2026-09-20T15:43:57Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/1222372021-07-05T14:03:20Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Oliver Jagoutz.
Bowman, Emilie Elisabeth.
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
mr-----
2019-09-17T19:49:23Z
2019-09-17T19:49:23Z
2019
2019
https://hdl.handle.net/1721.1/122237
1119388989
Thesis: S.M. in Geology, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 88-98).
The Red Sea rift is a nascent ultra-slow spreading ridge superimposed on the Afar plume. Based on high-resolution seismic data, the southernmost (south of the Danakil rift at 17.05°N), southern (17.05-19.75°N), and central (19.75-23.8°N) segments display seafloor spreading that is anomalously magma-rich compared to other ultra-slow spreading centers. In contrast, the northern segment (23.8-28°N) exhibits magma-poor extension along large-offset east- and west-dipping detachments. Sediment-corrected basement depths along the northern Red Sea reveal an axial valley as deep as the Gakkel Ridge (4200-5100 m). South of 19.75°N, plume-supported axial shoaling matches that of adjacent parts of Arabia, Africa, and the Gulf of Aden. Geochemically, the southernmost Red Sea is the locus of plume-ridge interaction. Here, E-MORBs are enriched in alkali, incompatible, and light rare-earth elements.
High mantle potential temperatures (T[subscript p]; 1326±5°C), melting pressures (12±0 kbars) and temperatures (1306±6°C), and fractionation pressures (5.3±1.6 kbars) calculated using the reverse fractional crystallization model of Brown (2019) suggest thickened oceanic crust created by high-degree partial melting of a plume-like source. North of the Danakil rift, T[subscript p] (1307± 11°C) spans a narrow range and is within the range of ambient mantle. The southern Red Sea contains N- to E-MORB depleted in alkali, incompatible, and light rare-earth elements indicating limited mixing with Afar plume material, while the central segment is host to the most depleted magmas along the ridge (La/Sm[subscript N] < 0.8). Within the southern and central regions, fractionation pressures (2.0±1.2 and 4.8±2.1 kbars, respectively) indicate lithosphere (5-15 km) thinner than that of normal ultra-slow spreading ridges (15-35 km).
In the northern Red Sea, high Na₈ and deep pressures of melting (10.4±1.4 kbars) suggest thickened lithosphere, undulations in which induce melt focusing into volcanic deeps. Based on these results, we propose that the Red Sea south of at least 26.5°N is an oceanic spreading center. We find that anomalously magma-rich spreading in the central and southern segments cannot be related to the Afar plume. Instead, the Danakil rift diverts plume-related mantle flow northeast beneath Arabia. Thus, the southern and central Red Sea must be characterized by vigorous mantle upwelling that causes heightened melt production and lithospheric thinning.
by Emilie Elisabeth Bowman.
S.M. in Geology
S.M.inGeology Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences
98 pages
eng
Massachusetts Institute of Technology
MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.
http://dspace.mit.edu/handle/1721.1/7582
Earth, Atmospheric, and Planetary Sciences.
North-south variations in structure, topography, and melting regime along the ultra-slow spreading Red Sea Ridge
Thesis
application/pdf
2019-09-17T19:49:21Z
Publication
Master
EAPS
unknown
unknown
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<Abstract>The Red Sea rift is a nascent ultra-slow spreading ridge superimposed on the Afar plume. Based on high-resolution seismic data, the southernmost (south of the Danakil rift at 17.05°N), southern (17.05-19.75°N), and central (19.75-23.8°N) segments display seafloor spreading that is anomalously magma-rich compared to other ultra-slow spreading centers. In contrast, the northern segment (23.8-28°N) exhibits magma-poor extension along large-offset east- and west-dipping detachments. Sediment-corrected basement depths along the northern Red Sea reveal an axial valley as deep as the Gakkel Ridge (4200-5100 m). South of 19.75°N, plume-supported axial shoaling matches that of adjacent parts of Arabia, Africa, and the Gulf of Aden. Geochemically, the southernmost Red Sea is the locus of plume-ridge interaction. Here, E-MORBs are enriched in alkali, incompatible, and light rare-earth elements.</Abstract>
<Abstract>High mantle potential temperatures (T[subscript p]; 1326±5°C), melting pressures (12±0 kbars) and temperatures (1306±6°C), and fractionation pressures (5.3±1.6 kbars) calculated using the reverse fractional crystallization model of Brown (2019) suggest thickened oceanic crust created by high-degree partial melting of a plume-like source. North of the Danakil rift, T[subscript p] (1307± 11°C) spans a narrow range and is within the range of ambient mantle. The southern Red Sea contains N- to E-MORB depleted in alkali, incompatible, and light rare-earth elements indicating limited mixing with Afar plume material, while the central segment is host to the most depleted magmas along the ridge (La/Sm[subscript N] < 0.8). Within the southern and central regions, fractionation pressures (2.0±1.2 and 4.8±2.1 kbars, respectively) indicate lithosphere (5-15 km) thinner than that of normal ultra-slow spreading ridges (15-35 km).</Abstract>
<Abstract>In the northern Red Sea, high Na₈ and deep pressures of melting (10.4±1.4 kbars) suggest thickened lithosphere, undulations in which induce melt focusing into volcanic deeps. Based on these results, we propose that the Red Sea south of at least 26.5°N is an oceanic spreading center. We find that anomalously magma-rich spreading in the central and southern segments cannot be related to the Afar plume. Instead, the Danakil rift diverts plume-related mantle flow northeast beneath Arabia. Thus, the southern and central Red Sea must be characterized by vigorous mantle upwelling that causes heightened melt production and lithospheric thinning.</Abstract>
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