Cruise 2012

Ready for departure

Written by Chris Scheingraber, Maria Tsekhmistrenko on lundi, 24 septembre 2012. Posted in Cruise 2012

22 September 2012

Looking for our containers.

The French and German scientific teams arrived well on the island of La Reunion. Unfortunately, our departure will be delayed (for a few days?) due to a strike of dockworkers that we learned about on short notice. Since they are supposed to load our equipment on board, the Marion Dufresne is still docking in Le Port de la Réunion. Despite the problems we are facing, the crew and the scientists are in good spirits. We just hope that the strike will end soon so that we can finally start our mission.

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30 scientists in a golden cage

Written by Heiner Igel on lundi, 24 septembre 2012. Posted in Cruise 2012

24 September 2012

Blogging from a golden cage.

Here we are, ready to fight the open seas and drop down a few dozen seismometers into the abyss of the Indian ocean .... BUT ... the dockworkers decided (after many years for the first time) to go on strike just the day when we were supposed to start loading. And they seem to continue. No end in sight.
Yes. We found "our" four large containers somewhere in the harbor but unfortunately - despite the increasing use of the ship's "gym" (two bikes, rowing machine, running machine, weights) - we do not feel strong enough to carry them to our dock without machine support.
It is day 4 on the ship. With no real task, except waiting. Some sit on the two chairs outside the scientific room with view to the rising slopes of volcanic La Reunion, waiting for the next eruption (Jason), that could be viewed from a comfortable distance. Others go running along the beautiful seashore park after leaving the ports' gate (2 km away from the ship), coming back with ideas for a new seismology rock song (Jean-Paul). It is amazing what the sudden unexpected availability of time can do to you! Marvelous! Inspiring!
What keeps us from jumping overboard in despair are the meals. 12:15 and 19:15. Four courses. Entrée, plats, cheese, dessert. Excellent French cuisine (another reason for the increasing use of the gym). Followed by coffee and discussions on science, the world, our situation, the region. What an opportunity to work with colleagues from La Réunion, Rodrigues, Mauritius, Madagascar, and to learn more about these remote regions!
This situation is dangerous! 30 scientists with lots of time, good food, no internet access? I think there could be some explosive new ideas around the corner!

Free the Marion Dufresne!

Written by Karin Sigloch on vendredi, 28 septembre 2012. Posted in Cruise 2012

27 September 2012

Political action. (Photo by Kasra Hosseini)

We are still in port, blocked by the strike of the harbor workers. Now the deal is that we get the harbor to ourselves, while the striking workers, camped in front of the main gate, are ensuring that nobody disturbs our ship on sabbatical.

Science has been all talk and no action so far (daily seminars, dinner discussions, dreams...). But witnessing much political action around us, we got into it ourselves. Our colleagues from La Réunion spent many hours at the main gate, trying to understand the concerns of the workers, and whether a pragmatic solution for our four blocked containers might be found. We also turned to the island's Prefect, since our experiment represents a major investment of taxpayer's money, and pertains to volcanic risk assessment.

The photo shows an earlier outreach effort in the "Free the Marion Dufresne" series: Wave "Good morning and SOS" to the Prefect. We learned that his helicopter was supposed to survey the scene of the deserted harbor early in the morning, so we also wanted to be seen. We chose the parking lot outside the ship, and white towels for good visual contrast, but the helicopter never appeared.

Yesterday we did manage to make direct contact with the Prefect, got a helpful response, and thought our problem solved – until that hope evaporated again at the harbor gate. Five days after our scheduled departure, our cruise leader can still only dream about scientific action on the seafloor...

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Departure!

Written by Maria Tsekhmistrenko on samedi, 29 septembre 2012. Posted in Cruise 2012

28 September 2012

This is what we have been waiting for: 48 ocean bottom seismometers (Picture: Chris Scheingraber).

Anxious waiting, nervous faces all around. But suddenly the tension melts away, gives way to joy. There they are!

Our four containers are finally being released; the harbor workers are pulling up in two big trucks. They have lifted their strike after one week. To say that we are "relieved" would be a gross understatement. After days of forced inactivity, the ship becomes happily busy. Our bulky ocean bottom seismometers are being unloaded from the containers by our technicians, and the ship crew hoists them onto the helicopter deck with cranes. It takes us about three hours, and now only a cyclope could keep us from leaving.

