UNNITHAN , Vikram

Large deep-sea fans are useful settings to study gas hydrate systems, the rapid burial of organic-rich sediment driving linked processes of gas generation, fluid expulsion and syn-sedimentary tectonism. The Nile deep-sea fan (100,000 km2) is a collapsing Late Cenozoic depocentre that is both a hydrocarbon province and an area of widespread...

Gas hydrates have been proven by coring at one site in the (eastern) Mediterranean Sea, but their wider extent remains uncertain. Here we present results from investigations of the potential Mediterranean gas hydrate system, suggesting that clathrates occur more widely and have been strongly impacted by glacial-interglacial climate forcing....

SEAGAS is a 3-year initiative to study processes in the deep sea, involving research groups in Brazil and Europe, including in Germany. The project is being coordinated by PUCRS in collaboration with Géoazur in Nice, France. The hosts have complementary strengths in marine geoscience as applied to submarine gas hydrates, consistent with the...

The Nile deep-sea fan is the largest Plio-Quaternary depocentre in the Mediterranean Sea, extending over an area of >150,000 km2 within which rapid deposition drives syn-sedimentary collapse tectonics, as well as widespread seafloor venting of mixed thermogenic and biogenic gases. It is thus an ideal setting for the near-seabed accumulation of...

Gas hydrates are ice-like compounds of water and volatiles (mainly methane) that are stable in deep-sea sediments due to high pressures and low temperatures. Changes in oceanographic conditions that reduce their stability field (e.g. sea level lowering, bottom water warming) have been suggested to trigger continental slope failures. The Amazon...

The Amazon River supplies one of the world's largest deep sea fans, a sedimentary depocentre over 10 km thick that occupies an area of nearly 330,000 km 2 from the shelf-break to water depths greater than 4000 m. Gas hydrates have been inferred to occur within the Amazon fan, based on seismic profiles showing discontinuous bottom simulating...

The stability of natural gas hydrate accumulations on continental margins has mainly been considered in terms of changes in seawater pressures and temperatures driven from above by climate. We present evidence from the Amazon deep-sea fan for stability zone changes driven from below by fluid upwelling. A grid of 2D and 3D multichannel seismic...

The Amazon River extends from the Andes to the Atlantic continental margin and has the world's highest flux of suspended sediment and terrestrial organic carbon to the ocean, leading to the formation of one of the world's largest deep-sea turbiditic fans, 10 km thick, down to water depths of 4500 m. The fan is undergoing gravitational collapse,...

The Brazilian continental margin contains natural gas hydrate (NGH) provinces known from bottom simulating reflections (BSRs). In the Amazon deep-sea fan, a BSR is recognised on the upper slope (700-2250 m depths), within a thrust-fold belt linked to gravitational collapse of the up to 10 km thick depocenter above detachment surfaces. Recurrent...

The submarine fans of large rivers are important sites of long-term carbon storage, but are also settings in which the rapid deposition of organic-rich sediment drives linked processes of gas and gas hydrate formation, fluid expulsion, mass failure and gravity tectonism. The Ama- zon River culminates in one of the world's largest deep-sea fans,...