Towards better Greenland source attribution for IRD via Pb in feldspar and Ar-Ar in amphibole

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Author(s): Storey, C.; White, L.; Foster, G. L.; Bailey, I.; Allen, G. R.
Author Affiliation(s): Primary:
University of Portsmouth, School of Earth and Environmental Sciences, Portsmouth, United Kingdom
University of Southampton, United Kingdom
Volume Title: AGU 2012 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2012; American Geophysical Union 2012 fall meeting, San Francisco, CA, Dec. 3-7, 2012. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English
Summary: The provenance of Ice rafted debris, IRD, deposited in marine sediments has great potential to fingerprint regions of present and past iceberg calving in the coastal zones of continental margins. In particular, the growth of the Greenland Ice Sheet during the Pliocene intensification of northern hemisphere glaciation (and perhaps earlier) could be tracked by studying IRD in well-dated deep sea drill cores. However, the IRD record is only as strong as the onshore land-based record of potential sources. Two minerals common within IRD that have been used previously and that show great promise in this regard are feldspar and amphibole. Pb isotopes in feldspar record a diagnostic signature of the continental crust within distinct geologic terranes. In particular, Greenland is composed of a number of distinct terranes with proven distinct Pb isotope signatures. Ar-Ar dating of amphiboles records the thermal history of a terrane when it was metamorphosed above or cooled below c.550°C. Due to distinctive metamorphic histories within different terranes this signature is also potentially diagnostic of a particular source area. The two minerals together could be particularly powerful but only if the potential areas of calving are well-characterised. Here we present data form fluvio-glacial sediments from sites around the margins of Greenland and discuss their diagnostic characteristics. We also apply the principle to some circum-Greenland core top IRD samples and Mid Pliocene IRD from ODP Site 907.
Year of Publication: 2012
Research Program: ODP Ocean Drilling Program
Key Words: 01 Mineralogy and Crystallography; Absolute age; Amphibole group; Ar/Ar; Arctic Ocean; Arctic region; Chain silicates; Chemical composition; Feldspar group; Framework silicates; Greenland; Lead; Marine sediments; Metals; Methods; Norwegian Sea; ODP Site 907; Ocean Drilling Program; Provenance; Sediments; Silicates
Coordinates: N691459 N691459 W0124154 W0124154
Record ID: 2014044736
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