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摘要
The Wushilong pluton is located at the northeastern end of Jiangnan Orogenic Belt, it is representative metallogenic pluton which is one of the largest plutons in Silurian in the district. Its geological characters show that Wushilong pluton intrudes along the axis of Taiping syncline. The main lithology is granodiorite, followed by adamellite. The LA-ICP-MS U-Pb dating results of the granodiorite intrusion is from148.9±2.0 Ma to 148.0±2.5 Ma. It shows that granodiorite was formed in the early Yanshan Period. The geochemistry of the granodiorite and adamellite show that they are potassium, high calc-alkaline and peraluminous rocks. The granodiorite has some similar features of adakites, but there is some differences: high SiO2 （＞ 65%）, High Sr/Y（sample mean＞21.7）and（La/Yb）N（sample mean＞15.33）ratios, high Al2O3（sample mean ＞15%）, low MgO（＜1.86%）, low Yb（＜2.50×10-6）and Y（＜ 23×10-6）values, low Sr（292.38×10-6 to 424.60×10-6）, etc. However, the adamellite has no similar features of adakites: low Al2O3（＜13.5%）, low Yb（1.29×10-6 to 2.42×10-6）, Low Sr（30.99×10-6 to 44.10×10-6）and Y（10.42×10-6 to 129.75×10-6）values contents, low Sr/Y（0.34～2.97）and low （La/Yb）N（3.32～7.41） ratios, etc. The REE partition map of the granodiorite is characterized by right-wing pattern, which is with P, Nb, Sr and Ti are strongly depleted. However, with weak negative Eu and Ba anomaly. The REE partition map of the adamellite is characterized by seagull type, which is with remarkable negative Eu anomaly, and more strong depletion in Ba, P, Nb, Sr and Ti. The granodiorite is I-type granite and the adamellite is A-type granite. These features show the granodiorite might originated from crust-mantle mixed source formed in the structural background of the transformation from extrusion to tension in the Early Yanshanian Period and the adamellite might mainly originated from crust source formed in the middlle Yanshanian extrusional tectonic setting, which may be closely related to the subduction of the paleo-Pacific Plate. The adamellite is richer in Mo than granodiorite. Geochemical characteristics show that the pluton has the metallogenic potential. ? 2022 Science Press.
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