Glacial tunnel valleys in the Eastern Goldfields of Western Australia cut below the Late Paleozoic Pilbara ice sheet
Introduction
The purpose of this paper is to report the discovery of a relict Late Paleozoic glacially-cut topography and associated glacial sedimentary infill exposed in open-cut gold mines near Kalgoorlie and Laverton in the Eastern Goldfields region of Western Australia (Fig. 1). We identify the broader significance of this discovery for constraining the thermal regime of the Late Paleozoic Pilbara Ice Sheet and for the Phanerozoic denudation history of the West Australian Shield (WAS).
WAS (Fig. 1) is a extensive (2 million km2) collage of Archean and Proterozoic terranes that only became a coherent crustal unit in the early Phanerozoic (Myers, 1990, Myers, 1993). It now forms an extensive upland surface of low relief but its Phanerozoic morphotectonic history is still poorly understood (Ollier et al., 1988). Some workers have proposed that Proterozoic peneplanation was followed by long-term tectonic stability and minimal Phanerozoic erosion (e.g. Finkl and Fairbridge, 1979, Sircombe and Freeman, 1999). Others have proposed strong uplift during the Mesozoic and deep denudation (up to 500 m) resulting in the removal of any pre-Cretaceous landforms (van de Graaff, 1981). The divergence of opinion regarding the denudation history is due in part, to a lack of data regarding the geomorphology of the shield. Unfortunately, the present day landsurface is underlain by Tertiary and Quaternary cover strata which obscure the underlying shield bedrock (see Ollier et al., 1988, Glassford and Semeniuk, 1995, Kern and Commander, 1995).
Section snippets
Late Paleozoic glaciation of Western Australia
Western Australia contains an extensive sedimentary record of Late Paleozoic (Late Carboniferous–Early Permian) glaciation preserved in several sedimentary basins that flank WAS (Crowell and Frakes, 1971, Hambrey and Harland, 1981, Eyles et al., 2001). A high latitude Pilbara Ice Sheet appears to have been initiated by uplift of the shield during the mid-Carboniferous Alice Springs Orogeny (c. 360 Ma) when Gondwana collided with Laurasia (Powell and Veevers, 1987, O'Brien and Christie-Blick, 1992
Late Paleozoic glacial tunnel valleys of the Eastern Goldfields region
The network of buried glacial valleys described here occur near Laverton in the Eastern Goldfields region some 100 km west of the nearest outcrops of Permian glacial deposits in the Officer Basin. Additional exposure of the same valley system occurs at Sand King near Kalgoorlie 250 km west of the nearest Officer Basin outcrops (Fig. 1). The Kalgoorlie–Laverton area hosts nickel and gold deposits in highly-deformed northwest–southeast-trending ‘greenstone’ belts. These are dominated by
Age and paleogeographic setting of tunnel valleys and tillites
Regional drilling programs by exploration companies demonstrate that the buried glacially-cut topography in the Laverton area is infilled by diamictites that are blanketed by shale. No outcrops occur but shales recovered by drilling at Thompson Well (Fig. 3) contain an Early Permian palynofloral assemblage (Kriewaldt, 1975). The same stratigraphic succession of tillites and Early Permian ‘postglacial’ shales is regionally widespread in the Officer Basin to the east (Paterson Formation; Jackson
Discussion
Data presented here represent a significant addition to existing knowledge regarding the erosional and depositional record of the Late Paleozoic ice sheet in Western Australia. Thick sedimentary records of Late Paleozoic glaciation occur in the sedimentary basins that lie outboard of the West Australian shield (Crowell and Frakes, 1971; Fig. 1, Fig. 2). In contrast, direct geomorphic evidence of former ice covers on the shield (e.g. striated bedrock, glacially-incised valleys) has hitherto,
Acknowledgements
This work would not have been possible without the logistical support of Metex Resources NL and Gilt Edged Mining NL. They provided access to open-cut mines at Lancefield and Sand King and subsurface drill data. Fieldwork was funded by the Natural Sciences and Engineering Research Council of Canada (Eyles) and the Cooperative Research Centre for Landscape Evolution and Mineral Exploration (de Broekert). We enjoyed useful discussions with Arthur Mory, Phil Playford, Don Glassford, John
References (60)
- et al.
Provenance record of a rift basin: U/Pb ages of detrital zircons from the Perth Basin, Western Australia
Sed. Geol.
(2000) Problems of a Late Paleozoic glaciation in Australia and subsequent climate in the Permian
Palaeogeo. Palaeoclimatol. Palaeoecol.
