关键词: 高Si花岗岩, 保山地块, 青藏高原, 三江地区, 原特提斯洋

Abstract: Integrated mineral chemistry, geochemistry and zircon UPbHf isotopic analyses were carried out on the highSi granite in the eastern Baoshan block.Results show that the highSi granite is Stype and shows calcalkaline, strongly peraluminous features. Zircon UPb isotopic analyses show that the highSi granite emplaced at 454 Ma with 800 to 1,100 Ma inherited zircon grains. Magmatic zircons from the highSi granite in the eastern Baoshan show similar Hf isotope compositions with those from coveal felsic intrusions in the Tibetan Plateau and its southeastern margin, implying their similar magmatic origin. Lines of evidence including mineral chemistry, zircon Hf isotopes, and geochemical simulation show a complex history of the highSi granite in eastern Baoshan: the parental magmas of the highsilica granite originated from partial melting of the regional sedimentary rocks; the melts underwent highdegree differentiation, and then assimilated wallrock during emplacement; some minerals experienced solidstate reequilibration after cooling. Similarities of the highSi granite in eastern Baoshan and the coeval Pinghe batholithin geochemical features imply their parallel processes of their petrogenesis.

Key words: highSi granite, Baoshan block, Tibetan Plateau, Sanjiang region, ProtoTethyan Ocean