Detrital zircon dating

28 Mar

Three different data sets of palaeocurrents suggested that the main sediment source of the Wangshi Group dinosaur bone beds was from the north−northwest of the Basin.

Only one data set had a provenance south of the basin.

The age of a single zircon grain is interpreted to be the crystallization age of a rock in the provenance.

A sedimentary deposit likely contains components from multiple crystalline sources as a result of multiple magmatic episodes in one locality, of tectonic juxtaposition of rocks of different ages, of mixing by confluence of drainage from multiple localities, and/or of recycling of older sediment and mixing with younger primary sources.

However, the provenance of the dinosaur bone fossils and the accurate depositional age of the bone beds remain ambiguous.

Through U–Pb dating of detrital zircons collected from six conglomerate samples from the dinosaur bone beds, we found that the youngest single grain age (YSG) of sample 090414-24-D was 77.3 Ma, representing the maximum depositional age of the dinosaur fossil beds and sediments.

On a larger scale, two or more tribes of detrital zircons from different origins may deposit within the same sedimentary basin.

Focus on the lithic grains allowed more specific characterization of the provenance, distinguishing between arc, low-grade metamorphic, high-grade metamorphic, ophiolitic, and sedimentary sources (e.g., Dickinson and Suczek, 1979; Ingersoll and Suczek, 1979; Mack et al., 1981, 1983; Hiscott, 1984).This also indicates that the Hongtuya Formation was deposited during the Campanian.Dating results revealed an age peak of 120–110 Ma, which corresponds with the peak age of volcanic rocks of the Lower Cretaceous Qingshan Group.The detrital zircon U-Pb age of the Suining Formation shows that this widespread formation should be assigned to the Cretaceous, not the Jurassic.This study sheds new light on the location of the Suining Formation in the stratigraphic column.