Archive of September 25th, 2007

Teacher at Sea log for September 25, 2007

One of the most interesting lines of study the scientists aboard this cruise pursue is the trace element and isotope composition of these rocks. These chemical fingerprints can tell us something about the composition of mantle plume that is hypothesized to form Hawaii. It is very important that all the rocks are collected in situ, and that all the rocks' origins are correctly labeled, so that the composition and morphology on the seafloor can be confidently and correctly mapped. A map of seafloor composition can help explain how composition varies with position in the mantle melting zone. Therefore, all of the members of the science team take time to describe the samples in the lab.

Once the rocks have been removed from the Jason 2 the team is meticulous to document where the rock came from. The rocks are each assigned a bag with the number of the dive and the number of the sample. The bags accompany the rocks through many steps. These steps include photographs, weighing, sketching and measuring. Ultimately each bag with its rock is stored in a 5-gallon bucket until it is carried to the university lab.

Everyone has noticed that Ashton and Ines have done a particularly wonderful job sketching the rocks. Their artistic skills are definitely appreciated by the entire science team.

Science Update by Ashton Flinder

The geological cruise has officially reached its halfway point and recent samples currently being collected from dive 300 should prove to be interesting. The weather remains only slightly sub par with isolated showers and mild trade winds.

Several distinct morphological characteristics have been noticed on dive 300 over the last two days. Characteristics include the increase in size and population density of fragments as a talus slope is approached. Slopes are typically marked by a distinct border of rapidly increasing inclination covered with medium sized intact pillows (typically around half a meter large). Slopes are mostly devoid of small clastic fragments, while the surrounding area leading up to the slope is pillow poor.

Prominent rippling in the sediment bottom has also been a distinct mark of the local terrain of dive 300. Crested ripples vary in wavelength between 5 to 25cm and are oriented along an east west axis, indicating north to south flow. These contour ripples have also been observed to be incorporated in areas of extensive tabular lithification, suggesting they could be long lived.

Dive 300 will end Tuesday evening after which the science team will make way to the northwestern side of Middlebank. Here the team will perform a bathymetric survey in order to identify possible locations for dive 301.

Presented by the School of Ocean and Earth Science and Technology at the University of Hawaii, with financial support from the National Science Foundation.