Mawson Formation

The Mawson Formation is a geological formation in Antarctica, dating to roughly between 185-181 million years ago and covering the Pliensbachian-Toarcian stages of the Jurassic Period in the Mesozoic Era.[1][2] Vertebrate remains are known from the formation.[3]

Mawson Formation
Stratigraphic range: Pliensbachian-Toarcian
~185–181 Ma
↓
TypeGeological formation
Unit ofFerrar Large Igneous Province
Sub-unitsCarapace Sandstone Member
Lithology
PrimaryVolcaniclastic mudstone
OtherVolcaniclastic gray & blue mudstone
Location
Coordinates76.9°S 159.4°E / -76.9; 159.4
Approximate paleocoordinates60.1°S 46.5°E / -60.1; 46.5
RegionStorm Peak
CountryAntarctica
Type section
Named forMawson Peak
Mawson Formation (Antarctica)

Description

The formation was deposited in an ancient lake, with hydrothermal influences, thanks to the relationships with the Kirckpatrick Basalt.[4] Sedimentary interbeds deposited over lava flows of the Kirkpatrick Basalt during the Early Jurassic splitting of Gondwana represent unusual freshwater paleoenvironments, with hotter conditions that allow to the diversification of the microbes (Archea).[5][6]

According to Barrett, "...the basalt-dominated Mawson Formation and tholeiitic flows (Kirkpatrick Basalt)...are included in the Ferrar Group." The Mawson Formation consists of diamictites, explosion breccias, and lahar flows, evidence of magma entering water-saturated sediments. The Kirkpatrick Basalts (180 Ma) have interbedded lake sediments with plant and fish fossils.[7][8]

Fossil content

There abundant Fossils of microorganisms, as members of the group Archea and other who take advantage of the hydrothermal activity[5][6][9]

Spinicaudata
Genus Species Location Stratigraphic position Material Notes
Carapacestheria C. disgregaris Carapace Nunatak Carapaces Related to the modern Cyzicus mexicanus[5][6]

Fish
Genus Species Location Stratigraphic position Material Notes
Oreochima O. ellioti Carapace Nunatak Various specimens An archaeomaenid pachycormiform fish[10]

Insects

Fossil insect wings not described to the genus level are known from the formation.[11]

Genus Species Location Stratigraphic position Material Notes
Caraphlebia C. antartica Carapace Nunatak wings A dragonfly[12]
Uralonympha U. sehopfi Carapace Nunatak A nearly complete specimen A stonefly nymph[12]
Coleoptera Indeterminate Carapace Nunatak Wing Unnamed and non compared[13]

Ostracoda
Genus Species Location Stratigraphic position Material Notes
Darwinula Darwinula sp. Carapace Nunatak Valves Common Early Jurassic ostracod[5][6]

Fungi
Genus Species Location Stratigraphic position Material Notes
Wood-decay fungus Indeterminate Carapace Nunatak Wood affected by pathogenic fungi Infestation traces and fungal parasitic interaction on several plants[14]

Plants

One of the best preserved fossil flora of the Antarctic.[15][16] Spores are Know[17]

Genus Species Location Stratigraphic position Material Notes
Nothodacrium N. warreni Carapace Nunatak Specimens A member of the family Podocarpaceae[18]
Masculostrobus M. warrenii Carapace Nunatak Specimens A member of the family Podocarpaceae[18]
Brachyphyllum Indeterminate Carapace Nunatak Specimens A member of the Coniferales[18]
Classostrobus C. elliotii Carapace Nunatak Specimens A member of the Cheirolepidiaceae[19]
Chimaerostrobus C. minutus Carapace Nunatak Specimens An indeterminate conifer pollen cone[20]
Polyphacelus P. stormensis Carapace Nunatak Specimens Fern petioles[21]
Zamites Indeterminate Carapace Nunatak Specimens Spermatophyta incertae sedis[5][6]

See also

References
  1. Ballance et al., 1971
  2. Burgess et al., 2015
  3. Elliot, 2013
  4. Bradshaw, 1987
  5. Babcock et al., 2006
  6. Stigall et al., 2008
  7. Barrett, P.J. (1991). Tingey, Robert (ed.). The Devonian to Jurassic Beacon Supergroup of the Transantarctic Mountains and correlatives in other parts of Antarctica, in The Geology of Antarctica. Oxford: Clarendon Press. pp. 122–123, 129, 145. ISBN 0198544677.
  8. Tingey, R.J. (1991). Tingey, Robert (ed.). Mesozoic tholeiitic igneous rocks in Antarctica: the Ferrar (Super) Group and related rocks, in The Geology of Antarctica. Oxford: Clarendon Press. pp. 159–160. ISBN 0198544677.
  9. Norris, 1965
  10. Schaeffer, 1972
  11. Bomfleur et al., 2011
  12. Carpenter, 1969
  13. Tasch, 1973
  14. Harper et al., 2012
  15. Bomfleur et al., 2007
  16. Gair et al., 1965
  17. Ribecai, C. (2007). Early jurassic miospores from ferrar group of carapace nunatak, south victoria Land, Antarctica. Review of Palaeobotany and Palynology, 144(1-2), 3-12.
  18. Townrow, 1967
  19. Hieger et al., 2015
  20. Atkinson et al., 2018
  21. Yao et al., 1991

