A geological and geophysical study of the Tendaho Graben in the Afar Depression, Ethiopia: insights into transitional continental rifting

"A detailed magnetic and gravity study across the Tendaho Graben (the Red Sea propagator within the Afar Depression, Ethiopia) revealed features that can best be interpreted as a continental rift undergoing oceanization. This NW-trending extensional structure is ~50 km wide and it is confined within well-developed NW-trending boarder faults that deform the 2 km thick and ~ 2 Ma basaltic flows of the Afar Stratoids. The age of the basaltic flows becomes progressively younger inward from the boarder faults until it reaches ~30,000 years close to the rift axis. The central part of the Tendaho Graben is characterized by a 10 km wide magnetic trough, the central part of which is dominated by a narrow zone (~3 km) of a relatively elevated magnetic anomaly that coincides with a linear region of hydrothermal activity. This magnetic geometry is similar in dimension and magnitude to that observed from magnetic stripes of typical mid-ocean ridges. Forward modeling of the magnetic data (combined with geochronological data) shows that the basaltic rocks within the magnetic trough were crystallized after 0.78 Ma under normal magnetic polarity. The width of the magnetic trough (10 km) and the age of basaltic rocks (<0.78 Ma) indicate a spreading rate of ~ 0.64 cm/year. However, to achieve the ~50 km width of the Tendaho Graben which started opening ~2.0 Ma, a 1.64 cm/year spreading rate is needed between 1.6 and 0.78 Ma. This suggests that the spreading rate with Tendaho Graben is slowing down and extension within Afar is accommodated somewhere else. A new model is proposed for the evolution of the Tendaho Graben based on fieldwork, the newly acquired magnetic data and geochronology"--Abstract, page iii.

Name thesis:degree_name

Ph. D. in Geology and Geophysics

Grantor

Missouri University of Science and Technology

Year dc:date.available

2016

Author dc:creator

• Bridges, David Lee

• Geology
• Geophysics and Seismology

Repository record dc:identifier

https://scholarsmine.mst.edu/doctoral_dissertations/2020

OAI identifier oai:identifier

oai:scholarsmine.mst.edu:doctoral_dissertations-3022