Deep Pacific Upside Down Waterfall

This passage from Helen Czerski's Blue Machine: How The Ocean Shapes Our World gives us a glimpse of the wondrous undersea universe we are just beginning to explore.

"We see upside-down waterfalls, she says. I don't understand what she means at first, and it takes me a few seconds to process the video as Deb keep talking. In those vertical chimneys, the walls crack and hydrothermal fluids come leaking out and  you get something that looks like half a toadstool growing out of a tree in an old growth forest. And suddenly I see it. This is a gigantic hydrothermal chimney looming out of the darkness, and hot water is indeed leaking out of its side. But because hot water is less dense than cold water, the hot water keeps flowing rapidly upwards. When it first hits cold water, its clearly dumped some minerals and made a ledge that sticks out- that's the toadstool shape that Deb is referring to. The water flowing upwards has had to flow outwards underneath the ledge before it can carry on upwards. But the ledge has developed a hollow on its underside like an upside-down bowl, so there is a pool of hot water there, held in the hollow as if it were filling up the inside of an umbrella. The boundary between hot and cold water shimmers like a mirror. And then the hot water is spilling out of its hollow and continuing upwards into the gloom. It really is an upside down waterfall".

Helen Czerski is watching this footage captured by a remotely operated vehicle exploring the area around the Juan de  Fuca Ridge, an undersea mountain chain a few hundred kilometers west of Seattle. Here, the Pacific and the Juan de Fuca tectonic plates diverge. Scientists are closely monitoring this ridge for seismic and volcanic activity, using a network of sensors  called the Regional Cabled Array. Deb Kelly is the Director of this project. Hydrothermal chimneys are sulfide and carbonate mineral deposits that form when hot mineral saturated sea water emerges through cracks in the ocean crust. The are common near mid oceanic ridges where the interaction of sea water and rock heated up by magma generates vigorous hydrothermal systems.

I'm only a quarter into this book and am enjoying every page of it. Highly recommended!

Volcanic Versus Human Carbon Dioxide Emissions

A couple of weeks ago Iceland awaited with much anxiety as magma made its way to the surface. A volcanic eruption seemed imminent. That danger seems to have passed for now. Seismicity has abated and magma may not break through and erupt.

Misunderstandings regarding climate change though shows no signs of receding as this comment shows - 

 Source: X - https://twitter.com/dremtee/status/1723427183182446871

Ever so often it is worth putting up the numbers:

Anthropogenic CO2 emissions - About 40-50  billion tons per year.

Volcanic CO2 emissions - Approximately 500 million tons per year.

Terry Gerlach of the U.S. Geological Survey has compiled global data on volcanic emissions  -  Volcanic Versus Anthropogenic Carbon Dioxide, published in EOS Transactions American Geophysical Union. 

This article is from 2011, but there are good explanations on volcanic emission rates and the observed discrepancy (which has increased in the 12 years since publication) between anthropogenic and volcanic emissions. 

What conditions limit volcanic CO2 emissions on present day earth? 

On average, magma contains about 1.5 weight percent dissolved CO2. Estimated annual magma production on earth amounting to about 80 billion tons won't create near enough volcanic CO2 to match human emissions. About 850 cubic kilometers of magma would be needed to be generated annually to create volcanic CO2 on an anthropogenic scale. So much magma production either under land or sea would not have gone unnoticed. 

Short lived volcanic eruptions like past events in Iceland, or Mt. Pinatubo, or Mt. St Helen's, although violent and spectacular,  didn't emit more than a few million tons of CO2. These amounts are too small to have a discernible warming effect. Large explosive eruptions in fact might cool the earth by a degree or so for a short time because the sulphur particles they emit reflect sunlight back in to space.

Can volcanism cause global warming? Yes, but over much longer time scales. 

Weathering of surface silicate rocks consumes about 500 -700 million tons of CO2 per year, offsetting the amount emitted by volcanoes. There has to be sustained volcanism at high emission rates for decades to hundreds of years to create an imbalance between weathering and volcanism and change climate. 