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At 3 p.m. everything is ready for departure. While the pilot is coming onboard and the crew is pulling in the ropes, the scientists are assembling on the superstructure in front, facing the harbor exit and the Indian Ocean. The sky is cloudy, it is drizzling, but nobody minds in the least – we are finally underway!

The harbor episode due to the strike already felt like an odyssey in itself, but now the real work is coming up. Still, we have used to time to get to know each other better and to bond. Our international group should be working together all the better for it.

First ocean-bottom seismometer deployed.

Written by Chris Scheingraber, Simon Stähler on dimanche, 30 septembre 2012. Posted in Cruise 2012

29. September 2012

First ocean-bottom seismometer deployed (Picture: Chris Scheingraber).

During the first day spent entirely on the sea, we set up the lab, tested the release mechanisms for the ocean-bottom seismometers, and successfully deployed the first seismometer.

Fully operational

Written by Chris Scheingraber, Maria Tsekhmistrenko on mardi, 02 octobre 2012. Posted in Cruise 2012

30 September 2012

Our colleague Olivier makes a quick cell phone call while the Marion Dufresne passes his native island of Rodrigues (500 km east of Mauritius, 33,000 inhabitants). (Photo: Karin Sigloch)

It seems like an endless and beautiful ocean is surrounding us. The last island on our journey (Rodrigues) rolled by hours ago, the last ship this morning. After the release of the first seismometer and a small celebration given by IPEV to honor this moment, we are getting into a daily routine.
Some of the scientists are working on recording and controlling bathymetry, gravity and magnetic data, while a smaller part are preparing seismometers for deployment. 24 hours a day, there is continuous activity. The OBS deployment teams do not care about meals or bedtimes, they have to be ready at all times. Even though we miss out on sleep and only rarely find the time to sit together and have a chat, we are definitely much happier with these circumstances than we were during the strike.

The workshop: ocean-bottom seismometers ready to take a dive. (Photo: Karin Sigloch)

Working the night shift, 2am – 4am

Written by Heiner Igel, Maria Tsekhmistrenko on mardi, 02 octobre 2012. Posted in Cruise 2012

2 October 2012

Night shift in the data acquisition room.

Man, this is a tough one. You don t know whether you sleep before the shift or you try to keep awake somehow ... with coffee, talking, going outside into the wind, playing badminton in the ship's belly.

Indian Ocean time 02:15:00. The scientific room is empty. We are taking the first reading of the data that we are acquiring. The scientist's shift work is dedicated to monitoring the proper working of the basic operations: the scan of the seafloor topography (bathymetry), the magnetometer that is towed on a long line behind the ship. The current values are written into the logbook every 15 minutes. That is done in 30 seconds. In the mean time one can read a book, talk, do guitar-fingering exercises or try a headstand without falling over. The next reading approaches fast.

Indian Ocean time 02:30:00. We are cruising at 15 knots. The seafloor is 4355 m below us. Two large screens show the seafloor in bright colors. The bathymetry is sensational. The Earth is having a party down there and unless we had these sophisticated instruments we would not notice. It would be like flying at night over the Alps or the Rhine graben. Below our ship there are ridges where oceanic crust is created and drifting apart. Hundreds of meters high. Linear features on all scales indicate the consequences of the seafloor dynamics with motions of several centimeters per year. 

In our daily seminar at 5pm in the conference room we are learning and discussing the marriage between such oceanic ridges with plumes. Plumes are (or are they not?) deep Earth features that appear to be static while the oceanic plates and the ridges move over them. Sometimes plumes and ridges attract each other, exchange some warmth ... and yes they do have a ball once they are together, spewing out loads of lava ending up as volcanic plateaus that may create big islands (such as the Azores, Iceland, and others). Sometimes the ridges have enough of the aging plumes, wander on looking for a 2nd spring. Sometimes they retire together.

