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IODP Expedition 330 Louisville Seamount Trail

Daily Science Report 26 -- Thursday, 6 January 2011


Site U1374 on 28.6°S Guyot 28° 35' 44.9988" S, 173° 22' 49.8" W
Louisville Seamount Trail
0 m above sea level

Today’s Cores U1374A-2R  (9.6-14.4 mbsf), U1374A-3R (14.4-20.4 mbsf), and U1374A-4R (20.4-25.1 mbsf) were retrieved with recoveries of 91%, 54% and 76% respectively and record the transition from the thin sedimentary cover into the igneous basement of this seamount. Core U1374A-2R retrieved the same, light-brown cemented sandstone already seen at the bottom of previous Core U1374A-1R that was recovered the day before. In contrast to the unconsolidated, upper part of this succession, no foraminifers were found in the cemented lower part of the sandstone. The main components are altered volcanic rock particles and igneous mineral grains. However, Section U1374A-2R-4 contains a 25 cm thick gastropod-rich horizon. The bedding structure of the sandstone indicates turbidite-like deposition. The sandstone is discordantly underlain by a thin (~ 1 m recovered) layer of conglomerate. Its well-rounded clasts are made of basaltic rocks coated with a thin layer of manganese and spotty annelid tube fossils. Below the conglomerate, a 10 cm thick foraminifer-rich limestone marks the transition to the first lava flow, which defines the top of the igneous basement at U1374A-3R-2, 89 cm (corresponding to 16.7 mbsf). The lava flow is composed of a highly pyroxene-olivine-phyric basalt that appears very similar to the uppermost flow that was found at the previous Site U1373 (located just 5.6 nm away on the eastern side of this seamount).