Stratno | Stratigraphic Name | Category | Contents | Last update 
24186|Black Mountain Sandstone|Name source|Named after Black Mountain, Canberra, ACT (Opik 1958).|16-MAY-23
24186|Black Mountain Sandstone|Unit history|Synonymy: none.|16-MAY-23
24186|Black Mountain Sandstone|Type section locality|Black Mountain (Opik 1958). Reference section (Lat 35o 17'S Long 149o 06'E) in cuttings along access road to the summit of Black Mountain (Owen 1987).  Here the formation is exposed as an upward facing sequence of grey fine- to medium-grained quartz sandstone with subordinate grey shale interbeds showing sedimentary structures typical of proximal turbidite deposit.  Top and bottom of the formation not exposed.|16-MAY-23
24186|Black Mountain Sandstone|Extent|Hills and ridges at Black Mountain, Jerrabomberra Hill, Ginninderra area and northwest Capital Hill.|16-MAY-23
24186|Black Mountain Sandstone|Thickness range|Estimates are >800 m (Crook and others 1973) and >450 m (Henderson 1981).|16-MAY-23
24186|Black Mountain Sandstone|Lithology|Thickly bedded, in places massive medium-grained sandstone in which siltstone and shale interbeds are more common lower in the sequence. Sedimentary structures include plane/cross/convolute laminations, load casts, flute moulds and slump units (Crook and other 1973).|16-MAY-23
24186|Black Mountain Sandstone|Depositional environment|Marine - prograding turbidite fan complex deposited by eastward-flowing turbidity currents.|16-MAY-23
24186|Black Mountain Sandstone|Relationships and boundaries|Base has gradational and conformable contact with State Circle Shale.  Topmost beds are now an erosion surface except for unconformable contact with late Silurian Camp Hill Sandstone (Opik 1958) - now obscured by Parliament House.|16-MAY-23
24186|Black Mountain Sandstone|Age reasons|Unfossiliferous. Early Silurian (Late Llandovery) by stratigraphic superposition with underlying State Circle Shale.|16-MAY-23
24186|Black Mountain Sandstone|Correlations|On similarity of lithofacies probably co-eval with Tidbinbilla Quartzite, Mundoonan Sandstone and uppermost beds of the Ryrie Formation and Murrumbateman Creek Formation.|16-MAY-23
24208|Camp Hill Sandstone Member|Name source|Named after Camp Hill, in Canberra, ACT (Opik 1958).|16-MAY-23
24208|Camp Hill Sandstone Member|Unit history|None.|16-MAY-23
24208|Camp Hill Sandstone Member|Type section locality|A deep road cutting on State Circle on the southwest side of Camp Hill (Lat 35o 185'S Long 149o 07'E) - the member rests with marked unconformity on early Silurian State Circle Shale.  The sequence consists of a thin basal grit (approx. 10cm thick) overlain by thinly bedded multicoloured siltstone and sandstone. The top is not exposed.|16-MAY-23
24208|Camp Hill Sandstone Member|Extent|Scattered outcrops in the central Canberra and Ginninderra areas; Murrumbateman Creek catchment and west of Queanbeyan.|16-MAY-23
24208|Camp Hill Sandstone Member|Thickness range|Estimated thickness up to 60m (Hendersen 1981).|16-MAY-23
24208|Camp Hill Sandstone Member|Lithology|Well-bedded sandstone and siltstone with thin shale partings.|16-MAY-23
24208|Camp Hill Sandstone Member|Depositional environment|Shallow marine.|16-MAY-23
24208|Camp Hill Sandstone Member|Relationships and boundaries|Overlies late Ordovician Pittman Formation and early Silurian State Circle Shale, Black Mountain Sandstone and Murrumbateman Creek Formation with major unconformity (Strusz and Henderson 1971, Crook and others 1973, Henderson 1978 and 1979).  The Camp Hill Sandstone passes gradationally upwards to mudstone and siltstone of the Canberra Formation. The top of the member is arbitrarily taken where mudstone dominates over sandstone.  It is the basal member of the Canberra Formation.|16-MAY-23
24208|Camp Hill Sandstone Member|Age reasons|Late Silurian (late Wenlock) based on the brachiopod Rhipidium (Berry and Boucot 1970).|16-MAY-23
24208|Camp Hill Sandstone Member|Correlations|None.|16-MAY-23
