Evolution and dynamics of the Qaidam Tertiary transform rift basin in Qinghai

The evolution and dynamics of the Qaidam Tertiary transform rift basin in Qinghai are explored on the basis of the analysis of sedimentary system associations, tectonics and stratigraphy, and magmatic hydrothermal fluid in dicators. The Qaidam Tertiary basin is a simple basin created by extensional faulting-dominated processes, and may be composed of the following depositional systems such as fan delta, subaqueous pluvial fan-nearshore turbidity currents, braid delta, perennial lake delta, and lake depositional systems. During different stages of the basin evolution, there occurred three types of filling patterns of alluvial fan-fan delta-littoral and shallow lake-gravelly braided stream deposits, nearshore subaqueous gravity flow-deep lake-fan delta deposits, and fan delta-littoral and shallow lake-river deposits. Furthermore, the Tertiary basin may undergo three evolutionary stages of initial rifting, extensional faulting, and transform and subsidence, all of which led to the formation of three tectonic sequences identified with the aid of palaeotectonic bounding surfaces and associated conformities. The formation and evolution of the basin are considered to be constrained by the formation and waning of mantle plumes and stress processes of the Himalayan orogeny.