Indian Ocean time 02:42:16. The phone rings. The bridge is calling. The captains' assistant starts speaking rapidly in French. "Attendez, je ne suis pas Français, lentement!" I am responding. He tells us that in eight minutes he will start slowing down the ship as we are approaching our next target location. We note that down in the log book and the technical assistant is turning on the sonar logging of the seafloor. We look at the screen and we see several flat connected horizontal lines zig-zagging away at the edges. The middle looks like a layer cake and that's just what we want. The sea floor is flat. Chances are good the seismometer will make itself comfortable in a flat position.

Now the place comes alive! The chief scientists and technicians appear to bring the baby safely off the back of the ship. When the final position is found the crane lifts the OBS off the ship. Very very slowly it is lowered down. Sometimes the waves are making problems and if the right moment isn't found the seismometers makes a rough landing on the water surface. The moment has come and it is off the hook. For a few moments one can follow the blinking white light receding into the abyss.

It would be so cool to accompany its way down to the seafloor with an onboard webcam. Have a glimpse of its location for the next year. Meet the shrimps that surround it. Well, that is something for the next generation. If all goes well in a year's time suddenly it is released off its steel case and floats up with exciting earthquake data coming from all over our planet.

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La Vie en Rose

Written by Carmen Gaina on mercredi, 03 octobre 2012. Posted in Cruise 2012

Or Science is really fun, enroll now ! (3 Oct 2012)

Rainbow and sunset over Mauritius Island

One has to be careful when making wishes: they may come true, and then you need to deal with the happiness overdose! For many years I was hoping to join a scientific cruise on a French vessel – I suppose the combination of learning from accomplished marine scientists and having French cuisine in the same time was the epitome of cruise experience for me. And voila – my wish was granted when one of the PI of this expedition, Karin Sigloch, kindly invited me to take part not only in a cruise on a French vessel, but also to experience an amazing adventure: peering into the deep oceans and then into the Deep-deep earth!

In less than one week we crossed fracture zones, mid-ocean ridges and volcanic edifices going through the evolution of the ocean floor like a quick tour from Rome, to Verona and than Milano, from ancient history to modern era. OBS deployments are our daily source of joy once they are delivered to the sea by a team of careful parents who want to make sure they prepared their children for their one-year foreign experience. The joy will be even greater next year when these children will come back full of knowledge from their year spent on the sea bottom – and then the mysteries of the Deep Earth will be finally revealed.
But for now we enjoy the rich life on boat –and the French cuisine, and the almost constant 22-23 degrees air temperature (water temperature is even better-but for various reasons we cannot enjoy that), and gorgeous sunsets and a bunch of amazing people.

The Marion Dufresne community is wonderfully diverse: the learned professors and senior scientists are happily playing basketball with the enthusiastic students – that is, of course, when their presence is not required for solving the scientific tasks, the multi-origin crew (among them French, Malgasy and Romanians) try to run smoothly the life on boat, and French (and English, and German, and some other languages) conversations around the table (whether in the laboratories, restaurant or seminar room) revolve around every imaginable subject – from seismology to marine biology, from George Clooney to GO, and from chili to best military airplanes.

My sunny life for the past two weeks had only one shadow: I missed the only lunch that served éclairs for desert!

To drop or not to drop?

Written by Karin Sigloch on jeudi, 04 octobre 2012. Posted in Cruise 2012

4 October 2012

Annotated map describing an OBS deployment (station RR17). (Read more bellow)

Among our most crucial decisions is where on the seafloor to drop our seismometers. Geometrically, the task is not unlike dropping them from an airplane at 3-6 km altitude, hoping that they will land in a suitable spot. Some luck is needed, because the seafloor is not mapped down to the meter scale, and because ocean currents can carry the OBS away laterally by several hundreds of meters before they reach the seafloor.

However, careful preparation can maximize the chances of a successful landing. The most basic requirement: the instrument should be recoverable when called to return to the surface – that may not be possible if it landed in a crevasse or tumbled over on a steep slope. Hence we seek out relatively flat spots of at least 1 km2 area. Such places can be found even in (underwater) mountain ranges, but dropping an OBS there requires more preparation than on a vast abyssal plain.