Cin-Ty Lee and Slyvia Dee 's  commentary on this subject explores the role of volcanism on global climate. 

Photomicrograph: Mineral Filled Vesicle

I came across this stunning image of a mineral filled vesicle on the September 2023 cover of Geology. The rock sample was collected from the Louisville Seamount Chain in SW Pacific Ocean.

 Source: Elmar Albers et.al. 2023- Timing of carbon uptake by oceanic crust determined by rock reactivity.

Vesicles in igneous rocks are spherical holes formed by expanding gas bubbles. As lava erupts, dissolved gases bubble out. Lava solidifies fairly rapidly on exposure either to air or water. The bubble shape is retained as a small cavity. It gets filled with minerals when magmatic fluids and mineral saturated seawater or groundwater circulate and react with the rock. 

The basalt rock in this study is about 50-74 million years old. The calcite in the vesicle precipitated within 8 million years of eruption. Alteration of undersea basalt is a CO2 sink. Basalt reacts with seawater, trapping carbon in carbonate minerals. The calcium required for formation of carbonate minerals is provided by the alteration of minerals like plagioclase. The study is trying to estimate how long such carbonation reactions continue. Carbonated oceanic crust eventually sinks into the mantle at subduction zones sequestering carbon from the surface for hundreds of millions of years.

This particular vesicle is filled with carbonate (calcite) and clay. Notice the beautiful banding suggestive of pulses of mineral formation. Among the brown and white layers are white bands of faceted saw tooth calcite. And the upper part of the vesicle is filled with large irregular shaped crystals. Surrounding the vesicle is the 'groundmass', made up of tiny crystals of plagioclase feldspar, iron oxide, and volcanic glass. There is no scale in the picture, but my guess is that the vesicle is a few hundred microns across.

In a hand sample a vesicular basalt will look like the example below. This is from the Deccan Traps near Pune. 

The vesicles here are much larger than the first example. Many are empty. Some vesicles have a lining of tiny crystals. Carbonation of terrestrial basalts also constitutes a carbon sink.  Combating global warming and achieving net zero emissions will require, foremost, a steep reduction in emissions, but additionally also removing carbon dioxide from the atmosphere and safely storing it in long term reservoirs. Such carbon removal and sequestration projects are exploring the potential of basalts and related igneous rocks as a long term carbon sink. 

Links: Volcanic Underworld, First Americans, Billion Year Old 3D Microfossils

Readings over the past few weeks.

1) Taking the First Steps Into a Newly Formed Volcanic Underworld: Maya Wei- Haas describes a fascinating landscape on the Canary Islands in the Atlantic Ocean. Volcanic eruptions and the transport of lava via underground tubes has formed a subterranean world of stacked lava tunnels and caves. Their mapping is ongoing and scientists hope to understand not just the details of volcanism and the hazards it poses, but also how life can colonize such nascent surfaces, powered by nutrients from minerals. As one of the scientists remarks- "lava tubes is a rare chance to watch an evolving ecosystem from time zero".

2) It looks like the 23ky old human footprints at White Sands are solid: What is the earliest securely dated evidence of people in the America's? In 2021, there was a report of human footprints from an ancient lake in New Mexico. Since the footprints themselves could not be dated, seeds of an aquatic plant that were found in the same layer were carbon dated to about 23 thousand  years ago. That result was greeted with caution. The main concern was that the seeds may have taken up much older lake water containing less of the radioactive isotope C14. This may have made the dated material look older than it actually was. 

Now, there has been more work on the geochronology of the site using two more independent lines of dating. The results agree with the previously estimated date of 23 thousand  years. ArcheoThoughts summarizes the dating methodologies. 

3) Discovery of oldest 3D-preserved microorganisms: Before organisms evolved the ability to build hard skeletons, their remains have been preserved as impressions on soft sediment or as chemical degradation products recognizable by a light carbon isotope signal. Stefanie Terp reports on a discovery of 3D preservation of microorganisms from a mine in Ukraine. They are 1.5 billion years old! 

