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Gopala Rao, D.
- Marine Magnetic Anomalies off the Southwest Coast of India and Their Analysis
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Authors
Affiliations
1 National Institute of Oceanography, Dona Paula, Goa., IN
1 National Institute of Oceanography, Dona Paula, Goa., IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 18, No 9 (1977), Pagination: 504-508Abstract
The observed magnetic anomalies are explained by sources equated to magnetized dykes, tabular bodies and semi-infinite slabs running NNE - ssw and lying at depths ranging from 2.5 km - 8.0 km. These may be attributed to intrabasement faulting in the magnetic basement and intrusives into the weaker zones of the basement. The observed relief of the magnetic basement may be attributed to the faults in this region. Several steep flanked highs and a regional prominent flat-topped terrace were noticed from the bathymetry.Full Text
- Compressional Wave Velocity and Index Properties of the Gabbroic Rocks Drilled at Hole 1105A of the Atlantis Bank, Southwest Indian Ridge
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Authors
Affiliations
1 Department of Geology, Osmania University, Hyderabad - 500 017, IN
2 National Institute of Oceanography, Dona Paula, Goa - 403 004, IN
1 Department of Geology, Osmania University, Hyderabad - 500 017, IN
2 National Institute of Oceanography, Dona Paula, Goa - 403 004, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 65, No 5 (2005), Pagination: 609-617Abstract
Compressional wave velocities (Vp) and index properties of 70 mini- gabbroic rock- core samples of 2.5 cm diameter x 2.1 cm long from 157.1 m below seafloor in Hole 1105A of the Atlantis Bank, Southwest Indian Ridge, were measured in the laboratory. Comparison of the Vps and onboard lithostratigraphy revealed that the Vps of the gabbros and olivine gabbros are very close and have the values 6.74±0.04 and 6.7±0.07 km/s , respectively. Oxides and oxide olivine gabbros have markedly lower Vps (6.53±0.076 and 6.59±0.077 kds) respectively as abundance of Fe-Ti oxide ' minerals vary as a result of alteration processes. They are also consistent with well-log results of Hole 1lO5A and Hole 735 B from the bank. The mean bulk density of the rocks is 2.93±0.15 gm/c3. The other index properties - porosity, void ratio and grain density and their means are consistent with model populations of the rock minerals.Keywords
Compressional wave velocities, Physical properties, Cores, Gabbroic rocks, Atlantis Bank, Southwest Indian Ridge.
- Sediment Pathways and Emergence of Himalayan Source Material in the Bay of Bengal
Abstract Views :309 |
PDF Views:154
Authors
Affiliations
1 Geological Oceanography, CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, IN
2 CSIR-National Institute of Oceanography, Regional Centre, 176, Lawsons Bay Colony, Visakhapatnam 530 017, IN
3 KDM Institute of Petroleum Exploration, Oil and Natural Gas Corporation Ltd, 9, Kaulagarh Road, Dehradun 248 195, IN
4 Oil and Natural Gas Corporation Ltd, Geophysical Services, A&AA Basin, Luit Bhavan, Cinnamara, Jorhat 785 704, IN
1 Geological Oceanography, CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004, IN
2 CSIR-National Institute of Oceanography, Regional Centre, 176, Lawsons Bay Colony, Visakhapatnam 530 017, IN
3 KDM Institute of Petroleum Exploration, Oil and Natural Gas Corporation Ltd, 9, Kaulagarh Road, Dehradun 248 195, IN
4 Oil and Natural Gas Corporation Ltd, Geophysical Services, A&AA Basin, Luit Bhavan, Cinnamara, Jorhat 785 704, IN
Source
Current Science, Vol 110, No 3 (2016), Pagination: 363-372Abstract
The sediment succession in the Bay of Bengal (BoB) records the signatures corresponding to India-Asia collision, regional climate change, and erosional processes of both the Himalayan orogen and Indian subcontinent. The Bengal Fan-the world's largest submarine fan-has long been studied to understand the link between the Himalayan tectonics and Asian monsoon. But, lack of detailed information on corresponding signals hampered the understanding of related processes of tectonics, climate and erosion. The present study of long-streamer seismic reflection profile data and information from deep drill well logs in the western BoB has revealed two different phases of sediment deposition. In the first phase, until Oligocene- Miocene (∼23 Ma), Indian peninsular rivers discharged sediments to the BoB which accumulated at a rate ∼20 m/m.y. with an aberration of two fairly enhanced sediment pulses during the periods from 65 to 54 Ma and 34 to 23 Ma. In second phase, since 23 Ma, the Ganges and Brahmaputra rivers added huge volumes of sediments to the bay at variable rates ranging from 40 to >1000 m/m.y. A distinct increase in sediment discharge (∼140 m/m.y.) during the Oligocene-Miocene (∼23 Ma) together with the development of regional onlap unconformity and the start of turbidity system provide an important age marker corresponding to rapid exhumation of the Himalaya, which intensified the erosional process and commencement of Bengal Fan sedimentation. Further rise in the rate of sedimentation during the period 6.8- 0.8 Ma is coincident with the change in monsoon intensity, but surprisingly not in agreement with the decrease in sediment rate reported at ODP Leg 116 sites in the distal Bengal Fan. Here we provide wellconstrained ages for the commencement and growth of the Bengal Fan, which can serve as benchmark information for understanding the interaction between the Himalayan exhumation and Asian climate.Keywords
Asian Climate, Bengal Fan, Continental Collision, Himalayan Tectonics, Ganges and Brahmaputra Delta.Full Text
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