(1996)Earth's glacial record and its tectonic setting
Earth Sci. Rev.
(1993)Characteristics and origin of coarse placer gold in Late Pleistocene sediments: Cariboo mining district, British Columbia, Canada
Sed. Geol.
(1995)- et al.
Palaeogeographic evolution of a rifted cratonic margin: SW Australia
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(1979) - et al.
Desert-aeolian origin of late Cenozoic regolith in arid and semi-arid Southwestern Australia
Palaeogeogr., Palaeoclimatol., Palaeoecology
(1995) Paleogeographic evolution of a rifted cratonic margin: SW Australia-Discussion
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(1981)Comparative petrological analysis between the Permian coals of India and Western Australia: Paleoenvironments and thermal history
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(1996)The origin of major incisions within the Pleistocene deposits of the North Sea
Mar. Geol.
(1990)- et al.
Stratigraphy and petroleum exploration objectives of the Permo-Carboniferous of the Barbwire Terrace and adjacent areas, northeast Canning Basin
Geol. Surv. West. Aust. Rep.
(1999)
Palynological correlation of the Western Australian Permian
Proc. Roy. Soc. Victoria
The tectonic framework of western Ausralia's Neoproterozoic to recent basins
The Sedimentary Basins of Western Australia
Petroleum Exploration Society of Western Australia
Glaciers and Glaciation
Boulder shapes and grain-size distributions of debris as indicators of transport paths through a glacier and till genesis
Sedimentology
Architectural element analysis applied to glacial deposits; anatomy of a drumlinized till sheet near Toronto, Canada
Geol. Soc. Am. Bull.
Palaeodrainages and Cainozoic palaeogeography of the Eastern Goldfields, Gibson Desert and Great Victoria Desert
Geol. Surv. West. Aus. Ann. Rep. 1973
Note on occurrences of boulders, possibly glaciated, near Leonora and Laverton, about 28° 30″ South
J. Proc. R. Soc. West. Aust.
Pre-Mesozoic ice ages: their bearing on understanding the climate system
Geol. Soc. Am. Mem.
Late Paleozoic glaciation of Australia
J. Geol. Soc. Aus.
Modeling late Paleozoic glaciation
Geology
The origin of deep buried channels of Elsterian age in northwest Germany
J. Quat. Sci.
Subaqueous mass flow origin for Lower Permian diamictites and associated facies of the Grant Group Barbwire Terrace, Canning Basin, Western Australia
Sedimentology
Glaciomarine facies within subglacial tunnel valleys: the sedimentary record of glacioisostatic downwarping in the Irish Sea Basin
Sedimentology
Lithofacies types and vertical profile models; an alternative approach to the description and environmental interpretation of glacial diamict sequences
Sedimentology
Permo-Carboniferous tectono-stratigraphic evolution and petroleum potential of the northern Canning Basin, Western Australia
Am. Assoc. Petrol. Geol.
Glaciated pavement in the Ripon Hills, Western Australia
J. R. Soc. West. Aust.
Inverse relationship between ice extent and the late Paleozoic glacial record
Geology
Cited by (54)
Significance of ferruginous pisoliths and interface sampling for gold exploration in the covered terrains
2022, Journal of Geochemical ExplorationRegolith characterization and landscape evolution for geochemical exploration of the covered Yamarna Terrane, Western Australia
2022, Journal of Geochemical ExplorationCitation Excerpt :This is related to the abundance of micas, particularly muscovite, (host of Rb in bedrock) and its residual concentration in saprolite compared to the transported cover where zircon is common. Evidence of ice flow directions in the north eastern Yilgarn Craton is derived from the glacial tunnel valleys and suggests eastward ice movement (Eyles and de Broekert, 2001). Furthermore, published ice flow directions (Mory et al., 2008) from the provenance of erratics also suggest eastward and north-westward ice movement.
Tunnel-valley fills in the Paraná Basin and their implications for the extent of late Paleozoic glaciation in SW Gondwana
2021, Journal of South American Earth SciencesCitation Excerpt :Ordovician tunnel valleys are reported in northern Africa and the Arabian Peninsula, where exhumed valley fills form sets of subparallel or cross-cutting, ribbon-like sandstone bodies (e.g., Ghienne and Deynoux, 1998; Douillet et al., 2012). Late Paleozoic tunnel valleys were reported by Visser (1988) and Eyles and Broekert (2001) in southern Africa and Australia, respectively. Depositional systems that fill tunnel valleys and the stratigraphic architecture of the valley fills are extremely variable.