A Jurassic Anoxic Event in the Pacific Based on Data from the West Kamchatka–Asian Region

Abstract

Based on allochthonous complexes of the Asian–West Kamchatka region, an Early Jurassic (Sinemurian–Toarcian) oceanic anoxic event (J-OAE) in the Nothern Pacific has been revealed for the first time. This event is indicated by sulfide-containing bituminous black cherts that accumulated under euxinic conditions of deep oceanic basins. The anoxia gradually weakened to end completely by the beginning of the Late Jurassic, when hematite jaspers began to accumulate in the aerated water mass. The J-OAE in the Pacific was synchronous to the global warming stage caused by worldwide magmatism; gas-hydrothermal contribution induced a euxinic regime of oceanic water, a change in the carbon cycle, and the change in the taxonomy of radiolarians revealed by Hori [3]. The J-OAE of the Pacific expands the time interval of the known T-OAE and is also supported by the data from other oceanic basins of the world.