3447|Canberra Formation|Name source|From the current Canberra Group.|16-MAY-23
3447|Canberra Formation|Type section locality|A fully representative type section is not available and much of the formation is not exposed. The basal part is well exposed at State Circle and Capital Circle, and a 300 m section near the top has been continuously cored in stratigraphic drillhole 145 (Henderson, 1978).|16-MAY-23
3447|Canberra Formation|Extent|The unit (Strusz and Henderson, 1971) extends from Gungahlin through Canberra City to Fyshwick.|16-MAY-23
3447|Canberra Formation|Thickness range|At least 1000 m. Full thickness not known, owing to faults of indeterminable displacement.|16-MAY-23
3447|Canberra Formation|Lithology|Sandstone, siltstone, shale, mudstone, limestone, tuff (coarse and fine and pyroclastics?), ashstone, dacite (flows or pyroclastics?).|16-MAY-23
3447|Canberra Formation|Relationships and boundaries|Overlies Black Mountain Sandstone, State Circle Shale and Pittman Formation unconformably. Overlain conformably by Ainslie Volcanics|16-MAY-23
3447|Canberra Formation|Identifying features|Reason for nomenclature change: The original Canberra Group was defined by Opik (1954; 1958) as comprising three formations - the Turner Mudstone, the Riverside Formation and the City Hill Shale in ascending order. The Canberra Group was redefined in 1971 for the first edition of the 1:50 000 geological map and explanatory notes to include also the Camp Hill Sandstone (underlying the Turner Mudstone) and the St.Johns Church Beds (overlying the City Hill Shale). Subsequent mapping, drilling and palaeontological studies have now reached a stage where it can be argued that the lithological and faunal distinctions between the five formations now comprising the Canberra Group are insufficient to justify the existence of all these units as separate formations. It is therefore proposed that the name Canberra Group be changed to Canberra Formation as being more in keeping with the concept of a formation in the stratigraphic nomenclature guide.  Further extension of Canberra Formation: Recent mapping has shown that the Fairbairn Group (Opik, 1954; 1958) is a lateral equivalent of the upper part of the proposed Canberra Formation, and that it contains no significant lithological or faunal distinctions from the Canberra Formation. The lateral equivalence of the Canberra Formation and Fairbairn Group is supported by the observation from recent mapping that both units are conformably overlain by the Ainslie Volcanics. Opik divided the Fairbairn Group into four formations - the Molonglo Ford Hornfels, the Molonglo Sandstone, the Molonglo River Formation and the Mahon Formation. It is proposed that these formations be dispensed with as formal units, and that the Fairbairn Group be discorded as a separate entity and become part of the Canberra Formation.  Members of Canberra Formation:  Two rock units in the proposed Canberra Formation are regarded as being sufficiently distinctive to be retained as members. They are the Camp Hill Sandstone and the City Hill Shale. A third unit, the Narrabundah Ashstone (Opik, 1954; 1958) was originally regarded as belonging to the Ainslie Volcanics. Mapping at Fyshwick has recently shown that the ashstone is contained within the proposed Canberra Formation. It is therefore proposed that the Ashstone also be designated a member.|16-MAY-23
3447|Canberra Formation|Age reasons|Middle to late Silurian from corals, brachiopods, trilobites, conodonts etc.|16-MAY-23
3447|Canberra Formation|References|78/028; B032; 79/04153;|16-MAY-23
25874|Deakin Volcanics|Name source|Named from the Canberra suburb of Deakin (Opik 1958).|16-MAY-23
25874|Deakin Volcanics|Unit history|None.|16-MAY-23
25874|Deakin Volcanics|Constituents|Mugga Mugga Porphyry Member.|16-MAY-23
