Eleanor Science Cafe tomorrow at the Eleanor Rooevelt High School cafeteria in Greenbelt, MD:

Evaluation of Potential Deep Sediment Methane Hydrate Deposits
Dr. Rick Coffin from Naval Research Laboratory Marine Biogeochemistry Section
5-7pm

Methane hydrates are recognized to exist in high concentrations in coastal oceans around the world. The Japanese are exploring the potential for hydrates in the Nankai Trough, off the coast of Tokyo Japan, for development as a dominant national energy source. This investigation has lead to Arctic tundra hydrate energy evaluation in the Mackenzie Delta and Prudhoe Bay by international governments, universities and industry. Exploration of for the hydrates depends on data from seismic profiling and deep sediment drilling. This approach to hydrate exploration is expensive. Recent studies have combined seismic profiles, shallow sediment geochemistry, heatflow and controlled source electromagnetics to predict deep sediment hydrate deposits. This approach provides a more thorough, less expensive, investigation prior to deep sediment drilling.

NRL has been involved in methane hydrate exploration of the coasts of New Zealand, Chile, Canada and in the Gulf of Mexico. In addition, there are current plans to survey sediment hydrate deposits off the northern coast of Alaska in the Beaufort Sea. These studies have shown a wide variation in the prediction of deep sediment methane hydrate deposits within and between the locations. General findings of these studies are the need for a thorough geochemical evaluation. Strong seismic blanking indicative of high vertical methane migration off the coast of Chile was observed to have a low vertical methane flux through the deep sediment. High vertical methane migration on Atwater Valley in the Gulf of Mexico was observed to be coupled with a high vertical chloride flux in the porewaters, which suggests deep sediment salt diapirs caused unstable sediment methane hydrate deposits. Bottom simulating reflection, coupled with seismic blanking were believe to indicate high vertical methane fluxes on the Hikurangi Margin off the coast of New Zealand. However, shallow sediment geochemical data taken through this region suggested very low deep sediment hydrate deposits.

This presentation will provide an overview of predicted methane hydrate deposits in different coastal regions and the advantages of combining different parameters in the evaluation. Work will include data from expeditions in the Gulf of Mexico at Atwater Valley and Alaminos Canyon, on the mid Chilean Margin, west of Concepion, and on the Hikurangi Margin, northeast of New Zealand. Data may be included from a September expedition on the Beaufort Sea. The approach will provide an overview of the benefits and issues with the interpretation of deep sediment hydrate deposits using different approaches for the field survey. This presentation supports combining a variety of parameters for these surveys.

Labels: maryland, meetings, oceans

The National Academies' Ocean Studies Board would like to announce that Dr. Paul G. Falkowski, Board of Governors' Professor at Rutgers University, will be the speaker for the tenth annual Roger Revelle Commemorative Lecture, scheduled for Tuesday, March 17, 2009 at 5:30pm. It will be held in the Baird Auditorium in the Smithsonian's National Museum of Natural History (10th Street and Constitution Avenue). Dr. Falkowski's talk is entitled:


The ocean has been a feature of Earth's surface for at least 4 of the past 4.5 billion years, and has provided the primary environment for the evolution of microbes that drive the biogeochemical cycles on Earth. Over this long period of time, the ocean has witnessed extreme changes, ranging from complete coverage with ice to extensive periods when there was no ice at all; periods of extraordinary extinction of animal life, to periods of dramatic evolutionary radiation of animals. Throughout all of Earth's history, the ocean has served as the primary backbone of life on the planet; and the core metabolic processes have been successfully transferred across vast stretches of geological time. Humans, in contrast, evolved only about 200,000 years ago, and in that short period of time have come to successfully outcompete and plunder many of Earth's living resources. Over the past 100 years, in particular, we have increasingly altered the trophic structure of the ocean as well as its physical circulation and chemical properties. While human impacts will surely alter ecosystem functions the core metabolism of the ocean will go on. Rather, ironically, humans are the fragile species that will lose capabilities of using the ocean as a source of food and novel molecules. Our future is intimately tied to that of the ocean. We have to begin viewing the oceans as a key component of the Earth system; one that we cannot live without.

This event is free and open to the public. For planning purposes, please complete this brief registration form. You are encouraged to post the event flyer or to forward it to your colleagues. For more information, contact Pamela Lewis.

Please visit Roger Revelle Lecture Series for information on Roger Revelle and on previous lectures.

