{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/33721"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/33721","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Geochemical characerization of endmember mantle components","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Workman, Rhea K"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Joint Program in Oceanography","school":null,"contributors":[],"advisors":["Stanley R. Hart."],"committee_chairs":[],"committee_members":[],"year":2005,"date_issued":"2005","date_published":"2005","updated_at":"2026-07-22T22:21:43Z","subjects":["Joint Program in Oceanography.","Earth, Atmospheric, and Planetary Sciences.","Woods Hole Oceanographic Institution."],"languages":["eng"],"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."],"rights_urls":["http://dspace.mit.edu/handle/1721.1/33721","http://dspace.mit.edu/handle/1721.1/7582"],"identifier_entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://dspace.mit.edu/handle/1721.1/33721"],"render_values":[{"text":"http://dspace.mit.edu/handle/1721.1/33721","href":"http://dspace.mit.edu/handle/1721.1/33721","code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/1721.1/33721","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Stanley R. Hart."]},{"key":"dc:contributor.department","label":"Department","values":["Joint Program in Oceanography","Massachusetts Institute of Technology. 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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."]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://dspace.mit.edu/handle/1721.1/33721","http://dspace.mit.edu/handle/1721.1/7582"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://dspace.mit.edu/handle/1721.1/33721","http://hdl.handle.net/1721.1/33721"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2005.","Includes bibliographical references."]},{"key":"dc:description.abstract","label":"Abstract","values":["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.","(cont.) The first is recycling of melt- impregnated oceanic lithosphere; the second is recycling of a mantle wedge impregnated with melt from a subducting oceanic plate."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph.D."]},{"key":"dc:title","label":"Title","values":["Geochemical characerization of endmember mantle components"]}]}],"canonical_facts":{"dc:contributor.advisor":["Stanley R. 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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.","(cont.) The first is recycling of melt- impregnated oceanic lithosphere; the second is recycling of a mantle wedge impregnated with melt from a subducting oceanic plate."],"dc:description.degree":["Ph.D."],"dc:identifier.uri":["http://dspace.mit.edu/handle/1721.1/33721","http://hdl.handle.net/1721.1/33721"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"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."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/33721","http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Joint Program in Oceanography.","Earth, Atmospheric, and Planetary Sciences.","Woods Hole Oceanographic Institution."],"dc:title":["Geochemical characerization of endmember mantle components"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:21:43Z"}