Scanning Electron Microscopy reveals the filamentous structure of these creatures. They are most likely a variety of fungi. Groundwater in the granite environment in which they lived was saturated with aluminum and silica. The microorganisms were covered and entombed in micrometer thin layers of aluminum silicate, perfectly preserving their delicate structure.

Field Photos: Iceland

More pictures arrived from different parts of the world. My friends visiting Iceland and the Alps sent me some stunning photos of landscapes and geology. 

Iceland. 

All pics by Biju Mohan.

Lava flows forming gentler slopes and steep rock faces. Notice the rough columnar jointing in the upper lava flow.

Where basalt plateau meets the sea. Cliffs and a wave cut platform.

Volcanic cone and crater.

A fissure or a crack through which lava would have poured out. These are present all over Iceland.  

Iceland predominantly has basalt volcanism, broadly the same rock type as the Deccan. It is one of the few locations where the Mid-Atlantic spreading center is exposed above sea level. This is a divergent plate boundary, where the European and North American tectonic plates (along with some micro-plates) are moving away from each other.

Biju asked me an interesting question; "Did the deccan area looked like present day Iceland sometime in the past? Is there evidence for numerous volcanoes in the Deccan?

Yes, a young Deccan volcanic terrain would have looked similar to Iceland in some aspects. Since in both places, the crust was pulled apart by extensional forces, long fissures or cracks formed and were the main passageways for magma to come to the surface. These fissures from where lava came out would have been visible in a young Deccan. They have eroded away now. What is left are dike swarms, essentially cracks plugged by sheets of magma. Many of these dikes represent the feeder passages from which lava ascended to the surface. So, an exhumed lower level is now visible. Volcanic cones would also have been visible. These have mostly been eroded away in the Deccan.

As such Deccan would not have seen the development of very large steep cones, since the lava type is runny, and does not pile up much to build cones. Iceland though, besides basalts,  has more of a silica rich sticky lava type, with more explosive volcanism,  and a more pronounced development of steeper volcanic cones. Remember the Eyjafjallajökull volcano that erupted in April 2010?

Fresh lava fields would have been clearly demarcated. In young volcanic terrains it is easier to pick out discrete eruptive episodes. Lava fields erupting from different vents overlap. Slightly older lava will change color due to weathering and also get colonized by plants. Fresher lava fields will be barren and likely steaming as well! In the much older Deccan , erosion has erased such differences. Exhumation doesn't always expose a pristine surface, rather a patchwork of vertical sections where one gets a two dimensional view is the common outcrop pattern, making recognition of such lava fields challenging to the untrained eye. 

Another similarity would have been the presence of active hydrothermal systems. Today, the Deccan volcanic system is extinct, but 65 million years ago, groundwater would have been heated by flowing through hot rock and proximity to magma. Fumaroles and hot springs would have been a common phenomenon. I have been collecting secondary minerals from the Deccan Traps since my college days, and I would have loved to have wandered through a young Deccan volcanic terrain, where hot mineral saturated water were depositing silica, calcite, and zeolite minerals in cracks and cavities of the basalts. 

The oldest lava flows in Iceland are mid- Miocene in age. Erosion has been sculpting landscapes for a good 15 million years. The result is some uncanny similarities with the Deccan. The 'Trap' topography, alternations between gentler and steeper slopes is also seen in Iceland. And along the Konkan coast, basalt and laterite sea cliffs look over flat wave cut platforms just like the Iceland coast. 

Sea cliff and a wave cut bench, Harnai, Konkan.

 

I'll close with this beautiful Iceland landscape. 

Coming soon.. Dolomite Alps and a geological conundrum.

Links: Long Covid, Galapagos Islands, Origin Of Life

 I enjoyed reading these over the past few days.

1) Clues to Long Covid:  The disease that has affected us over two long years is still quite a mystery. Jennifer Couzin-Frankel has written a very informative article on the quest to understand Long Covid and how to treat it. 

2) The Galapagos Is a Glimpse of Eternity.  Geology influence organismal habitat and life habits. Penguins nesting in lava tubes. Tortoises finding warm volcanic vents to raise their body temperatures. Paul Stewart describes the landscapes of the Galapagos Islands with its amazing biodiversity, now threatened by climate change. 