Labels: dc, meetings, oceans, smithsonian

The February meeting of the Potomac Geophysical Society will be held February 19th at the Fort Myer Officers' Club in Arlington, VA in the Campaign Room. This month's talk will be: Listening to a Melting Arctic Ocean - Singing the Blues?, by Peter N. Mikhalevsky, SAIC, VA.

Abstract:
The waters of the Arctic Ocean have been warming since the mid 1990's. Average maximum temperatures have risen by more than 1°C. In the last 20 years submarine measurements of sea ice draft have shown a 40% reduction in average sea ice thickness while satellite remote sensing has shown a 14% reduction in sea-ice extent over the same period decreasing at a rate of 3-5%/decade (thicker multi-year ice at 7-10%/decade). Forecasts indicate that if these trends continue the Arctic Ocean could be ice-free, "A Blue Arctic Ocean" before the end of this century. Significant effort is needed to expand our observational capabilities in the Arctic Ocean to support better modeling, forecasting and improve our understanding of this critical ocean and the linkages to global climate. One technique - acoustic thermometry - has been shown to be a very effective for monitoring average heat content and average temperature in the Arctic Ocean and in particular in the Arctic Intermediate Water (AIW) layer. Two experiments conducted in 1994 and 1999 measured the warming and demonstrated the feasibility of long term observations. Plans are in process to incorporate acoustic thermometry and tomography in in-situ Arctic Ocean observatories.

Dinner Menu
Chicken Marsala (House salad & vegetables, rolls and butter)
Tira Mi Su
Coffee / tea
A vegetarian meal can be substituted by request.

Reception at 6:30. Dinner at 7:30. Talk at 8:30 PM. Allow 15 minutes for security entering Ft. Myer as all civilian vehicles are searched. To ensure access to and from Fort Myer use the Hatfield Gate, open 24 hours a day (https://webmail-1.nvcc.edu/exchweb/bin/redir.asp?URL=http://www.fmmcmwr.com/directionsmyer.htm). If you wish to attend dinner ($25), please make reservations with Joydeep Bhattacharyya at 703-676-4373 or via E-mail at Joydeep.bhattacharyya@saic.com. If you wish, please feel free to attend the talk without dinner. Non-members and guests are welcome. Visit the PGS web site at https://webmail-1.nvcc.edu/exchweb/bin/redir.asp?URL=http://www.potomacgeophysical.com%2520/ for new meeting announcements, etc.

Labels: climate change, global warming, meetings, oceans, pgs

Cool idea. Check it out.

Labels: art, blogs, climate change, global warming, ice, oceans

There's a new study out I read about today in New Scientist which took squid and put them in a tank of ocean water that was equilibrated to simulated atmospheric concentrations of carbon dioxide predicted for the year 2100. The oceans were also warmer in temperature, again simulating predicted future conditions. In these acidic oceans, the squid's metabolic levels dropped by 31%, and the time they spent contracting their muscles dropped by 45%. I didn't get to read the full study, which is behind a Proceedings of the National Academy of Sciences paywall, but the abstract online hints that these mini-oceans were about 0.3 pH units lower than modern ocean values. The abstract doesn't say how much warmer the experimental tanks were, but notes that water's ability to hold oxygen decreases with warmer temperatures. The lack of oxygen may be the prime reason for the squid's diminished activity.
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Journal reference: DOI: 10.1073/pnas.0806886105

Labels: CO2, critters, mollusks, news, ocean acidfication, oceans

Yesterday, I showed you some sand, including some green sand from Green Sands Beach on the big island of Hawai'i. Today, I'll show you some more images from Green Sands. Let's start by orienting ourselves: We're on the south side of the island, just east of Ka Lae (a.k.a. South Point). Here's a Google Map of the cove (Mahana Bay) where Green Sands Beach (a.k.a. Papalakoa Beach) is located:


To get there from the Ka Lae parking area, you can either drive a four-wheel-drive vehicle over some very rough "roads" or you can hike about 2 miles along the coast. When I visited last week, we hiked. It's a pleasant walk, and there's plenty of green sand to be seen en route to the official Green Sands Beach. Here's the coast: basalt and grassy pastureland, with plenty of wind:


A view looking down into the cove where the green sand beach is located:


So, just why is the sand here green? It's full of olivine, which is weathering out from the local rocks. At first, I assumed the source was the local porphyritic basalt. The fine-grained basalt contains many large phenocrysts of olivine, and when the basalt breaks up, these dense grains tend to be concentrated together. Here's some of that olivine-rich basalt:


