The stratigraphy, sedimentology and palaeoenvironment of the Late Precambrian Umberatana Group in the Mount Remarkable – Alligator Gorge area, South Australia

Abstract

Detailed stratigraphic mapping has revealed fifty lithofacies of variegated clastic and carbonate sediments within the Umberatana Group in the Mount Remarkable – Alligator Gorge map area. These comprise twenty-four mappable units described under stratigraphic terminology as defined by Forbes (1971). Three stromatolite groups are identified within the Brighton Limestone (Tungussia and Inzeria) and Etina Limestone Member (?Baicalia). Faulting is of three generations, namely i. Strike-slip faulting between Upper Tapley Hill and Lower Brighton Limestone time, ii. Lower Brighton Limestone – Lower Wilmington Formation penecontemporaneous faulting, and iii. Post-lithification faulting associated with regional uplift and deformation terminating Adelaide Geosyncline sedimentation. Facies mapping of a fault-rock deposited during penecontemporaneous faulting allows a relative chronology of fault activity to be determined. Palaeoenvironmental interpretations involving stratigraphic and sedimentological attributes reveal a marine regression-transgression-regression cycle, within glacial to warm and humid climes, being responsible for the stratigraphy.