The Biostratigraphy of Middle and Late Cambrian Faunas of Northern Victoria Land, Antarctica
Most of the material refers to northern Victoria Land and was collected over two summer seasons (1974-75 with NZARP and in 1981-82 as part of the International North Victoria Land Expedition which was supported by ANARE). As shown on the maps in the publications the area of collection is bounded by...
| Other Authors: | , , |
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| Format: | Dataset |
| Language: | unknown |
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Australian Antarctic Data Centre
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| Online Access: | https://researchdata.ands.org.au/biostratigraphy-middle-late-land-antarctica/699712 https://data.aad.gov.au/metadata/records/ASAC_143 http://nla.gov.au/nla.party-617536 |
| Summary: | Most of the material refers to northern Victoria Land and was collected over two summer seasons (1974-75 with NZARP and in 1981-82 as part of the International North Victoria Land Expedition which was supported by ANARE). As shown on the maps in the publications the area of collection is bounded by latitudes 71 to 73 degrees S and 162 to 166 degrees E. Altitude was generally between 1500 and 2500 metres. From the abstracts of some of the referenced papers: New evidence bearing on the age and correlation of the Cambrian-Ordovician Bowers Supergroup of northern Victoria Land is outlined. Constraints in the age range of the lower unity, the Sledgers Group are derived from a variety of fossils including a small assemblage of polymerid trilobites in a limestone clast from conglomerate; an age range within the middle Cambrian older than the late Middle Cambrian Boomerangian Stage is most probable. Clastic sedimentation infilling the Bowers depositional depression thus commenced in about the early Middle Cambrian, considerably later than the late Precambrian to Early Cambrian age previously inferred. Similarly, the basaltic volcanism represented by the Glasgow Formation is now known to be of Middle Cambrian age rather than Vendian to Early Cambrian. The conformably overlying Mariner Group is now well dated by trilobites and ranges from late Middle Cambrian (Undillan or Boomerangian) to Late Cambrian (late Idamean or early post-Idamean) in age. The youngest unit, the predominantly fluviatile Leap Year Group, contains a trace fossil assemblage consistent with a Late Cambrian to Ordovician age. The Bowers Supergroup, is thought to have formed part of a zone of Cambrian rifting, subsidence, rapid sedimentation and volcanism that extended through Western Tasmania, providing a link between the Antarctic and Australian segments of Gondwanaland in Cambrian time. New stratigraphical and palaeontological data from Early Palaeozoic Bowers Group of northern Victoria Land indicates that its depositional basin was probably closely linked with the Dundas Trough of western Tasmania. On the basis of these data, a revised reassembly of the Australo-Antarctic portion of Gondwanaland is proposed. 54 trilobite taxa from 15 new localities in the Bowers Terrane of Northern Victoria Land, including the first fossils from Molar Formation, are described. The fossils indicate an age range from late Middle Cambrian (Boomerangian or older) to mid Late Cambrian (late Idamean). At Reilly Ridge, the Spurs Formation crops out in a number of fault-bounded slices; the new fossils indicate marked lateral facies contrasts between slices and suggest considerable lateral displacement along the bounding faults. At Houliston Glacier, trilobites of Mindyallan age in Molar Formation imply that the boundary between the Molar and Spurs Formations is strongly time transgressive. New specied described in this paper are Reillopleura braddocki gen. et sp. nov. and Notoaphelaspis horizontalis sp. nov. Faunal affinites are mainly with the Ellsworth Mountains (West Antarctica), western Queensland, and China. Middle Cambrian, or probably Middle Cambrian, trilobites were collected at six localities in the Heritage Range of the Ellsworth Mountains, including Yochelson Ridge, Drake Icefall area, Edson Hills, Liberty Hills (two locations), and Marble Hills. The total fauna includes 14 genera (2 new) and 32 species (5 new). Due to original preservation and/or deformation, a number of the forms are not assignable to specific taxa. The new taxa described herein are Peronopsis deons sp. nove., Pagetia edsonensis sp. nov., Sohopleura drakensis gen. et. sp nov., Pseudobergeronites spinosa gen. et sp. nov., and Blountia perplexa sp. nov. The trilobites were found in formations of the upper Heritage Group (springer Peak Formation, Drake Icefall Formation, and Liberty Hills Formation). The trilobite faunas described show affinities with faunas from northern Victoria Land (Antarctica), Tasmania, Queensland, China, Kazakhstan, and North America. All faunas are probably Middle Cambrian in age (Templetonian and Boomerangian on the Australian biochronological scale). |
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