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Geochemistry and Petrogenesis of Quartz Diorite in Tagong Area of Northwest Sichuan(PDF)

《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]

Issue:
2015年第03期
Page:
1-13
Research Field:
基础地质与矿产地质
Publishing date:

Info

Title:
Geochemistry and Petrogenesis of Quartz Diorite in Tagong Area of Northwest Sichuan
Author(s):
LAI Shao-cong ZHAO Shao-wei
1. State Key Laboratory of Continental Dynamics, Northwest University, Xi’an 710069, Shaanxi, China; 2. Department of Geology, Northwest University, Xi’an 710069, Shaanxi, China
Keywords:
quartz diorite Early Cretaceous geochemistry petrogenesis granite partial melting of lower crust Songpan-Ganzi orogenic belt Northwest Sichuan
PACS:
P588.12
DOI:
-
Abstract:
Tagong area of Northwest Sichuan is located in the east of Qinghai-Tibet Plateau, and belongs to the southeast margin of Songpan-Ganzi orogenic belt. The quartz diorites in Tagong area form in Early Cretaceous with K-Ar isotopic ages of 134-136 Ma, and emplace into Late Triassic strata. Mass fractions of SiO2 are 61.37%-62.25%, A/CNK values are 0.93-0.95, mass fractions of total alkali are 5.46%-5.77%, Rittmann indexes are 1.62-1.74, so that the samples belong to subalkaline metaperaluminous high-K calc-alkaline series quartz diorites. The rocks have relative high Mg# values with the isotopic geochemical characteristics of high contents of Sr and low contents of Nd. N(87Sr)/N(86Sr) is 0.712 589-0.713 009 with the initial N(87Sr)/N(86Sr) of 0.709 503-0.709 878, N(143Nd)/N(144Nd) is 0.512 135-0.512 196 with negative εNd(t) of -8.6--7.5; Nd and Hf model ages are 1.33-1.41 Ga and 1.13-1.37 Ga, respectively. The quartz diorites belong to undifferentiation Ⅰ-type granitoids with late- to post-collision caused by partial melting of ancient lower crust mafic materials at the continental margin-intercontinental orogenic setting in Northwest Sichuan.

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Last Update: 2015-05-27