But apparently the major local source of olivine are some ash/lapilli layers that make up the prominent headland on the cove's eastern edge, as seen as the "backdrop" in this photo:


A close-up of the sand on the beach, with my fingertip for scale:


And a (repeated showing) of a handful of the stuff:


These green grains don't last especially long -- olivine isn't stable over geologic timescales at the earth's surface, and so it chemically degrades and weathers away. Thus, green sand beaches are extraordinarily rare on the planet Earth (according to Wikipedia, there are two: this one, and one in Guam). You've got to have a source of olivine right there, continually adding new green grains to the mix at a rate which matches or exceeds the rate at which they are being chemically broken down.

On the back side of the beach, draped up against the outcrops of ash and lapilli, is a big slope of sand piled up at the angle of repose. I really liked the patterns made between the olivine and the dark grains as small "avalanches" flowed down the "slip face" of this pile:


I even made a pointless little movie showing these mini-avalanches of green sand:

...Or not pointless? Maybe the sandman, new on the geoblogoblock, can tell me more about what's happening here.

A poorly-lithified chunk of green sandstone (cemented with halite from seawater, apparently, as it crumbled readily in my hands):


Some green sand on a basalt cobble (which itself hosts plenty of olivine phenocrysts):


And now a closer look at some of these ash/lapilli layers which are supposedly the main source of all this olivine. These ash layers were erupted by a cinder cone called Pu'u Mahana, and apparently date to 49,000 years ago:


Some of these layers are better lithified (probably due to welding, a phenomenon that occurs when pyroclastics are erupted at higher temperatures and then deform around one another as the particles settle) and thus stand out as little 'shelves' that are more resistant to erosion by the waves and wind:


Close-up of the ash/lapilli layers, with my fingertip again providing a sense of scale:


After an hour of swimming and relaxing on the beach, we climbed back up to the plateau above the beach, where we noticed this contact between lower ash/lapilli layers and overlying basalt flows:

Notice also all the white stuff filling in fractures here. I'm betting it's calcite, especially considering the little stalactites hanging down, but I didn't have any acid with me, and I neglected to collect any to confirm that assumed identity once I got home. Mea culpa.

Hiking back along the coast to the west, we encountered more beautiful olivine basalt. Porphyritic and vesicular, this stuff just about made me cry, it was so beautiful:


I was delighted when we detoured along one of the little unnamed coves between the official Green Sands Beach and the car, and found this:


This green sand was greener than the official Green Sands Beach:


A reprise of yesterday's image of this beautiful stuff:


We noticed some footprints of a mongoose (introduced species) crossing the green sand:


Close-up of the mongoose tracks:


There was also a nice accumulation of basaltic cobbles (some porphyritic, some not, almost all vesicular) mixed in with chunks of coral:


Wow. What a cool place! Unique in my experience, and pretty close to unique in the world. If you're ever on the big island, you've got to check it out. As a geologist, visiting Green Sands Beach imparts big bragging rights: it will make all your friends green with envy!

Labels: basalt, hawaii, oceans, sediment, travel

As I mentioned a few posts back, I spent the week of Thanksgiving on the big island of Hawai'i. I had an exam scheduled in one of my classes, and I pre-recorded the lecture for my other class (via Smartboard), so I was free to kick back and relax on my travels. However, I find it's difficult to turn the inner geologist off, and so I spent a lot of my time checking out the cool geology of this unique island. I've got a lot of photos to share and stories to tell, but I'll start off simple: here are sand samples from four beaches in Hawai'i:






As you can no doubt tell, these sands are dominated by, respectively from top to bottom: calcareous hash (fragments of shells and corals), basalt fragments, olivine crystals flavored with basalt fragments, and a greater proportion of olivine crystals. They are respectively from "Sixty-Nines" Beach (west side of island; named for the milepost on the nearby road, so get your mind out of the gutter), Punaluu Harbor (south side of island), Green Sands Beach (south side of island), and a nameless cove between Green Sands and Ka Lae (a.k.a. South Point, on the south side of the island -- and in fact the southernmost point in the entire United States).

Labels: hawaii, minerals, oceans, sediment, tech, travel

This was in last month's Scientific American: "Birth of an Ocean: the evolution of Ethiopia's Afar Depression." Great photos.

