JETTING EFFECTS IN VESICULAR IMPACTITES ON PRESSURE RELEASE

Impact cratering has over the last decades been established as an important process affecting large scale structures as e.g. planetary surfaces. The high-energy processes certainly also holds the potential for substantial changes in the minerals composition, as e.g. reflected in formation of glasses and the like as a result of the impact. At peak impact the gas within the vesicles are taken to extremely high pressures. In this study we have been looking for evidence on possible effects that the gas release, that occur towards the end of the impact event, may have on the impact. We have done this by studying the morphology of the impact vesicles by high-resolution scanning microscopy of Pt-coated specimens. The vesicular impactite formed at Lonar Lake, India is one of a number of specimens investigated

Based on morphology observed different types of interactions can be discerned:

Material moved as an entity deposited in the vesicles (and associated sprays)

Fragile structures suggested to be forming by the influence of jets, as small orifices forms and connect neighboring vesicles having large pressure differences.

Surface melting and roughening as friction from the jets partially melts the surface in the vesicle.

Chemical vapor deposited minerals on vacuole surfaces.

These structures might be used to learn more about the late stages of the impact formation.