3) From Pre Biotic Soup To Fine Grained RNA World. I often come across new articles breathlessly announcing that organic molecules of various types have been found on asteroids. But whatever the source of different molecules, it is specific conditions on early earth that we need to understand to arrive at a sensible theory of the origin of life. Fine article by Philip Ball.

Links: Tonga Volcano, Old Carbon, Indian Palaeontology

 Sharing these readings.

1) My first impression of the massive Volcanic eruption in Tonga was the mushrooming ash plume seen in a satellite imagery. Over the days more sensors have captured additional information about this event. When it is safe, geologists will travel to the site to sample the volcanic debris and subject it to detailed textural and geochemical analysis to piece together the journey of magma from its source to its explosive entry on the surface.

Scientific American has a good summary - Why the Tonga Eruption Was So Violent, And What to expect next. 

2) Debate is an integral part of scientific progress. One common platform to engage in a critique and discussion with your colleagues is the Comment and Reply section in scientific journals. You can submit a note explaining the issues you have about a paper, and it is published along with the author’s response. I am across a good example of this in the journal Science. The topic was the recent announcement of roughly 22,000 year old human footprints from Lake Otero, New Mexico. These dates suggest that humans  were present in North America during the Last Glacial Maximum, a few thousand years earlier than what other data has indicated.

The debate revolves around the accuracy of dating these footprints. Of particular interest here is the problems one can encounter with carbon dating a sample. Living beings have amounts of the radioactive isotope carbon 14 in them in equilibrium with the atmosphere. After death, the amount of this isotope in organic tissue starts decreasing due to natural radioactive decay of carbon 14. Knowing the decay rate and measuring its proportion in the organic material gives us estimates of how old the sample is. But what if the source of carbon is old? For example,  it is from very old groundwater or from the bottom of a lake which is not exchanging gases with the atmosphere? The carbon 14 values in such a réservoir will be very low due to ongoing decay and no replenishment of newly formed carbon 14 from the atmosphere. If organisms consume carbon from such a reservoir (which contains carbon 12 and carbon 13 too) and then are sampled , they will be estimated to be older than they really are. 

The Comment and Reply focuses on this problematic aspect of recognising and correcting for the ‘reservoir age’ of carbon 14. Of pointed importance too is the context and location of collected samples. 

A very informative debate on the nuances of sampling and assigning ages. 

Comment- Évidence of humans in North America during the last glacial maximum. 

Reply- Evidence of humans in North America during the last glacial maximum. 

3) I have posted about this topic before. Thé challenges and triumphs of Indian palaeontology very well described by Kamala Thiagarajan in this recent article. 

Why India’s Fossil Wealth Has Remained Hidden. 

Previously, Sreelatha Menon had written about the lack of importance palaeontology is accorded in the earth sciences and the devastation this neglect is inflicting to palaeontology education, awareness, and research. Her essay is worth reading too; What do you do when palaeontology is itself endangered in India?

Books: Volcanoes, Mammals, Himalayas

 New arrivals on my book shelf.

Fire and Ice: Volcanoes of the Solar System. Earth has them. So does the Moon and Mars. While eruptions on these three is molten silicate magma, there is plenty of variety in the rest of the Solar System. Io has sulphur rich emissions which drape the surface with a coating of  sulphur. Pluto has eruptions of nitrogen, methane, and ammonia that solidifies to form icy rock. Tidal forces unleased by Saturn on its moon Enceladus ruptures the moon's surface and triggers eruptions of fluids that fall back as snow and also contribute to the formation of Saturn's rings. Volcanologist Natalie Starkey delves into our current understanding of volcanoes of the Solar System and what we can learn from them about planetary evolution. Fascinating topic!

