岩的岩浆锆石和变质锆石年龄相近,均为~2.57 Ga,其地质意义需进一步工作来确定.奥长花岗质岩脉的形成时代为2.60 Ga.闪长质片麻岩侵入条带状英云闪长质片麻岩和奥长花岗质岩脉,岩浆锆石年龄为2.52 Ga,存在2.66~2.69 Ga外来锆石.研究表明,泰山地区存在不同时代(~2.7 Ga和~2.6 Ga)英云闪长质片麻岩,仅根据野外特征难以相互区别.该剖面所记录的岩浆构造热事件是鲁西地区新太古代地质演化的缩影,但缺失~2.7 Ga TTG岩石记录.Previous studies on the Neoarchean geology in western Shandong were mainly regional with few reports on the outcrop scale. Detailed field observation and SHRIMP U-Pb zircon dating are carried out in this study on rocks in a road cutting section in the Lihang area, western Shandong, where different types of rocks are very fresh and show complex and various relationships.Banded tonalitic gneiss and fine-grained tonalitic gneiss have magmatic zircon ages of 2.62 Ga and 2.63 Ga, respectively, which are considered to be the crystallization times of the rocks. Another banded tonalitic gneiss has similar magmatic and metamorphic zircon ages of ~2.57 Ga. More work is required to determine its geological meaning. A trondhjemitic dyke has a formation age of2.60 Ga. A diorite dyke intruding banded tonalitic gneiss and trondhjemitic vein has magmatic and metamorphic zircon ages of 2.52 Ga and 2.51 Ga, respectively, with 2.66-2.69 Ga xenocrystic zircons. Combined with previous work, it is concluded that there are tonalitic gneisses of different ages(~2.7 Ga and ~2.6 Ga) in the Taishan area, which are difficult to be distinguished from each other in field. The geological records in this section may be an epitome of Neoarchean geological history of western Shandong but without ~2.7 Ga TTG record.

关 键 词：新太古代 岩浆作用 泰山 鲁西 锆石SHRIMP定年 岩石学 

分 类 号：P588.12[天文地球—岩石学] P597[天文地球—地质学]