Meyer Desert Formation
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The Meyer Desert Formation is a glacigenic, mostly non-marine sedimentary sequence that forms the upper part of the Sirius Group in the central Transantarctic Mountains. It is notable for containing the youngest known macrofossils of terrestrial plants and palaeosols found anywhere in Antarctica, preserved at elevations of ~1,760 m above sea level and approximately 500 km from the South Pole. Some earlier works included it within a broader “Sirius Formation,” but this usage has been largely abandoned.[1]
| Meyer Desert Formation | |
|---|---|
| Stratigraphic range: | |
Meyer Desert Formation exposed in the Oliver Bluffs on the flanks of the Beardmore Glacier | |
| Type | Geological formation |
| Unit of | Sirius Group |
| Overlies | Cloudmaker Formation |
| Thickness | 185 m (607 ft) |
| Lithology | |
| Primary | Diamictite, sandstone, siltstone |
| Other | Peat, marlstone |
| Location | |
| Coordinates | 85°07′S 166°35′E |
| Region | Transantarctic Mountains, Meyer Desert, Dominion Range |
| Country | Antarctica |
| Extent | Oliver Bluffs, Beardmore Glacier region |
| Type section | |
| Named for | Meyer Desert |
| Named by | McKelvey et al., 1991 |
Biota
The Meyer Desert Formation at Oliver Bluffs preserves a short-lived Pliocene interglacial tundra.[1] Mean summer temperatures reached ~4–5 °C for 1–2 months, with 24-hour daylight, permafrost, strong katabatic winds, very low precipitation, and a growing season of only 6–12 weeks.[1][2][3]
The landscape was a low-relief, gravelly braided outwash plain with unstable moraines, scattered shallow ponds, and thin peat lenses. Vegetation consisted of prostrate Nothofagus shrubs, dense vascular cushion plants up to 30 cm across, moss hummocks, scattered buttercups, sedges, and rare mare's-tail in wet hollows.[1][3] This setting was similar to the windswept cushion bush and fellfields of Patagonia and Tierra del Fuego above 800–1000 m, but also to highland modern Tasmania and New Zealand.[3]
Fossil Nothofagus leaves show that intermittent warm periods allowed Nothofagus shrubs to cling to the Dominion Range as late as 3-4 Ma (mid-late Pliocene).[2] After that, the Pleistocene glaciation covered the whole continent with ice and destroyed all major plant life on it.[4] More recent data records similar floras at least until the Miocene in the Antarctic Peninsula.[5]
Animals
| Genus | Species | Affinity / family | Image |
|---|---|---|---|
| Antarctotrechus[6] | balli | Carabidae |  |
| Curculionidae[7] | "Morphotype 1" | Listroderini (aff. Listroderes) |  |
| "Morphotype 2" | Listroderini (aff. Falklandius/Telurus) |  | |
| Cyclorrhapha[8] | Indet. | aff. Cochliomyia |  |
| Lymnaeidae[9] | Indet. | aff. Chilina |  |
| Osteichthyes[3] | Indet. | Freshwater taxon, likely a Galaxiidae[10] | |
| Ostracod[11] | Indet. | Putatively non-marine ostracods | |
| Pisidium[9] | sp. | Sphaeriidae |  |
Plants
| Genus | Species | Affinity / family | Image |
|---|---|---|---|
| Cushion plants[3] | Indet. | Donatiaceae, Apiaceae, Caryophyllaceae or Asteraceae | |
| Cyperaceae[3] | "Morphotype 1" | Sedges | |
| "Morphotype 2" | Sedges | ||
| Hippuris[3] | sp. | Hippuridaceae |  |
| Marchantiaceae[3] | Indet. | Liverwort | |
| Nothofagidites[3] | (Fuscospora) lachmaniae | Nothofagaceae (cf. Nothofagus) |  |
| Nothofagus[12] | beardmorensis | Nothofagaceae (aff. Nothofagus gunnii) | |
| Poaceae[3] | Indet. | Grass | |
| Podocarpidites[3][13] | "sp. b" | Podocarpaceae (Aff. Pilgerodendron or Lepidothamnus) |  |
| Pottiaceae[3] | Indet. | Moss, other 4 unnamed types are found | |
| Ranunculus[3] | sp. | Ranunculaceae |  |
| Reniform seed[3] | Indet. | ?Chenopodiaceae, ?Caryophyllaceae or ?Myrtaceae | |
| Tricolpites[13] | sp. | Polygonaceae or Lamiaceae | |
| "sp. 2" | Polygonaceae or Lamiaceae |