Formation Epoch and Its Geological Implications of Paleoprotozoic A-Type Granite in Shizuizi of Jingyuan County, Ningxia Province
详细信息
- 责任者：Gao Shanlin (Research Institute of Petroleum Exploration and Production ; SINOPEC ; Beijing 100083 ; China) ; Lin Jinyan
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(8)
- 关键词：A型花岗岩 ; A-type granite ; 铀—铅计时 ; U-Pb dating ; 宁夏 ; Ningxia
- 页码：p.2676-2684
- 图表：6 illus., 2 tables, 53 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Shizuizi A-type granite is found in the southern part of Helan aulacogen,western margin of the North China Craton and mainly consist of K-feldspar granite porphyry. The granite is characterized by high silicon and rich potassium,including Na2O + K2O average 7. 61% ,K2O/Na2O = 2. 17 ～ 7. 39,Al2O3 = 10. 59% ～ 11. 84% ,and its A/CNK = 0. 86 ～ 1. 11(1. 01 on average),and thus is belong to subalkaline metaluminous to weakly prealuminous series,identified as A-type granite. The abundance of ∑REE is high,ranging from 340. 4 × 10-6 to 468. 9 × 10-6. The granite show a LREE enrichment pattern and obviously intermediate negative Eu anomalies. The trace element geochemistry is characterized evidently by negative anomaly of high strength field elements Ta,Nb, Ti,etc. and positively Rb,Ba,Th,etc.,and shows the characteristics of post-orogenic granite. The LA-ICP-MS zircon U-Pb age is 1803 ± 15Ma,which indicates that the Helan aulacogen is formed during Late Paleoprotozoic,and is related to the break-up of the North China Craton from the Columbia supercontinent during the end of Late Paleoprotozoic period.
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