The Virgin Hills Formation is a geologic formation dating to the Late Devonian epoch, specifically the Frasnian and Famennian stages. It is located in the Kimberley of Western Australia. The formation represents inter-reef facies deposited as a section of an extensive reef system that fringed the south-west Kimberley Block of what is now Western Australia. Its rocks record a staggering diversity of animals, particularly ammonoids, conodonts and trilobites, and it additionally records the Kellwasser extinction event at the Frasnian–Famennian border, showcasing the disappearance of much of the indigenous life, before their replacement by newcomers from outside the Canning Basin.McNamara, K. J. & Feist, R. (2015). The effect of environmental changes on the evolution and extinction of Late Devonian trilobites from the northern Canning Basin, Western Australia. Geological Society, London, Special Publications, 423, 251–271.
Biochronology & Stratigraphy
Conodont Zones Each species is sorted into time-correlated conodont zones, which is a common method of establishing specific biostratigraphic zones in many formations.Saupe, F. & Becker, R. T. (2022). Refined conodont stratigraphy at Martenberg (Rhenish Massif, Germany) as base for a formal middle/upper Frasnian substage boundary. Palaeobiodiversity and Palaeoenvironments, 102, 711–761.Becker, R. T. (2000). Palaeobiogeographic relationships and diversity of Upper Devonian ammonoids from Western Australia. Records of the Western Australian Museum Supplement, 58, 385–401. As seen in the table below, the zones with only number codes are Frasnian in age, and the ones with only conodont species names are Famennian in age, although both do have conodont names.
McWhae Ridge Eastern Calyx Corner (13b)McNamara, K. J. & Feist, R. (2006). New styginids from the Late Devonian of Western Australia—the last corynexochid trilobites. Journal of Paleontology, 80(5), 981–992. Casey Falls (southeastern) (13b) Phacopid Gully (13a, 13b) Scutelluid Bed (12) Berigora Gully (12) Esko's Gully (12) Western Cheiloceras Bed (rhomboidea) Frutexites Bed (Lower–Middle crepida) Upper Beloceras Bed (13a) Lower Beloceras Bed (12) Bugle Gap (11) Windy Knolls (11–13a) Horse Spring (6–11, 12, 13b) Siphon Spring (12)
It is important that one does not tie conodont zones to localities as indivisible units, and instead as two separate parts that are used together. This is because, first, some localities, such as Horse Spring in zones 6–11, 12, and 13b, skipping 13a, can occur in non-contiguous conodont zones. Second, as mentioned before, conodont zones are time-based and are used globally, while the localities are stratigraphically based and specific to the Virgin Hills Formation. If in the Localities column and a cell for example says 'McWhae Ridge (Base, etc.,)', that means one of the localities is an unspecified part of the McWhae area. This also applies if it simply says 'McWhae Ridge' without any specific localities, and this also applies to Bugle Gap, which has the locality 'Windy Knolls', and can also be referred to without a specified locality. It should also be noted that the Casey Falls locality occurs within both Virgin Hills and the overlying Bugle Gap Limestone (not to be confused with the Bugle Gap locality of the Virgin Hills Formation).
Ammonoid Zones & correlation In regard to ammonoids, they have been designated to a more precise biochronological order in the form of zones and subzones, most of which are named after one of the ammonoids found there, although many of them are not endemic to that particular zone. This spans the entire Canning Basin, including the Napier and Gogo Formations, but in the Virgin Hills Formation the zones begin at UD I-E1 (UD standing for Upper Devonian, though it is optimal to omit this part) and conclude at III-C. These have been mapped to conodont zones, making it possible to convert ammonoid zones to conodont zones. However, vice