The configuration of Greater Gondwana-Evidence from LA ICPMS, U-Pb geochronology of detrital zircons from the Palaeozoic and Mesozoic of Southeast Asia and China

Detrital zircons from samples of Palaeozoic to Mesozoic sedimentary rocks have been collected in Malaysia, Thailand, Laos, Vietnam, Cambodia and China, dated by the LA ICPMS, U-Pb technique and assigned to tectonic terranes or regions within terranes. The combined results from each region or terrane are compared with published detrital zircon age data from Australia, Asia and elsewhere using Kolmogorov-Smirnov (K-S) statistics.

Generally low P-values (probability values) are found when comparing terranes, possibly because each large terrane sourced zircons from different areas. However, very high P-values obtained in this study suggest that the Indochina terranes (Truong Son, Loei and Central Vietnam), southern China terranes (Ailaoshan, NE Vietnam, Yangtze) and the Tethyan Himalayas may have been close to similar source areas. This supports models that place South China and the Indochina terranes close to the western Himalayas. The Early Palaeozoic palaeobiogeographic data and single sample K-S comparisons from the Himalayas and from Australia suggest that North China was close to Gondwana, but our K-S inter-terrane comparisons do not support this hypothesis. High Kolmogorov-Smirnov P-values of 0.895 are found between the Late Cambrian-Early Ordovician Tarutao Formation of Sibumasu and the Ordovician Tumblagooda Sandstone Fm of Western Australia. High P values of 0.925 and 0.958 are also found between the Tethyan Himalaya and the Tarutao Formation. Visual comparisons of probability plots of zircons from quartzite clasts from the Tarutao Formation and from quartzite and granite clasts in Permian glacimarine mudstones (Kaeng Krachan Group, Sibumasu) have age spectra in common with terranes of western and northern Australia particularly the Meso-Neoproterozoic-age Pinjarra-East Antarctic-Eastern Ghats Orogen and the northern Australian area affected by the c.1850 Ma Barramundi Orogeny. A characteristic widespread assemblage of zircons previously recognized along the length of the Himalayas by Myrow et al. (2010) with a dominant peak at 950 Ma and other peaks at 600 Ma (Pan African Orogeny), at 1200-1000 Ma (Grenvillian Orogeny) and at 2500 Ma are also found in the peri-Gondwana Terranes of Truong Son, South China, Qiangtang, Lhasa and Sibumasu and suggest a common distal source region in the Pinjarra-East Antarctic-Eastern Ghats Orogen.

The formations of the Triassic Lampang and Song Groups of northern Thailand are dated using zircons and their detrital zircons suggest probable sources from the Indochina terranes for basins of the Sukhothai Terrane.