CORRELATION OF AEOLIAN STRATIGRAPHY ACROSS THE GREENHEUGH PEDIMENT, GALE CRATER: YEAH, IT'S MORE STIMSON FORMATION

International audienceThe Stimson formation (Siccar Point group) is recognized to represent a major change in depositional style and climate within Gale crater during the Hesperian period [1,2,3,4]. Deposition in Gale was dominated by aqueous processes in what is interpreted to be a relatively humid climate prior toStimson formation accumulation [5]. A depositional hiatus and some duration of erosion encapsulated by the base Siccar Point Group unconformity followed [6]. The deposition of the Stimson formation (currently the lowermost unit of the Siccar Point group) commenced in conditions apparently dominated by aeolian processes in an arid environment [1], subsequently the Stimson sandstones were lithified by an episode involving the flow of water within the subsurface [1,2,5,8].Internally, the Stimson formation records temporal changes of aeolian dune morphologies associated with changing dune size and sediment availability common across an evolving dune field, and changes of sediment transport directions, associated with fluctuating wind strength and direction at multiple temporal scales [3].Since Sol 2600, the Curiosity rover has been circumnavigating the Greenheugh pediment capping unit. This is a distinctive body of rock that covers an area of ~2.6 km2 (Fig.1) and occurs at the mouth of Gediz Vallis, a prominent canyon eroded into the lower slopes of Mt. Sharp. The capping unit is formed of Stimson formation strata [4]. The base of the capping unit is interpreted to form part of the base Siccar Point Group unconformity, which separates the strata from the underlying Mount Sharp group and the overlying Siccar Point group. Here we document changes in the stratigraphy and internal architecture of Stimson formation between the northern and southeastern flanks of the pediment capping unit to characterize variability in sedimentary geometries, facies, and sediment transport directions. Our observations provide constraints on the geologicand paleoclimate history of Gale crater