25874|Deakin Volcanics|Type section locality|Cutting along the Tuggeranong Parkway between Hindmarsh Drive and the Cotter Road overpass (Lat 35o 20'S Long 140o 03'E). Roadcuts expose the basal position of the Deakin Volcanics as a weathered southwest-dipping sequence of interbedded rhyodacitic ignimbrite, sandstone, siltstone and shale.  Southwards the section passes up into a massive and locally banded rhyodacitic ignimbrite. The top and bottom of the formation are not exposed. Minimum thickness exposed is estimated as 400m.|16-MAY-23
25874|Deakin Volcanics|Extent|Good outcrop development south of the Deakin Fault in the Weston Creek, Tuggeranong and Lanyon areas.  Poorly exposed in the Belconnen area but northwards better exposures are found west of Gooroomon Ponds Creek.  Formation wedges out south of Tharwa by fault contact with the Colinton volcanics.|16-MAY-23
25874|Deakin Volcanics|Thickness range|In the Weston Creek area Henderson (1981) estimated 1000 m, but may reach 1500 m in the Tuggeranong area.|16-MAY-23
25874|Deakin Volcanics|Lithology|Rhyodacitic ignimbrite, lava (Mugga Mugga Porphyry Member), tuff, tuffaceous shale and minor quartz sandstones and volcanic breccia - units show reddish brown alteration.|16-MAY-23
25874|Deakin Volcanics|Depositional environment|Shallow marine conditions initially with eventual establishment of subaerial environment.|16-MAY-23
25874|Deakin Volcanics|Relationships and boundaries|At the base the Deakin Volcanics appear to overlie the Yarralumla Formation conformably but overlap disonformably on to the Mount Painter Volcanics. At the top the Deakin Volcanics pass conformably up into the Laidlaw Volcanics but contacts are not exposed; the units units are distinguished by petrology and geochemistry.|16-MAY-23
25874|Deakin Volcanics|Age reasons|Constrained by the early Ludlovian age of the underlying Yarralumla Formation (Strusz 1984), the Yass Formation (Link and Druce, 1972) and also the overlying Laidlaw Volcanics (Wyborn and others 1982).|16-MAY-23
25874|Deakin Volcanics|Correlations|The formation has petrological and chemical similarities with the Colinton Volcanics and may be coeval with the basal units of the Laidlaw Volcanics (Wyborn and others 1982).|24-JUN-23
25874|Deakin Volcanics|Defn author|R. S. Abell, 1990.|16-MAY-23
24274|Federal Golf Course Tonalite|Name source|From Federal Golf Course between Garran and Hughes (GR917/880)|16-MAY-23
24274|Federal Golf Course Tonalite|Unit history|None.|16-MAY-23
24274|Federal Golf Course Tonalite|Type section locality|Federal Golf Course (Lat 35o 20'S Long 149o 06'E). A boulder of the tonalite can be seen near the course curator's depot about 100m northwest of the clubhouse.|16-MAY-23
24274|Federal Golf Course Tonalite|Extent|Forms subdued topography and is poorly exposed over an area of about 1.0 km2 southwest of Red Hill.|16-MAY-23
24274|Federal Golf Course Tonalite|Lithology|The tonalite consists of plagioclase, biotite, hornblende and late interstitial quartz with inclusions of plagioclase and mafics. The intrusion is considered as I-type based on presence of hornblende, a low isotopic strontium ratio and coincidence with a small aeromagnetic anomaly (BMR 1978).|16-MAY-23
24274|Federal Golf Course Tonalite|Relationships and boundaries|No exposed contact. Detailed mapping shows the intrusion is discordant across the strike of the Yarralumla  Formation and lower units of the Deakin Volcanics.  Hornfelsing of the Yarralumla Formation along Red Hill ridge is probably due to this intrusion. The tonalite show similarities with tonalites in the Late Silurian I-type Jindabyne Suite (Hine and others, 1978).|16-MAY-23
24274|Federal Golf Course Tonalite|Age reasons|A Rb-Sr age of 417+/-8Ma only indicates a minimum Late Silurian (Ludlovian) age for the tonalite.  However it appears to be younger than the Laidlow Volcanics (Rb-Sr age 421+/-2Ma given by Wyborn and others, 1982).|16-MAY-23
12438|Mount Ainslie Volcanics|Name source|Named after Mount Ainslie in Canberra (GR962/947).|16-MAY-23
12438|Mount Ainslie Volcanics|Unit history|Ainslie Series (Mahoney and Taylor 1913); Ainslie Volcanics (Opik 1958); Gladefield Volcanics (Moore 1957).|16-MAY-23
