• 责任者：Huang Xiongfei (State Key Laboratory of Geological Processes and Mineral Resources ; School of Earth Sciences and Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Mo Xuanxue
• 刊名：Acta Petrologica Sinica
• 出版年：2013
• 卷期：29(11)
• 关键词：火山岩 ; volcanic rocks ; 铀—铅计时 ; U-Pb dating ; 秦岭 ; Qinling Mountains
• 页码：p.3968-3980
• 图表：7 illus., 3 tables, 77 refs.
• 分类号：0801
• issnNo：ISSN1000-0569
• isbnNo：CN11-1922/P

     Strong magxnatic activities dominated by the Early Indosinian and Late Indosinian high potassic calc-alkaline granitoids （245 - 234Ma and 225 -205Ma, respectively） and a small amount of volcanic rocks were developed in western Qinling orogenic belt in Early Mesozoic. The volcanic rocks from Tanchang area of West Qinling, as reported in this paper, are acid rocks which contain mainly rhyolite with minor trachyte and dacite. These volcanic rocks erupted in the early Late Triassic limited by the zircon U-Pb age of 229Ma of the rhyolite. Tanchang volcanic rocks belonging to the peraluminous, shoshonitic to high- K calc-a/kaline series are characterized by enrichment in Rb, Ba, Th, U, K, relative depletion in Nb, Ta, Ti, P, （S7Sr/S6Sr） i = 0. 7048 -0. 7068, εNd （t） =  - 4. 3 - - 4. 0 and depleted mantle model ages ranging from 1.20Ga to 1.24Ga. Tanchang volcanic rocks were generated by partial melting of the K-rich meta-mafic protolith in lower crust while some of them might also be related with the contamination of a very small amount of mantle-derived or upper crustal materials, and the depth of the source was ca. 40km. The West Qinling terrane has Mesoproterozoic-Neoproterozoic crustal basement with a relatively large heterogeneity in different regions showing an affinity to Yangtze block. The time of the initial collision between North China block and Yangtze block in West Qinling might be close to 229Ma. Tanchang volcanic rocks were formed in the crustal thickening geodynamic environment mainly characterized by compression on the whole and shearing-extension in local part.