Chemostratigraphic Correlation of Upper Permian Lavas from Yunnan Province, China: Extent of the Emeishan Large Igneous Province

摘要

Although the mantle plume model has been increasingly adopted for generation of the Emeishan basalts, doubts have been cast on the viability of this model because of the relatively small dimensions of this large igneous province (LIP) compared with typical LIPs. The Emeishan LIP was traditionally thought to be bounded on the southwest by the Ailaoshan-Red River (ASRR) fault zone. However, pre-Cretaceous strata in the Jinping area, southwest of the ASRR fault zone, are comparable to those at Binchuan in the western margin of the Emeishan LIP. This correlation is reinforced by similar chemostratigraphic variation of Upper Permian basalts from these spatially separated regions. Therefore, the Jinping basalts, which crop out approx 500 km southeast of the Binchuan counterpart, are interpreted as a dismembered part of the Emeishan basalts that were displaced to the present location by mid-Tertiary sinistral movement along the ASRR fault. We suggest that the ASRR fault does not bound the Emeishan LIP. Thus, this LIP has a much larger extent, and its western sector may have extended toward the Paleo-Tethyan ocean, and may have been destroyed by closure in the Triassic.