Title: Zircon U-Pb Dating and Tectonic Significance of the Shipingchuan Granite in Southeastern Zhejiang Province,SE China
Abstract: The Shipingchuan K-feldspar granite is situated in south—central volcanic belt of southeastern Zhejiang Province. LA-ICP-MS zircon U-Pb dating yields a weighted mean 206Pb/238U age of 102.5±1.2 Ma (MSDW=2.1)for the Shipingchuan granite intrusion,implying its end of early Cretaceous crystallization time. Petrography and chemical compositions show that it belongs to high-K calc-alkaline series characterized by high silicon,enriched in kalium and aluminum but depleted in iron,magnesium,phosphorus and titanium.SiO2 and K2O contents range from 74.79% to 77.79% and 4.26% to 7.97% respectively. A/CNK values vary from 0.98 to 1.10,indicating a metaluminous to weakly peraluminous character. The rocks are enriched in Rb,Th,U and K,but depleted in Sr,Ba,Nb,P and Ti. REEs are characterized by intermediate negative Eu anomalies with Eu/Eu* =0.33~0.50 and exhibit right-dipping V patterns with LREE enrichment. [n(87Sr)/n(86Sr)]i andeNd(t) values (t=102.5Ma)of the Shipingchuan intrusion range from 0.70801 to 0.71012 and -8.76 to -8.63 respectively,showing the intrusion is the result of mixing by crustal and mantle materials.Mineralogy and geochemistry suggest that the Shipingchuan K-feldspar granite intrusion is a highly fractionated I-type granite. Trace elements features display that the pluton was a post-collisional granite and formed in an extensional tectonic setting in the end of early Cretaceous. These results indicate the Shipingchuan granite is related to back-arc extension due to high angle subduction of the paleo-Pacific plate,caused by northward movement of Indian plate.
Publication Year: 2009
Publication Date: 2009-01-01
Language: en
Type: article
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Cited By Count: 19
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