[Elektronische Ressource]

Crustal structure of the Mid-Atlantic Ridge at 5° south : two contrasting spreading segments / vorgelegt von Lars Planert

Englisch

2006

Online-Ressource (217 S.)

Druckausg.: Planert, Lars: Crustal structure of the Mid-Atlantic Ridge at 5° South

Kiel, Univ., Diss, 2006

URN: urn:nbn:de:gbv:8-diss-18374

*Mittelatlantischer Rücken / Ozeanische Erdkruste

Dewey Dezimal-Klassifikation: [DDC22ger] 551.136091635

The structure of the oceanic crust at the Mid-Atlantic Ridge at 5ʿ 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 5ʿS 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 5ʿS 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.