1. Главная
  2. Ресурсы
  3. Библиотечный поиск
A Late Eocene ageproposal for theLoreto Formation(Brunswick Peninsula,southernmost Chile),based on fossilcartilaginous fishes,paleobotany and… Rodrigo A. OteroTeresa TorresJ.P. Le Roux2012 год

A Late Eocene age proposal for the Loreto Formation (Brunswick Peninsula, southernmost Chile), based on fossil cartilaginous fishes, paleobotany and radiometric evidence
статья из журнала

Полный текстСтраница публикацииПубликация в OpenAlex
Аннотация: We present new data on the paleoichthyology, paleobotany and radiometric results of the Loreto Formation in the Brunswick Peninsula of southernmost Chile, that allow us to propose a Late Eocene age. The rich diversity of fossil cartilaginous fishes (Chondrichthyes, Elasmobranchii) recognized in upper levels of this unit includes the taxa Carcharias aff. ‘hopei’ (Agassiz), Odontaspis sp., Carcharoides catticus (Philippi), Striatolamia macrota (Agassiz), Anomotodon sp., Macrorhizodus praecursor (Leriche), Galeorhinus sp., Abdounia sp., Hexanchus sp., Squatina sp., Hexanchidae indet., Myliobatis sp., Myliobatoidea indet., and Ischyodus dolloi Leriche. This assemblage has clear ecological affinities with Eocene Tethyan fauna previously described in the Northern Hemisphere, and also has common elements with Eocene cartilaginous fishes from Antarctica. Additionally, a paleobotanic study of this unit identified leaf imprints of Asplenium sp., Pteris sp., Podocarpus sp., and abundant angiosperms including Nothofagus lanceolata Dusen, N. simplicidens Dusen, N. variabilis Dusen, N. cf. alessandri Espinosa, N. subferruginea (Dusen), Hydrangea sp. and Phyllites spp. Wood remains of Nothofagoxylon scalariforme Gothan and Araucariaceae cf. Araucarioxylon Kraus were also identified. Additionally, pollen grains indicate gymnosperms and angiosperms: Podocarpidites otagoensis Couper, Retitricolpites sp., Tricolpites sp., Liliacidites sp., Polyporina sp., Nothofagidites cincta Cookson, and Nothofagidites cranwellae Couper, having affinities with Eocene florae, and being consistent with the age of the fossil fishes. Finally, a SHRIMP U-Th-Pb analysis of two samples collected from the studied beds provided thirty-eight and sixty zircon grains, indicating a clear main peak at 36.48±0.47 Ma (MSWD=1.5) and 36,73±0.50 Ma (MSWD=0.65). The integrated results indicate that the upper part of the Loreto Formation has a minimum Priabonian age, supporting previous reassignations of this part of the formation into the Late Eocene, and differing from the Oligocene age proposed in its original definition.
Год издания: 2012
Авторы: Rodrigo A. Otero, Teresa Torres, J.P. Le Roux, Francisco Herve, C. Mark Fanning, Roberto E. Yury-Yáñez, David Rubilar-Rogers
Издательство: National Geology and Mining Service
Источник: Andean geology
Ключевые слова: Paleontology and Evolutionary Biology, Evolution and Paleontology Studies, Ichthyology and Marine Biology
Другие ссылки: Andean geology (PDF)
Andean geology (HTML)
Redalyc (Universidad Autónoma del Estado de México) (PDF)
Redalyc (Universidad Autónoma del Estado de México) (HTML)