Anomalous subsidence on the rifted volcanic margin of Pakistan: No influence from Deccan plume |
| |
| Authors: | Grme Calvs Peter D Clift Asif Inam |
| |
| Institution: | aSchool of Geosciences, University of Aberdeen, Meston Building, Kings College, Aberdeen, AB24 3UE, United Kingdom;bGeowissenschaften, Universität Bremen, Klagenfurter Strasse, 28359 Bremen, Germany;cNational Institute for Oceanography, ST-47-Block 1, Clifton, Karachi 75600, Pakistan |
| |
| Abstract: | The role of hotter than ambient plume mantle in the formation of a rifted volcanic margin in the northern Arabian Sea is investigated using subsidence analysis of a drill site located on the seismically defined Somnath volcanic ridge. The ridge has experienced > 4 km of subsidence since 65 Ma and lies within oceanic lithosphere. We estimate crustal thickness to be 9.5–11.5 km. Curiously < 400 m of the thermal subsidence occurred prior to 37 Ma, when subsidence rates would normally be at a maximum. We reject the hypothesis that this was caused by increasing plume dynamic support after continental break-up because the size of the thermal anomalies required are unrealistic (> 600 °C), especially considering the rapid northward drift of India relative to the Deccan-Réunion hotspot. We suggest that this reflects very slow lithospheric growth, possibly caused by vigorous asthenospheric convection lasting > 28 m.y., and induced by the steep continent–ocean boundary. Post-rift slow subsidence is also recognized on volcanic margins in the NE Atlantic and SE Newfoundland and cannot be used as a unique indicator of plume mantle involvement in continental break-up. |
| |
| Keywords: | subsidence break-up plume Indian Ocean lithosphere |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
