Glassy microspherules (microtektites) from an upper devonian limestone.

The properties of microspherules recovered from an Upper Devonian marine limestone immediately overlain by a geochemical anomaly of siderophile and chalcophile elements are similar to those of impact-derived microtektites. These microspherules are glass, have splash-form shapes, contain spherical vesicles and lechatelierite inclusions, and show oxide compositional variations similar to those in known microtektites. These characteristics suggest that these Upper Devonian microspherules have an impact origin. A bolide impact may have occurred about 365 million years ago on the South China Plate and caused a faunal extinction on eastern Gondwana.