12438|Mount Ainslie Volcanics|Type section locality|Southern slopes of Mount Ainslie (Lat 35o 17'S Long 149o 09'E). Section consists mainly of bluish-grey massive dacitic tuff, dacitic agglomerate, ashstone and shale.  Relationships between units are deduced by inference of stratigraphic superposition. Thickness estimated at 700m. Base and top not exposed.|16-MAY-23
12438|Mount Ainslie Volcanics|Extent|Three major north-northeast trending belts. Mount Ainslie-Mount Majura-Gooroo Hill ridge; low hills east of Majura Road continuing south to Fyshwick; Spring Range area between Hall and Namina Hill (GR887/244).|16-MAY-23
12438|Mount Ainslie Volcanics|Thickness range|A minimum thickness of 700 m (Hendersen 1981).|16-MAY-23
12438|Mount Ainslie Volcanics|Lithology|Massive and foliated bluish grey dacitic tuff, dacitic agglomerate and shale.|16-MAY-23
12438|Mount Ainslie Volcanics|Depositional environment|Early volcanic units deposited from eruptive centres marginal to shallow marine shelf. Younger unit suggest establishment of subaerial conditions.|16-MAY-23
12438|Mount Ainslie Volcanics|Relationships and boundaries|Conformity of bedding dips indicates Mount Ainslie Volcanics overlie the Canberra Formation conformably.  Top most beds eroded in many places but between Hall and Nanima Hill the Mount Ainslie Volcanics are overlain disconformably? by the Mount Painter Volcanics.  This boundary is otherwise mapped by petrographic and chemical differences between the two volcanic formations.|16-MAY-23
12438|Mount Ainslie Volcanics|Age reasons|Late Wenlock deduced from fossil assemblages in the underlying Canberra Formation (Strusz 1983).|16-MAY-23
12438|Mount Ainslie Volcanics|Correlations|With the Walker Volcanics and Paddys River Volcanics (Owen and Cas 1980, Strusz 1982).|16-MAY-23
24403|Mount Painter Volcanics|Name source|Named after Mount Painter in Canberra (Opik 1958).|16-MAY-23
24403|Mount Painter Volcanics|Name source|(Orig. Defn) From the current Mount Painter Porphyry (Opik, 1954; 1958).|16-MAY-23
24403|Mount Painter Volcanics|Unit history|(Orig. Defn) The present name, Mount Painter Porphyry, was given by Opik, based on a conclusion that the rock was essentially intrusive and more or less homogeneous. Recent studies both petrological and chemical have shown that the unit is essentially volcanic with several different components with slightly different petrological and chemical characteristics. No evidence has been found to suggest that the intrusive phases are other than minor. Moreover intrusive contacts have also been observed in association with other established volcanic units and not now regarded as sufficient evidence to override the petrologically volcanic feature.|16-MAY-23
24403|Mount Painter Volcanics|Unit history|Mount Painter Porphyry (Opik 1958).|16-MAY-23
24403|Mount Painter Volcanics|Type section locality|Area of pasture land and pine plantation bounded by the Winslade and Deakin Faults in the north and by the Molonglo River and Lake Burley Griffin in the south (Lat 35o 17'S Long 149' 03'E).|16-MAY-23
24403|Mount Painter Volcanics|Type section locality|(Orig. Defn) Mount Painter, 6 km northwest of Canberra City, was designated by Opik as the type locality.|16-MAY-23
24403|Mount Painter Volcanics|Description at type locality|The formation is exposed as boulders and tors of massive bluish-grey dacitic crystal tuff containing garnet with local development of agglomerate with lithic and compacted pumice. Top and bottom are not exposed.|16-MAY-23
24403|Mount Painter Volcanics|Extent|(Orig. Defn) In belt extending from the Coppins Crossing area to Narrabundah.|16-MAY-23
24403|Mount Painter Volcanics|Extent|A folded southeast - trending belt extending from Coppins Crossing towards Narrabundah and Jerrabomberra Creek. North of the Deakin Fault the formation extends from Gooromon Ponds Creek northwards to Yass.|16-MAY-23
