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. 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 KT boundary is thought to be in the pingling region, at the point of contact between the Zhenshui & Shanghu 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 . == Paleobiota of the Nanxiong Formation ==