Wednesday, September 28, 2016

Introducing the crew

Welcome to the Tan-1611 blog! My name is Jack Whattam. Normally you would find me studying for an MSc in Geology at Victoria University of Wellington, having almost finished my first year I will be starting a thesis project looking the 2011-2012 Puyehue-Cordon Caulle eruption in Southern Chile.  However, I am taking a short break from studies as I was lucky enough to be offered a place onboard the R/V Tangaroa with GNS and NIWA to conduct research along Colville Ridge.

Fig. 1.  The R/V Tangaroa berthed at Centre Port in Wellington to load on supplies and scientific gear.

The 5- 17 Ma old Colville Ridge is a major 1300 km long submarine feature extending from north of New Zealand towards Fiji. Between 31˚S and 33˚S the Colville Ridge has never been mapped in detail or sampled and is therefore virtually unknown. This voyage builds on two previous voyages in 2013 and 2015 mapping the Colville Ridge further south (Fig. 2)

The TAN1611 voyage will survey the seafloor topography and recover rock samples from the Colville Ridge between 31° S and 33° S (see Fig. 2).  More specifically, this involves using multi-beam sonar, magnetic, and gravity measurements of the seafloor along a series of transect lines, followed by dredging to bring up rock samples.  The multi-beam, gravity, and magnetic data are used to create maps on the seafloor while the dredging operations ‘ground truth’ these other observations.

The information gained from this trip will provide a framework for further work looking at seafloor geology of this Colville Ridge section to better understand the highly dynamic tectonic history of New Zealand’s vast marine territory. These maps furthermore provide the framework for following research expedition using high tech equipment such as autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs).

 
Fig. 2 - map of voyage survey area.

Before leaving the Wellington harbour we had to run some safety tests, checking that the rescue boat was in good working order and calibrating the ships compass, as well as inducting the newbies like myself into the way of ship life. We departed from Wellington at 2 pm on Monday the 26th and made our way around Cape Palliser and northwards on our ~60 hour transit to the research area. 

The first 36 hours of transit were over rough seas and a few of the crew fell to the dreaded seasickness.  The weather has cleared up for now and everyone seems to have perked up.

The sea conditions then (left) and now (right). The photos don't do justice to the change in swell height and surface chop from day two to day three.
 
Fabio and Christian unloading the magnetometer for setup and dry testing before we arrive at the study site.



While we are still in transit life onboard is still relatively quiet so I will take this opportunity to introduce the other members of the scientific crew:

Fabio Caratori Tontini (GNS Science) - Fabio is a marine geophysicist, and one of the two cruise leaders and chief scientists onboard the R/V Tangaroa.  He will be in charge of running the gravity and magnetic surveys of the seafloor.

Christian Timm (GNS Science) - Christian is a petrologist and the second cruise leader and chief scientist.  He will be in charge of the rock dredging at the end of the trip and will be assisting with the collection of geophysical data for the first two weeks.

Tineke Stewart (GNS Science) - Tineke is a technician in the marine geoscience department at GNS Science. Her role for this voyage will be to assist with the collection of multi-beam bathymetric data.

Tim Kane and Susi Woelz (NIWA) - Tim and Susi are multi-beam technicians from NIWA and will be in charge of the running of the multi-beam instrument with help from Tineke.

Rachel Barrett (Victoria University of Wellington) - Rachel is geophysicist in the middle of her MSc thesis year at Victoria University.

That is all for now, but look out for updates over the next few weeks as we get stuck into the science.

Monday, September 12, 2016

Colville Ridge

GNS scientists are embarking on a 21 day voyage to the northern Colville Ridge NE of New Zealand to undertake the first ever systematic marine survey of the seafloor in this area.

The survey will collect a suite of geophysical parameters such as gravity, magnetic and bathymetry data as well as rock samples collected by dredge.

This voyage builds on two previous surveys of the southern and mid Colville Ridge undertaken in 2013 and 2015 respectively, providing the first comprehensive seafloor map and geophysical data sets. Combined, these new data sets will provide fundamental information to scientists studying plate tectonics, mineralization and understanding the geological setting NE of New Zealand.