24403|Mount Painter Volcanics|Thickness range|In Gooromon Ponds Creek area the estimate is 1000m.  South of the Deakin Fault estimates >1000m (Henderson 1981).|16-MAY-23
24403|Mount Painter Volcanics|Thickness range|(Orig. Defn) Unknown.|16-MAY-23
24403|Mount Painter Volcanics|Lithology|(Orig. Defn) Acid volcanics - dacite, tuff, minor lenses of ashstone and tuffaceous sediments.|16-MAY-23
24403|Mount Painter Volcanics|Lithology|Dark bluish-grey dacitic crystal tuff with prominent quartz and feldspar phenocrysts and also containing lithic xenoliths, dacitic autoliths and rafts of jasperised sediment. Minor interbeds of tuffaceous sandstone and siltstone.|16-MAY-23
24403|Mount Painter Volcanics|Depositional environment|Subaerial.|16-MAY-23
24403|Mount Painter Volcanics|Relationships and boundaries|(Orig. Defn) The base of the unit is not exposed, owing to faults. The upper contact is poorly defined but probably interfingers with the lowest parts of the Deakin Volcanics and Yarralumla Formation. Some contacts appear to be intrusive, however petrological studies of thin sections representative of the great majority of the unit indicate a consistently volcanic texture.|16-MAY-23
24403|Mount Painter Volcanics|Relationships and boundaries|Base not exposed owing to faults and poor exposure. In the Fairlight area the Mount Painter Volcanics may overlie the Walker Volcanics unconformably (Sufni Hakim 1985). Top is unconformable with trangressive Yarralumla Formation and Deakin Volcanics. North of Gooromon Ponds Creek there is a lower disconformable? boundary with Mount Ainslie Volcanics while the top is unconformable with the transgressive Yass Formation and Deakin Volcanics.|16-MAY-23
24403|Mount Painter Volcanics|Age reasons|Late Wenlock. Stratigraphically based on the Wenlock age deduced for the underlying Walker Volcanics (Chatterton and Campbell 1990, Strusz 1982) and the early Ludlow age of the overlying Yarralumla and Yass Formations (Strusz 1984, Wyborn and others 1982).|16-MAY-23
24403|Mount Painter Volcanics|Age reasons|(Orig. Defn) Late Silurian or possibly late Middle Silurian by virtue of the relation to the fossiliferous late Silurian Yarralumla Formation. Also a possible tongue of the volcanics underlie fossiliferous late Middle Silurian shale and limestone 2 km northwest of Coppins Crossing.|16-MAY-23
24403|Mount Painter Volcanics|Correlations|Unknown.|16-MAY-23
24403|Mount Painter Volcanics|Proposed publication|(Orig. Defn) Coppins Crossing 1:10 000 Engineering Geology Sheet.|16-MAY-23
24403|Mount Painter Volcanics|Proposer|(Orig. Defn) Henderson G.A.M.|16-MAY-23
24403|Mount Painter Volcanics|State(s)|(Orig. Defn) NSW [?? - Check Defn card]|16-MAY-23
24407|Mugga Mugga Porphyry Member|Name source|Derived from Mount Mugga Mugga (813m) at GR 932/855.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Name source|(Orig. Defn) From the current Mugga Mugga Porphyry.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Unit history|(Orig. Defn) Recent mapping shows that the porphyry is not intrusive as previously interpreted (Opik, 1954; Strusz and Henderson, 1971) but is part of the Deakin Volcanics. Member status for the porphyry is therefore considered appropriate.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Unit history|Synonymy: Mugga Series (Mahoney and Taylor 1913); Mugga Mugga Porphyry (Opik 1958, Strusz and Henderson 1971).|16-MAY-23
24407|Mugga Mugga Porphyry Member|Type section locality|(Orig. Defn) Mugga Quarry|16-MAY-23
24407|Mugga Mugga Porphyry Member|Type section locality|A large quarry near the summit of Mount Mugga Mugga (Lat 35o 22' S Long 149o 07'E) about 0.5 km south of Hindmarsh Drive (Owen 1987).|16-MAY-23
