Shatsky Rise and large igneous provinces

One more day, and we'll be deploying seismic gears, i.e., to be ready for a seismic survey over Shatsky Rise. In case you've just started to follow this blog lately, I'd like to explain (briefly) why we're taking so much pain to get to this place called Shatsky Rise. First of all, there are some unusual regions called "Large igneous provinces" on this planet, which are highlighted by red in the map shown here. These provinces have very thick crust, meaning that they are products of intensive volcanic activities in the past. The western Pacific is particularly loaded with quite a few massive oceanic plateaus such as Ontong Java Plateau, Shatsky Rise, and Hess Rise, all of which are classified as large igneous provinces. One of the biggest problems in earth sciences right now is why and how these provinces are formed. Shatsky Rise, for example, is as big as the state of California, and geologically speaking, it was formed nearly instantly. The scale of volcanism is thus much more substantial than our familiar volcanoes. The formation of these oceanic plateaus represents extreme events in Earth's history, but nobody is sure why we have such things to begin with. Of course, we have hypotheses and speculations, and people are debating endlessly who is right, but here's a fact: we just don't have good enough data to test any hypothesis with confidence.

So, this is why we're sailing to Shatsky Rise and get some deeply-penetrating seismic data, which will help us distinguish between various ideas. But wait a minute. Why did we choose to study Shatsky, instead of other plateaus? We have several good reasons, and one of them is that we already know that the rise was formed at a ridge-ridge-ridge triple junction (situations about other plateaus are much more ambiguous). If you don't know about this geological jargon, don't worry. In this context, it just means that this special geological setting allows us to interpret seismic data in a very simple way. Getting clear-cut data is vital, especially when people have been debating for so many years.

The team "awesome"

Sam, Cécilia and Adria

Hello!

It’s eleven o’clock and it’s the team "awesome" which is at the controls. What is this unbelievable team? The team "awesome" is an international group composed of Sam, the Chinese, Adria, the Spanish and me, Cécilia, the French. Our shift is from 4PM to 12AM. As we are still traveling to Shatsky Rise (right now, we are approximately at 26° 154°E), we aren’t really busy and we have to find fun activities to stay awake. And so far, we have always been inspired. For example, last night we played cards and the loser had to execute a punishment like find a camera on the ship in a limited time and make a sign to others in the science lab, keep one’s balance during one minute… not easy on the ship (believe me), or keep in mind 15 words without any connection. Now when you say « chocolate» to Sam he will reply instinctively « computer »!

My name is Cécilia Cadio. I received a PhD from Institut de Physique du Globe de Paris. Since August 2011, I am postdoc at Yale and I work with Jun Korenaga. My current research focuses on the thermal structure of the oceanic lithosphere and on its interaction with the underlying geodynamical processes from gravity and bathymetry data. Although my research is not related to the study of the Shatsky Rise, I’m really happy to take part to this research cruise and to learn new things about seismics. Moreover, I come from Brittany, a land of sailors… and the best region in the world. So I could not resist to the call of the sea!

A message from the South Atlantic

Hello readers, this is Will and I am almost exactly half a world away from Langseth. You may have seen in other blogs that I am one of the PIs on the Shatsky seismic project, was there for the previous cruise of Langeth in 2010, and was supposed to be there this time. Unfortunately, ship scheduling did not permit it because I ended up with two cruises scheduled for the same time. I am currently on the R/V Melville in the south Atlantic Ocean where we have just wrapped up our work investigating the Walvis Ridge seamounts. I am at 35°S and 1°W, almost exactly at the spot half-way around the world from Shatsky Rise. Although we have just finished our work, it will take Melville about 4 days to get back to land because we are in the middle of the ocean. By that time, Langseth should be shooting seismic lines.

I had hoped to be onboard Langseth for this cruise, which is an extra cruise for our project because the last one had much bad luck and could not finish our seismic lines, even with 60 days at sea. For a while, it looked like I might have 24 hours to get from Cape Town to Yokohama (the original starting place for the Langseth cruise), but ship schedules shifted and the two cruises overlapped. There are many considerations in setting up ship schedules and PI schedules is only one of them. After 49 days at sea on the Melville, I’m not sure how useful I would be to my colleagues on Langseth because I have been working all that time without a break and I am very tired and my brain is about fried. When you are a PI on a cruise, you typically work 12 hours a day. Ship operations may not take your complete attention, so I am often working on writing a paper or a chapter for my textbook, but you need to be there and watching all the time so that if something goes wrong or a decision has to be made, you are on top of it. So for the last 45 days, I get up in the morning and have coffee, go workout, spend 12 hours or more in the lab, go to bed, and repeat. My biggest source of entertainment is to read a paperback novel for a little while before I fall asleep. Oceanographic cruises are very demanding, but there is no other way to get the data that we seek so far from land.

