摘要
中生代巴彦喀拉-松潘甘孜地体向东昆仑地体斜向俯冲,在东昆仑南缘形成一条巨型的韧性剪切带。剪切带中发育的旋转碎斑、书斜构造、解理阶步、云母鱼、S-C组构、不对称褶皱、雁列脉等宏微观构造,显示剪切带兼具右行和左行的特征,且右行早于左行剪切,但总体以左行剪切为主。对西大滩糜棱岩化花岗岩和小南川未变形花岗岩进行了LA-ICP-MS锆石UPb测年,西大滩岩体侵位于199.3±2.2Ma,小南川岩体形成于196.4±1.3Ma。西大滩与小南川岩体中的锆石为典型的岩浆锆石,其年龄代表了岩体侵位的时代。鉴于2个岩体的变形程度完全不同,东昆仑南缘在199~196Ma之间发生了左行韧性剪切。
As a result of oblique subduction of the Bayan Har-Songpan-Garze terrane toward the East Kunlun terrane in Mesozoic,a major ductile shear zone formed along the southern margin of the East Kunlun terrane. Ductile deformation phenomena observed in the ductile shear zones, such as porphyroclasts, porphyroclastic structure, cleavage-step, mica fish, S-C fabric, asymmetrical folds and echelon veins, implying both dextral and sinistral shear characteristics. The dextral shear is earlier than the sinistral shear. However, the sinistral shear is the dominant feature in these ductile shear zones. LA-ICP-MS U-Pb dating of zircons from the mylonitization granite in Xidatan and the undeformed granite in Xiaonanchuan yielded ages of 199.3±2.2Ma and 196.4±1.3Ma, respectively.Zircons dated here are typically formed via magma crystallization, which means that their ages could represent the emplacement time of the two plutons. The deformation degree of the two pluton, which is completely different from each other, indicates that the southern margin of the East Kunlun left-lateral ductile shear zone should have formed in 199~196Ma.
出处
《地质通报》
CAS
CSCD
北大核心
2017年第6期987-1000,共14页
Geological Bulletin of China
基金
青海省地质勘查基金项目<青海省昆仑河地区金多金属矿整装勘查区找矿部署研究>(编号:2016020003ky003)
国家自然科学基金项目<新疆西天山吐拉苏浅成低温热液-斑岩型金成矿系统物质与时空结构研究>(批准号:41572062)
<内蒙古哈达门沟-柳坝沟金矿床碱交代作用与金钼成矿关系研究>(批准号:41302064)