The other morning we had a challenging case, a targeted OBS site on the steep flank of the Mascarene plateau. The only prior bathymetry information came from "Sandwell", a jargon referring to maps extrapolated from measurements of gravity satellites – very smoothed and blurry sea-scapes compared to reality, but much better than nothing (see annotated map). "Sandwell" suggested a little flat embayment in the plateau flank, but as we approached, the highly-resolving ship bathymeter gradually revealed a steeply incised canyon, 2800 m beneath the surface. No sediments to flatten out even a small area. We collectively pondered the evolving scene, and imagined mud avalanches rushing down the canyon channel. Fact or fiction? No way to tell. It seemed unwise to drop the OBS there.

With not many options available, we targeted a small protruding ledge a few miles up-flank on Sandwell's map. The approach was steep and unpromising, but suddenly sediments started showing up on the screen of the sediment sounder. The saddle area turned out to be narrower and shifted compared to the Sandwell prediction, but 1.5 miles wide and reasonably flat seemed lucky under the circumstances. We dropped the OBS above the likely equivalent of an Alpine meadow, bounded by a steeply incised mountain stream, perhaps with bottom-dwelling fish instead of grazing cows. It had taken us two hours, but had also satisfied our curiosity. Expert bathymetrist Jérôme summed it up: "Interesting – so that's what a canyon may look like for Sandwell."

* Picture Caption : 

Annotated map describing an OBS deployment (station RR17). Before our arrival, we had only the blurry bathymetric information that fills most of the picture (“Sandwell”, extrapolated from gravity satellite measurements). In real time, we replaced a ~10 km wide swath beneath our ship track with the ship’s own, more highly resolving measurements (top left to bottom right). It revealed that the seafloor in this area was not smooth at all – it took some cruising to find even a small flat spot.

Floating seminar

Written by William Jason Morgan on jeudi, 04 octobre 2012. Posted in Cruise 2012

4 October 2012

Detailed bathymetry measured by our ship has been laid over a coarser, pre-existing deep-ocean map. Note the canyon that appears on the highly resolved swath. The swath is about 10 km wide, the canyon is located around 3000 m depth.

One of the more interesting aspects of a research cruise is the 'floating seminar' atmosphere. I don't mean the daily afternoon presentations in the conference room by one of the cruise participants, as interesting as they are, I mean the daily interactions of persons with various specialties from various institutions all focused on a single research project. Seeing how the ocean bottom seismometers (OBSs) are assembled, tested, deployed over the side (gently!); having discussions of what can go wrong, tales of past mistakes, improvements being made all give one a better understanding of how a seismic experiment is planned and executed far beyond what one can get from reading journal articles of OBS results.

Another center of activity and discussion is the monitor screen that displays each 'sweep' of the incoming bathymetric data. The 'multibeam' bathymetry of the Marion Dufresne has acoustic sensors that look not only straight down to the seafloor but also are aimed outward to receive echos from many angles away from straight down. Then the return echos of the many sensors are put together in the system's computer, and a 'swath' of bathymetry is produced. The moving ship results in a ≈5-km-wide ribbon of seafloor depths mapped, analogous to laying out a series of aerial photographs for land mapping.

The general locations of each OBS site were selected when the experiment was planned, but the precise location for a 'drop' is made while looking at the bathymetry collected at the site. At this time, many eyes gather in the lab around the bathymetric screen -- all looking for that perfect flat, not too rocky, not too steep spot on the ocean floor. Lots of murmur in the peanut gallery as Karin and Guilhem make the final choice -- sometimes the initial 'X' is abandoned and a 'better' place several kilometers away is selected instead.

The bathymetric screen showing the swath of bathymetry collected as we steam from drop-point to drop-point is a constant focus of interest. Many so-called "seafloor canyons" have been seen in the swaths. These features are tens of meters deep and hundreds of meters wide; they are commonly made by avalanches on the steep slopes of continental shelves which create a fast moving mixture of water and suspended sand which cuts away the flat mud on the seafloor much like a river cuts away land surface. Near continents, such 'canyons' can be traced for hundreds of kilometers; the source here mid-ocean would most likely be collapse of the slopes around the carbonate banks and islands of the Mascarene Plateau. Our cruise isn't mapping them -- following them from beginning to end -- but we have crossed and noted perhaps a half-dozen on our zig-zag path from site to site and wonder collectively where and how each may have originated.

And last night the sky was brilliant; a bright Milky Way and the bow of the ship pointing directly toward the Southern Cross.