Bibliography
  • Atkinson, B. A., Serbet, R., Hieger, T. J., & Taylor, E. L. (2018). Additional evidence for the Mesozoic diversification of conifers: Pollen cone of Chimaerostrobus minutus gen. et sp. nov.(Coniferales), from the Lower Jurassic of Antarctica. Review of Palaeobotany and Palynology, 257, 77-84
  • S.D. Burgess, S.A. Bowring, T.H. Fleming, D.H. Elliot High-precision geochronology links the Ferrar large igneous province with early Jurassic ocean anoxia and biotic crisis Earth Planet. Sci. Lett., 415 (2015), pp. 90-99
  • Hieger, T. J., Serbet, R., Harper, C. J., Taylor, T. N., Taylor, E. L., & Gulbranson, E. L. (2015). Cheirolepidiaceous diversity: An anatomically preserved pollen cone from the Lower Jurassic of southern Victoria Land, Antarctica. Review of palaeobotany and palynology, 220, 78-87
  • D.H. Elliot The geological and tectonic evolution of the Transantarctic Mountains: a review Geol. Soc. Lond. Spec. Publ., 381 (2013), pp. 7-35
  • Harper, C. J., Bomfleur, B., Decombeix, A. L., Taylor, E. L., Taylor, T. N., & Krings, M. (2012). Tylosis formation and fungal interactions in an Early Jurassic conifer from northern Victoria Land, Antarctica. Review of Palaeobotany and Palynology, 175, 25-31
  • Bomfleur, B., Schneider, J. W., Schöner, R., Viereck-Götte, L., & Kerp, H. (2011). Fossil sites in the continental Victoria and Ferrar groups (Triassic-Jurassic) of north Victoria Land, Antarctica. Polarforschung, 80(2), 88-99
  • Stigall, A. L., Babcock, L. E., Briggs, D. E. G., & Leslie, S. A. (2008). Taphonomy of Lacustrine Interbeds in the Kirkpatrick Basalt (Jurassic), Antarctica. PALAIOS, 23(6), 344–355. doi:10.2110/palo.2007.p07-029r
  • Bomfleur, B., Schneider, J., Schöner, R., Viereck-Götte, L., Kerp, H., Cooper, A. K., & Raymond, C. R. (2007, August). Exceptionally well-preserved Triassic and Early Jurassic floras from North Victoria Land, Antarctica. In Antarctica: a keystone in a changing world. Proceedings of the 10th International Symposium on Antarctic Earth Sciences, US Geol. Surv., OF-2007-1047, extend. abstr (Vol. 34)
  • Babcock LE, Leslie SA, Elliot DH, Stigall AL, et al. 2006. The “Preservation Paradox”: microbes as a key to exceptional fossil preservation in the Kirkpatrick Basalt (Jurassic), Antarctica. The Sedimentary Record 4: 4–8
  • Yao, X., Taylor, T. N., & Taylor, E. L. (1991). Silicified dipterid ferns from the Jurassic of Antarctica. Review of Palaeobotany and Palynology, 67(3-4), 353-362
  • P. Tasch. 1973. Jurassic beetle from southern Victoria Land, Antarctica. 47:590-592
  • M.A. Bradshaw Additional field interpretation of the Jurassic sequence at Carapace Nunatak and Coombs Hills, south Victoria Land Antarctica N. Z. J. Geol. Geophys., 30 (1987), pp. 37-49
  • Schaeffer, Bobb. "A Jurassic Fish from Antarctica". American Museum of Natural History, 1972
  • P.F. Ballance, W.A. Watters The Mawson Diamictite and the Carapace Sandstone, formations of the Ferrar Group at Allan Hills and Carapace Nunatak, Victoria Land, Antarctica N. Z. J. Geol. Geophys., 14 (1971), pp. 512-527
  • F. M. Carpenter. 1969. Fossil insects from Antarctica 76: 418–425
  • J. A. Townrow. 1967. Fossil plants from Allan and Carapace Nunataks, and from the Upper Mill and Shackleton Glaciers, Antarctica. 10(2):456-473 ISBN 0-520-24209-2
  • Gair, H. S., Norris, G., & Ricker, J. (1965). Early mesozoic microfloras from Antarctica. New Zealand Journal of Geology and Geophysics, 8(2), 231-235
  • Norris, G. (1965). Triassic and Jurassic miospores and acritarchs from the Beacon and Ferrar groups, Victoria Land, Antarctica. New Zealand journal of geology and geophysics, 8(2), 236-277
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