Tianxin Cretaceous Volcanic Rock in Xingguo, South Jiangxi: Zircon U-Pb Dating and Its Tectonic Setting

CHEN Zhen-yu; WANG Deng-hong; CHEN Zheng-hui; HOU Ke-jun; ZHAO Zheng

2012 Vol. 31, No. 3

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CHEN Zhen-yu, WANG Deng-hong, CHEN Zheng-hui, HOU Ke-jun, ZHAO Zheng. Tianxin Cretaceous Volcanic Rock in Xingguo, South Jiangxi: Zircon U-Pb Dating and Its Tectonic Setting[J]. Rock and Mineral Analysis, 2012, 31(3): 543-548.

Citation:

Tianxin Cretaceous Volcanic Rock in Xingguo, South Jiangxi: Zircon U-Pb Dating and Its Tectonic Setting

1.
Key Laboratory of Metallogeny and Mineral Resource Assessment, Ministry of Land and Resources, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
2.
Key Laboratory of Metallogeny and Mineral Resource Assessment, Ministry of Land and Resources, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
3.
Key Laboratory of Metallogeny and Mineral Resource Assessment, Ministry of Land and Resources, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
4.
Key Laboratory of Metallogeny and Mineral Resource Assessment, Ministry of Land and Resources, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China
5.
Key Laboratory of Metallogeny and Mineral Resource Assessment, Ministry of Land and Resources, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China

Received Date: 30 December 2011

Revised Date: 22 March 2012

Publish Date: 28 June 2012

Abstract

Abstract

The Nanling area is famous for its widely distributed granites. There are also many volcanic rocks there, but cretaceous volcanic rocks are rare. In this paper, based on field survey, we investigate the rock formation time of Tianxin andesitic-porphyrite by Laser Ablation-Multicollector Inductively Coupled Plasma-Mass Spectrometry (LA-MC-ICPMS) zircon U-Pb dating, and determine its age to be (102.3±0.5) Ma. This result indicates that the stratum relation considered before should be adjusted, the Tianxin andesitic-porphyrite must have erupted in the late Cretaceous but not the late Jurassic period, the included sandstone breccia belongs to the early cretaceous Ganzhou group and the stratum covering on the andesitic-porphyrite belongs to the Nanxiong group, not the Ganzhou group. However, this result also indicates that, in this area, the magma activity from early to late was a reverse evolution from acid to neutral to mafic-ultra mafic during the Yanshanian period, and this might be related to the magma activity of the deep mantle, and possibly a production of tectonic event in the South China continental crust from thickening to thinning.
- Tianxin /
- andesitic-porphyrite /
- LA-MC-ICPMS /
- zircon