The genesis of Jitang duplex granites in east Tibet: Evidence from the zircon UPb age and rock geochemistry

FAN Bingliang; ZHANG Xinli; YU Tao; BAI Tao; FENG Dexin

2019 Vol. 38, No. 8

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FAN Bingliang, ZHANG Xinli, YU Tao, BAI Tao, FENG Dexin. The genesis of Jitang duplex granites in east Tibet: Evidence from the zircon UPb age and rock geochemistry[J]. Geological Bulletin of China, 2019, 38(8): 1274-1286.

Citation:

FAN Bingliang, ZHANG Xinli, YU Tao, BAI Tao, FENG Dexin. The genesis of Jitang duplex granites in east Tibet: Evidence from the zircon UPb age and rock geochemistry[J]. Geological Bulletin of China, 2019, 38(8): 1274-1286.

The genesis of Jitang duplex granites in east Tibet: Evidence from the zircon UPb age and rock geochemistry

1.
Geothermal Geological Survey Party, Tibet Bureau of Geology and Mineral Exploration and Development, Lhasa 850000, Tibet, China
2.
Northern Qinghai-Tibet Plateau Geological Processes and Mineral Resources Laboratory, Qinghai, Xining 810012, Qinghai, China
3.
Qinghai Geological Survey Institute, Xining 810012, Qinghai, China
4.
College of Science, Tibet University, Lhasa 850000, Tibet, China
5.
Department of Geology College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China

More Information

Corresponding author: ZHANG Xinli, 317558467@qq.com

Received Date: 19 December 2018

Revised Date: 22 March 2019

Publish Date: 15 August 2019

Abstract

Abstract

Jitang duplex granites are located in the northern section of the Lancang River magma belt, and serve as an important window for studying the evolution process of Lancang River juncture zone. In this paper, the LA-ICP-MS zircon U-Pb chronology and rock geochemistry of biotite monzonitic granite and granitic diorite in Jitang duplex granites of Kakagong area along northern Lancang River were studied. The results show that the selected zircon samples exhibit obvious growth ring zone, the Th/U ratio is generally higher than 0.4, and the typical magma zircon has average weighted ²⁰⁶Pb/²³⁸U age of 222.8±1.5Ma (MSWD=1.60, n=16), 213.6±1.1Ma (MSWD=0.98, n=20) and 221.1±1.5Ma (MSWD=1.30, n=15), suggesting Late Triassic. The geochemical characteristics of rocks show that the Jitang biotite monzonitic granite and granitic diorite have relatively consistent content of main and trace elements, and their changing characteristics are also consistent. It is shown that these two kinds of rocks might have been derived from the same magma, and the Jitang duplex granites belong to the aluminum S-type granite, which has the same petrogeochemical properties as Lincang granite and Newcastle granite, and has a unified tectonic magmatic activity mode along the Lancang River granite belt. The formation of Jitang duplex granites was related to the thickening and warming of the crust and the deep melting effect related to the shearing and stretching period of lithosphere, with the closure time of Lancang Jiang Ocean was probably at about 273Ma.
- Jitang duplex granites /
- rock geochemical characteristics /
- LA-ICP-MS zircon U-Pb age /
- rock genesis

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References

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