Facies Analysis of Regressive-Transgressive Deltaic Cycles from the Mesoproterozoic Roper Group, Greater McArthur Basin, Australia

The Velkerri-Moroak (V-M) sequence typifies one of several single large-scale (up to ca. 2000 m thick), mudstone-dominated regressive clastic coastal to fluvio-deltaic cycles in the Mesoproterozoic Roper Group (Greater McArthur Basin). A sedimentological synthesis is presented of ca. 4 km of core from several key and extensively cored wells that are located along a ca. 150 km-long depositional dip profile, which is parallel to the inferred sediment transport pathway (from SE to NW), and in the Beetaloo Sub-basin where normal to amplified regressive and transgressive successions are optimally developed for facies preservation. Building on previous studies, six genetically-related facies associations (FA) are identified, from proximal to distal: Braidplain-Paralic (FA1.1 BPP), Fluvio-Tidal Transition (FA1.2-FTT), Proximal Delta Front (FA2.1-PDF), Distal Delta Front (FA2.2-DDF), Subaqueous Delta Front (FA3-SDF), and Basinal Muds (FA4-BM).