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Geoscience ›› 2020, Vol. 34 ›› Issue (01): 64-73.DOI: 10.19657/j.geoscience.1000-8527.2019.013

• Petrology • Previous Articles     Next Articles

Geochemical Characteristics and Geological Significance of Silurian Volcanic Rocks of Balonggongge’er Formation in Southern Qilian Mountain(withdrawal)

CHAI Yun(), ZHAO Juan, LI Debiao, MA Zhengting, AN Zhao, WEI Youning, WANG Chengyong   

  1. Qinghai Geological Survey, Xining, Qinghai 810001, China
  • Received:2018-12-25 Revised:2019-03-12 Online:2020-03-05 Published:2020-03-07

Abstract:

Volcanic rocks of the Balonggongge’er Formation in the Calete area are composed of calc-alkaline pyroclastic rocks and volcanic lavas. LA-MC-ICP-MS zircon U-Pb dating on the meta-dacite of this formation yielded an age of the Late Silurian according to the weighted average age of (418.7±2.7) Ma, representing the first age reported for this formation. Geochemical data show that the volcanic rocks are featured by their high Al2O3 and low TiO2, relatively high total rare earth element contents (ΣREE), LREE enrichments, distinct LREE/HREE fractionation and negative Eu anomalies. The rocks show marked enrichments in Rb, Th and K, slight enrichments in La, Ce, Ba and Nb, and depletions in Nb, Sr, P and Ti. Comprehensive analysis indicates that the volcanic rocks in this area were formed in a continental arc setting.

Key words: southern Qilian, Balonggongge’er Formation, volcanic rock, LA-MC-ICP-MS zircon U-Pb dating

CLC Number: