992 resultados para 162-984


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Sediment spectral reflectance measurements were generated aboard the JOIDES Resolution during Ocean Drilling Program Leg 162 shipboard operations. The large size of the raw data set (over 1.3 gigabytes) and limited computer hard disk storage space precluded detailed analysis of the data at sea, although broad band averages were used as aids in developing splices and determining lithologic boundaries. This data report describes the methods used to collect these data and their shipboard and postcruise processing. These initial results provide the basis for further postcruise research.

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The Cenozoic volcanic activity on Iceland has been recorded in North Atlantic sediments drilled during several Ocean Drilling Program (ODP)/Deep Sea Drilling Project legs (Legs 104, 151, 152, 162, and 163). Leg 162 (North Atlantic-Arctic Gateways II) recovered ash layers at Sites 982, 985, and 907 (Jansen, Raymo, Blum, et al., 1996, doi:10.2973/odp.proc.ir.162.1996). The revisited Site 907 was first drilled during Leg 151, and the ash from this site has been described in detail by Lacasse et al. (1996, doi:10.2973/odp.proc.sr.151.122.1996) and Werner et al. (1996, doi:10.2973/odp.proc.sr.151.123.1996). Site 982 is located within the Hatton-Rockall Basin on the Rockall Plateau, which is situated west of the British Isles. Site 985 is located northeast of Iceland at the foot of the eastern slope of the Iceland Plateau, adjacent to the Norwegian Basin. Here we report chemical analyses of Neogene tephra layers from Holes 982A, 983B, 982C, 985A, and 985B. The sedimentary sequence at Site 982 spans the lower Miocene-Holocene; Site 985 recovered sediments spanning the upper Oligocene-Holocene. Twenty-two distinct ash layers and ash-bearing sediments were sampled in Holes 982A-982C (Cores 162-982A-16H through 24H, 162-982B-14H through 56X, and 162-982C-15H through 27H), and 59 ash layers were sampled in Holes 985A and 985B (Cores 162-985A-11H through 59X, and 162-985B-11H through 14H). Almost 50% of the sampled ash is strongly altered (predominantly from Site 985). A cluster of altered thin layers in the lower Pliocene of Site 985 (top of Unit III) is remarkable.