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IODP Expedition 330 Louisville Seamount Trail

Daily Science Report 31 -- Tuesday, 11 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

Cores U1374A-27R to -33R (140.0-182.3 mbsf) were retrieved with 91% recovery and continue to deliver variably altered volcaniclastic breccia. It is still unclear to what extend the breccia was transported and reworked before deposition. Some intervals appear autobrecciated (possible lava flow fragments) other intervals represent sedimentary interbeds (with bivalve fragments between volcanic clasts). Well-preserved clasts can be found next to completely altered material whereas other clasts have a relatively fresh interior but show broad alteration rims. Overall, the breccia seemed to be of diachronous origin (rock unit of varying age) with volcanic material (clast, lava fragments) forming the bulk of the material with some cracks and voids subsequently filled by background sedimentation. Eventually, calcite and occasionally zeolite precipitated in the remaining space.  Minor, possible in situ (?) lava flows can be found within the breccia such as in Sections U1374A-31R-6 and -32R-4 but the description of these units is still underway. Meanwhile, the co-chief scientists and expedition manager are busy reviewing the site reports submitted for previous Site U1373.