THE KAMURA EVENT DETECTED IN A SHELF FACIE OF NE S. CHINA BLOCK: CARBON ISOTOPE STRATIGRAPHY OF THE CAPITANIAN (PERMIAN) LIMESTONES IN NE JAPAN AND PRIMORYE (FAR EAST RUSSIA)

The first major extinction of the Permian occurred during the Capitanian (Late Guadalupian). Detailed analyses on the Capitanian extinction were carried out mostly in low-latitude sections, e.g. Texas, S. China, and Japan. The significant sea-level drop and coeval selective extinction of tropical fauna suggest the appearance of global cooling and relevant extinction. In order to check the oceanic conditions in poorly analyzed higher latitudes, we analyzed C-isotope stratigraphy in the Capitanian limestones at Iwaizaki in NE Japan and at Senkina Shapka in Primorye. The upper ca. 40 m-thick interval of the Iwaizaki Limestone and ca. 200m-thick part of the Senkina Shapka section (Chandalez Fm) recorded high positive δ¹³C_carb values that range up to +6 ‰. These results confirm that the topmost Iwaizaki Limestone and Chandalez Fm recorded the "Kamura event", which was first detected in mid-oceanic paleoatoll limestones. Thus the global nature of the Kamura event was confirmed. The Kamura event likely recorded the efficient burial of organic matter during the Capitanian. In contrast, during the Kamura interval, δ¹³C_org values remain low around -25 ‰, leading Δ¹³C values up to 30 ‰. Such large Δ¹³C values were likely derived from the methanobacterial activity likely under reducing conditions , in particular, within an expanded oxygen minimum zone (OMZ).