Zinc-Lead Mineralization on the Southeast Lennard Shelf, Canning Basin, Western Australia

Abstract

Mississippi Valley-type (MVT) deposits are carbonate-hosted, Zn-Pb deposits with their type examples in the Mississippi Valley area of the USA. MVT deposits are: (i) stratabound but epigenetic in the nature of their mineralization; (ii) occur on the periphery of sedimentary basins in platform facies above basement highs; (iii) lack any association with igneous activity; (iv) have a simple mineralogy of marcasite, pyrite, galena and sphalerite. These deposits are the result of the passage of large volumes of metal-bearing brines (Sverjensky, 1986; Anderson and Macqueen, 1988), and thus provide a record of the large-scale movement of crustal hydrothermal fluids (Bethke and Marshak, 1990; Halliday et al., 1991). MVT deposits are controversial, with current scientific debate about: (i) the causes of large-scale movement of crustal hydrothermal fluids and the focussing mechanism necessary to form the deposits; (ii) the timing of mineralization; (iii) the nature of the deposition site; (iv) the source of the sulfur required for base-metal precipitation and whether the sulfur was acquired at the deposition site or was carried with the ore solution; (v) the nature and characteristics of any alteration halo to the mineralization. All of these controversies are discussed in this field guide, but two specific aspects are singled out for special attention. These are the nature of the deposition site and the timing of mineralization.

Devonian Reef Complexes of the Canning Basin, Western Australia: A Historical Review

“…Those fluids dissolved carbonates, forming cavity systems in which the sulfides were precipitated. Some mineralization is also interpreted to have replaced Devonian carbonates and evaporites (Tompkins et al, 1994b;Vearncombe et al, 1995). Unlike the exhalative sulfides, the epigenetic Zn-Pb sulfides postdate marine cements, regional dolomitization, and the onset of stylolitization.…”

“…Hot (up to about 90ºC) zinc-, lead-, and iron-bearing brines were probably derived from thick Devonian shales in the Fitzroy trough. The expelled fluids were channeled along faults into carbonates of the Devonian reef complexes on the adjoining Lennard shelf, where Zn-Pb sulfides were precipitated in fractured carbonates, hydrothermal karst cavities, and evaporitic beds (Vearncombe et al, 1995).…”

“…THERE IS A consensus view that the economic Zn-Pb mineralization known in Devonian reef complexes of the Lennard shelf, in the Canning basin of Western Australia, is epigenetic (Ringrose, 1989;Murphy, 1990;McManus and Wallace, 1992;Tompkins et al, 1994a, b;Christensen et al, 1995;Vearncombe et al, 1995). However, an earlier phase of syngenetic mineralization, associated with stromatolite buildups, has recently been recorded in the same general area and is interpreted to have formed as mounds over cool-fluid seepages on the sea floor (De Kever, 1998;Mason, 1998;Playford and Wallace, 1998;.…”

Stratal architecture and platform evolution of an early Frasnian syn‐tectonic carbonate platform, Canning Basin, Australia

“…Despite this limited success over several decades, the newest conventional oil discovery in the Fairfield Group in 2011 highlights continued prospectivity. The older Frasnian platforms are better known as hosts of Mississippi Valley‐type sulphide deposits for which the importance of faulting in their formation has also been emphasised (Vearncombe et al ., ; Wallace et al ., ; Miller et al ., ).…”

The Magnitude of Exhumation in the Kidson Sub-Basin, Western Australia, Usingthermal and Compaction Techniques

“…The Kidson Sub-basin also contains the largest halite formation in Australia (Hashimoto et al, 2018), one a the most cost-effective methods for underground hydrogen storage (Lord et al, 2014). The Sub-basin also has significant mineral resource prospectivity, such as for Uranium (Botten, 1984) and sediment-hosted base metals (McCracken et al, 1997;Passmore and Towner, 1987;Ringrose, 1984;Veamcombe et al, 1995).…”