“It’s déjà vu all over again”

Written by Karin Sigloch on lundi, 08 octobre 2012. Posted in Cruise 2012

6 October 2012

“It’s KUMing home” – was it them who told the dock workers that the Marion Dufresne would be back in port?

"It's kuming home" -- Was it them who gave away the Marion Dufresne's return to port?


Halfway through the experiment, we were going to stop briefly in La Réunion on October 9, in order to pick up more colleagues and material. And guess what, yesterday the dock workers announced a strike for that day. No joke. This time a nationwide general strike of harbor workers and others.

The human mind tries to make sense of things. The first strikes in 10 years, and both on the only days that we need the dock workers? They must have been missing us, our friends from the dock – longing for another rendez-vous at the harbor gate, no doubt. Has nobody else been talking to them since we left? Who has leaked the plans for our stopover, and how do we plug this leak, given that we'll have to return to port once more at the end of the cruise?

But they blundered, this time by giving us more than 24 hours notice. Yesterday was spent with frantic phone calls and deliberations, a scramble to advance our port visit by one day: to rush in our colleagues from Europe for Leg 2, to accommodate the people leaving, and to design a new deployment route that minimizes the loss of time. Plans for this counterstrike are well advanced: Rendez-vous in Le Port on the 8th – in full working gear!

The whale and the butterfly (digression about rounds on the water)

Written by Jérôme Dyment on lundi, 08 octobre 2012. Posted in Cruise 2012

7 October 2012

On Rhum-Rum, we are not doing rounds in the water...  but nice drawings indeed!

Of us, marine geophysicists, who wander on the oceans, looking for indices to better understand how the seafloor forms, ages, and disappears, some are saying that we are doing rounds on the water. It is untrue, indeed! A short glimpse to the route map of cruise Rhum-Rum - routes achieved during the first leg, routes to be done during the second one - clearly shows that, if we do accumulate some mileage, it is certainly not doing circles but much more complicated figures, which await patiently an improbable Sigmund Freud to decipher their deep meaning, their psychoanalytic signification. This aspect appeared to me when, just after my PhD thesis - otherwise said in the Middle Age - I boarded the first Marion Dufresne for cruise MD67. Possibly affected by our short stop in Kerguelen Island when approaching the study area, our path was drawing a giant penguin superimposed to the structures of the Kerguelen Plateau and the Enderby Basin. Years later, when I was leading cruise Magofond 3 on R/V Suroît south-east of the Canary Islands, I rapidly noticed that our tracks were making a big M then a smaller A - we did not reach the end of the word, but were then making deep-towed magnetic profiles across the Cretaceous Quiet Zone to try to unravel one of the greatest remaining enigmas of geomagnetism. And today, finishing Rhum-Rum Leg 1, the two wide loops that we made to the East - almost touching Rodrigues, and Mauritius twice - and to the West - in a rather shy approach to the Big Island of Madagascar - let me think of the (truncated - we lost 6 days!) wings of a giant butterfly (Figure 1), whose body would be made of the inner circle of ocean bottom seismometers that we consciously dropped all over around La Reunion Island... Should we imagine the caterpillar, moving up from the deep Earth mantle with ascending currents of the inferred plume, cocooning in the heat of the Fournaise then metamorphosing to butterfly and taking advantage of our cruise to escape, like an allegory of the Truth coming out of the well - I wouldn't dare to say in what apparel!

As I write Leg 2 remains to be done, and I will unfortunately not be there to contribute more than through some maps - again - left onboard to the best use of the chief scientists. I already see, in the projected tracks, the shape of a whale (Figure 1), its noose on the Rodrigues Triple Junction - this peculiar point where three mid-ocean ridges meet. The whale's front follows the Central Indian Ridge, its mouth would be located in that small area of the Southwest Indian Ridge where eight ocean bottom seismometers will be deployed very near to each other - may be to detect a possible raging "baleenache"... Paradoxically, I imagine the dorsal fin on the side without any active ridge ("dorsale" in French), in the Madagascar and southern Mascarene basins, as an indication of other, fossil spreading centers that we would not have properly detected yet.

