Crustal structure of the Mid-Atlantic Ridge at 5° South : two contrasting spreading segments.

Planert, Lars (2006) Crustal structure of the Mid-Atlantic Ridge at 5° South : two contrasting spreading segments. Open Access (PhD/ Doctoral thesis), Christian-Albrechts-Universität, Kiel, 209 pp.

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Abstract

The structure of the oceanic crust at the Mid-Atlantic Ridge at 5° South is investigated using wide-angle seismic data. Here, two morphologically contrasting spreading segments are separated by a 70 km offset transform fault. Applying a first-arrival tomography and a joint refraction and reflection tomography the obtained models show strong lateral heterogeneity in both velocities and Moho depths. In the segment north of the 5°S fracture zone (FZ) the along-axis crustal thickness thins from 9 km at the segment center to 5-6 km at the segment ends. In contrast to the magmatically robust northern segment, spreading south of the 5°S FZ rather seems to be tectonically controlled. Here, an inside corner high has been split by a change in location of active seafloor spreading. Most parts of this segment are underlain by anomalously thin crust with the thinnest portions associated with the flanks of the inside corner high and a fossil second order ridge-axis discontinuity. The crust formed at the inside corner reveals throughoutly higher velocities than corresponding outside corner crust, which is consistent with models of asymmetric crustal accretion along a detachment fault.

Document Type: Thesis (PhD/ Doctoral thesis)
Thesis Advisor: Flueh, Ernst R. and Reston, Timothy J.
Keywords: Mittelatlantischer Rücken, Ozeanische Erdkruste, seismic velocity structure, Mid-Atlantic Ridge, oceanic crust, transform fault, median valley, joint refraction and reflection tomography, inside corner high, Monte Carlo uncertainty analysis
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: No
Date Deposited: 03 Dec 2008 16:52
Last Modified: 10 Jan 2023 10:58
URI: https://oceanrep.geomar.de/id/eprint/5802

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