Getting time on the Langseth is huge for a marine geophysicist. We spend years writing grant proposals in hopes that we will be one of the lucky ones to get a cruise (which we hope to be able to go on). The Langseth is our “telescope” for seeing deep into the Earth to help unravel its secrets. Previous cruises to Shatsky Rise had only small-source, single channel seismic profiling equipment, so they could only see through the sediments to the top of the igneous rock (we often call it “basement”). With Langseth’s large airgun array and multichannel streamer, we have a system that can bounce sound waves off horizons that are many kilometers deep – and this can tell us about the structure of the Shatsky Rise volcanoes, which helps us to figure out how they formed. I will be following Jun and my students and hoping that the cruise will be successful. I know that they are in good hands with the Langseth seismic techs who are really good at what they do.

(posted on behalf of Will Sager)

Hello, Mariana

Good morning, world. Right now, we are approximately located at 20°N 150°E. This is the first blog that I have ever written so we will see how it goes. My name is Teddy Them and I am finishing my MS in Oceanography at Texas A&M University. After several weeks of contemplation, on the first day of this cruise I decided to accept an offer from Virginia Tech to begin a PhD this August. My current research at Texas A&M involves reconstructing past climate conditions by analyzing the geochemical properties and abundances of fossil foraminifera recovered from Florida Straits sediment cores. While at Virginia Tech, I will study the geochemistry, stratigraphy, and sedimentology of organic-rich shales deposited during the Early Jurassic in what is now British Columbia. Although my research is not related to the current cruise mission, I am interested in seismics and was given the opportunity by Will Sager (Co-PI) to be a watchstander on MGL1206.

Right now, my duties include logging coordinates and ocean conditions every 30 minutes and monitoring some of the equipment by constantly checking the monitors for anything abnormal. As you can see from the picture, this is enough to keep us all busy. I share my duties with Tanya (postdoc at the University of Wyoming) and Heidi (undergraduate at the University of Hawaii), who will also blog later this week. Because we are still traveling to Shatsky Rise, stress levels are low. However, I’m sure when we start the science portion of the cruise everything will change. Luckily, our shift is from 8AM to 4 PM, which gives us time to see every sunrise and sunset, something I am trying to advantage of each morning and evening.

Yesterday, we crossed the Mariana Trench, which I hope was a momentous occasion for all of us; it definitely was for me. This trench formed (and continues to form) because the Pacific Plate is slowly colliding with and subducting beneath the Mariana Plate, a process which has been occurring for millions of years. The result of this geologic process is an area home to the deepest part of the ocean, a section of the Mariana Trench called Challenger Deep. To celebrate crossing the trench, we tried to get as many of the crew as possible to sign a metal plate (see picture). For this occasion, I was given the opportunity to throw the commemorative plate off the ship and into the deep hadal zone some 8500 meters, or 5.3 miles, below us! Sam recorded the video as I tossed the plate off the ship and I’m sure I will enjoy that for a very long time. The seafloor is continuously being imaged by utilizing multibeam bathymetry data (you can see Mariana Trench in the middle of the picture).

I guess that's all I have to say for now. I look forward to updating everyone next week after we begin science operations.

Shatsky, see you in five days!

Since we started our voyage (#MGL1206) on R/V Marcus G. Langseth from Guam in the morning of Mar 24, 2012, it will take us about five days transit to the research site: Shatsky Rise. This is Sam writing this blog, a PhD student from Texas A&M university. Exciting to visit Shatsky again this year. Yes, I say "again" because I sailed on Langseth for 60 days in 2010, shooting seismic over Shatsky Rise. Actually, this cruise is a second leg of the 2010 cruise to finish up the multi-channel seismic data collection. I have been working with Dr Will Sager since fall 2009, in a study of the structure of Shatsky Rise oceanic plateau for my PhD degree. As you can tell from the above, I am kind of familiar with Shatsky Rise, R/V Marcus G. Langseth and seismic research cruise. One thing I can tell you is that Shatsky Rise is interesting enough to study due to various scientific rationale. As one of the largest oceanic plateau around the world, Shatsky Rise is important to exploring processes of basaltic volcanism and the formation and evolution of oceanic plateaus. However, it's poorly understood because it's submarine and in remote location from land, which makes it difficult to sample and study. But science is going on and that's why we are trying hard to acquire geophysical data in order to reveal the mysterious facts inside Shatsky Rise.


