期刊
PRECAMBRIAN RESEARCH
卷 316, 期 -, 页码 275-290出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.precamres.2018.08.022
关键词
Tibet; North Lhasa terrane; East African Orogen; Zircon U-Pb dating; Geochemistry and isotope
资金
- National Science Foundation of China [41522204, 41502216, 91755103, 41872240]
- Ministry of Science and Technology of China [2016YFC0600304]
- Institute of Geology of the Chinese Academy of Geological Sciences [J1705, YYWF201704]
- Chinese Geological Survey Project [DD20160123-05, DD20160345]
The North and South Lhasa terranes in the central Tibetan Plateau were traditionally considered to be one block in the Precambrian and originate from the northeastern India or northern Australia. In this contribution, we report Middle Neoproterozoic (ca. 760 Ma) gabbros in the North Lhasa terrane. The gabbros can be subdivided into two groups. The group-1 gabbros (ca. 766 Ma) are calc-alkaline and exhibit arc-like geochemical features. They have high I-sr (0.708 to 0.710) and low zircon epsilon(Hf)(t) (-2.0 to +1.0) and whole-rock E-Nd(t) (-2.4) values, and were probably generated by partial melting of an enriched subduction-modified lithospheric mantle. By contrast, the group-2 gabbros (ca. 766 and 758 Ma) belong to the tholeiitic series and are geochemically similar to N-MORB. Their low I-Sr (0.705 to 0.706) and high positive zircon epsilon(Hf)(t) (+5.6 to +8.8) and whole-rock epsilon(Nd)(t) (+2.6 to +3.8) values are indicative of an N-MORB-type depleted mantle source. The presence of these coeval N-MORB- and arc-type gabbros is related to an arc and back-arc system, and indicates an age equivalent to the northern EAO (East African Orogen). Integrating previous studies with the data presented in this contribution, we suggest that the North Lhasa terrane was most likely separated with the South Lhasa terrane in the Precambrian and originated from the northern EAO.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据