Amazon Fan biomarker evidence against the Pleistocene rainforest refuge hypothesis?

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doi: 10.1002/jqs.1567
Author(s): Maslin, Mark A.; Ettwein, Virginia J.; Boot, Christopher S.; Bendle, James; Pancost, Richard D.
Author Affiliation(s): Primary:
University College London, Environmental Change Research Centre, London, United Kingdom
Other:
University of Bristol, United Kingdom
University of Glasgow, United Kingdom
Volume Title: JQS. Journal of Quaternary Science
Source: JQS. Journal of Quaternary Science, 27(5), p.451-460. Publisher: John Wiley and Sons for the Quaternary Research Association, Chichester, United Kingdom. ISSN: 0267-8179
Note: In English. 127 refs.; illus.
Summary: Ocean Drilling Program Leg 155 Site 942 on the Amazon Fan is an ideal location for monitoring palaeoclimatic changes within a significant proportion of the Amazon Basin. We present n-alkane δ13C and taraxerol and laevoglucosan concentration records from this site covering the last 38 ka. The entire n-alkane δ13C record is constrained between -31 ppm and -34 ppm, which is well within the isotopic range occupied by C3 vegetation. The concentration and relative abundance of taraxerol, a mangrove indicator, varies by over an order of magnitude, but seems to have had no effect on the n-alkane δ13C record. The laevoglucosan concentrations are extremely low during the last glacial period, suggesting a relatively low occurrence of forest fires. Laevoglucosan concentrations are highest between 13.5 and 12.5 ka, suggesting an increased incidence of Amazon forest fires at the very end of the Younger Dryas. These records, combined with previously published pollen records from Site 932, reveal no evidence for massive incursions of grasslands into Amazonia during the last glacial period, despite evidence of reduced outflow of the Amazon River indicating more arid conditions. We therefore suggest that savannah encroachment, as proposed by the Pleistocene refuge hypothesis, can be refuted as an explanation for high species endemism within the Amazon Basin, and alternative explanations are required. Abstract Copyright (2012), John Wiley & Sons, Ltd.
Year of Publication: 2012
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Aliphatic hydrocarbons; Alkanes; Amazon Fan; Atlantic Ocean; Biochemistry; Biomarkers; C-13/C-12; Carbon; Cenozoic; Chemical composition; Equatorial Atlantic; Fires; Forests; Hydrocarbons; Isotope ratios; Isotopes; Leg 155; N-alkanes; North Atlantic; ODP Site 942; Ocean Drilling Program; Organic compounds; Paleoecology; Paleoenvironment; Pleistocene; Quaternary; Rain forests; Refugia; Stable isotopes; Upper Pleistocene; Upper Weichselian; Weichselian; Younger Dryas
Coordinates: N054433 N054433 W0490528 W0490528
Record ID: 2013008209
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom