An eastern extension of the layered-only zone of Australasian tektites

Abstract The Australasian tektite strewn field is the largest and youngest known in the Cenozoic, and its bilateral symmetry indicates an oblique impact oriented from northwest to southeast. Muong Nong–type (layered) tektites are the largest, least shocked, and most proximal tektites in the strewn field. The spatial relationship between the layered-only zone in the central Indochina Peninsula, where only Muong Nong–type tektites occur, and the undiscovered source crater remains understudied. Here, we report the spatial distribution and stratigraphic occurrence of Australasian tektites in China, revealing that southwestern Hainan Province has another layered-only zone (~6300 km2), whereas splash-form tektites dominate farther north. We demonstrate that the two confirmed layered-only zones are symmetric about the impactor trajectory, consistent with ejecta patterns formed by oblique impacts on extraterrestrial planetary bodies. Considering the absence of layered-only zones in the uprange direction, these findings constrain the source crater to the Yinggehai–Song Hong Basin and suggest that it is likely concealed by thick terrigenous sediments.