Gravity strike angles: A modern approach and tool to estimate the direction of impactors of meteoritic craters

Abstract

The conditions of meteoritic impacts are generally unknown. It is not easy to estimate the impactor direction; a general solution to this problem does not exist. We seek an estimate of the impactor direction by means of a novel method; it is based on the gravity aspects (descriptors). These are various functions of the gravitational potential. They are derived from the global gravitational field models expressed in harmonic geopotential coefficients, collected and computed by other authors from various satellite and terrestrial data. We discovered that especially the gravity aspect called the strike angle is appropriate to assess the impactor direction in specific circumstances. We want to detect if the strike angles contain any anisotropy. We observe that the strike angles are combed within a certain distance from the impact craters owing to the peculiarities of the impact event (substrate and impactor conditions). They provide evidence about the stress anisotropy, specifically about the target material and in some cases about the impactor direction. The strike angles seem to be parallel to the weakness in the strength of the rock, e.g. direction schistosity and or presence of the microfaults. The strike angles probably follow the anisotropy of the rocks changed by the impact explosion. It is known from the literature that disrupted rocks in proximity to impact structures contain economically useful minerals and even hydrocarbon deposits. We present examples for the Earth and the Moon (craters, mare, catenae), using the recent gravity models EIGEN 6C4 and GRGM1200A, respectively.