Paper No. 271-3
Presentation Time: 9:00 AM-6:30 PM
STABLE AND RADIOGENIC STRONTIUM ISOTOPE (δ88SR, 87SR /86SR) IN SEAWATER ACROSS GUADALUPIAN-LOPINGIAN BOUNDARY (PERMIAN)
In order to reconstruct the secular change in stable and radiogenic strontium isotope ratios of Permian seawater, we analyzed mid-oceanic paleo-atoll and shelf limestones that span across the Guadlupian-Lopingian boundary; i.e. at the Akasaka section in Japan deposited on a mid-Panthalassan paleo-seamount at 12 degree South, and at the Lianshan section in S. China deposited on a carbonate platform on the equatorial eastern Tethys. Stable strontium isotope ratios (δ88Sr) of the Capitanian (late Guadalupian) to Wuchiapingian (early Lopingian) carbonates were measured by TRITON TIMS, by correcting isotope fractionation during mass spectrometry with 87Sr-84double spike. The newly obtained δ88Sr profile of Middle-Late Permian seawater shows an interval of lowδ88Sr values throughout the Capitanian, which is followed by a rapid increase across the G-L boundary. This profile is positively correlated with that of 87Sr/86Sr ratio, suggesting a sharp change in balance between carbonate burial flux and carbonate dissolution flux across the G-L boundary. The Capitanian minimum in seawater 87Sr/86Sr and the following rapid increase was likely driven by a major change in erosion/weathering of continental crusts probably in relation with global glaciation/deglaciation.