Geochemical characerization of endmember mantle components

This thesis uses trace elements and radiogenic isotope tracers to define elemental abundances in reservoirs of the Earth's mantle, including EM2 (the Enriched Mantle 2), as seen in the Samoan hotspot track, and DMM (the depleted upper mantle), which is sampled at mid-ocean ridges. Together these components comprise up to [approx.] 50% of the total mantle mass. Much of the mantle's chemical heterogeneities are suspected to originate by either the removal of mass from the mantle (in the case of DMM) or the addition of mass to the mantle through subduction zones (in the case of EM2). We show that DMM represents mantle that 1) has been previously depleted by 2-3% melt removal, 2) mass-balances well with the continental crust, 3) has only 15% of the radiogenic heat production in primitive upper mantle and 4) can generate present-day ocean crust by 6% aggregated fractional melting. EM2 is classically interpreted as mantle material enriched in trace elements through the ancient, subduction-zone recycling of terrigenous sediments; here we show this model is unlikely and provide two other working hypotheses.

Department dc:contributor.department

Joint Program in Oceanography

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Workman, Rhea K

Advisor dc:contributor.advisor

• Stanley R. Hart.

• Joint Program in Oceanography.
• Earth, Atmospheric, and Planetary Sciences.
• Woods Hole Oceanographic Institution.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/33721
• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Identifier URI

http://dspace.mit.edu/handle/1721.1/33721

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/33721