Oceanic ridge off-axis deep structure in the Mansah region (Sumail massif,Oman ophiolite) |
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| Authors: | Jousselin D Nicolas A |
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| Institution: | (1) Laboratoire de Tectonophysique CNRS/UM2, Place E. Bataillon, 34095 Montpellier cedex 05, France;(2) Present address: Department of Geological sciences, University of Oregon, Eugene, OR 97401, USA |
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| Abstract: | Large scale structural mapping of the Oman ophiolite indicates that the Mansah area (Sumail massif) was a ridge off-axis region at the time the ophiolite was detached. This paper presents a detailed structural mapping of the region. We show that, as opposed to other off-axis areas, it contains plunging lineations, correlated with a thick Moho transition zone and chromite pods, indicative of a mantle diapir. However this diapir has a discontinuous structure, it is bounded by shear zones and types of diabases that are not found elsewhere in Oman; it also has a broken crust, strongly affected by hydrothermal alteration. This suggests that Mansah fossilized an off-axis diapir intruding a cooling lithosphere. It may be a good candidate to be the root of an off-axis seamount such as those found in the East Pacific, and may bring new insights into this particular volcanism which we are only beginning to explore. |
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| Keywords: | diapir mantle Oman ophiolite seamount structure |
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