Abstract
The origin of the Lhasa terrane in South Tibet remains enigmatic. In this study, we performed new U—Pb isotopic analyses on detrital zircons from Late Paleozoic metasedimentary rocks in the eastern end of the Lhasa terrane. The detrital zircon ages range from Archean to Paleozoic, with major peaks at ca. 2500 Ma, 1650-1500 Ma, ca. 1170 Ma, ca. 950 Ma, and ca. 580 Ma. Integrated with data from previous studies, the updated database shows that (1) the Early Paleozoic metasedimentary rocks in the Lhasa terrane contain abundant ca. 950 Ma detrital zircons, and (2) the Late Paleozoic metasedimentary rocks in the eastern end of die Lhasa terrane possess a higher proportion of ca. 950 Ma detrital zircons dian that in the rest of the Lhasa terrane. While the older (ca. 1170 Ma) Grenvillian detrital zircons could be supplied by multiple sources, the younger (ca. 950 Ma) Gren-villian detrital zircons have a single source from the Indian continent. Thus the above observations suggest that the Lhasa terrane has a strong affinity with Indian Gondwana during the Paleozoic. Abundance change in the distinctive ca. 950 Ma detrital zircons with stratigraphic age and position in the Lhasa terrane is interpreted to have been resulted from tectonic activity and climatic variation. We here emphasize that tectonic and climatic factors played an important role in the detrital zircon record of sedimentary rocks.
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