Daily Science Report: Saturday February 5th

Jason surfaced at just after 8am with a haul of 15 more rocks which means we now have over 300 samples on board. We specifically targeted the dike-gabbro transition and we were successful in bringing back an equal mix of gabbros and dikes. Next we carried out another short magnetometer and multibeam survey. Finally, we launched Sentry, now decorated with the Patriots logo and Nemo like eyes, at 1:30pm in the south-eastern end of site B for a 20 hour dive to look for more lower crustal gabbro outcrops. Fingers crossed that tomorrow we see a Sentry map which reveals numerous targets for us to dive on.

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Daily Science Report: Friday February 3rd

Daily Science Report: Friday February 3rd

Sentry was recovered at lunchtime and another superb Sentry map showed exactly where the outcrops were, but alas, none at the deepest depths. We carried out a brief ship multibeam and magnetometer survey to get us to the launch site for Jason and we sent off Jason to search for gabbros at the base of the sheeted dike outcrops, which are clearly visible on the two previous Sentry maps and ground-truthed by dives from the 2005 Atlantis cruise led by Jeff Karson. We completed processing the rocks from the previous Jason dive & interestingly the sampling suggests an abrupt gabbro dike transition.

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Daily Science Report: Thursday February 2nd

Daily Science Report: Thursday February 2nd

We recovered Jason at 8am and eagerly anticipated looking at our haul of 44 new samples from near the gabbro-dike transition. We had zig-zagged up a transect which covered 950 vertical metres and found plenty of outcrop and…. lots of slope parallel low temperature faults. Extensive fault surfaces were common with clear slickenlines in both outcrop and hand sample. We mostly recovered gabbro of various types, with intruding dolerite dikes in the upper part of the section, but the majority of the rocks have a low temperature cataclastic overprint. We then briefly deployed the magnetometer to get a new magnetics traverse as we migrated back to site A and we launched our second Sentry dive in that area at noon. This time, Sentry worked upslope towards more steep, difficult, terrain and we plan to site our next Jason dive tomorrow based on this mapping. We now have 9 days left and are starting to feel the pressure to get everything completed before we have to leave for Chile.

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Daily Science Report: Wednesday February 1st

Sentry came back on deck at 11am and we were soon looking at a new 1-2m resolution 4 x 2km bathymetric map of the SE part of site A. Unfortunately the deeper slopes are largely sediment covered and so, not good targets for finding gabbro outcrops. We are hoping the next Sentry dive to the NW will produce the outcrops we need. But despite, the lack of outcrop, we did collect another important magnetics data set to help define the 3rd dimension of the magnetic stripes. At approx. 1pm, we launched Jason for a short 1 day dive aimed at sampling the gabbros below, and also across, the gabbro dike transition at site B. We used the previous Sentry map to find outcrop and have been zig-zagging our way up the steep slope trying to map and collecting samples. The area is clearly extensively faulted, and we’ll likely have a complicated puzzle to solve tomorrow.

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Daily Science Report: Tuesday January 31st

Our Jason “Freeblast” transect ended at 6am & we recovered Jason on deck at about 8:30am. We now have 242 samples totaling ~ 2600 lbs in weight, and we are currently processing the samples that came on board with Jason. As soon as we recovered Jason we moved to site A, which is a another fault bounded block, 18km to the WNW of site B and launched Sentry for a 20 hour dive. Our main target here is mapping the 3rd dimension of the magnetic stripes, but we’re also looking for deep gabbro outcrops. Tomorrow we dive with Jason on the upper most gabbros near the dike-gabbro transition at site B. Lucas took some stunning shots of Jason during recovery using a camera attached to the end of a recovery pole. Forthcoming attractions on the web include “a day in the life of a rock.” – not to be missed. Weather is good & getting better and we’re hoping for more successful dives during the remaining 11 science days.

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Daily Science Report: Monday January 30th

We just completed our “Zodiac” transect with Jason after another elevator run and are about to start a short transect which we’ve called “Freeblast”. At times, today’s dive made the pilots concentrate, with near 100m high, vertical, gabbro walls of massive gabbro, which were also very difficult to sample. But, we now have209 samples on board and expect to get close to 250 by the time Jason is recovered in the morning. Next we move over to site A and will be surveying with Sentry tomorrow & mapping the 3rd dimension of the magnetic stripes at that locality. Star rock of the day is a pyroxene bearing troctolite, with 4cm diameter, dendritic, olivines and rare 3cm long clinopyroxenes. 

