Woodgreen, Northern Territory : explanatory notes
Northern Territory Geological Survey
E-Publications; E-Books; PublicationNT; Australia 1:100 000 Geological Map Series
Australia 1:100 000 Geological Map Wood 5458; Australia 1:250 000 Geological MapAlcoota SF5310; Australia 1:250 000 Geological MapAlcoota SF5310
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Geology; Georgina Basin; Arunta Region
Northern Territory Government; Northern Territory Government
Australia 1:100 000 Geological Map Series
Attribution International 4.0 (CC BY 4.0)
Northern Territory Government
5 Unit, map symbol, thickness Lithology Depositional environment Stratigraphic relationships Cambrian Narpa Group Chabalowe Formation (_Cmc?) Maximum 342 m in HUCKITTA Surface: ferruginous chert rubble and sandstone; chert displays relict carbonate textures and stromatolites. Subsurface in BARROW CREEK: dolostone, sandstone, evaporite Restricted or marginal marine sabkha Unconformable on Octy and Central Mount Stuart formations; no overlying unit in WOODGREEN; probably overlain unconformably by Tomahawk Formation in UTOPIA Shadow Group Octy Formation (_Clo) <150 m Brown and white sandstone and quartzite; basal mudstone Shallow marine, above wave base Unconformable on Central Mount Stuart Formation Ediacaran Mopunga Group Central Mount Stuart Formation Adnera Member (PLLPsa) <200 m Red-brown, purple and white crossbedded sandstone and quartzite, interbedded with mudstone Deltaic Conformable and gradational on Tops Member Tops Member (PLLPst) 100580 m Red-brown and purple crossbedded sandstone and arkose, interbedded with mudstone; reduced grey-green cupriferous horizons; dolostone and anhydrite in lower third in subsurface Marginal or restricted marine lower part, deltaic upper part Probably conformable on Grant Bluff Formation Grant Bluff Formation (LPra) 150 m White, brown and reddish, thinly bedded, tabular, fine sandstone; local coarse to pebbly sandstone; interbedded mudstone Shallow marine, mostly above storm wave base Conformable on Elyuah Formation Elyuah Formation (PLLPel) 94 m Subsurface: dark grey to black micaceous mudstone with thin, fine-grained micaceous sandstone interbeds; basal conglomerate. Surface: rare outcrop of red and white mudstone Shallow marine, mostly below storm wave base Unconformable on Oorabra Arkose, Boko Formation and Arunta Region rocks Cryogenian Keepera Group Oorabra Arkose (LPor) <100 m Coarse to granular and pebbly red-brown arkose, conglomerate, red-brown felspathic sandstone, mudstone Fluviatile and fluvioglacial Conformable or disconformable on Boko Formation; unconformable on Arunta Region rocks; lenticular Boko Formation (PLLPbo) <30 m Glacial diamictite: red-brown mudstone matrix, striated and faceted clasts (quartzite, granite, metamorphic rocks) up to 2 m size Non-marine till Unconformable on Arunta Region rocks; lenticular table2. Lithostratigraphy of Georgina Basin in Woodgreen. Unit, map symbol, lithology Landforms Distribution and relationships Depositional processes Alluvial deposits (Qa) Sand, silt, gravel Active stream channels and floodplains Throughout WOODGREEN, concentrated around hills and ranges; gradational with Qr, Qc Fluvial deposition Lacustrine deposits (Qp) Silt, minor sand Playa lakes and swamps in local depressions Mainly in northern WOODGREEN; in depressions within Qa, Qs, Qr Lacustrine deposition, evaporitic precipitation Red aeolian sand (Qs) Red, well sorted sand and sandy soil Flat plains and gently sloping deposits around ranges and hills Mainly in northern WOODGREEN over Georgina Basin rocks; locally concentrated around southeastern sides of hills Aeolian deposition Colluvial red soil (Qr) Flat plains Throughout WOODGREEN; most extensive in west Colluvial sheet flood deposition Colluvial deposits (Qc) Fan and outwash gravel and sand Sloping and fan-shaped deposits around ranges Northern WOODGREEN Alluvial and debris flow deposition, mass wasting Soil over subcrop (Cz/s) Coarse feldspathic and micaceous soil Slightly elevated and poorly vegetated areas commonly surrounding granitic and metamorphic outcrop Around outcrops of Arunta Region granite and metamorphic rocks Residual soil developed by in situ breakdown of bedrock, minor transportation Quartz gravel (Czq) Apron around quartz-bearing source Associated with Arunta Region rocks Residual accumulation of quartz lag Calcrete (Czc) Nodular white calcrete Low mounds and ridges Along palaeochannels in western WOODGREEN; also in northeastern corner of WOODGREEN Precipitation from groundwater in palaeochannels; exposed during later denudation Waite Formation (Czw) Chalcedony, chalcedonic limestone; sand, gravel and mud at depth? Isolated low hills and in palaeochannels Isolated outcrops in southern and eastern WOODGREEN Lacustrine and fluviatile deposition Dissected fans (Czt) Ferruginised gravel and cobbles Sloping deposits associated with ranges, but now inactive and commonly detached from source Northern WOODGREEN; associated with sandstone ranges Alluvial and debris flow deposition, dissection Ferricrete (Czf) Low rises Throughout WOODGREEN; most widespread in west Deep weathering and lateritisation associated with old land surface Silcrete (Czs) Resistant capping over mainly granitic rocks Mostly in southern-central WOODGREEN; associated with Woodgreen Granite Complex Precipitation of silica associated with old land surface table3. Cenozoic lithostratigraphy in Woodgreen.
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