24407|Mugga Mugga Porphyry Member|Description at type locality|The locality exposes approximately 90 m of well jointed, massive, blue-grey rhyodacite containing phenocrysts of quartz, plagioclase, pink potash feldspar and biotite. A faint compositional banding dips 20o SW.  The rock is veined by calcite, epidote and haematite.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Extent|Extends from Red Hill along Mugga Mugga Ridge and thence across Jerrabomberra Creek where is abuts against the Deakin Fault.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Extent|(Orig. Defn) The unit extends from Red Hill along the Mugga Mugga Ridge to Mugga Quarry and thence to the ACT/NSW border south of Queanbeyan.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Thickness range|(Orig. Defn) Ranges to about 400 m.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Thickness range|Henderson (1981) gives 300 m, but locally the unit may reach 600 m.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Lithology|(Orig. Defn) Rhyodacite|16-MAY-23
24407|Mugga Mugga Porphyry Member|Lithology|A compact blue and mauve-grey porphyritic rhyodacite with the minor tuffaceous siltstone and shale.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Depositional environment|A lava flow extruded in a largely subaerial environment.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Relationships and boundaries|(Orig. Defn) Member of Deakin Volcanics. Conformably overlies Yarralumla Formation and conformably overlain by higher parts of the Deakin Volcanics. Distinguished in field by relatively coarse texture compared to overlying volcanics.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Relationships and boundaries|A member of the Deakin Volcanics. Conformably overlies the Yarralumla Formation and overlaps to lie disconformably on the Mount Painter Volcanics.  The porphyry is conformable with higher units in the Deakin Volcanics.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Age reasons|(Orig. Defn) Late Silurian by virtue of its relation to the Late Silurian Yarralumla Formation.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Age reasons|Early Ludlow based on its stratigraphic position above the Yarralumla Formation and base of the Deakin Volcanics. A radiometric age of 414+/-9Ma for the Mugga Mugga Porphyry Member relates to the intrusion of the younger Federal Golf Course tonalite which reset the isotopic chemistry of the porphyry.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Correlations|None.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Proposed publication|(Orig. Defn) Canberra, ACT and Queanbeyan, NSW 1:50 000 geological map and explanatory notes.|16-MAY-23
24407|Mugga Mugga Porphyry Member|Proposer|(Orig. Defn) Henderson G.A.M.|16-MAY-23
24407|Mugga Mugga Porphyry Member|State(s)|(Orig. Defn) NSW [?? - check defn card!]|16-MAY-23
24420|Narrabundah Ashstone Member|Name source|Named after the Canberra suburb of Narrabundah (Opik 1958).|16-MAY-23
24420|Narrabundah Ashstone Member|Unit history|None.|16-MAY-23
24420|Narrabundah Ashstone Member|Type section locality|A disused quarry in the suburb of Narrabundah ( Lat 35o 20'S Long 149o 9'E). BMR Strat. drillhole (C284) penetrated 30m of hard pale grey fine to medium-grained tuff below the floor of the quarry (Henderson 1983); this core is stored at the BMR Core and Cuttings Laboratory, Fyshwick, ACT.  Supplementary reference section: Exposed in roadcutting in Fairbairn Avenue (Lat 35o 18' Long 149o 10') - a westerly dipping sequence of tuffaceous sandstone and fine to medium grained tuff 56m thick. Top and bottom of unit not exposed.|16-MAY-23
24420|Narrabundah Ashstone Member|Extent|Apart from a few scattered outcrops its distribution is known mainly from drillholes and trench excavations in the Fyshwick-Narrabundah area.|16-MAY-23
24420|Narrabundah Ashstone Member|Thickness range|Estimated at up to 70m (Hendersen 1981).|16-MAY-23
24420|Narrabundah Ashstone Member|Lithology|Fine-medium grained tuff with cherty laminations and pale brown tuffaceous sandstone.|16-MAY-23
24420|Narrabundah Ashstone Member|Depositional environment|Volcaniclastic submarine mass-flow deposit laid down by turbidity currents in locally deeper parts of the Canberra-Yass Shelf (Owen and Cas, 1980).|16-MAY-23
