U-Pb Geochronology and Geochemical Characteristics of the Rhyolite Porphyry in the Baishantang Mine, Gansu and Their Geological Implications
详细信息
- 责任者：Hui Weidong (Faculty of Earth Resources ; China University of Geosciences ; Wuhan 430074 ; China) ; Zhu Jiang
- 刊名：Geology and Prospecting
- 出版年：2013
- 卷期：49(3)
- 关键词：流纹斑岩 ; rhyolite porphyry ; 铀—铅计时 ; U-Pb dating ; 甘肃 ; Gansu Province
- 页码：p.484-495
- 图表：illus., 2 tables, 33 refs.
- 分类号：0801
- issnNo：ISSN0495-5331
- isbnNo：CN11-2043/P
摘要
The LA-ICP-MS zircon U-Pb dating yields a 206Pb/238U age of 394.9 ± 2.3Ma (MSWD =1.5) for rhyolite porphyry in the Baishantang mine,Gansu,implying its Late Devonian intrusion.Geochemistry analyses show that the rocks are typically potassium-rich (K2O=4.34%~8.75%) and peraluminous (A/CNK= 1.12~1.65).REE is characterized by obvious negative Eu anomalies.The elements K,Rb,Ba,U and Pb are rich in the rhyolite while Nb,Ta,Sr,P,Ti are depleted.The geochemical data,coupled with the published Sr-Nd isotopic analysis,indicate that the Baishantang rhyolite was most likely generated by partial melting of the old crust material.We propose that the rhyolite was formed at a continental volcanic arc that was closely related to subduction.
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