Glacitectonism, subglacial and glacilacustrine processes during a Neoproterozoic panglaciation, north-east Svalbard

Palaeoenvironmental reconstruction of Neoproterozoic successions has beenthe subject of long-standing debate, particularly concerning the interpretationof diamictites. The Wilsonbreen Formation of north-east Svalbard is a 130 to180 m thick diamictite-dominated glacigenic succession deposited during alate Cryogenian (Marinoan) glaciation. Previous research has highlighted acomplex sedimentary architecture with evidence of subaqueous, subglac ialand non-glacial conditions. This study combines well-established sedimento-logical techniques with the first sedimentological application of the aniso-tropy of magnetic susceptibility technique in Neoproterozoic glacialsediments, to investigate the origin and palaeoenvironmental significance ofglacigenic sediments within the Wilsonbreen Formation. A range of lithofa-cies occurs within the succession, dominated by massive diamictites, sand-stones and conglomerates. Some of these facies display evidence of primarydeformation and can be grouped into a Deformed Facies Association; these areinterpreted to have been formed through glacitectonic deformation in a sub-glacial environm ent. Fabric investigation reveals that this deformation was associated with glacier flow towards the north. In addition, an UndeformedFacies Association records deposition in ice-proximal and ice-distal subaq ue-ous environments. Taken together with intervening non-glacial facies, the gla-cigenic sediments record a seri es of advance–retr eat cycles, with ice flowinvolving sliding and sediment shearing below wet-based ice.