Acoustically stratified seismic images are widely used in studies of sedimentation mechanisms producing thick sedimentary aprons on continental rises. However, insuffcient vertical resolution of seismic records commonly restricts a more detailed interpretation of individual reflectors within accumulations to reconstruct specifc short‐term sedimentological events. (Reflectors correspond to boundaries between sedimentary layers with different acoustic properties and are imaged in seismic records as continuous lines.) Very high resolution (VHR) seismic profiling conducted during Cruise 33 of the Russian research vessel Akademik Ioffe (2011) provided correlation of acoustic reflectors, distanced from one another by less than 50 centimeters, with thin sedimentary layers recovered by gravity cores.
Комплексными исследованиями (эхолотирование, сейсмопрофилирование, магнитометрия) в 42 рейсе НИС «Академик Борис Петров» (2017 г.) была исследована подводная гора в основании западного склона древнего северного сегмента Восточно-Индийского хребта в районе 0.5° с.ш. В результате выполненных исследований выявлены особенности морфологии, разломной тектоники и глубинного строения этой вулканической постройки. Восточно-Индийский хребет образован магматизмом плюма Кергелен на 50° ю.ш. в зоне гигантского меридионального разлома. Исследованная подводная гора образовалась намного севернее в результате двухэтапного магматизма в поперечном разломе ЮЗ-СВ простирания, что определило ее линейную форму. Сначала на первом этапе (68.5 млн лет назад) на 42° ю.ш. образовалась ее основная западная часть, а позже (50 млн лет назад) на 28° ю.ш.-восточная. Интервал времени между формированием основного массива Восточно-Индийского хребта и этапами последующего магматизма, образовавшего западную и восточную вершины горы, составляет около 9.5 и 28 млн лет соответственно.
The Osborne Plateau is a large intraplate elevation in the eastern part of the Indian Ocean, which has been poorly studied by geological and geophysical methods. In cruise SO258/1 on RV Sonne, were collected new data with Parasound seismic profiling and multi-beam echo sounder survey. Fractures in the sedimentary cover, which extend to the bottom surface, indicate on high neotectonic activity in the area of the Osborne Plateau. It can continue up to the present, as well as in the adjacent segment of the Ninetyeast Ridge, where strong earthquakes are recorded. Two reflectors in the upper part of the sedimentary cover mark global regressive changes in the World Ocean level at the boundary of the Miocene / Pliocene and Pliocene / Pleistocene. The reflector in the sediments at the boundary of the Lower / Upper Pliocene is associated with a change in the regional hydrodynamic regime at the time in the eastern Indian Ocean. The rocks dragged on the Osborn Knoll are identical to volcanic rocks of the Ninetyeast Ridge, confirming their assumed genetic similarity, but they are more identical to basalts of the Kerguelen plateau. Extremely modified vitroclastic tuffs appear to have been formed as a result of explosive volcanic eruptions of alkaline basalts or foidites in subaeral or relatively shallow water conditions and represent the most recent eruption in the region.
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