Grenville-era Crustal Architecture of Central Australia, and its Importance in Constraining Rodinia Models.

The ca. 1320-1150 Ma Musgravian Orogeny of central Australia is often considered as part of a global system of orogenic belts that transected the super-continent Rodinia during the Grenvillian-era (ca. 1300-1100 Ma), and is commonly interpreted to extend eastwards and connect with contemporaneous orogens in Laurentia. Accurate definition of the architecture and regional kinematics of the Musgrave Province at this time will constrain the tectonics and configuration of Rodinia in the late Mesoproterozoic. Structural understanding of the Musgravian Orogeny is hampered by the development of east-trending crustal scale shear zones during the late Neoproterozoic Petermann Orogeny that have locally reoriented earlier architecture. Distant from these shear zones, where there is greater preservation of early architecture, outcrop is sparse. To analyse Musgravian Orogeny architecture and kinematics, high-fidelity aeromagnetic interpretation and analysis has been applied in a region distant from major Petermann Orogeny shear zones. Our analysis indicates that Musgravian Orogeny architecture is defined by a series of NE trending steeply dipping reverse faults and upright, parallel folds. These structures are truncated by ca. 1180-1150 Ma. Pitjantjatjara Supersuite granitoid intrusions. Throughout the Musgrave Province, Pitjantjatjara Supersuite plutons are located along NE-ENE trending faults, and this structural relationship can be extrapolated to magnetic anomalies observed over the Officer and Amadeus basins: These anomalies possess the distinctive magnetic signature of the Pitjantjatjara Supersuite and are aligned in NE trending chains that connect the Pitjantjatjara Supersuite with ca. 1150 Ma. granites in the Albany Fraser Province and Warumpi Province. Continental scale NE trending structures are therefore interpreted to have been important in controlling the emplacement of ca. 1150 Ma granitoids. In Australia, the distribution of ca. 1150 Ma granitoids defines a continuous and coherent northeast trending orogenic belt connecting the Albany Fraser, Musgrave and Warumpi provinces. The geometry and extent of this orogenic belt precludes a direct connection between the Musgrave Province and contemporaneous orogens in Laurentia. Any model of Australian orogenic activity during the Grenvillian era, must take account of the NE oriented architecture, and intracontinental termination of the orogenic belt. Continental reconfiguration within Australia via the rotation of the South Australian Craton can adequately explain the Grenville-aged architecture of Australia.