  

Beasts Before Us: The Untold Story of Mammal Evolution and Origins. Untold because most authors begin where the Dinosaurs end. The starting point is  usually at 66 million years ago, when a meteorite changed the world in an instant, reorganizing and vacating ecosystems into which mammalian lineages radiated. The story told by Elsa Panciroli goes way back, when Synapsids, the branch that led to mammals diverged from the common ancestor of mammals and reptiles. Repeat three times before going to sleep every night. Mammals did not evolve from Reptiles. These two groups shared a common ancestor in the Carboniferous about 300 million years ago. More and more fossils  are revealing that these early mammalian lineages were quite diverse, and not mere stunted underlings to the more popularly known Dinosaurs. For a lucid audio discussion of this book, listen to Elsa Panciroli on Paleocast Podcast- Beasts Before Us. 

 

 Himalaya: A Human History. My friend Emmanuel Theophilus is sure to like this one. I am thoroughly enjoying it. I didn't know much about ancient Tibet and Nepal, and what a rich history these two regions have! Ed Douglas tells these stories with panache and verve. And with a light touch. Lost empires,  ancient trade routes, master craftsman, art, architecture, spiritual masters, crafty power brokers, bloody military campaigns, missionaries, adventurers, botanists, colonialism, and recent geopolitics.  It really is an enthralling narrative of the epic history of this mighty mountainous region. I'll use the word 'remote' more carefully hence in my conversations about the Himalaya. This one is for you Theo!  

Himalaya Overview, African Population History, Iceland Volcano

 From past couple of weeks:

1) This is a fine synthesis of geological, geophysical, seismic and geodetic data of the growing Himalaya mountains. The review examines the interplay and feedbacks between seismic cycles and tectonic deformation. Earthquakes result in rock deformation and faulting. Tectonic structures developed this way over million of years, in turn, influence stress accumulation and the extent and location of earthquakes.

Building the Himalaya from tectonic to earthquake scales.

2) Holocene-age ancient DNA and genetics of extant populations is increasing our understanding of African population history.

The deep population history in Africa. 

3) The remarkable drone footage of the ongoing eruption of Geldingadalir volcano in Iceland.

Email subscribers who can't see the embedded video can view it here- Iceland Volcanic Eruption.

Articles: Herculaneum, Magma Ascent, Early Human Migration, Indian Cheetah

Some interesting articles on a variety of topics that I came across in the past few weeks.

1) What Really Happened at Herculaneum?

This off course refers to the violent eruption of Mount Vesuvias in 79 A.D.  A new study analyses the way bone and soft tissue react to extreme heat and proposes that the people found dead at Herculaneum did not vaporize but died of asphyxiation.

2)  The long wait and rapid rise of deep magma.

Magma can reside in deep chambers at the boundary between the crust and mantle for thousands of years before rising to the surface rapidly in a matter of a few days.

3) Neanderthal Genes Hint at Much Earlier Human Migration From Africa.

It was thought that 60,000 years ago modern humans migrated out of Africa and interbred with Neanderthals beginning around 40,000 years ago. As a result all non-Africans carry some Neanderthal DNA. A new DNA analysis technique now suggests that an earlier wave of humans migrated out of Africa some 200,000 years ago and interbred with Neanderthals. Their descendants back migrated to Africa carrying with them the legacy of this earlier mating. As a result, Africans too carry a genetic legacy of Neanderthals.

4) Introduce the cheetah, with caution and guidelines.

There is a proposal to introduce the African cheetah into the Indian landscape. Neha Sinha argues that a grasslands policy needs to be put in place first.
 

Does Volcanism Cause Global Warming Or Cooling?

On million year time scales, does volcanism cause global warming or cooling?

The answer is both, depending upon the longevity of the volcanism and it effluents. Prolonged volcanic emissions over tens of thousands to millions of years of greenhouse gas carbon dioxide will warm the earth's surface. But magmatism and volcanism creates continental crust. During volcanic episodes and after the magmatic system dies, this new crust consumes carbon dioxide in chemical weathering reactions. This draw down of atmospheric carbon dioxide can result in global cooling, as is inferred to have resulted in the Cenozoic beginning around 30 million years ago, after collision of the India -Eurasian plates. Volcanism and tectonic activity can both warm and cool the earth's surface as magmatic arc systems grow and die.

