All good things come to an end and so does the Archimedes-I cruise. For 48 days, 39 scientists and 31 crew members were onboard of the RV Sonne, cruising the Lau Basin in the south-west Pacific. The cruise was one of a kind because in contrast with other large cruises, on which many different disciplines work on a variety of scientific topics, the Archimedes-I cruise combined forces by integrating various techniques to investigate one overarching question: What processes drive crustal growth in the intra-oceanic domain?
Welcome to Fiji. © Philipp Brandl
To answer that question we acquired 46.600 km2 of bathymetry, magnetics and gravity data. This is the equivalent of 7 percent of the Tongan land and sea surface, which is quite an impressive number! We dredged 41 stations and recovered a nice assembly of rock types from an arc-back-arc domain. The Automated Underwater Vehicle (AUV) did 8 dives for high resolution mapping. We acquired 960 kilometers of reflection seismic data with a 4 km long streamer and we deployed 130 OBS stations along three profiles with a total length of 630 km and, very important, a 100 percent recovery rate. Heat flow and gravity coring was attempted and even though it was more difficult than anticipated to break through the top layer of volcanoclastic rocks, we managed to add some more datapoints to this area.
Even though it was more difficult than anticipated to break through the top layer of volcanoclastic rocks, we managed to add some more heat flow and gravity coring datapoints to this area
We have been extremely lucky with the weather. There was only one day we couldn’t work because of the tropical cyclones that were passing through the region. Besides the good weather, we could not have acquired this vast amount of data without the many people with different disciplines who worked together to make this happen. This is not an easy task, but throughout the cruise the spirits were high and this added for sure to the productiveness of the cruise.
Apart from the collaborative scientists, we could not have performed so well without the skilled crew of the RV Sonne. The OBSes would still be floating around and the dredges full of rocks would have never made it to the deck without ‘die mannschaft’. Come to think of it, we would have never left the harbour without them. A very big ‘thank you’ to the crew is in place here.
Welcome to Suva. © Philipp Brandl
Since this is the last blog entry of a series of blogposts on the Archimedes-I cruise, the circle of our voyage would not be complete without some anecdote about our return to the harbour. I’ve written about lost luggages, packing the ship and leaving the harbour, about how to stay fit onboard, about superstitiousness at sea and about women roaming the oceans. Like always at sea, life is a bit unsure and the schedule can change in no-time. As I am writing this, we are in transit to the port of Suva, Fiji. We are not sure yet if we will have a place in the harbour, maybe we will lay at anchor for some time. There is also some excitement going on with the containers in which we store our equipment, because some of them have not yet arrived. This cruise has been full of unforeseen challenges, but we have dealt with them all. So the only thing left to do is hope that these containers arrive and we can go into port. And even if this doesn’t work out as scheduled, tomorrow we will see some land, at last.
Many thanks for following this blog and keep the wind in your sails!
This blog post was published at the cruise's website on 26 January 2019.