编号：CDUT-2020-63

标题：Origin and evolution of the Neoproterozoic Dengganping Granitic Complex in the western margin of the Yangtze Block, SW China: Implications for breakup of Rodina Supercontinent

入藏号： WOS:000558896300004

中国科学院文献情报中心期刊分区（升级版）：地球科学2区

本校作者：邹灏*；刘行；蒋修未；李阳

来源出版物：Lithos 卷：370 文献号：105602

出版年：2020年

第一地址：成都理工大学

关键词：Rodinia超大陆；灯杆坪杂岩；裂解；锆石U-Pb定年；Hf-O-Nd同位素

代表图：

扬子西缘地质图及研究区位置图

扬子西缘新元古代构造演化模式图

摘要：A better understanding of the origin and evolution of widespread Neoproterozoic granites along the western margin of the Yangtze Block is important in locating the position of South China within the Rodinia Supercontinent, and the mechanism by which the supercontinent was fragmented. Published and our new detailed geochronological and geochemical data from the Dengganping Complex show that it formed during an extended magmatic event during the Neoproterozoic. This was during the emplacement of a fractionated ca. 815 Ma syenogranite, which was followed by partial melting during ca. 740 Ma and the emplacement of a biotite monzogranite. The geochemistry of the syenogranite indicates it is: (1) a peraluminous high-K type of granite; (2) calc-alkaline; (3) fractionated; (4) enriched in Th, U, Zr, Hf and LREE (LREE/HREE values of 5.3–9); (5) depleted in Nb and Sr; (6) has a negative Eu anomaly (δEu = 0.3–0.5); (7) has whole rock εNd(t) value of −0.7 to +0.5; (8) has zircon εHf(t) value of −1.7 to +5.2; and (9) has zircon 18O values ranging from 5.13 to 7.38‰. These characteristics are indicative of a source derived from the partial melting of crustal material. The biotite monzogranite is: (i) peraluminous calc-alkaline to high-K calc-alkaline; (ii) enriched in LREE (LREE/HREE = 9.9–14.6), Rb, Ba, Th and U; (iii) depleted in Nb and Ta; (iv) has weak negative δEu and δCe anomalies; (v) has whole rock εNd(t) value of between −3.2 and −1.8; has relatively high positive zircon εHf(t) values of +4.1 to +13; and has zircon 18O values ranging from 3.44 to 6.75‰. These features are indicative of partial melting of a juvenile mafific crust that might have experienced a high-temperature water-rock interaction. By comparing the geochronology of Neoproterozoic magmatic rocks along the faulted western margin of the Yangtze Block, it is suggested that the region was part of the Rodinia Supercontinent when it started to breakup during widespread rifting between ca. 825 and 710 Ma. We believe the fault zone formed in response to an opening ocean was induced by the presence of a mantle plume during this period.

文章链接地址： https://www.sciencedirect.com/science/article/pii/S0024493720302395?via%3Dihub