Volcanism also ejects sulfur particles into the atmosphere. These particles block and reflect sunlight away and this albedo effect may result in cooling of the earth's surface. Volcanic ash falling on both land and sea may act as a fertilizer, enhancing organic productivity and further drawing down and sequestering carbon dioxide through increased organic carbon burial. A recent paper published in Geology by Gerilyn Soreghan and colleagues (open access) points to a temporal coincidence between explosive eruptions and glacial conditions during the Late Paleozoic. The researchers suggest that the prolonged icehouse conditions from around 360 million years ago to 260 million years ago resulted from explosive volcanism and effects of sulfate aerosols.

This paper has prompted a thoughtful commentary (open access) by Rice University geologists Cin-Ty Lee and Sylvia Dee on the broader controls of volcanism and crustal weathering on global climate. On the particular question of whether the Late Paleozoic ice age was a result of sulfate ejections, they differ somewhat from the authors of the study. Cin-Ty Lee and Sylvia Dee point out that the residence time of sulfur particles in the atmosphere is just a few years. To maintain a global icehouse for a 100 million year period would require large explosive eruptions every few years over tens of millions of years.

They point to an example of another period of enhanced magmatic activity in the Cretaceous Period. Field evidence from the continental interior of the U.S. shows just about 200 eruptions over a 10 million year period. Only a few of these were large enough to have ejected significant amounts of aerosols into the stratosphere. That is not to say that sulfate aerosol albedo cannot cool the planet. But it may happen over shorter 1000-10,000 year time scales. In case of the Late Paleozoic icehouse, they suggest that the pattern of cooling may hint at the causative factor. Numerous short-lived cooling events would be suggestive of explosive volcanism as the cause.

On longer time scales carbon dioxide will play a larger role in modulating climate. Explosive eruptions and resulting sulfate particle emissions are only a small component of magmatic flux. On the other hand, CO2 degassing is taking place even without eruptive activity. Long lived magmatic activity will result in a warming trend due to an increase in atmospheric CO2.  Post magmatism, a drop in atmospheric CO2 levels and cooling due to silicate weathering also takes place on longer million year time scales.

An extract from Cin-Ty Lee and Sylvia Dee commentary:

More broadly, the nature by which volatiles are exchanged between planetary interiors and their surfaces is rich with complexity. The magnitude and style of magmatism not only controls volatile degassing but also erosion, weathering, radiative balance, and biological productivity. How magmatic processes change through time and with geodynamic states is an area ripe for interdisciplinary research and new discoveries. Soreghan et al.’s work is an example of how investigating these processes from deep time to the present, as well as on Earth and other planets, will force us to rethink how planetary systems operate.

The geologic record shows that enhanced phases of volcanic activity sustained over thousands of years can cause the earth's climate to tilt towards a long lasting greenhouse or an icehouse. People who claim that the warming of the earth's surface over the past few decades is due to natural causes like volcanic eruptions and not fossil fuel burning must understand the time scales and amounts involved. Even big volcanic eruptions that occur every few years emit only a few million tons of CO2. Awkwardly, for anthropogenic warming deniers, these eruptive events may result in a short term cooling phase due to the effects of sulfate aerosols. A recent survey puts the total global emissions due to volcanic eruptions and non-eruptive degassing of magma to be about 0.3 billion tons per year. In contrast, human activity is putting 30-40 billion tons of CO2 in the atmosphere every year.

Explosive volcanism as a key driver of the late Paleozoic ice age.
Does volcanism cause warming or Cooling?