Now you know why I entitled this essay "the whale and the butterfly". It is open to analysts and other psychiatrists, professional or not, to further investigate the matter - delirium is not unusual in geosciences!

End of Leg 1 -- heading south now

Written by Karin Sigloch on jeudi, 11 octobre 2012. Posted in Cruise 2012

8 October 2012

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 The first leg of our cruise ended today. As the Marion Dufresne approached La Réunion in the morning, visibility of the 3000 m high volcanic island was excellent. Our dream is to image equally clearly to 3000 km depth. (Photo: Nicolas Villeneuve)

 

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Entering Le Port and relieved to see that the large harbor machines were working. We had arrived one day early just to avoid another harbor strike tomorrow.


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 In the early evening, we had to say farewell to 11 colleagues, who had been interested mainly in exploring the region around the Mascarene islands. Leg 2 will consist of a 7000 km long round to the far south of the islands. Six new colleagues came onboard, among them the French OBS team with another 9 seismometers.

 

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All unloading and loading got done in time. We left the harbor late in the evening, happy to get back onto the ocean.

 

 

First French OBS deployed

Written by Karin Sigloch on jeudi, 11 octobre 2012. Posted in Cruise 2012

11 October 2012

Last night the first French OBS was launched. First deployments are special, so the event was well attended despite the late hour. Unfortunately, night deployments are not easy to capture…

Last night the first French OBS was launched. First deployments are special, so the event was well attended despite the late hour. Unfortunately, night deployments are not easy to capture...

...so here the same thing again in bright daylight. French OBS #2 started its voyage to the ocean bottom this morning. Seven more will follow, interleaved with 25 German OBS. The advantage of the French model is that it records seismic waves down to lower frequencies.

…so here the same thing again in bright daylight. French OBS #2 started its voyage to the ocean bottom this morning. Seven more will follow, interleaved with 25 German OBS. The advantage of the French model is that it records seismic waves down to lower frequencies.

The way they were…

Written by Carmen Gaina on jeudi, 11 octobre 2012. Posted in Cruise 2012

11 October 2012

The way they were…

For the last two days we were collecting data and deploying OBS in the southern Mascarene Basin, following "highways" from the youngest part of this ocean (about 60 million years) to the oldest part (probably older than 80 million years). Yesterday we have reached one of the points closest to Madagascar, and therefore had a "glimpse" at the early history of this region.
This sent us back in time approximately 80 million years ago – so how was it like back then?

Well - first of all, Madagascar was much closer to the Indian subcontinent and the Mascarene basin was in his early days (I mean million years). At that time they were both travelling northward from southern latitudes (northern Madagascar was situated at about 30 degrees south), having left Antarctica in the Mid Cretaceous time. Older oceans in the vicinity (the Somali and Mozambique basins) already reached maturity by the time new oceanic crust started to form between India and Madagascar. Shortly before that happened, bursts of volcanic activity affected Madagascar's margins and probably formed a huge volcanic plateau south of it - the Madagascar plateau. This was because at that time, another plume, older than Reunion – the Marion plume, was in the vicinity of the southern Madagascar (and the incipient Mascarene oceanic basin) and created magmatic pulses now and then. Whether this also reached the young Mascarene basin – is difficult to say –but we do see some unexplained higher plateaus close to the SE Madagascar margin, and believe that a tiny portion of it was imaged by the multibeam system just yesterday.

The following map, despite its (too) bright colours is a real map that catches a moment in the Mascarene basin's childhood. Decades of geological and geophysical data collection, interpretation and modelling makes now possible to construct such a snap in time. One can observe the position of the main land masses and their older history (geology from Archean to Cretaceous), around them reconstructed oceanic seafloors (shown by the present day free air gravity-which can give an idea about the structure of the oceanic crust under the sediments), and even an ocean that doesn't exist anymore, consumed by subduction somewhere between India and Arabia. The location of the mighty Marion plume is also shown, as we can trace back its position through knowledge of plate tectonics and mantle dynamics.

This story will have more details in the months and years to come, once the data collected now will be processed and interpreted by the RUM-RHUM project participants. And it will help us understand the tumultuous life of the Indian Ocean at the time of significant tectonic and magmatic activity that may have contributed to global changes like sea level rise and changes in seawater geochemistry. Stay tuned!

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