Geochemical characteristics and petrogenesis of the Neoproterozoic Eshan highly fractionated I-type granites, western Yangtze block

被引：0
|
作者：
Li G. [1 ]
Chen Y. [1 ]
Shang Z. [1 ,2 ]
Liu S. [1 ]
机构：
[1] School of Earth Science and Resources, China University of Geosciences (Beijing), Beijing
[2] China Fire and Rescue Institute, Beijing
来源：
Earth Science Frontiers | 2024年 / 31卷 / 03期
关键词：
highly fractionated I-type granites; Neoproterozoic; tectonic setting; west margin of Yangtze block;
D O I：
10.13745/j.esf.sf.2023.6.18
中图分类号：
学科分类号：
摘要：
The Eshan highly fractionated I-type granites, situated in the western margin of the Yangtze block, represent a significant component of the Neoproterozoic magmatic belt within the region. A comprehensive investigation into their magma source» genesis, and tectonic settings can provide insights into the evolutionary trajectory of the Neoproterozoic crust. This study conducts zircon LA-MC-ICP-MS U-Pb dating and geochemical analyses on the Eshan highly fractionated I-type granites. The results indicate that these granites predominantly consist of red medium-coarse granite and gray-white medium-coarse granite, formed at approximately 746 ± 34 Ma (MSWD = 4.2) and 732 ± 30 Ma (MSWD = 3.3), respectively. Geochemical analysis reveals a highly fractionated I-type signature characterized by elevated levels of SiC)2 (70.32%-78.41%), Na2O (3.09%-3.94%), and K2O (5.13%-7.35%), while exhibiting lower concentrations of CaO (0.52%-0.90%), TiO2(0.001 %-0.025%), and P2O5 (0.061 %-0.097%). The rocks exhibit enrichment in K, Rb, Th, and depletion in Nb, P, and Ti. Sr-Nd isotope analysis shows eNd (t) values ranging from -10.8 to - 7.5, with two-stage Nd model ages (T dm2)falling within the range of 2.3 to 2.0 Ga. Integrating these findings with regional geological studies, it is proposed that the Eshan highly fractionated I-type granites originated from the underplating of mantle- and/or juvenile mafic lower crust-derived magma that intruded the upper crust, triggering partial melting of Paleoproterozoic medium- to high-potassium basaltic rocks and biotite gneiss under an extensional tectonic regime. Subsequently, these granites were formed through a process of high fractional crystallization. © 2024 Science Frontiers editorial department. All rights reserved.
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页码：20 / 39
页数：19
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