versa is not fully possible, as conodont zones are generally broader and can span multiple ammonoid zones. Note that [ur] means low diversity upper range zone, which is defined by the extinction of several species. A collapsed table below displays this biostratigraphical mapping.Becker, R. T.; House, M. R. (2009). Appendix 2: Devonian ammonoid biostratigraphy of the Canning Basin. In: Playford, P. E.; Hocking, R. M.; Cockbain, A. E. (2009). Devonian reef complexes of the Canning Basin, Western Australia. Geological Survey of Western Australia, Bulletin, 145, 415–439. +Correlation of Ammonoid & Conodont Zonation (Canning Basin)StageSubstageGerman AgesKeyAmmonoid ZonesAmmonoid SubzonesConodont ZonesFamennianUpperHembergianIII-CProtactoclymenia euryomphalaN/Atrachytera ZoneIII-B3Falcitornoceras sp. M [ur]Uppermost marginifera ZoneIII-B2Pseudoclymenia australis Pseudoclymenia australis III-B1Sporadoceras angustisellatumIII-A2Sporadoceras equalePernoceras delepineiUpper marginifera ZoneMiddleIII-A1Sporadoceras equaleNehdenianII-I2Dimeroceras sp.Cycloclymenia sp.II-I1Dimeroceras sp.II-HSporadoceras teichertiN/AII-G2Maeneceras meridionaleMaeneceras latilobatumLower marginifera ZoneII-G1Maeneceras meridionaleII-F2Paratornoceras polonicum Acrimeroceras clarkeiLowerII-F1Paratornoceras polonicum rhomboidea ZoneII-E2Praemeroceras petterae Praemeroceras primaevumII-E1Praemeroceras petterae II-DOxytornoceras sp.N/AUppermost crepida–Lower rhomboidea ZoneII-C"Falcitornoceras" sp. 1Upper crepida ZoneII-BMiddle crepida ZoneII-A[no ammonoids; extinction]triangularis–Lower crepida ZonesFrasnianUpperAdorfianI-L2Crickites lindneriManticoceras cordatum [ur]Zone 13clinguiformisI-L1b“Manticoceras“ guppyiZone 13bI-L1aCrickites lindneriZone 13aUpper rhenanaI-KManticoceras sp. 5N/AI-J3Maternoceras retorquatumClauseniceras sp.Zone 12Lower rhenanaI-J2Virginoceras erraticumI-J1Maternoceras retorquatumZone 11I-I2Playfordites tripartitusN/AI-I1Costamanticoceras koenenijamieaeMiddleI-HBeloceras tenuistriatumZones 8–9Upper hassiI-G2bMesobeloceras thomasiZone 8Lower hassiI-G2aMesobeloceras houseiZone 7I-G1Naplesites naplense Gp.Zone 6punctataI-F3Sphaeromanticoceras affineI-F2Gogoceras nicolliZone 5I-F1Prochorites alveolatusI-E3Manticoceras sp. 1I-E2Ponticeras discoidaleI-E1Probeloceras lutheri lutheri
Trilobita
Harpetida
Harpetidae GenusSpeciesLocalitiesConodont ZoneImagesEskoharpesMcNamara, K. J., Feist, R. & Ebach, M. C. (2009). Patterns of evolution and extinction in the last harpetid trilobites during the Late Devonian (Frasnian). Palaeontology, 52(1), 11–33.E. boltoni McWhae Ridge (Berigora Gully)12E. guthae McWhae Ridge (Phacopid Gully)13aE. palanasus McWhae Ridge (Calyx Corner, Phacopid Gully)13a–13bE. wandjina McWhae Ridge (Berigora Gully, Esko's Gully)12GloboharpesG. teicherti McWhae Ridge (Berigora Gully)12G. friendi McWhae Ridge (Berigora Gully, Esko's Gully)12G. aff. teicherti McWhae Ridge (Berigora Gully)
Odontopleurida
Odontopleuridae GenusSpeciesLocalitiesConodont ZoneImagesGondwanaspisFeist, R. & McNamara, K. J. (2007). Biodiversity, distribution and patterns of extinction of the last odontopleuroid trilobites during the Devonian (Givetian, Frasnian). Geological Magazine, 144(5), 777–796.G. dracula Bugle Gap McWhae Ridge11–12G. spinosa Bugle Gap McWhae RidgeG. sp. A Bugle Gap11G. sp. B McWhae Ridge13bG. sp. C McWhae Ridge
Phacopida
Phacopidae GenusSpeciesLocalitiesConodont ZoneImagesAcuticryphopsFeist, R., McNamara, K. J., Crônier, C. & Lerosey-Aubril, R. (2009). Patterns of extinction and recovery of phacopid trilobites during the Frasnian–Famennian (Late Devonian) mass extinction event, Canning Basin, Western Australia. Geological Magazine, 146(1), 12–33.A. acuticeps McWhae Ridge (western side Base; Phacopid Gully)13aA. klapperi McWhae Ridge (Calyx Corner, Phacopid Gully)13bBabinopsB. planiventer Ant HillUpper crepida–rhomboideaB. minor McWhae Ridge (Base, Casey Falls)HouseopsH. beckeri McWhae RidgeUpper triangularisH. canningensis McWhae RidgeLower–Middle crepidaH. sp. A McWhae RidgeUpper triangularisTrimerocephaloidesT. sinevisus Bugle Gap (Windy Knolls)13aT. (?) linguiformis Bugle Gap (Windy Knolls) Harpetid Bed11TrimerocephalusT. tardispinosus Sprite RidgerhomboideaT. mimbi McWhae Ridge
