Locating northern Qiangtang on the margin of Gondwana or Laurasia? Evidence from detrital zircon geochronology

Abstract

• The Permian sandstones of the northern Qiangtang terrane are quite possibly sourced from Gondwana-affinity terranes, such as the southern Qiangtang and Lhasa terranes. • The northern and southern Qiangtang terranes were essentially a unified block during the Late Paleozoic. • The northern Qiangtang terrane was located on the northern margin of Gondwana during the Permian. The relationship between the northern Qiangtang terrane and other blocks in Gondwana and Laurasia continents is still controversial. Here we report U-Pb ages of detrital zircons from the Lower-Middle Permian Nuoribagaribao Formation in the northern Qiangtang terrane, which provides new evidence to constrain the tectonic affinity of the northern Qiangtang terrane during the Late Paleozoic. Sandstones from the middle and upper parts of the Nuoribagaribao Formation contain dominant Ordovician to Devonian (480–360 Ma, peaking at 368 Ma) and Late Paleoproterozoic to Early Mesoproterozoic (1800–1400 Ma, peaking at 1557 Ma) detrital zircons. The U-Pb age spectrum of detrital zircons of them is consistent with those of the Carboniferous strata in the southern Qiangtang and Lhasa terranes to the south; this indicates that rather than being sourced from the Yangtze Block to the east and the Eastern Kunlun-Qaidam-Qilian terrane to the north, the sediments of the Nuoribagaribao Formation were most probably sourced from the Carboniferous strata in the southern Qiangtang and Lhasa terranes to the south or shared the same sources as them. The high similarity of detrital zircon age patterns between the northern and southern Qiangtang terranes, together with other lines of geological evidence, such as paleomagnetism and paleontology, indicate that the northern and southern Qiangtang terranes were essentially a unified block during the Late Paleozoic and were located on the northern margin of Gondwana.