摘要
阿克苏地区位于新疆塔里木克拉通西北缘,是研究塔里木克拉通前寒武纪演化的关键地区.该区出露有较好的前寒武系变质基底和沉积盖层,包括新元古界阿克苏群,南华系巧恩布拉克组和尤尔美那克组以及震旦系苏盖特布拉克组和奇格布拉克组.震旦系苏盖特布拉克组主要为一套红色河流相,湖相砂岩—粉砂岩序列,底部发育有砾岩和玄武岩夹层.本文对苏盖特布拉克组顶底两个沉积岩样品进行了LA-ICP-MS碎屑锆石UPb定年,旨在揭示苏盖特布拉克组的源区特征以及区域构造演化历史.碎屑锆石年龄谱指示出600～680Ma、730～900Ma、1800～2050Ma和2300～2600Ma四期构造-岩浆活动,与塔里木克拉通广泛发育的前寒武系岩体时代相匹配,说明塔里木克拉通可以为苏盖特布拉克组提供直接的物源.这四期构造-岩浆活动分别反映了塔里木克拉通对泛非造山、Rodinia超大陆、Columbia超大陆和新太古代—古元古代早期全球陆壳生长事件的响应.苏盖特布拉克组碎屑锆石记录落入碰撞背景盆地范围.结合区域地质资料,苏盖特布拉克组沉积可能代表了该区由会聚背景向伸展背景的转换.
The Aksu area is situated in the northwestern margin of the Tarim Craton, Xingjiang Province, and is a pivotal area in understanding the Precambrian evolution history of the Tarim Craton. The Precambrian metamorphic basement and sedimentary cover including Neoproterozoic Aksu Group, Nanhua Qiaoenbrak and Yuermeinak formations, and Sinian Sugetbrak and Qigebrak formations are well outcropped in the region. The Sinian Sugetbrak Formation is mainly consisted of fluvial and lacustrine facies sandstones and siltstones following conglomerates and basalt layers in the bottom. In the article, LA-ICP-MS U Pb isotopic dating was used for detrital zircons from two Sugetbrak sedimentary samples, in order to reveal the provenance characteristics of the Sugetbrak Formation and the tectonic evolution history in the region. Detrital zircon U-Pb age spectra shows that four periods of tectonomagmatic events have occurred at 600- 680Ma, 730-900Ma, 1800-2050Ma and 2300-2600Ma, which is consistent with the ages of widely developed Precambrian litho-units in the Tarim Craton, indicating the Tarim Craton could be the direct provenance for the Sugetbrak Formation. These four periods of tectonomagmatic events reveal the influences of the Pan-African event, Rodinia supercontinent, Columbia supercontinent and Neoarchean to early Paleoproterozoic global continental growth in the Tarim Craton respectively. The detrital zircon record of the Sugetbrak Formation falls into the fields for basins with collisional setting. Combining with regional geology, the Sugetbrak Formation probably represent the transition from a convergent setting to an extensional setting in the region.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2015年第1期149-162,共14页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41272211)
南京大学内生金属矿床成矿机制研究国家重点实验室基金项目(编号2009-I-01和ZZKT-201110)资助的成果
