TECTONIC CAVES: FORMATION MECHANISMS AND IMPLICATIONS FOR IN SITU RESOURCE UTILIZATION

Subterranean void spaces on planetary bodies are a critical area of study for both astrobiology and in situ resource utilization. The ubiquitous nature of extensional fractures, normal faulting, and pit crater chain formations found on terrestrial planets, asteroids and icy moons suggests that dilational faulting may be a dominate formation mechanism for creating subsurface void space, ie. tectonic caves.

Dilational faulting can occur when extensional strain is applied across mechanically stratified layers, or where hybrid mode failure occurs under low differential stress. The geometry of these dilational faults in the subsurface have a significant influence on the flow and storage of fluids and volatiles as well as mineral deposition on earth and likely plays a similar role on solid bodies in our solar system. Thus characterizing dilational faulting will yield insight into the subsurface permeability architecture of planetary bodies of interest, allowing a better understanding of the potential for volatile/fluid transport and mineralization within these voids spaces over geologic time.

Dilational faults often reveal themselves in the form of collapsed pit crater chains, which can often be identified in visual imagery. Analyses of pit craters can, in turn, help constrain the degree of potential void space available in the subsurface as well as help define the permeability architecture. The identification of pit chains and dilational faulting on a wide range of bodies – from small asteroids to icy moons to large terrestrial planets – raises important questions regarding the near-surface crustal porosity of solid bodies in our solar system and their capacity to store vital resources. The ubiquitous nature of dilational faulting and their signature pit crater chains make them an easily identifiable target on many planetary bodies of interest, providing a peek into the subterranean environment that may exist.

Understanding the relationship between pit crater chains, dilational faulting and subsurface voids space will be critical in future solar system exploration. Because pit crater chains are a more easily observed surface feature, they can serve as good proxy indicators of dilational faulting and subterranean cavernous tectonic voids.