Search

A late Mesoproterozoic detrital zircon (DZ) age population, which was previously considered diagnostic of a link between the Lhasa terrane and northwest Australia, occurs in other Gondwanan components, thus obscuring the paleogeographic position of the Lhasa terrane in Gondwana. Here we compiled large‐n (n ≥ 300) DZ U‐Pb data from the Lhasa terrane and potential source regions in various proposed reconstructions, and attempted to synthesize the Lhasa DZ age spectra through DZ mixing modeling. Our modeling results support the Permo‐Carboniferous Lhasa terrane having received sediment from NW Australia (mainly the Perth basin) rather than India or Africa. This, in combination with stratigraphic and paleontological evidence from the northern margin of eastern Gondwana positions the Paleozoic Lhasa terrane adjacent to the boundary between Australia and India. This study suggests that the DZ mixing modeling method based on large‐n DZ data can be used effectively for constraining paleogeographic reconstruction of continents. Plain Language Summary: Present‐day eastern Asia is Earth's only major craton that has been constructed within the last 550 Ma by the successive aggregation of peripheral microcontinents that rifted from Gondwana, and thus offers special insights into how continental accretion occurs. Accurate paleogeographic reconstruction of these continental fragments is crucial for understanding the complex history of assembly of eastern Asia. As a major continental sliver, the origin of the Lhasa terrane remains highly controversial. The radiometric ages of detrital zircon (DZ) grains have been used extensively to constrain its paleogeographic position. However, a notable ca. 1,250–1,050 Ma DZ age population, once thought diagnostic of association with Australia, occurs in many other Gondwanan continents. This results in three competing models that position the Paleozoic Lhasa terrane adjacent to NW Australia, northern India or eastern Africa. We compiled large sample (n ≥ 300 grains) DZ U‐Pb data from these potential source regions, and synthesized the Lhasa DZ age spectra using these age data from each proposed reconstruction. Our results show that the Lhasa Permo‐Carboniferous sediments were sourced from NW Australia (mainly the Perth Basin) rather than India or Africa. Our findings locate the Paleozoic Lhasa terrane outboard of the boundary between Australia and India. Key Points: Detrital zircon mixing modeling indicates that the Lhasa Permo‐Carboniferous sediments came mainly from the Perth basin, AustraliaThe Paleozoic Lhasa terrane spanned the boundary interval between Australian Gondwana and Indian GondwanaThe inverse Monte Carlo modeling method based on large‐n detrital zircon data can be used in paleogeographic reconstructions of continents [ABSTRACT FROM AUTHOR]

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 the Lhasa terrane possess a higher proportion of ca. 950 Ma detrital zircons than 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) Grenvillian 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. • Detrital zircons of Paleozoic metasedimentary rocks in the eastern Lhasa terrane. • Abundant ca. 950 Ma detrital zircons occur in these metasedimentary rocks. • The Lhasa terrane has a strong affinity with Indian Gondwana in the Paleozoic. • Tectonic and climatic factors influence the distribution of detrital zircons. [ABSTRACT FROM AUTHOR]

Highlights: [•] Zircon U–Pb dating, geochemistry and Hf isotope composition for the Bomi Complex. [•] The basement of the Lhasa terrane is Mesoproterozoic. [•] The protoliths of the granite gneisses are aluminous A-type granites. [•] The protoliths of the biotite gneisses were related to a subduction process. [•] The Bomi Complex may be related to the southeastern India during Mesoproterozoic. [ABSTRACT FROM AUTHOR]