24420|Narrabundah Ashstone Member|Relationships and boundaries|A conformable member unit near the top of the Canberra Formation.|16-MAY-23
24420|Narrabundah Ashstone Member|Age reasons|Unfossiliferous. Late Wenlock based on fossil and stratigraphic evidence for the Canberra Formation.|16-MAY-23
24420|Narrabundah Ashstone Member|Correlations|Probably in part co-eval with volcanic units in the Canberra Formation north of the ACT-NSW border.|16-MAY-23
15299|Pittman Formation|Name source|Defined and named by Opik (1954, 1958) in Creeks (including Etheridge Creek) in Pittman Valley, southeast of the Canberra Suburb of Aranda (approx GR906/957) - Canberra 1:100 00 topo sheet 8727 edition 2).|16-MAY-23
15299|Pittman Formation|Unit history|East of Canberra the "Murriara Formation" (Phillips 1956 and Moore 1957); Captains Flat/Hoskinstown are the "Beverly Beds" and "Railway Slates" (Glasson and Paine 1965) also "Foxlow Beds" with "Bullongong Shale" (Stauffer and other 1964, Oldershaw 1965 and Richardson 1979).|16-MAY-23
15299|Pittman Formation|Constituents|Acton Shale Member.|16-MAY-23
15299|Pittman Formation|Type section locality|Bed of Etheridge Creek (lat 35o 16'S Long 149o 05'E). Sandstone, shale and chert with estimated thickness of 73m. Section representative of middle part of the Pittman Formation dated by Nicoll (1980) as Llanvirnian age (Pygodus serrus conodont zone). Top and bottom not exposed. Supplementary Reference Sections:  Molonglo Gorge (lat 35o20' Long 149o15') northeast of Queanbeyan - continuous section of folded sandstone, silstone and shale; Cullarin Block (Late 35o05' Long 149o20'). Similar section along incised portion of Brooks Creek; eastern end of Ginninderra Drive, Canberra (Lat 25o15' Long 149o06') weathered sequence of sandstone and shale.|16-MAY-23
15299|Pittman Formation|Extent|Formation crops out over full length of the Cullarin Block and a faulted wedge-shaped inlier in the Canberra-Yass Shelf.  Eastern extent along the line of the Whiskers and Narongo fault zones where formation is in juxtaposition with late Silurian rocks of the Captains Flat Graben.|16-MAY-23
15299|Pittman Formation|Thickness range|Estimate of 800m in Canberra district (Henderson 1981) and >1200m in Captains Flat area (Oldershaw 1965).|16-MAY-23
15299|Pittman Formation|Lithology|Quartz-rich sandstone, siltstone, shale with minor black shale, chert and calcareous sandstone; regionally metamorphosed to quartzite, phyllite, psammatic/pelitic/knotted schist and locally calc-silicate rock.|16-MAY-23
15299|Pittman Formation|Depositional environment|Marine; turbidity flow deposition; sedimentary structures show northerly transport direction.|16-MAY-23
15299|Pittman Formation|Relationships and boundaries|Base not exposed.  Top is unconformable with Early Silurian State Circle Shale, Murrumbateman Creek Formation and Ryrie Formation - also with units of Late Silurian Canberra Formation, Cappanana Formation and Cooper Creek Shale.  Contacts otherwise faulted or top removed by erosion.|16-MAY-23
15299|Pittman Formation|Age reasons|Middle Ordovician ranging from Darriwilian to early Bolindian using graptolite fossils (Webby 1981).|16-MAY-23
15299|Pittman Formation|Correlations|Probably correlative (in part) with Nugar beds, Adaminaby beds, Birkenburn beds, Jerrawa beds and Tallong beds (Webby 1981).|16-MAY-23
17298|State Circle Shale|Name source|Named after State Circle road cutting, Canberra, ACT (Opik 1958).|16-MAY-23
17298|State Circle Shale|Unit history|Synonymy: None.|16-MAY-23
17298|State Circle Shale|Type section locality|Northwestern road cutting on State Circle near the South African Embassy at Lat 35o 18' Long 149o 06' (Opik 1958; Strusz and Henderson 1971). Formation comprises about 60 m of non-calcareous sandy shale and dark grey shale with beds of fine-grained sandstone.  Upper and lower boundary relationship not exposed (this locality is now party obscured by a retaining wall and shrubs). REFERENCE LOCALITY: Cutting in northeastern part of State Circle between Commonwealth Avenue and Kings Avenue (Lat 35o 18'S Long 149o 07'E). Here the formation consists of buff-coloured laminated siltstone and shale with fine sandstone beds contorted by slumping. The age of the sequence is late Llandovery as indicated by the graptolite Monograptus exiguus (Strusz and Jenkins 1982).  The upper boundary at this locality is unconformably overlain by the Camp Hill sandstone member, the basal unit of the Canberra Formation.|16-MAY-23
