Late Paleozoic gravity flow depositional systems in the Mandula Basin of the Solonker Belt, Inner Mongolia, China: towards a volcanic-associated submarine environment

Abstract

The Solonker Belt is an important tectonic unit of the Central Asian Orogenic Belt in Inner Mongolia, China and the sediments in the Solonker Belt record the paleogeographic evolution of the Paleo-Asian Ocean. This study characterizes the spatial distribution of the lithofacies and lithofacies associations, and environment variations in the Mandula Basin. The Upper Carboniferous to Lower Permian Amushan Formation shows typical features of slump deposits occurred in the lower slope environments. The Lower to Middle Permian Baotege Formation develops the channelized lobes, channel–levee–overbank, and hemipelagic/pelagic deposits that are formed in the base of slope to basin floor environments. The Lower to Middle Permian Dashizhai Formation represents volcanic edifice and volcaniclastic aprons in the basin floor. The Middle Permian Zhesi Formation includes the shallow water reefs, deep-water biogenetic limestones, and volcaniclastic aprons developed in the abyssal slopes of the volcanic edifice. The sedimentary facies in the Mandula Basin constitute two depositional systems: the continental slopes adjacent to marginal carbonate platform and the volcaniclastic aprons associated with volcanic edifice in the basin floor. The Mandula Basin is an extensional deep-water basin and akin to the marginal sea of an ocean.