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Daily Science Report: Sunday January 29th

Today is scientific “hump” day, the term we use for passing over the half way point. The overall cruise “hump” day is still to come, but we now have just 13 days left to do science. Today was all Jason. We finished the “tangerine trip” dive, and started a new traverse which we called the “zodiac” dive. We completed last nights elevator recovery and have just carried out another elevator recovery tonight. Now we have 187 samples on board, and importantly, many are oriented. Over 175 are gabbros and we should pass the 200 sample mark tomorrow. There is a high proportion of classic 30% plagioclase, 30% olivine, troctolite and we even saw and sampled a 1 metre diameter “splotch”  of anorthositesitting in the middle of the troctolite unit. Igneous layering is quite common and we’ve noticed one example of possible isoclinal folding.  Last, but not least, a spectacular squid came to visit Jason today. The video will be on the site soon.

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Daily Science Report: Saturday January 28th

We recovered Sentry at 8am and immediately moved to the location where we left the last Jason dive, now informally termed the “tangerine trip” dive (with the previous dive now called “the nose” dive and the 2005 dive in this location, the “prophet” dive). So far we have 22 more rocks on board Jason and an elevator will soon bring these rocks back to the ship. As with earlier dives, the outcrop is extensive, with in places 90m high cliffs, and we’ve been making extensive field observations as we go along. One of our key tasks is to recognize and understand the three sets of faults in our area: i) the ridge related abyssal hill faults, ii) the Pito Deep rift related faults and iii) a later generation of related, small offset, faults reflecting gravitational collapse of the steep walls of the Deep. Description is complete for all of the rocks from the previous dives. The next 25 or so should be on deck early tomorrow morning.

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Daily Science Report: Friday January 27th

We recovered Sentry at 10:00am in the morning and eagerly awaited it’s data. The bathymetry revealed a very steep (60-70o) back wall, but few outcrops beneath those we already knew about. We also extended our magnetic mapping of the third dimension of the magnetic stripes. During the day we carried out another short ship multibeam and magnetometer survey, extending our map to the south and crossing onto the Easter microplate. At 7pm, after re-charging it’s batteries, we launched Sentry again for another survey. Fingers crossed the weather is good to launch Jason in the morning. Finally, we also oversaw the good ship “Jackelope” undergoing its first “sea-trials”. The plan is to launch it from the Atlantis as we leave the area. NOAA will track its journey across the Pacific at this website http://educationalpassages.com/boats/00-171000921/

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Daily Science Report: Thursday January 26th

The multibeam & magnetometer survey ended at 9am & we immediately launched Sentry for another ~ 24 hour survey (dive 422) on very steep terrain which exposes the dike-gabbro transition. Once again we are collecting bathymetric data, magnetic data and also “sniffing” for possible vent fluids. If we see a significant area of exposure below this transition, we’ll be back to sample with Jason. Sentry will be recovered in the morning & in the meantime we’ve continued to cut & describe the rocks we have.

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Daily Science Report: Wednesday January 25th

We recovered Jason at 10:30pm & now have a collection of samples representative of ocean crust: ~130 gabbro samples, 1 sheeted dike and 2 basalts. We spent most of the day doing a lateral sampling traverse to connect up our first dive to Jason transect 3 of the Jeff Karson led 2005 cruise to Pito Deep. As in earlier reports, the outcrop is near 100%, permitting us to photograph field relations such as layering and cross cutting relationships and to track both the abyssal faults and the later rift related faults. Samples weigh up to 30 kilos and many show spectacular layering/foliation/fabrics; we even produced a 3-D image of one of the gabbros; the first “virtual rock” collected at sea? Maybe in the future, rock sampling cruises will produce 3-D images/reconstructions of all samples? Just before midnight, we put out the magnetometer and set off the multibeam the NW corner of our site. Sentry launch in the morning.

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Daily Science Report: Tuesday January 24th

“We went, we saw, … & were surprised”. Yesterday night, we took Jason to the western part of our site hoping to extend our gabbro transect and instead found beautiful outcrops of EPR (East Pacific Rise) pillow basalts and dikes at 5.0km, almost 2km below the dike-gabbro transition in the centre of our study site. But, it was important to ground-truth these outcrops, especially for the magnetic inversion, and it taught us a cautionary tale regarding being careful about the Pito Deep rift faulting at the site. So instead, we performed a reconnaissance survey of the south western part of this site and returned to the main gabbro outcrop site (~4500m) at 11:00am. Since then we’ve been collecting more gabbros on traverse that links our first traverse to the one from the Jeff Karson 2005 cruise to this area. Highlights included spectacular modal layering, but I leave you to guess whether it was dipping away or towards the ridge.

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Daily Science Report: Monday January 22nd

Another day, another dive. We recovered Sentry in the early pm & looked at another spectacular bathymetric map, which we used to site part of the next Jason dive, which was launched after dinner. Today’s target is to go deep, to 5.1km below sea level, in order to try to get a deep section of the gabbroic crust. There’s definitely outcrop down there- but is it gabbro?? We’ll find out later this evening. Rock cutting & describing from the latest dive was also proceeding well. The uppermost samples are much more heterogeneous compared to those below, with very large variation in grain sizes, high aspect ratio plagioclase, veins and cross cutting dikes. We also did two successful live broadcasts to schools today.

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