Volcanism And The Demise Of Neanderthals

In addition to the many proposed reasons, something more to think about:

From Geology (early edition)-

Campanian Ignimbrite volcanism, climate, and the final decline of the Neanderthals - Benjamin A. Black, Ryan R. Neely, and Michael Manga

The eruption of the Campanian Ignimbrite at ca. 40 ka coincided with the final decline of Neanderthals in Europe. Environmental stress associated with the eruption of the Campanian Ignimbrite has been invoked as a potential driver for this extinction as well as broader upheaval in Paleolithic societies. To test the climatic importance of the Campanian eruption, we used a three-dimensional sectional aerosol model to simulate the global aerosol cloud after release of 50 Tg and 200 Tg SO2. We coupled aerosol properties to a comprehensive earth system model under last glacial conditions. We find that peak cooling and acid deposition lasted one to two years and that the most intense cooling sidestepped hominin population centers in Western Europe. We conclude that the environmental effects of the Campanian Ignimbrite eruption alone were insufficient to explain the ultimate demise of Neanderthals in Europe. Nonetheless, significant volcanic cooling during the years immediately following the eruption could have impacted the viability of already precarious populations and influenced many aspects of daily life for Neanderthals and anatomically modern humans.

Widely varying climatic conditions and resource availability may have hit Neanderthals more than "modern" humans. A number of reasons are given including the ability of "modern" humans to set up long distance networks facilitating exchange of technology and ideas.... Off course some would argue that the Neanderthals  never really became extinct. Their genetic legacy lives on in us. There is no doubt that interbreeding between the two human populations means that Neanderthal genes are with us today, but certainly a way of life, a particular morphology, social mores and perhaps a unique language (s) did disappear.

Gold And Metal Exploration In The Deep Sea

The recent interest in metal sulphide deposits localized around deep sea hydrothermal vents has been nicely summarized in an article in the New York Times.

Gold and copper are the main metals of interest along with silver, zinc and cobalt. The deposits are not randomly distributed on the sea floor but are near undersea volcanic activity with the Pacific areas along Papua New Guinea and Fiji being of special interest.

Years ago as a student I had visited the National Institute of Oceanography in Goa, India. At that time the thrust of research was on the origin and distribution of manganese nodules which could be found in several zones in the Indian ocean. That never became a commercial venture due to probably the low concentration of the nodules and the high costs of extraction.

These new ventures though are going to be operating on a gigantic scale:

...Last year, Nautilus won a 20-year lease to mine a rich deposit in the Bismarck Sea, in the southwestern Pacific. The mounds are a mile down. The company says the site holds about 10 tons of gold and 125,000 tons of copper.

Nautilus plans to start mining next year but also cites possible delays. It is building robots up to 25 feet tall that are to collect sulfides and pump them to the surface. Barges are then to carry the seabed minerals to Rabaul, a Papua New Guinea port some 30 miles away.

Robots 25 feet tall and maybe even taller in the future.

Hollywood won't be far behind..

New Volcanic Island In The Red Sea

Nearly coinciding with the New Year, volcanic activity of the west coast of Yemen has given rise to a new volcanic island.

 From the NASA Earth Observatory article:

An eruption occurred in the Red Sea in December 2011. According to news reports, fishermen witnessed lava fountains reaching up to 30 meters (90 feet) tall on December 19. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites observed plumes on December 20 and December 22. Meanwhile, the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite detected elevated levels of sulfur dioxide, further indicating an eruption.

The activity in the Red Sea included more than an eruption. By December 23, 2011, what looked like a new island appeared in the region....

....The volcanic activity occurred along the Zubair Group, a collection of small islands off the west coast of Yemen. Running in a roughly northwest-southeast line, the islands poke above the sea surface, rising from a shield volcano. This region is part of the Red Sea Rift where the African and Arabian tectonic plates pull apart and new ocean crust regularly forms.

 The Red Sea is one arm of a great three armed rift system that includes the Gulf of Aden and the East African rift valley as the other two arms. If you want to know more about divergent plate boundaries and rifting along this complex system I would recommend this primer at Geology.com.

And don't forget to check out the image comparison tool with its cool slider at the NASA Earth Observatory website by clicking on the View Image Comparison option.

Volcanoes And The Extinction Of Us

 "Morn came and went, and came, and brought no day/ And men forgot their passions in the dread/ Of this their desolation . . ."

...Lord Byron wrote this in the aftermath of the Tambora eruption in 1815 which darkened skies over England for weeks. Apparently quite a few artists were profoundly affected by this eruption. Mary Shelley got depressed and wrote Frankenstein while others like JMW Turner painted the bright sunsets that were brought about by haze forming suspended ash all over Europe.

