HR: 0830h
AN: S41C-01    [Abstracts]
TI: The Role of the Palmerville Fault to Mineralization in Northeast Australia: Results from Deformation and Fluid Flow Numerical Modeling
AU: * Vos, I
EM: Ivo.Vos@sci.monash.edu.au
AF: Ivo Vos, pmd*CRC / ACRC, School of Geosciences, Monash University, PO Box 28e, VIC 3800 Australia
AU: Potma, W
EM: Warren.Potma@csiro.au
AF: Warren Potma, pmd*CRC, CSIRO, PO Box 1130, Bentley, WA 6102 Australia
AU: Bierlein, F
EM: fbierlein@tsrc.uwa.edu.au
AF: Frank Bierlein, pmd*CRC / TSRC, School of Earth and Geographical Sciences, University of Western Australia, Crawley, WA 6009 Australia
AB: Major fault systems that penetrate deep into the crust are poorly understood but important architectural elements of the Earth. Conceptually and empirically, these structures can provide pathways and foci for both mineralising fluids and magmatism into the upper crust. We investigate the north-to northwest-striking Palmerville Fault, which forms a major structure in northeastern Australia, delineating the boundary between the Palaeozoic Hodgkinson Province and Proterozoic rock assemblages to the west. This terrane-bounding fault played a pivotal role in the evolution of the Hodgkinson Province throughout the Palaeozoic. No mineral occurrences are known along the north-striking section of the Palmerville Fault. Where the strike of the Palmerville Fault changes to northwest (resembling a major jog), the fault system is punctuated by granites and volcanics that host several major gold-copper and skarn deposits. In contrast, a number of north- to northwest-striking fault structures that traverse the Hodgkinson Province and parallel the Palmerville Fault, are associated with orogenic gold-rich regions. In order to understand the processes controlling mineralization in the basin sequence of the Hodgkinson Province, we have integrated spatial data sets, geological, structural and geophysical mapping of major structures, geophysical `worming', and forward modeling of the subsurface structure of the major fault systems. By doing so, we were able to overcome limitations imposed by the limited exposure and relatively low data density in the Hodgkinson Province. Our multi-disciplinary approach allows insight into the nature of the terrane-bounding fault and its significance in the tectonic evolution of the province. Results from this study suggest that the Palmerville Fault represents an eastward-dipping listric normal fault that controlled opening of the Hodgkinson Basin in the Ordovician to Devonian. During basin inversion in the Late Devonian to Carboniferous the fault played a crucial role in gold mineralization in the Hodgkinson Province acting as a major ore fluid conduit. Here, we expand our understanding of the Palmerville Fault by applying deformation and fluid flow numerical modeling scenarios to our fault model. We investigate the role of the Palmerville Fault in mineralization processes throughout the Hodgkinson Province using coupled mechanical and fluid numerical modeling software. A number of fault geometries with varying orientation, dip and crustal depth are considered. Our models provide insights into the loci of dilation and fluid flow with varying geometries, which can then be compared with the Palmerville and adjacent faults in the Hodgkinson Province. Results from our study prove useful in understanding why the major Palmerville Fault itself remained barren, with mineralisation occurring in parallel second-order faults. Furthermore, additional insights are gained on the tectonic evolution of the Hodgkinson Province based on an augmented understanding of the processes that control mineralization in the province. As such, results from our study may be applicable to orogenic gold-rich regions around the world where gold endowment is spatially associated with second-order structures rather than primary fault structures.
DE: 3210 Modeling
DE: 5104 Fracture and flow
DE: 8110 Continental tectonics--general (0905)
DE: 8159 Rheology--crust and lithosphere
DE: 9330 Australia
SC: Seismology [S]
MN: 2005 Joint Assembly