Proetida
Aulacopleuridae GenusSpeciesLocalitiesConodont ZoneImagesOtarionO. fugitivum McWhae Ridge (Phacopid Gully)13bO. sp. Siphon Spring12
Proetidae GenusSpeciesLocalitiesConodont ZoneImagesCanningboleC. henwoodorum Siphon Spring12C. latimargo Horse Spring McWhae Ridge (Calyx Corner, Casey Falls, Phacopid Gully)13bC. macromma Horse Spring11–12C. sp. aff. macromma Horse SpringCyrtosymboleC. playfordi Sprite RidgerhomboideaPalpebraliaP. initialis Bugle Gap (Windy Knolls)11P. pustulata McWhae Ridge (Lower Beloceras Bed)12?P. sp. A McWhae Ridge (Calyx Corner)13bPalpebralinaP. pseudopalpebralispseudopalpebralis Bugle Gap (Windy Knolls) McWhae Ridge (Phacopid Gully)13aP. pseudopalpebralisultima McWhae Ridge (Calyx Corner)13bP. minor McWhae Ridge (Lower Beloceras Bed, Berigora Gully)12P. ocellifer Bugle Gap (Windy Knolls)RudyboleR. adorfensis angusta Bugle Gap (Windy Knolls) Horse Spring11–12R. brecciae McWhae Ridge (Calyx Corner, Phacopid Gully)13bR. depressa McWhae Ridge (Calyx Corner, Casey Falls, Phacopid Gully)
Tropidocoryphidae GenusSpeciesLocalitiesConodont ZoneImagesChlupacipariaFeist, R. & McNamara, K. J. (2013). Patterns of evolution and extinction in proetid trilobites during the late Devonian mass extinction event, Canning Basin, Western Australia. Palaeontology, 56(2), 229–259.C. C. planiops Bugle Gap (Windy Knolls)13aC. (Australoparia) australis Bugle Gap (Windy Knolls)12C. (A.) lata Siphon SpringPteropariaP. extrema Bugle Gap (Windy Knolls) McWhae Ridge (Lower Beloceras Bed, Berigora Gully)12
Corynexochida
Styginidae GenusSpeciesLocalitiesConodont ZoneImagesTelopeltis T. intermedia McWhae Ridge (Base, Phacopid Gully)13aT. microphthalmus McWhae Ridge (Calyx Corner & Phacopid Gully)13a–13bT. woodwardi Bugle Gap Horse Spring McWhae Ridge (Base, Berigora Gully, Scutelluid Bed) Siphon Spring11–12T. aff. intermedia McWhae Ridge13aT. aff. woodwardi McWhae Ridge (Scutelluid Bed)12
Ammonoidea
Agoniatitida
AcanthoclymeniidaeKorn, D. & Bockwinkel, J. (2022). The early gephuroceratid ammonoids from the Roteisenstein Formation of Dillenburg (Cephalopoda, Ammonoidea). European Journal of Taxonomy, 823, 10–47.Becker, R. T.; House, M. R.; Kirchgasser, W. T. (1993). Devonian goniatite biostratigraphy and timing of facies movements in the Frasnian of the Canning Basin, Western Australia. Geological Society, London, Special Publications, 70, 293–321. GenusSpeciesLocalitiesAmmonoid ZoneConodont ZoneImagesAcanthoclymeniaA. neapolitana West of McIntyre Knoll (WCB 367)I-F1–I-F25ProbelocerasP. lutheri lutheri McPhee Knoll (WCB 366)I-E1–I-E35P. lutheri ssp.I-E3P. aff. lutheri West of McIntyre Knoll (WCB 367)I-F1gen. aff. P. sp. West of McIntyre Knoll (WCB 367)I-F2ProchoritesP. alveolatus West of McIntyre Knoll (WCB 367)I-F1–I-F25
Beloceratidae GenusSpeciesLocalitiesAmmonoid ZoneConodont ZoneImagesBelocerasB. tenuistriatum Horse Spring (WCB 364) McWhae Ridge (WCB 371A) McWhae Ridge (WCB 371B) McWhae Ridge Trench (WCB 372)I-H–I-L1b8–13bB. tenuistriatum glenisteriI-I211MesobelocerasM. housei East of McPhee Knoll (WCB 366)I-G2a7M. thomasi Horse Spring (WCB 364) McWhae Ridge Trench (WCB 372)I-G2b–I-J38–12NaplesitesN. naplense Horse Spring (WCB 364)I-G16N. sp.
Gephuroceratidae GenusSpeciesLocalitiesAmmonoid ZoneConodont ZoneImagesArchocerasA. varicosumI-L1b13bCarinocerasC. vagansI-G2b8ClausenicerasC. scheldenseI-J2–I-J312C. cf. expectatus McWhae Ridge (WCB 371B)I-J212C. sp.I-J3CostamanticocerasC. koeneni I-I1–I-J211–12C. tuberculatum McWhae Ridge (WCB 371A)I-J111–12C. sp.I-G2b–I-J28–12CrickitesC. lindneri McWhae Ridge (WCB 371B)I-L1a–I-L1b13a–13bManticocerasM. cordatum McPhee Knoll (WCB 365)