Simon Winchester has a good article in the Guardian on volcanic eruptions of the past and their impact on humans and on their capacity to wreck havoc on global ecosystems.

He comes out distinguishing the aftereffects of earthquakes and volcanoes. Earthquakes kill a lot more people but in terms of long lasting impacts on organisms, volcanoes are more lethal. Earthquakes don't cause extinctions unlike the ill-effects of volcanoes which can linger on for weeks or even years after, resulting in a more widespread environmental damage and extinctions of local and sometimes global reach.

The article is mostly about the impacts of volcanoes on biology but I can't help pointing out that recent massive earthquakes have had very important, potentially long lasting, social impacts of local and regional significance.

After the 2004 Sumatra earthquake, the separatist movement which was gathering strength in the island of Aceh lost steam due to the utter devastation of its population and infrastructure. A peace agreement with the Indonesian government resulted in restoring peace and stability after decades of violence.

On a more villainous note,  in the aftermath of the 2005 Kashmir earthquake, the social arms of the terrorist organizations Lashkar-e-Taiba and Hizbul Mujahideen rushed in to provide help to the local populations in the absence of prompt government relief and gained enormous popular support making it that much harder to uproot them.

Coming back to the article..one minor quibble I have is about his section on the rates of mass extinctions. He says that two to 5 major extinction events occur in the world every million years or so. This is in reference to "profound and world changing" mass extinctions and I am puzzled by this statistic. Surely he means every few tens of millions of years or so, especially since he is linking these events to flood basalt volcanism? Or does he mean flood basalts from Iceland volcanoes in the past few million years have triggered mass extinctions on a million year frequency? Extinction is occurring all the time and occasionally there will be a spike over and above the background extinction rate brought about by catastrophic events, local and regional and only rarely global ..but what does he exactly mean by "two to five major extinction events"? are these local or global events...and do we really have paleontological methods to resolve events that closely spaced?

Iceland sits atop a mantle hot spot that coincides with a mid-oceanic ridge. This underlying heat engine may be the modern representative of the hot spot responsible for past flood basalts provinces of Greenland and in the British Isles which formed during the early Cenozoic opening of the north Atlantic.  Seen in this context, is the recent Iceland eruption the beginning of a more prolonged volcanic activity that might threaten our very existence?

That's off course pure speculation in an article that is otherwise full of information and interesting facts..but it does make you a bit uneasy....

Tip: Nanopolitan

Iceland: Why Such An Explosive Eruption At A Mid-Oceanic Ridge?

Over at Nobel Intent John Timmer talks to  Dr. Jeff Karson of Syracuse University who explains the conditions that produce the ash rich explosive eruptions generally associated with subduction zones and not the mid-oceanic ridge setting of Iceland.

He identifies two factors:

1) Unlike most mid-ocean ridge settings the magma underneath Iceland have a silica rich rhyolitic component along with the copious basalt. Silicic magmas which form rhyolites contains more dissolved volatiles that fizz out of solution as the magma ascends and the pressure on it is released. Hence rhyolitic volcanism tends to be explosive.

2) The ice cover over Iceland. As hot magma comes in contact with ice, it vaporizes it and produces explosive steam, contributing along with other volatiles to a violent eruption.

 Credit: Nasa

Why is there rhyolite at a mid-oceanic setting which is usually dominated by basalts?

Two possible answers: One is that it forms through fractional crystallization of a tholeiitic magma. Some geochemical work on the Iceland igneous province suggest though that this might not be the dominant mechanism at work. Instead, partial melting of older crust may be at work. Iceland differs in this respect with Hawai where fractional crystallization of basalts do not produce rhyolite. In Iceland tectonics keeps bringing to depth earlier extrusives. Ascending magmas interact with this earlier formed crust which is heterogenous in character being made up of basalt and containing silicic segregations from earlier cycles of solidification and this interaction likely generates rhyolitic composition magmas.