Revisiting the paleomagnetism of Muong Nong layered tektites: Implications for their formation process

Abstract

AbstractAmong Australasian tektites, the so‐called Muong Nong tektites stand out for their peculiar layering and blocky aspect. Although the source crater for the Australasian tektites is not known, Muong Nong tektites are generally considered as a relatively proximal ejecta. The mechanism responsible for the formation of the layering has been a matter of debate. In this work, we revisit the paleomagnetism of Muong Nong tektites. They retain a thermoremanent magnetization acquired during cooling below 585 °C in the presence of the ambient geomagnetic field, and carried magnetite in most samples, although at least one sample containing metallic iron was detected. The inclination of the paleomagnetic direction with respect to the layering plane clusters around 18 ± 12°, compatible with the inclination of the geomagnetic field for this latitude at the time of impact. This indicates that the layering of the Muong Nong tektites was subhorizontal while they were cooling below 585 °C. The preferred scenario for the formation of the layering of layered tektite is therefore by horizontal shear in pools or sheets of molten material.