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TAPHONOMY OF BENTHIC FORAMINIFERAL TESTS OF THE AMAZON SHELF

2003; Cushman Foundation for Foraminiferal Research; Volume: 33; Issue: 2 Linguagem: Inglês

10.2113/0330132

1943-264X

Claudia Gutterres Vilela,

Marine Biology and Ecology Research

Research Article| April 01, 2003 TAPHONOMY OF BENTHIC FORAMINIFERAL TESTS OF THE AMAZON SHELF Claudia Gutterres Vilela Claudia Gutterres Vilela 1 Departamento de Geologia/IGEO/CCMN, Universidade Federal do Rio de Janeiro, Ilha do Fundão-21949-900 Rio de Janeiro-RJ-Brasil 1E-mail: vilela@geologia.ufrj.br Search for other works by this author on: GSW Google Scholar Author and Article Information Claudia Gutterres Vilela 1 Departamento de Geologia/IGEO/CCMN, Universidade Federal do Rio de Janeiro, Ilha do Fundão-21949-900 Rio de Janeiro-RJ-Brasil 1E-mail: vilela@geologia.ufrj.br Publisher: Cushman Foundation for Foraminiferal Research Received: 30 Mar 2001 Accepted: 09 Apr 2002 First Online: 03 Mar 2017 Online ISSN: 1943-264X Print ISSN: 0096-1191 © 2003 Journal of Foraminiferal Research Journal of Foraminiferal Research (2003) 33 (2): 132–143. https://doi.org/10.2113/0330132 Article history Received: 30 Mar 2001 Accepted: 09 Apr 2002 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Claudia Gutterres Vilela; TAPHONOMY OF BENTHIC FORAMINIFERAL TESTS OF THE AMAZON SHELF. Journal of Foraminiferal Research 2003;; 33 (2): 132–143. doi: https://doi.org/10.2113/0330132 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search Abstract Benthic foraminifera of box core and piston core samples were collected from the Amazon middle to outer shelf. The assemblages and their taphonomic features confirmed a record of oceanographic changes from the early Holocene to the present. Foraminiferal data in conjunction with sedimentological, stratigraphic, seismic, and isotopic results point to three contrasting depositional environments. The first environment is that of a fluid mud with silt and organic laminations. A seismic discontinuity was observed and interpreted as an erosional surface between the fluid mud, and an underlying much denser mud. This fluid mud, deposited during the last 100 years, shows a very high sedimentation rate, with the erosional phase lasting for 700 years. The characteristic species of the dominant Ammonia beccarii Pseudononion atlanticum assemblage are opportunistic at the sediment-water interface. At deeper substrate intervals, the assemblage can be matched with that at the sediment-water interface, but they also show taphonomic effects of reworking and erosion. The second environment is characterized by relict sediment, which includes an older suite of foraminifera mixed with modern tests. This assemblage differs from the recent one by including large relict species dominated by Quinqueloculina bicostata, Q. lamarckiana, Amphistegina lessonii and Eponides repanda. Two hypotheses account for the relict assemblage: periods of low sea-level and mixing with younger sediments in deeper water. The third environment is in front of the Amazon River mouth. The cores taken here contain abnormal, large tests of Flintina bradyana. The strong currents and tides of the Amazon shelf could cause large tests to move along the seabed by bed-load transport processes. In living foraminifera, such tests may break and later regenerate abnormally. Such occurrences vary stratigraphically and geographically, demonstrating hydrodynamic variations in time and space. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.