Where was South China in the Rodinia supercontinent?: Evidence from U–Pb geochronology and Hf isotopes of detrital zircons

Abstract

U–Pb geochronology and Lu–Hf isotopic studies on detrital zircons from late Neoproterozoic sediments of the Cathaysia block, South China, show abundant Grenville-age (∼1.0 Ga) and Neoarchaean populations, and minor Eoarchaean (∼3.8 Ga), Paleo- to Mesoarchaean (3.3–3.0 Ga), Mesoproterozoic (1.7–1.4 Ga) and Pan-African (0.70–0.54 Ga) populations. This is the first report of ∼3.8 Ga material in the crust of the Cathaysia block. The presence of euhedral ∼1.0 Ga zircons indicates that a Grenville orogenic belt was within or very close to the southern Cathaysia block. However, the provenance containing the ∼3.8 Ga, 3.3–3.0 Ga, ∼2.5 Ga, ∼1.0 Ga and 0.70–0.54 Ga zircon populations cannot be found in the South China Block; the combination of zircon age distributions and the rounded, strongly abraded shapes of the Archean zircons suggesting long transport is consistent with derivation from other continental terranes previously linked with the southern part of the South China Block. Comparison with the tectono-magmatic history and compositions of rocks in western Laurentia – eastern Australia and eastern India – East Antarctica – western Australia, we suggest that these late Neoproterozoic sediments may have originated mainly from Eastern India-East Antarctica. This indicates that the South China Block was linked with the Eastern India - East Antarctica continents in the late Neoproterozoic rather than being located between the western Laurentia and eastern Australia continental blocks. U–Pb and Hf-isotope studies on detrital zircons provide an important independent constraint on the palaeogeography of the South China Block in the context of the breakup of Rodinia and the subsequent assembly of Gondwana in late Neoproterozoic time, and insights into the relationship between the Cathaysia and Yangtze blocks.