Daily Science Report 10 -- Thursday, 23 February 2012
We continue to traverse to the northeast in between the Tristan and Gough seamount trails (see region map). This middle seamount trail is proving challenging to acquire good basalt specimens. Two dredging attempts were made at Mapple but no ideal (or even less ideal) samples were recovered. We recovered pelagic ooze (full of calcareous critters) and a few fist size rocks. During one of the attempts the dredge’s chain net managed to get flipped over and back inside the dredge, thus blocking the dredge from recovering any material.
While heading over to the seamount northeast of Mapple on the way to Hosea we discovered an unknown small seamount that we aptly named after a small Beluga whale. This small seamount has now provided us with the best specimens as of yet. The pictured sample below is of a vesicular pillow basalt from Beluga. Another dredge attempt at Hosea produced mainly manganese crusts and lithified sediment with only a small amount of basaltic debris.
In the center of the sawed face we observe a great cross-section of pipe vesicles that are created by gas (e.g. CO2, SO2) rising upward and coalescing together when the hot magma out gases upon its eruption. As the lava cools the ‘pipes’ are frozen in their position when the lava crystallizing around the trapped gas. Pipe vesicles point toward the cooling surface, in this case the light/dark brown rim shown at the top of the basalt in the picture.
The weather has been amazing with mostly clear blue skies and calm ocean waters. Unfortunately right now it looks to be a little stormy to the south, which is where we are currently heading.
Daniel Heaton
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