Among 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.

中文翻译：

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重新审视芒农层状陨石的古地磁特性：对其形成过程的启示

在澳大拉西亚的玻陨石中，所谓的孟农玻陨石因其独特的分层和块状外观而脱颖而出。尽管不知道澳大利亚玻陨石的源陨石坑，但芒农玻陨石通常被认为是相对近端的喷射物。导致分层形成的机制一直存在争议。在这项工作中，我们重新审视了 Muong Nong tektites 的古磁性。它们保留了在环境地磁场存在下冷却至 585°C 以下期间获得的热剩磁，并在大多数样品中携带磁铁矿，尽管至少检测到一个含有金属铁的样品。古地磁方向相对于分层平面的倾角聚集在 18 ± 12° 左右，与撞击时该纬度的地磁场倾角相适应。这表明 Muong Nong tektites 的分层在低于 585 °C 时是亚水平的。因此，形成层状tektite分层的优选方案是通过熔池或熔融材料片材中的水平剪切。