25.01.2015 Views

IASPEI - Picture Gallery

IASPEI - Picture Gallery

IASPEI - Picture Gallery

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy<br />

(S) - <strong>IASPEI</strong> - International Association of Seismology and Physics of the Earth's<br />

Interior<br />

JSS013 Oral Presentation 2224<br />

Magmatic underplating of crust beneath the Laccadive Island, NW Indian<br />

Ocean<br />

Dr. Sandeep Gupta<br />

Seismic Tomography National Geophysical Research Institute, Hyderabad<br />

Shyam Rai, Santosh Mishra<br />

Laccadive Island is the northern segment of Chagos- Laccadive Ridge (CLR), a prominent aseismic<br />

topographic/tectonic feature in the NW Indian Ocean. Despite its significance in providing critical linkage<br />

between the hotspot and genesis of islands, it is poorly investigated using modern seismological tools.<br />

We investigate the crustal velocity structure beneath Laccadive Island through receiver function<br />

modelling of teleseismic waveform recorded on the island broadband station during January April 2005.<br />

The crustal velocity structure suggests ~16 km thick oceanic crust with layers of 0.5, 1.0, 6.0,8.0 km<br />

thickness and shear velocities of 0.65, 2.2, 2.95, 3.98 km/s, respectively at depth. This is followed by<br />

~10 km thick layer of shear velocity ~4.3 km/s layer. Further deep, at depth of 26 km, we observer<br />

uppermost mantle shear velocity 4.8 km/s. The presence of intermediate lower crust-mantle velocity<br />

layer could be interpreted as the underplating of mantle-derived melt at the base of oceanic crust which<br />

progressive deepen the crust-mantle boundary at 26 km. The melt was produced during the interaction<br />

of Indian plate with the Reunion hotspot. Continuity of crustal underplated material beneath Laccadive<br />

could be traced to Laxmi Ridge in the north and to Reunion Island in the south, suggesting this to be<br />

trace of the hotspot. This result along with measurements over other hotspot linked oceanic islands<br />

reinforces that crustal underplating is their common heritage.<br />

Keywords: laccadive island, magmatic underplating, crustal structure

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!