T148 Birth and Death of Supercontinents

Monday, 20 October 2014
1:00 PM - 5:00 PM
118

THE WERNECKE SUPERGROUP AND ITS ROLE IN RECONSTRUCTIONS OF NORTHWESTERN LAURENTIA, EAST AUSTRALIA AND SOUTH CHINA AS PART OF WESTERN COLUMBIA

Paper number: T148-12
Program: Technical Sessions
Time: 3:55 PM – 4:10 PM

Authors

Abstract

Detrital zircon geochronology, Nd isotope geochemistry and whole-rock geochemistry of the Paleoproterozoic Wernecke Supergroup of Yukon are presented with the aim of reconstructing the origin and evolution of the Wernecke basin, determining provenance, and proposing counterparts on Laurentia and other continents. Detrital zircon geochronology from the Wernecke Supergroup shows a bimodal age distribution that reflects ages of source rocks on Laurentia. The older age population ranges between ca. 2800 and ca. 2300 Ma, the younger between ca. 2000 and ca.1600 Ma. The spectra are comparable with the Muskwa, Athabasca, and Dubawnt successions of western and northern Canada. A 1660 Ma maximum depositional age of the Wernecke Supergroup was determined using the six youngest detrital zircon grains, and a Pb-loss age of 272±10 Ma which affected Paleo- and Mesoproterozoic rocks in the Wernecke Inlier.

Detrital zircons of the Wernecke Supergroup with ages <1.75 Ga might have originated from small volcanic units of northern Laurentia, or from juvenile arc rocks along the southern Laurentian margin that developed during the Mazatzal and Yavapai orogenies. Alternatively, this population may have been derived from igneous suites of eastern Australia, allowing a correlation with northwestern Laurentia. In that case the western counterparts of the Wernecke Supergroup could have been the Tarcoola Formation (Gawler Craton) and the Willyama Supergroup (Curnamona Province) of South Australia, and the Isan Supergroup of North Australia. Other non-Laurentian sedimentary successions that might correlate with the Wernecke Supergroup include the Dongchuan-Dahongshan-Hondo assemblages of southeast Yangtze craton (South China).

In addition to the detrital zircon data, major and trace element geochemistry and Nd isotope geochemistry of the Wernecke Supergroup were also compared with possible source on cratonic Laurentia, east Australia, and South China. The integration of these data sets supports the correlation among the Canadian Paleoproterozoic sedimentary successions. Notably, it is also compatible with eastern Australia and the Yangtze craton positioned adjacent to northwestern Laurentia