Publication Date:
2019-09-23
Description:
The Murray Ridge/Dalrymple Trough system forms the boundary between the Indian and
Arabian plates in the northern Arabian Sea. Geodetic constraints from the surrounding con-
tinents suggest that this plate boundary is undergoing oblique extension at a rate of a few
millimetres per year. We present wide-angle seismic data that constrains the composition of
the Ridge and of adjacent lithosphere beneath the Indus Fan. We infer that Murray Ridge,
like the adjacent Dalrymple Trough, is underlain by continental crust, while a thin crustal
section beneath the Indus Fan represents thinned continental crust or exhumed serpentinized
mantle that forms part of a magma-poor rifted margin. Changes in crustal structure across the
Murray Ridge and Dalrymple Trough can explain short-wavelength gravity anomalies, but a
long-wavelength anomaly must be attributed to deeper density contrasts that may result from
a large age contrast across the plate boundary. The origin of this fragment of continental crust
remains enigmatic, but the presence of basement fabrics to the south that are roughly parallel
to Murray Ridge suggests that it separated from the India/Seychelles/Madagascar block by
extension during early breakup of Gondwana.
Type:
Article
,
PeerReviewed
Format:
text
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