A preliminary study on petrogenesis of the Shisha Pangma leucogranites
Leucogranite plays a vital role in studying geodynamic processes within collisional orogenic belts.This study conducts a preliminary geochronological and geochemical analysis of leucogranite samples from the Himalayan orogenic belt near the climbing base camp at the Mount Shisha Pangma's 5800m.The samples are categorized into biotite granite and two-mica granite based on mineral assemblages,differing in geochemical characteristics and deformation.Biotite granite exhibits low Si but is rich in Al,Mg,Fe,and K in whole-rock geochemistry,with an aluminum saturation index A/CNK of 1.06.Two-mica granite,on the other hand,shows high Si content but is deficient in Mg,Fe,K,and Ti characteristics with A/CNK of 1.11～1.17.Two-mica granite displays noticeable negative anomalies of Eu in rare earth elements compared to biotite granite,being enriched in Sn,U,and depleted in Ba,Sr,Zr,Hf,etc.This indicates crystallization of plagioclase,biotite,zircon,monazite,and apatite within the magma.Monazite in both types of granite yields consistent U-Th-Pb ages of 22.9±0.2Ma,22.7±0.5Ma,and 22.7±0.7Ma,slightly earlier than previously reported,suggesting the development of the South Tibetan Detachment System in the region in line with the central Himalayan orogen.The study proposes that the Shisha Pangma leucogranites represent magma active concurrently with the South Tibetan detachment during the post-collisional extension stage.
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NSTL
万方数据
维普
