Seymour Island B1 (Cretaceous to of Antarctica)

Where: Antarctica (64.3° S, 56.8° W: paleocoordinates 62.3° S, 67.6° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Lopez de Bertodano Formation (Seymour Island Group), Late/Upper Campanian to Late/Upper Campanian (83.5 - 61.6 Ma)

• Section B1 have 210 m. The section contains 112 samples: 01-112.

•The formation was subdivided into 10 lithologic units by Macellari (1984b, 1988). Units 1 to 9 (~1100 m thick) span the upper Campanian and Maastrichtian,and the uppermost Unit 10 (up to 90m thick) is Tertiary (Danian).The formation is disconformably overlain by deltaic sediments of the Paleocene Sobral Formation.

• formation-level stratigraphic resolution

Environment/lithology: marginal marine; silty, sandy lithology not reported

• These sediments were deposited in relatively low-energy, shallow shelf to marginal marine environments.

•Although Mesozoic tectonic reconstructions of the Antarctic Peninsula- South America region are not universally accepted, it is generally agreed that the James Ross Island basin contains sedimentary and volcanic strata deposited in a back-arc terrain (e.g. Elliot 1988).

• Seymour Island is a small (20km), seasonally ice-free island in the James Ross Island basin at the northeastern end of the Antarctic Peninsula. Upper Cretaceous strata on Seymour Island are placed in the López de Bertodano Formation (Rinaldi et al. 1978; Rinaldi 1982; Macellari 1984b, 1988), which is 1190m thick, richly fossiliferous, poorly consolidated, and composed predominantly of grey sandy silts. It includes mud-rich units in the lower part; some fine-grained, often calcareous, sandstone beds throughout the formation; and glauconite beds in the uppermost part.

Size class: microfossils

Preservation: original sporopollenin

Reposited in the USNM

• Spores from the Cretaceous part of the Lopez de Bertodano Formation discussed here are from a discontinuous section ( A5 through A11) collected during reconnaisance field-work in 1982, and section B1 collected in 1983/84. Another 12 samples from section A19 were examined. Samples were taken from holes dug about 10-30 cm into well-exposed outcrop, in part to avoid surficial slope wash. Surface weathering was not significantat most of these localities, although samples were collected from freshly exposed escarpments where possible.

•Material will be housed in the National Museum of Natural History, Smithsonian Institution, Washington, D.C.

Primary reference: R. A. Askin. 1990. Cryptogam spores from the upper Campanian and Maastrichtian of Seymour Island, Antarctica. Micropaleontology (36)141-156 [C. Jaramillo/C. Jaramillo]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 167588: authorized by Carlos Jaramillo, entered by Carlos Jaramillo on 24.03.2015

Creative Commons license: CC BY (attribution)

Taxonomic list

• Recycled spores and pollen are common throughout the upper Campanian and Maastrichtian sediments of Seymour Island. They include rare Permian and Triassic species, recognizable by their diagnostic morphology. Some are of substantially darker color, but many of these Permian-Triassic specimens are surprisingly light-colored (yellow) and well-preserved, suggest- ing a history that included negligible thermal alteration (Askin and Elliot 1982).
Pteridopsida
  -
 Salviniales - Azollaceae
Azolla spp. Lamark 1783
 Gleicheniales - Matoniaceae
 Gleicheniales - Gleicheniaceae
Clavifera triplex Bolkhovitina 1966
 Polypodiales -
Polypodiisporites speciosus Khan and Martin 1971
  -
Grapnelispora cf. evansii Stover and Partridge 1984
Lycopsida
 Lycopodiales -
Camarozonosporites ohaiensis Dettmann and Playford 1968
  - Selaginellaceae
Ceratosporites equalis Cookson and Dettmann 1958
  - Lycopodiaceae
Retitriletes nodosus Srivastava 1975
Retitriletes cf. eminulus Srivastava 1975
Retitriletes austroclavatidites Döring et al. 1963
  - Isoetaceae
Echinosporis "sp. 1" Krutzsch 1967
Bryopsida
  -