Nanxiong Formation
The Nanxiong Formation is a Late Cretaceous geologic formation in Jiangxi and Guangdong Provinces. Dinosaur remains are among the fossils that have been recovered from the formation.
Description
It consists of continental siliciclastic red beds, with fauna which similar to that of the Nemegt Formation. It has been dated to about 66.7 ± 0.3 million years ago. It is the lowest unit of the Nanxiong Basin, a small graben created during Mesozoic rifting. Buck et al. state that it overlies Jurassic granite basement, and is conformably overlain by the Shanghu Formation. Alternative stratigraphic schemes for the Nanxiong basin have been proposed, one of which refers to the Nanxiong succession as the Nanxiong Group, and dividing it into the Yuanpu, Zhutian and Zhenshui formations, and overlying the Albian to Turonian Changba Formation.The Depositional environment is made up of alluvial fan facies consisting of sheetflood deposits and ephemeral braided rivers. Adjacent to these are ephemeral saline playa facies recording features such as; root traces, desiccation cracks, and calcareous paleosols. In situ desert varnish and minor paleosol development on alluvial facies due to inactivity are indicative of arid conditions. Stable carbon and oxygen isotopes from Dinosaur eggshells were used to estimate a mean annual temperature between, with positive isotope perturbations around the K/Pg boundary indicating periods where temperatures may have exceeded.