Labels: africa, oceans, plate tectonics, rift valleys, salt

Labels: art, geologic time, oceans, plate tectonics

This weekend, I walked down to the Smithsonian Institution's National Museum of Natural History to check out their new Sant Ocean Hall (previous mentions on this blog).

The new exhibit hall has been under construction for a long time, and opened to the public the previous weekend. I've got a few photos here to share some of what I saw, but the museum also maintains their own Flickr page, which has additional (and better) photographs.

It's pretty cool. There are suspended specimens of both giant squid and also this coelacanth (with "pup" at upper right):


The exhibit has a lot of cool stuff having to deal with the geological aspects of oceanography, too, like this interactive exhibit about drill cores and how geologists interpret sediment. It would make an ideal visit for Historical Geology students:


The thing that caught my eye at first was a series of skeletons showing the evolution of whales over time, and in particular the shrinkage and eventual absence of their hind limbs and hips. I failed to note the name of the first one (falsely thinking I could look it up online!), but the more distant two specimens are Dorudon and Basilosaurus:


And they've got a nice C. megalodon jaw reconstruction holding lots of authentic teeth:


There are lots of smaller fossils, too. I was really impressed by the substantial portion of the hall which was given over to ancient oceans, as preserved in the sedimentary record. Here's a case showing some stunning fossils, including a MASSIVE asaphid trilobite and the best receptaculid ("sunflower coral") that I've ever seen:


A lot of trilobites are on display, most donated by Bob Hazen, of the Carnegie Institution and George Mason University. Here's a lovely Olenellus from Pennsylvania:


Also, you'll find Dunkleosteus, mosasaurs, and this Placinticeras ammonite with mosasaur bite marks running across it.


Here's a rudist clam, one of a half-dozen diverse and chunky specimens on display:


Lastly, I'll show a photo that's part of their display on the Burgess Shale. They include some imagery from Walcott's journal documenting actual fossil specimens that are displayed right along with it. Pretty cool -- a sort of window onto historical paleontological field work.


I also wanted to mention a really neat display called "Science on a Sphere," where a suspended sphere about six feet across gets imagery projected on it from the inside, accompanying narration that explains phenomena like plate tectonics, El Nino, the thermohaline "conveyor belt," and so forth. This YouTube video (not mine) gives a small taste of the Sphere as it explains surface currents using rubber duckies:



All told, it's a great exhibit, and you should check it out next time you're in DC.

Labels: fish, fossils, museums, oceans, smithsonian

Joel Achenbach reports in today's Washington Post about the Smithsonian Institution's newest addition: the Sant Ocean Hall, which opened this weekend at the National Museum of Natural History. I plan to go check it out myself this week, but until I get the chance to report, consider Mr. Achenbach's words.

Labels: dc, museums, oceans, smithsonian

I saw David Byrne (formerly the frontman of the Talking Heads) perform last night in Baltimore. He did a great job, as he always does. (This was my fourth time seeing him in concert.)

One of the Talking Heads biggest hits (featured on NPR's list of the most influential songs of the previous century) was "Once in a Lifetime" (1984). Listening to him sing it again last night, I was struck by the geological undercurrents. I thought I would share a few of the topical lyrics that have a peripheral relevance to this blog:

On hydrology:

"Letting the days go by/let the water hold me down
Letting the days go by/water flowing underground
Into the blue again/in the silent water
Under the rocks and stones/there is water underground"

On oceanography:

"Water dissolving...and water removing
There is water at the bottom of the ocean
Carry the water at the bottom of the ocean
Remove the water at the bottom of the ocean!"

On the principle of uniformity ("uniformitarianism"):

"Same as it ever was, same as it ever was,
Same as it ever was, same as it ever was"

Also, from a different Talking Heads tune ("Life During Wartime"), Mr. Byrne offers us this epistle, clearly referring to the value of studying for open-book geology lab practicals:

"Burn all the notebooks
What good are notebooks?
They won't help me survive!"

Mr. Byrne may be coming to a concert hall near you. Check out his tour dates here. Listen to his new album for free online here. He also keeps a blog (which he calls a "journal," and it occasionally features geological musings, as in this example.)

Labels: geology, music, oceans, water resources

Labels: fossils, mammals, meetings, oceans, psw, smithsonian

Just a few weeks left until the National Museum of Natural History (Smithsonian Institution) opens the doors of its new Ocean Hall to the public (Saturday morning, September 27). I'm particularly excited that it contains an exhibit on ancient seas, including a Basilosaurus skeleton!

Labels: dc, museums, oceans