Provenance of Late Paleozoic Strata on the Passive Margin from Northeast Siberia: A Nd Isotopic Study

Sergey Malyshev

Late Paleozoic strata within the northeastern part of the Siberian Craton and adjacent Verkhoyansk fold and thrust belt (FTB) form a northward and eastward-thickening wedge that thickens to a maximum of 6 km on the eastern slope of the Siberian Craton. The Carboniferous deposition contrasts strongly with the earlier platform carbonate and clastic deposition environments in that westerly derived clastic flooded the northeastern Siberia. Siliciclastic strata of Carboniferous and Permian age that are exposed in the northeast Siberia have been sampled for isotopic studies in order to determine their provenance. The whole-rock Sm-Nd analysis of shale and sandstone samples from Siberia platform and Verkhoyansk FTB are isotopically heterogeneous with eNd values varying from −1.3 to −11.5 at the time of deposition. eNd isotopic signatures for 340−290 Ma period ranges from −11.5 to −1.3 represent mixing of isotopically evolved and juvenile sources to produce the observed signature. Juvenile source could be considered as some magmatic terranes from Western Siberia. Isotopic data for 290−250 Ma period ranges from −5.8 to −2.0 and requires involvement of a more juvenile source. Within the Siberian craton, there is no known magmatic source which could make juvenile contribution to the sediment record. Our present working model is that most of the middle-late Permian sediments are detrital material that came from eroded Western Siberia basement or was reworked from the Neoproterozoic Taimyr clastic wedge.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013