GSA WA Sep speaker - Dr Sam Spinks "The WA Manganese Belt: WA’s potential as a battery metals state"

Recording of our September seminar entitled "The WA Manganese Belt: Debunking the myth of the Proterozoic sedimentary ‘manganese hiatus’, and demonstrating WA’s potential as a battery metals state" by Dr. Sam Spinks (CSIRO). Abstract Manganese (Mn) is becoming increasingly important as a battery metal alongside nickel and cobalt as we transition to carbon-free energy technologies, but given the much greater global abundance and lower price of Mn compared to its battery metal relatives it has received much less exploration interest. The scale of the global challenge to adopt battery technologies in the near term is staggering, and the resources required for this are vast, and therefore there is a clear potential for Mn to play a key role. This talk aims to introduce the formation processes and scale of the ‘WA Manganese Belt’, which occurs throughout the Proterozoic basins of NW Western Australia, and their potential to contribute to WA’s role as a battery metal State. Sedimentary manganese (Mn) deposits are by far the largest, most widespread, and economically important sources of the metal globally. Distribution of deposits are thought to be restricted to 2 major periods of deposition of primary (non-BIF) Mn, during the early Paleoproterozoic (2.3-1.8 Ga) and from the mid-Neoproterozoic to throughout the Phanerozoic (~0.8 Ga), with a notable absence in the Mesoproterozoic (1.6-1.0 Ga). The coincidental deposition of gigantic sedimentary Mn deposits after the Great Oxygenation Event (GOE) and the Neoproterozoic Oxygenation Event (NOE), highlights the control of redox changes on their temporal distribution. The Mesoproterozoic is widely regarded as a time of redox evolutionary stasis with persistently low oxygen in the atmosphere and oceans, which coincides with an apparent hiatus in sedimentary Mn deposition. This is inconsistent with the widespread stratiform Mn deposits that form a prominent arc in the Mesoproterozoic Bangemall and Oakover basins in Western Australia, which contain resources of at least many hundreds of millions of tonnes of Mn. However, resource estimates for these deposits are lacking, they are largely unstudied, and their formation mechanisms are poorly understood so their significance in the global context has yet to be realized. Our recent sedimentological, mineralogical and geochemical studies on supergene Mn deposits and underlying manganiferous stratigraphy of the Bangemall Supergroup show that the marine sediments of the ~1.45 Ga Ullawarra Formation and ~1.11 Ga Ilgarari Formation demonstrate they are texturally and mineralogically identical to other major sedimentary Mn deposits such as the gigantic Kalahari Mn field in South Africa. New paleoredox data indicate oxygenation of the water column concurrent with Mn deposition, which suggests a fluctuating redox state of the atmosphere and oceans during the late Mesoproterozoic and is consistent with the other periods of global Mn deposition around the GOE and NOE. Furthermore, the 1.11 Ga deposits such as Butcherbird (Figure 1) collectively contain more Mn than any subsequent 0.1 Ga time interval in the Neoproterozoic or Phanerozoic. The 1.45 Ga deposits are lacking any resource estimate, but likely contain at least as much Mn as the younger counterparts nearby. Therefore the ~900 km WA Manganese Belt likely represents two of the most widespread Mn depositional periods in Earth history and has the potential to be important as a resource of the future. Biography Sam Spinks is an ore deposit and exploration geoscientist, born in Scotland and was educated at the University of Aberdeen (BSc. Hons.; PhD). Following his doctoral training he worked in greenfields gold exploration in South Sudan and conducted postdoctoral research on critical metals in sediment-hosted copper deposits before relocating to Australia in 2014, joining the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Mineral Resources unit. Sam is currently a Senior Research Geoscientist, and his current focus is working with mining and exploration companies and State surveys to develop new geochemical exploration methods and understand ore genesis, particularly in base metal (Zn, Pb, Cu, Mn), boutique metal and gold mineral systems. He also has an active interest in geobiology and biogenic cycling of metals.