Paleo–Stress Field Reconstructions for Veins in the Middle Murray Formation: New Evidence for Multi‐Generational Deformation in Gale Crater, Mars

Abstract Veins, or mineral‐filled rock fractures, record information about the stress conditions and fluid flow history of a rock body. Interactions between different vein sets as well as between veins and the host rock can elucidate the relative timing of fracture and vein formation and inform formation mechanisms. Widespread vein networks in Gale crater, Mars document multiple episodes of brittle rock deformation and subsurface fluid flow. In the Sutton Island and Blunts Point members of the Murray formation, at least three prominent vein sets are identified by their orientation, thickness, color, and texture: (a) thin, curviplanar (and sometimes anastomosing) veins that are typically sub‐horizontal and sub‐parallel to bedding; (b) thin, steeply dipping veins; and (c) thick, multicolored, steeply dipping veins. We infer hydrofracture as the mechanism for formation of the fractures in all three vein sets and provide evidence for hydrofracture formation during both exhumation and burial processes. Cross‐cutting relationships indicate that sub‐horizontal veins formed first followed by formation of thin, steeply dipping veins and finally, formation of thick, steeply dipping veins. This sequence of fracture and vein forming events provides a new constraint on the depositional, erosional, and diagenetic history of Mount Sharp.