I will process the multi-channel seismic (MCS) data during this cruise with the help of ProMAX, which is a popular seismic processing program in industry. I still can remember my first time to use ProMAX to process marine seismic data is when I was on Langseth in 2010. Comparing to conventinal land seismic data processing which I used to work on before I came to US, marine seismic is relatively simpler. But we still need to be very careful to make sure things working well. Anyway, I have already got the experience on how to process MCS data from 2010 cruise, what I am going to do for this cruise is to basically apply the same flows and repeat the work once again.

Here is a picture showing the processing workstation I set up in the main lab on Langseth ship, and we named it Carina. It's sitting there quietly right now and waiting for the MCS data coming in after 5-day transit to the site.

Langseth sailed off

In the morning of March 23rd, I was able to meet successfully the rest of the science party and then headed to the U.S. Navy Base, where Langseth was located, and at 8 a.m. of March 24th, we finally sailed off to Shatsky Rise. It's really exciting to be back to Langseth, seeing all of these highly capable people.

Here I'd like to introduce our science party (shown above, without myself). From left to right, Yanming, Sam, Patrick, Heidi, Adria, Joey, Tanya, Teddy, and Cecilia. This is quite a diverse group. Yanming, Sam, Joey, and Teddy are from Texas A&M, Patrick, Cecilia, and myself from Yale, Adria from University of Barcelona, Tanya from University of Wyoming, and Heidi from University of Hawaii. This cruise is a collaboration between Yale (Jun Korenaga) and Texas A&M (Will Sager), but Will couldn't make it to the cruise because he's on a different cruise right now. I was initially planning to bring more Yale people, but some of them couldn't come, so Will and I looked for other places for watchstanders. I asked them to take turns and post a blog, so you'll read a lot more about them shortly.

By the way, when I got to my stateroom, I had a nice surprise from the previous chief scientist. There was a note on the desk with two bags of coffee beans, which reads "Jun, hope you have a productive and successful cruise! - Nathan Miller (chief sci. on MGL1205)." What a nice thing to do! Thank you so much, Nathan.

Leg 2 will start soon

OK, it's time to restart the blog. Leg 2 of Shatsky cruise will start on March 24th, 2012. This time R/V Marcus G. Langseth departs from Guam and arrives at Honolulu, Hawaii. I flew in Guam last night (very late, after 1AM). By the way, for those who are new to this blog, I'm Jun Korenaga, professor of geophysics at Yale, and the chief scientist of the upcoming cruise MGL1206.

I had never been to Guam, so this is my first time of being here. Actually, the original Shatsky cruise (Leg 1) was supposed to start from Guam, but because of several happenings which I'd like to forget and actually don't remember well any more, it was changed to depart from Honolulu (and end in Honolulu as well if you remember).

I found Guam kind of attractive. Not really crowded like Oahu, and quite calm. Maybe just because it's not a tourist season yet. Guam's economy is supported by tourism, which is composed mainly of visitors from Japan, and Japanese spring break won't start until next week. By the way, the photo above was taken from my hotel room. A cape-like feature in the middle is called Two Lovers Point. Sounds like a romantic place to visit, but I have a bunch of things to do before the cruise...

Until very recently, I thought Guam was part of the US. Well, it's a US territory, but I didn't realize that shipping to Guam from the mainland US was regarded as international. I was planning to ship a special kind of magnetometer to be used in this cruise, and asked the shipping department with a two-week notice. The magnetometer turned out to be a bit too expensive (as an international shipment), and a lot of paperwork was needed to 'export' it to Guam. To my greatest dismay, the shipping department couldn't ship it in time (darn!). What a hell, but this cruise is primarily a seismic cruise, so I can live with that.

Another, perhaps more critical problem is that my cell phone doesn't work in Guam, which I just found out last night. Doesn't AT&T have a coverage here? My plan is to meet the rest of the science party tomorrow morning and then leave for the naval base (where Langseth is located) together. I hope I'll see everybody then, so there will be no need to use a cell phone!