%0 Journal Article
%T The stratigraphy of cretaceous mudstones in the eastern Fuegian Andes: new data from body and trace fossils Estratigraf赤a de las fangolitas del Cret芍cico en los Andes Fueguinos orientales: Nuevos datos de cuerpos y trazas f車siles
%A Eduardo B. Olivero
%A Francisco A. Medina
%A Mar赤a I. L車pez C.
%J Revista de la Asociaci車n Geol車gica Argentina
%D 2009
%I Asociaci車n Geol車gica Argentina
%X The stratigraphy of Cretaceous marine mudstones in the Fuegian Andes, roughly equivalent to Charles Darwin's clay-slate formation, remains a still unsolved problem. Previous records of Albian, Turonian-Coniacian, and Santonian-Campanian bivalves are combined with new findings of the Late Albian inoceramid Inoceramus anglicus Woods, and the Maastrichtian ammonites Diplomoceras sp., Anagaudryceras sp., Maorites densicostatus (Kilian and Reboul), Maorites sp., and Pachydiscus (Neodesmoceras) sp. to further constrain the Cretaceous stratigraphy of the eastern Fuegian Andes. In addition, new records of distinctive trace fossils and ichnofabric are meaningful for stratigraphic division and delineation of paleoenvironmental settings in these Cretaceous mudstones. The Lower Cretaceous ichnoassemblage of Chondrites targioni (Brongniart) and Zoophycos isp. is consistent with the inferred slope-volcaniclastic apron settings of the Yahgan Formation; Nereites missouriensis (Weller) reflects distal basin plain depositional settings for the Beauvoir Formation. In the Upper Cretaceous, the "Estratos de Buen Suceso" record the earliest extensively bioturbated horizons, reflecting prolonged well-oxygenated bottom conditions. In the Bah赤a Thetis Formation, organic-rich, channel margin or distal basin slaty mudstones record the last occurrence of inoceramid bivalves in the Austral Basin; the generalized absence of trace fossils is consistent with dysoxic bottom conditions. The thoroughly bioturbated Policarpo Formation, records a marked change in paleoceanographic conditions. The strong contrast in the intensity of bioturbation between the Upper Campanian-Maastrichtian Bah赤a Thetis Formation, almost devoid of trace fossils, and the highly bioturbated Maastrichtian-Danian Policarpo Formation reflects a change from dysoxic-anoxic to well ventilated conditions, probably associated with a cooling trend of bottom waters in the austral deep oceans. En los Andes Fueguinos la estratigraf赤a de las fangolitas del Cret芍cico marino (clay-slate formation de Charles Darwin), constituye un problema no enteramente resuelto. Datos previos de bivalvos del Albiano, Turoniano-Coniaciano, y Santoniano-Campaniano, junto con nuevos hallazgos de inoceramidos del Albiano tard赤o, Inoceramus anglicus Woods, y amonites maastrichianos, Diplomoceras sp., Anagaudryceras sp., Maorites densicostatus (Kilian y Reboul), Maorites sp., y Pachydiscus (Neodesmoceras) sp. se utilizan para obtener una mejor resoluci車n estratigr芍fica. Adem芍s, nuevas asociaciones distintivas de trazas f車siles permiten ajustar la int
%K Clay-slate formation
%K Inoceramidos
%K Amonites
%K Trazas f車siles
%K Cret芍cico
%K Andes Fueguinos
%K Clay-slate formation
%K Inoceramid
%K Ammonites
%K Cretaceous
%K Trace fossils
%K Fuegian Andes
%U http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S0004-48222009000100008