Details of the abstract
|Title of paper||Sedimentary copper mineral systems: Large scale resistivity footprints in the Adelaide Rift Complex, South Australia|
|List of authors||Author, B. Kay, Co-author, G. Heinson, Co-author, K. Brand, Co-author, S. Thiel, Co-author, G. Boren|
|Affiliation(s)||University of Adelaide, University of Adelaide, Beurea of Meteorology, Geological Survey of South Australia, University of Adelaide|
In the sedimentary copper mineral system, it’s generally agreed that the first order control is their location adjacent to failed rift basins and passive margin settings, that typically form during the breakup of the super-continents. The basinal architecture allows the deposition of oxidised syn-rifted red beds, sometimes with mafic or bimodal volcanics, which act as the source for the leaching of metals. Post rift marine and lacustrine sediments deposited later can produce areas of contained organic rich reductants necessary to form a chemical trap for the precipitation of sulphides, sometimes with large lateral extent. Evaporite sequences above the permeable post-rift sediments act as a hydrological seal, and occasionally as a source for downward moving brines through evaporite dissolution, which allows the possibility of long lasting intra-basinal fluid flow systems within which convective cells can develop with additional heat.|
In this study, we collect broadband MT data from 82 sites across the Northern Mount Lofty Ranges in the Adelaide Rift Complex. Sites are arranged at 10 km intervals in a rectangular grid covering 100 km N-S and 80 E-W. We supplement our newly collected MT sites with legacy data from the region and invert the entire dataset using a 3D inversion algorithm. The resulting 3D resistivity model reveals a localised elongated upper crustal conductor (~ 5 Ohm.m) spanning from the Burra to Kapunda Copper deposits which is constrained by structural dynamics from basin inversion during the Delamerian Orogeny. We argue that that this crustal conductor, is essentially the large-scale footprint of a sedimentary copper mineral system where highly saline fluids were sourced from evaporitic dissolution from the Callana Group strata.
|Session Keyword||3.0 Exploration, Monitoring and Hazards|