A Neoproterozoic ice advance sequence, Sperry Wash, California

The Kingston Peak Formation is an archetypal Cryogenian succession that crops out across the Death Valley region of eastern California. Above pre-glacial strata (KP1), two distinct glacial phases have been recognized and are interpreted to be allied to the panglacial Sturtian (KP2 and KP3) and Marinoan (KP4) icehouse events. The thickest and most extensive unit, KP3, forms the entire exposed section at Sperry Wash. At this locality, ice-distal turbidites are succeeded in turn by ice-medial and ice-proximal facies, comprising a spectrum of ice-rafted debris-bearing turbidites, debrites and shales. These are overlain by ice-marginal grounding-line fan deposits interbedded with glacitectonically deformed heterolithics, supporting local advance to an ice-contact position. The succession records accumulation within a glacier-fed subaqueous shelf, wherein the clear progradational signature is driven by ice advance towards the south-east. Evolution of the subaqueous complex is five-fold, comprising: (i) ice-distal outwash; (ii) build-out of ice-medial depositional lobes; (iii) ice-proximal deposition and increased calving; (iv) resumed ice-margin advance; and (v) growth of ice-contact grounding-line fan. This sequence is unique in the Death Valley region for recording the first evidence of advance to ice-marginal and ice-contact settings, thereby enabling the location of the glacier terminus to be documented for the first time.