17298|State Circle Shale|Extent|Crops out poorly around Black Mountain, Jerrabomberra Hill and northwest Belconnen.|16-MAY-23
17298|State Circle Shale|Thickness range|Greatest known thickness of 113 m logged in BMR drillhole C5 (Henderson 1978). However, maximum thickness may be closer to 200 m (Strusz and Henderson 1971).|16-MAY-23
17298|State Circle Shale|Depositional environment|Deepwater marine turbidite deposit (Crook and other 1973).|16-MAY-23
17298|State Circle Shale|Relationships and boundaries|Basal contact not exposed but discordance in dip with underlying Pittman Formation suggests an unconformable relationship (Crook and others, 1973). The formation is overlain conformably by the Black Mountain Sandstone and unconformably by the late Silurian Camp Hill Sandstone member (Strusz and Henderson 1971).|16-MAY-23
17298|State Circle Shale|Age reasons|Upper part of the Llandovery (Fronian stage) from monograptids (Opik 1958). Confirmatory evidence from Rb-Sr age of 435+/-7Ma (Bofinger and others 1970).|16-MAY-23
17298|State Circle Shale|Correlations|Lower part of the Ryrie Formation (Gungoandra Siltstone) and lowermost beds of the Murrumbateman Creek Formation.|16-MAY-23
20879|Yarralumla Formation|Name source|Named after the Canberra suburb of Yarralumla (Opik 1958).|16-MAY-23
20879|Yarralumla Formation|Unit history|None.|16-MAY-23
20879|Yarralumla Formation|Type section locality|Suburb of Yarralumla in and around the old Commonwealth brickpits (Lat 35o 18'S Long 149o 00'E). The formation is exposed as well bedded, olive-green calcareous mudstone and siltstone and some nodular dark-grey cherty limestone. The sequence is folded into open asymmetrical anticlines with shallow plunge southwards.  The locality is fossiliferous (Strusz 1980 and 1984).  Top and bottom of the formation are not exposed.|16-MAY-23
20879|Yarralumla Formation|Extent|Two main outcrops belts; one extends from Red Hill Ridge to Lake Burley Griffin and the other from Woden Valley towards the Molonglo River.|16-MAY-23
20879|Yarralumla Formation|Thickness range|Henderson (1981) gives an estimate of 100-300m.|16-MAY-23
20879|Yarralumla Formation|Lithology|A clastic sequence of calcareous and tuffaceous mudstone and siltstone with minor interbeds of limestone and quartz sandstone.  Ashfall tuff and a few rhyodacitic flows were deposited coevally with the marine sequence.|16-MAY-23
20879|Yarralumla Formation|Depositional environment|Shallow marine with deltaic environments temporarily established at the basin margin. Coeval deposition of volcaniclastic sediments suggests sporadic volcanism at the centres close to the site of marine deposition.|16-MAY-23
20879|Yarralumla Formation|Relationships and boundaries|Lower contact may be unconformable since the Yarralumla Formation appears to transgress the upper most beds of the Mount Painter Volcanics. Upper contact with Deakin Volcanics is complex. The Yarralumla Formation is overlain with apparent conformity by the Mugga Mugga Porphyry Member (basal member of the Deakin Volcanics) but elsewhere appears to pass gradationally up into the basal sediments and bedded pyroclastics of the Deakin Volcanics.|16-MAY-23
20879|Yarralumla Formation|Age reasons|Early Ludlow from shelly marine fauna (Strusz 1984). Upper age limit constrained by contact metmorphism attributed to the tonalite intrusion which gives a Ludlovian radiometric date of 417+/-8 Ma.|16-MAY-23
20879|Yarralumla Formation|Correlations|Barrendella Shale (Opik 1958); Yass Formation (Owen and Cas 1980).|16-MAY-23
