Affiliation:
1. 1 Laboratorio de Geología Andina, Centro Austral de Investigaciones Científicas (CADIC-CONICET), B. A. Houssay 200, 9410 Ushuaia, Tierra del Fuego, Argentina
2. 2 Universidad Nacional de Tierra del Fuego (UNTDF-ICPA), 9410 Ushuaia, Tierra del Fuego, Argentina
Abstract
Abstract
Miocene thin-bedded turbidites from Tierra del Fuego record scarce graphoglyptids and two unusual ichnoguilds composed of diminutive elite trace fossils. The first, a monoichnospecific Cylindrichnus ichnoguild, consists of crowded, post-depositional burrows formed in surface sediments during the final phase of turbidite deposition. The second, a pre-depositional Helminthopsis ichnoguild, consists of dense aggregates of simple trails, mainly Helminthopsis and Helminthoidichnites, occupying a very shallow tier in organic-rich mud covering the sea floor prior to turbidite deposition. The trace makers of Cylindrichnus were opportunistic suspension/detritus feeding organisms, probably polychaetes, which bloomed during high flux of labile organic matter brought to internal and external levees by turbidity currents. The trace makers of Helminthopsis and Helminthoidichnites were probably nematodes that grazed on organic-rich muddy sediments with abundant disseminated pyrite associated with Kinneyia-like and other problematic wrinkle structures, suggesting sulfur-cycling chemosynthetic microbial communities originated during interturbidite phases. The rhythmical alternation of the Cylindrichnus and Helminthopsis ichnoguilds clearly differentiate the thin-bedded turbidites of the Viamonte Formation from channel-levee complexes elsewhere, stressing the point that ichnoassemblages reflect sets of environmental parameters and not necessarily particular depositional settings.
Publisher
Society for Sedimentary Geology
Subject
Paleontology,Ecology, Evolution, Behavior and Systematics
Reference84 articles.
1. Microbial sulfate reduction rates and sulfur and oxygen isotope fractionations at oil and gas seeps in deepwater Gulf of Mexico;Aharon,;Geochimica et Cosmochimica Acta,2000
2. Biologic and geologic characteristics of cold seeps in Monterey Bay, California;Barry,;Deep-Sea Research, Part I, v,1996
3. Bow-shaped, concentrically laminated polychaete burrows: a Cylindrichnus concentricus ichnofabric from the Miocene of Tarragona, NE Spain;Belaústegui,;Palaeogeography, Palaeoclimatology, Palaeoecology,2013
4. The Santa Barbara Basin is a symbiosis oasis;Bernhard,;Nature,2000
5. The stratigraphy and structural evolution of the central and eastern Magallanes basin, southern South America;Biddle,,1986