Crocket, Kirsty C. et al. (2012): Continental weathering fluxes during the last glacial/interglacial cycle; insights from the marine sedimentary Pb isotope record at Orphan Knoll, NW Atlantic
Leg/Site/Hole:
Related Expeditions:
IODP 303 IODP 303 U1302 IODP 303 U1303
Identifier:
ID:
2012-049922
Type:
georefid
ID:
10.1016/j.quascirev.2012.02.004
Type:
doi
Creator:
Name:
Crocket, Kirsty C.
Affiliation:
University of Bristol, School of Geographical Sciences, Bristol Isotope Group, Bristol, United Kingdom
Role:
author
Name:
Vance, Derek
Affiliation:
Role:
author
Name:
Foster, Gavin L.
Affiliation:
Role:
author
Name:
Richards, David A.
Affiliation:
Role:
author
Name:
Tranter, Martyn
Affiliation:
Role:
author
Identification:
Title:
Continental weathering fluxes during the last glacial/interglacial cycle; insights from the marine sedimentary Pb isotope record at Orphan Knoll, NW Atlantic
Year:
2012
Source:
Quaternary Science Reviews
Publisher:
Elsevier, International
Volume:
38
Issue:
Pages:
89-99
Abstract:
Regional weathering intensity must have changed dramatically at high latitudes during the Quaternary as a consequence of repeated continental glaciation. Investigation of these glacial/interglacial changes at high temporal resolution is possible with the recent development of Pb isotopes in FeMn oxyhydroxide phases as a proxy for region-specific weathering intensity, where increases in the radiogenic component are thought to correspond to increased continental weathering fluxes. Here we present a Pb isotope record sourced from the FeMn oxyhydroxide fraction in marine sediments from IODP Sites U1302/3 on Orphan Knoll ( approximately 3500 mbsl, NW Atlantic), spanning the last 37 ka. Located at the eastern edge of the Laurentide Ice Sheet (LIS), Site U1302/3 is well-placed to monitor changes in weathering intensity associated with LIS glacial history. Overall, the data show a close correspondence to local surface water delta (super 18) O, with least radiogenic values during times of heavy delta (super 18) O (glacial maximum) and most radiogenic values during times of light delta (super 18) O (Holocene). This supports the prediction that weathering intensity in glaciated regions of the North Atlantic correlates with the exposure age of glacial debris. Superimposed on these background trends are extreme radiogenic excursions (e.g. variation in (super 206) Pb/ (super 204) Pb from approximately 19.2-21.0) contemporaneous with Heinrich events and the Younger Dryas. These data are substantially more radiogenic than existing records from the NW Atlantic, and most likely represent episodes of exceptionally high inputs of pre-formed FeMn oxyhydroxides during drainage of the LIS. Due to its extreme isotope composition, at least in the NW Atlantic region, Pb would appear to be a good proxy for the fluxes of weathered continental material and perhaps, by inference, nutrients to the surface ocean. Abstract Copyright (2012) Elsevier, B.V.
Language:
English
Genre:
Serial
Rights:
URL:
Coverage: Geographic coordinates: North:50.1200 West:-45.4100 East:
-45.3800 South:50.1000
Keywords: Quaternary geology; alkaline earth metals; Atlantic Ocean; Cenozoic; chemostratigraphy; cores; Expedition 303; Expeditions 303/306; glacial environment; Heinrich events; Holocene; Integrated Ocean Drilling Program; interglacial environment; IODP Site U1302; IODP Site U1303; isotope ratios; isotopes; Laurentide ice sheet; lead; marine sediments; metals; North Atlantic; Northwest Atlantic; Orphan Knoll; paleo-oceanography; paleoclimatology; Pb-206/Pb-204; Quaternary; radioactive isotopes; sediments; Sr-87/Sr-86; stable isotopes; strontium; weathering;
.