Martin, Pamela A.

Patton, Genna M.

Voelker, Antje H. L.

Repositório do LNEG

AGU Fall Meeting 2009 You may print by clicking on this Print  button. To return to the previous page, close thisbrowser window or click the 'X' button in the top right corner of the page. ID# PP31B-1327Location: Poster Hall (Moscone South)Time of Presentation: Dec 16 8:00 AM - 12:20 PM Trace and Minor Element/Ca Ratios of Planktonic Foraminifera in the Iberian MarginDuring Heinrich EventsG. M. Patton1; P. A. Martin1; A. Voelker21. The Department of the Geophysical Sciences, The University of Chicago, Chicago, IL, USA.2. Instituto Nacional de Engenharia, Tecnologiae Inovacao I.P., Alfragide, Portugal. During the last glacial and deglacial period (16kya-46kya), the Iberian Margin experienced localsea surface temperature fluctuations as a result of melting icebergs from catastrophic calvingsof the Laurentide Ice Sheet (Heinrich Events). Coinciding with the coldest stadials of Dangaard-Oeschger cycles seen in the Greenland ice cores, Heinrich Events result in North Atlantic deepwater changes that can have a widespread impact. Using planktonic foraminiferal Mg/Ca, wehave reconstructed sea surface temperature for Heinrich Events one (H1), four (H4) and five(H5) from core MD99 2339 in the Gulf of Cadiz (35.88°N; 7.53°W, 1170m) and core MD95 2040on the Iberian margin (35°34.91’N; 9°51.67’ W, 2645m). Locally, all three of these events arequite intense showing oxygen isotope excursions of approximately 1.5 parts per mil.Low Mg/Ca values during the Heinrich Events imply significant local and, possibly, regionalcooling. For example, temperatures derived from Mg/Ca during H1, H4 and H5 in the Gulf ofCadiz show a temperature oscillation of approximately 6-7°C between the start and end of eachHeinrich Event. While this is a large temperature oscillation, it is of slightly smaller amplitudethan the approximate 10°C swing implied by assemblage data for winters (Voelker et al., 2006)in the Gulf of Cadiz. Using Mg/Ca in conjunction with O-18 also allows us to calculate changesin salinity that result from the melting of extremely isotopically light ice. Salinity changes helpdistinguish among potential drivers of temperature oscillations in these cores, including regionalclimatic change, circulation changes and melting ice.In addition to Mg/Ca from the planktonic species G. bulloides, we measured eleven other traceand minor element/Ca ratios during H1, H4 and H5 in both MD99 2339 and MD95 2040. Highsedimentation in core MD95 2040 allows for sampling at a resolution of approximately 90 yearsduring H1. We focused on this period of extremely high resolution prior to, during and after theHeinrich Event to determine precise trends in each of the trace and minor element/Ca ratios.Ice rafted debris in the core allows us to identify the timing of local melting relative to otherchanges. Comparison of multi-element data from the two cores helps to identify links betweentemperature and shifts in ocean circulation.ScholarOne Abstracts® (patent #7,257,767 and #7,263,655). © ScholarOne, Inc., 2009. All Rights Reserved.ScholarOne Abstracts and ScholarOne are registered trademarks of ScholarOne, Inc.Terms and Conditions of Use

Trace and minor element/Ca ratios of planktonic foraminifera in the Iberian Margin during Heinrich events

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Trace and minor element/Ca ratios of planktonic foraminifera in the Iberian Margin during Heinrich events

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