Koennecke, Lis Kathrin (1997): Early development of the southern Kerguelen Plateau (Indian Ocean) from ocean bottom seismograph and multichannel seismic reflection data. 85 pp., georefid:2003-064381

Cretaceous terrestrial and terrigenous sediment recovered from Ocean Drilling Program (ODP) sites on the Kerguelen Plateau (southern Indian Ocean) indicate a long history of subaerial exposure. We examine late syn- and early post-constructional processes on the southern plateau, using ocean bottom seismograph (OBS), multichannel seismic (MCS), and ODP data. Near-range OBS data are used to develop velocity-depth models for eight locations in the sedimentary Raggatt Basin. The resulting models are constrained by refracted and reflected signals, including multiples and converted shear waves, as well as by migrated MCS data. These models allow us to examine the characteristics and distribution of Lower Cretaceous lava flows, determine the extent and distribution of Albian to Coniacian/Santonian terrestrial and terrigenous sediments over the Kerguelen Plateau, and re-examine Maestrichtian and Paleocene seismic sequences. For the Albian/Aptian basement complex, predominantly composed of flood basalt, we define an upper and a lower series. The upper series is characterized by a P-wave velocity of approximately 4.7 km/s, an increase of intercalated terrestrial sediment and altered flow-tops towards the top, and a decrease in flow thickness, while the lower series is marked by velocities of approximately 5.4 km/s and contains thicker flows and less sediment. Similar observations have been made for Broken Ridge, and for large igneous provinces worldwide. A volcanic center in the Raggatt Basin is characterized by relatively low seismic velocities, and dipping reflections at the flanks of Raggatt Basin have been recorded as refractions. Terrestrial and terrigenous sediment of the Raggatt Basin, immediately overlying basement, is characterized by a seismic low velocity layer with velocities ranging from 2.2-2.9 km/s and a thickness of more than 1100 m at the center of the basin. Nearby source regions (e.g. Banzare Bank and other elevated areas south of the basin) account for a terrestrial and terrigenous sediment volume of approximately 12,500 km3, deposited over approximately 20 my. A major shift in the depositional center of the Raggatt Basin began during Santonian to early Maestrichtian time, and concluded by early Late Paleocene time in the central basin, earlier than previously assumed.
West: 62.0000 East: 80.0000 North: -45.0000 South: -62.0000
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Provider: SEDIS Publication Catalogue
Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=2003-064381 (c.f. for more detailed metadata)
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