Geophysical evidence for late stage magmatism at the central Ninetyeast Ridge,Eastern Indian Ocean |
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| Authors: | Kopf A Klaeschen D Weinrebe W Flueh ER Grevemeyer I |
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| Institution: | 1.GEOMAR, Forschungszentrum für Marine Geowissenschaften, Christian-Albrechts-Universität zu Kiel, Wischhofstraße 1–3, 24148, Kiel, Germany
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| Abstract: | The Ninetyeast Ridge is a well-studied hot spot trail in the Indian Ocean. A recent geophysical survey in its central portion
near 17° S included Hydrosweep bathymetric mapping, Parasound echosounder profiles, and high resolution seismic reflection
data. These data reveal a number of small cones of a few hundreds of meters in diameter and up to 200 m height. Seismic evidence
exists regarding a magmatic origin of these features. Different events of basaltic flow and tuff deposition intercalated with
hemipelagic oozes of Eocene to present age, as being known from nearby drilling, allow dating of these latest stages of volcanic
activity. An activity of at least 6 Ma longer than termination of the dominant constructional phase of the ridge can be demonstrated.
These eruptions occur at shallow water depth, and seem to be related to tectonic lineaments in the area. Transtensional stresses
together with a more durable magmatic source beneath this part of the ridge allow magma to ascend along pull-apart structures.
The age discrepancy found calls for special attention when trying to reconstruct global plate motions.
This revised version was published online in November 2006 with corrections to the Cover Date. |
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