Pleistocene deposits of the Amazon Fan; a palynological analysis of holes 940A, 944A, and 946A (ODP Leg 155)

Author(s): Hoorn, Carina
Author Affiliation(s): Primary:
University of Amsterdam, Hugo de Vries Laboratory/Centre for Geo-ecological Research, Amsterdam, Netherlands
Volume Title: Proceedings of the IX international palynological congress
Volume Author(s): Goodman, David K., editor; Clarke, Robert T.
Source: Proceedings - International Palynological Conference, Vol.9, p.329-338; IX international palynological congress, Houston, TX, June 23-28, 1996, edited by David K. Goodman and Robert T. Clarke. Publisher: International Palynological Conference, s.l., International. ISSN: 0254-7201. ISBN: 0-931871-06-9
Note: In English. 28 refs.; illus., incl. strat. cols., 1 table, geol. sketch map
Summary: This paper presents a summary of a palynological study carried out for the Ocean Drilling Program, Leg 155. The study focused on the composition and distribution of organic matter in sediments of the Amazon Fan during the Pleistocene glacial/interglacial sequences. Samples from holes 940A, 944A, and 946A showed that glacial lowstand deposits are characterized by large concentrations of a palynological assemblage composed of Andean and tropical lowland taxa, minor amounts of reworked Paleozoic, Cretaceous, and Tertiary taxa, and large volumes of organic debris (e.g. wood, vessels, epidermis, cuticles). In general, these intervals do not contain many taxa diagnostic for the lowland savannah's. In all the studied sites, there is an increase of ferns, fern allies, reworked reworked and corroded palynomorphs, and fungal spores at the time of the last glacial episode. Interglacial highstand deposits are characterized by low concentrations of the terrigenous palynological assemblage and a predominance of marine microfossils. Although no marked differences exist in the composition of the organic matter along the fan, there is a decrease in the concentration of palynomorphs from proximal to distal sites. No compositional difference between the levees and the debris flow was observed. The palynological sequences in the Amazon deep sea fan give no indication of major vegetational changes in the lowlands. If extensive savannah vegetation existed in Amazonia during the Pleistocene glacial intervals, as claimed in the refugia theory, they were either obliterated or not recorded in the sediments of the Amazon Fan.
Year of Publication: 2001
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Amazon Fan; Atlantic Ocean; Cenozoic; Floral list; Leg 155; Microfossils; Miospores; North Atlantic; ODP Site 940; ODP Site 944; ODP Site 946; Ocean Drilling Program; Organic compounds; Paleoclimatology; Paleoenvironment; Palynomorphs; Plantae; Pleistocene; Pollen; Pteridophyta; Quaternary; Sea-level changes; Spores
Coordinates: N050836 N050836 W0473144 W0473144
N055622 N055622 W0474526 W0474526
N065658 N065658 W0475510 W0475510
Record ID: 2003069194
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.