Daily Science Report, 13 September 2014 LOCATION: Hole U1441A (28°25.6379′N, 142°43.5390′E, 4447 m water depth; proposed Site BON-6A) SCIENCE UPDATE: Cores U1441A-15R to 20R penetrated from 131.5 to 189.9 mbsf and recovered 5.9 m (10%). A wiper trip was conducted from 82 to 187 mbsf and 2.7 m of fill was cleaned from the bottom of the hole. Cores U1441A-10R and 13R–16R contain a homolithic breccia deposit that is well cemented in Cores 14R–16R and composed of angular to subrounded volcanic clasts in a matrix of coarse volcanic sand. All of the lava clasts are likely from the same flow or source. Large, coarser grained clasts are found in the upper parts of Core 10R. Below that fine-grained to aphanitic volcanic clasts dominate. The coarser grained clasts have diktytaxitic textures and rare pipe vesicles. The fine-grained to aphanitic volcanic clasts are characterized by segregation pipe vesicles up to several centimeters long, and commonly retain portions of their chilled or glassy margins, showing that they originate from a pillow lava flow. The segregation vesicles are filled with a frothy glass, probably formed by continued outgassing of the late stage intra-telluric melt from the crystalline portion of the rock. Pipe vesicle orientations within individual clasts are subparallel, but their orientations vary widely between pieces, indicating that these are in fact clasts and not an intact lava flow. This is consistent with the recovery of well-cemented breccia in Cores U1441A-13R and 14R. The Hole U1441A rocks are interpreted to represent a mass wasting deposit.
Posted on: Sun, 14 Sep 2014 21:15:13 +0000
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