Daily Science Report 22 -- Sunday, 2 January 2011
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Drilling in hole U1373A slowly progressed (with 1 m/hr average penetration rate) but with increasing drilling depth more weight can be applied on the drill bit resulting in progressively faster penetration. Cores U1373A-2R (9.6-14.1 mbsf), -3R (14.1-18.6 mbsf), -4R (18.6-23.8 mbsf), -5R (23.8-28.0 mbsf) and -6R (28.0-32.7 mbsf) were retrieved with 53% average recovery. The cores show a succession of conglomerates and breccias with volcanic clasts up to boulder size. Nine different clast types could be identified based on distinct phenocryst assemblage and vesicularity. The conglomerate in Cores U1373A-2R and -3R possibly host two brecciated lava flows. The interval from the bottom of Core U1373A-3R to the end of Core U1373A-4R is interpreted as “beach rock”, a slightly carbonate-cemented sediment consistent of bedded sand and gravel with abundant biogenic components (shell fragments). It contains well-rounded volcanic clasts. The largest clast (U1373A-4R-1A, 0-20 cm, #1) is covered by annelid tube fossils. At noon, the site summary meetings for previous Site U1372 continued with presentations by the Igneous Petrologists, Structural Geologists and Alteration Petrologists.
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