Geochronology and Geochemistry of the 890 Ma I-Type Granites in the Southwestern Yangtze Block:Petrogenesis and Crustal Evolution

• 作者: Chenglong Shi Heng Zhang Jibiao Zhang Xiaozhong Ding Yanxue Liu Yu Zou
• 来源期刊: 地球科学学刊（英文版）
• 年，卷（期）: 2020,（6）
• 页码范围: 1216-1228
• 页数: 13页
• 语种: 英文

摘要

The tectonic evolution of the southwestern Yangtze Block during the Early Neoproterozoic pe-riod is still controversial because of the limited quantities of 1000–860 Ma magmatic rocks. In this study, our new LA-ICP-MS zircon U-Pb dating results demonstrate that the Yanbian granodiorites in the southwest Yangtze Block were emplaced at 894.6±7.4 Ma, representing the product of an 894 Ma magmatism. The Yanbian granodiorites are metaluminous to weak peraluminous with A/CNK values of 0.8–1.1, resembling I-type granitoids. They are characterized by right-inclined REE patterns with moderate to insignificant nega-tive Eu anomalies (δEu=0.6–0.9). Their primitive mantle-normalized trace element patterns are character-ized by depletion of Nb, Ta and Ti and weakly enrichment of Th. Considering the positive whole-rock εNd(t) (+5.8 to +6.8), we propose that these granodiorites originated from the partial melting of juvenile mafic lower crust. The Yanbian I-type granitoids have low Y and Nb contents similar to volcanic arc igneous rocks in the Y-Nb plot for tectonic discrimination. In conclusion, Early Neoproterozoic Yanbian granodiorites have gen-erated in a compression setting in an active continental margin. Together with previous studies from the southwestern Yangtze Block, we suggest that the 894 Ma subduction-related Yanbian granodiorites represent the early stage of subduction at the southwestern margin of the Yangtze Block.

作者信息

序号	姓名	单位	发文数	被引次数	H指数	G指数
1	Jibiao Zhang		1	0	0.0	0.0
2	Xiaozhong Ding		1	0	0.0	0.0
3	Yanxue Liu		1	0	0.0	0.0
4	Heng Zhang		1	0	0.0	0.0
5	Chenglong Shi		1	0	0.0	0.0
6	Yu Zou		1	0	0.0	0.0