Canadian Earth Science for @PMHarper – 7: very old warm seas in what is now Nunavut (and why there is a Lead-Zinc ore body there)

The preamble to this review series is here. All reviews in this series are categorized as “Canadian Earth Science for @PMHarper” (see right hand column).

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Turner, E.C., 2009, Mesoproterozoic carbonate systems in the Borden Basin, Nunavut. Canadian Journal of Earth Sciences, v. 46, p. 915-938

near Arctic Bay 2

Figure 1. Borden Peninsula near Arctic Bay. Image Source: Google Earth

Canada has immense mineral resources. The Geological Survey of Canada (GSC), a branch of the Earth Sciences Division of Natural Resources Canada is responsible for most basic geologic mapping north of 60oN (and a lot more); the Provincial and Territorial Geological Surveys do all other basic geologic mapping (plus a lot more).

Why do we need basic geologic mapping? Because a geologic map (analog/digital) is the basis for justifying investments in developing and managing a territory as well as the basis for further fundamental geological research. Whether it is resource development, hazard mitigation, groundwater management, or any other human intervention in the land, a basic understanding of underlying geology is a necessary start.

This article is an outflow of a “North of 60″ geologic mapping project, namely that of the Borden Peninsula of Baffin Island, Nunavut. The peninsula sits at 72-73N and is essentially uninhabited, except for the small community of Arctic Bay.

The area under investigation is about 250 x 50 km large. Is it a priority to do geologic mapping all the way up there? Yes, because this area is rich in mineral resources: there is, or rather was, a Lead-Zinc mine: the Nanisivik mine. It operated from 1976 to 2002. The mine site has been cleaned up since 2007 and the community of Arctic Bay has been left with a mixed blessing (see further ‘Additional information’ below).

Finding natural resources is like a sophisticated treasure hunt: the first findings are the ones that stare you in the face. When those run out, you start scratching your head: would there be more? A better understanding of the different rock formations and their relations is then required. That’s what the original goal of this project was: improving understanding of the geological formations that host these ores.

But if you understand this ore-setting better, you can also improve your understanding of other Lead-Zinc ore bodies in comparable geologic settings elsewhere in the world (e.g. in Nova Scotia): studying comparable geologic sites increases the understanding of comparable (not: the same) mineral occurrences.

The rocks of the Borden Basin are about 1.2 billion (1,200,000,000) years old and the formations under investigation consist largely of limestone and dolostone. Limestone is Calcium Carbonate (CaCO3) and dolostone or dolomite is Calcium Magnesium Carbonate (CaMg(CO3)2).

Limestone can form in inorganically and organically. In the inorganic process, seawater evaporates in warm latitudes and shallow seas. As it evaporates, supersaturated carbonate precipitates around tiny grains of sand and the result are extensive and thick beaches and lagoons made up of ooids. This process has been going on for billions of years and is still going on today: most of the beaches on the Bahamas are made up of ooids.

027-Joulters-Key-From-South-Bahamas 200px-JoultersCayOoids

Figure 2. Ooids. Left: Joulter’s Cay, Bahamas – an extensive, thick carbonate platform made up largely of ooids. Right: ooids under the microscope. Each ooid is less than 2 mm in diameter.

But most marine limestone is formed as a result of biological processes: organisms build calcareous (CaCO3) external skeletons (shells, reef structures) by extracting dissolved carbonate from sea water. However: skeleton-building organisms did not exist 1.2 billion years ago – it would take another 600 million years for the first ones to evolve.

Some algae and bacteria also secrete carbonate, mostly in thin filaments that build on top of each other and look like tree rings when you see them in cross section. Algae and bacteria were pretty much the only living organisms back 1.2 billion years ago and some of these algae still exist today: they are called stromatolites and the most famous place where they occur is Shark Bay in western Australia, a UNESCO World Heritage site.

shark bay    stromatolite modern stromatolite proterozoic

Figure 3: Stromatolites ‘algal mounds’. Left: people looking at stromatolite mounds in Shark Bay, western Australia. Middle: Shark Bay stromatolite cut in half. Right: 1 billion year old stromatolite, looking the same as modern-day Shark Bay stromatolite. 

Earth was very different 1.2 billion years ago. Atmospheric oxygen was about 1% of today’s and the sun only had about 3/4 of its current strength. While scientists are still debating the details of the atmospheric and oceanic conditions of this era, there appears to be enough evidence to suggest that earth was relatively warm and could support lots of primitive life. Plate tectonics, the process of mid-ocean spreading, subduction and continent motion, was working too.

Baffin Island Borden Basin Google Earth and Geol map

Figure 4. Left: Geologic Map of the Borden Peninsula (Turner, 2004a). Right: Google Earth image at approximately the same scale. 

Let’s look at the geologic map of the Borden Peninsula and put a Google Earth image next to it (Figure 4). Stunning! The geologic map displays rock formations oriented in a NW-SE direction. The Google Earth image shows clear NW-SE lineaments. So yes: the structure (a geologic basin) in which these limestones precipitated 1.2 billion years ago is recognizable to the naked eye today.

The lineaments on the satellite image are indicative of the structure, i.e. the basin in which these limestones were laid down. The structure (faults) tell us that the basin was formed in a process called rifting. Because we know that plate tectonics was working then as it is today, you should imagine the environment being somewhat comparable to the Red Sea: a narrow seaway at a relatively low latitude (warm!). The Red Sea too is part of a (rather complex) rift system, lying at the upper extent of the East African Rift.

It gets better (what did we ever do before Google Earth?). Let’s fly to the area of the red arrow on the Google Earth image in figure 1 and drop our imaginary plane down:

Baffin island flying from SE

Figure 4. Google Earth close-up image of the area at the red arrow in Figure 1. The lineaments on the satellite image represent a distinct valley through which a river runs, building a small delta into Milne Inlet. 

There you go: the relief we see today on far away Borden Peninsula reflects the remainder of the relief of 1.2 billion years ago. Pretty amazing.

During rifting, heat rises upwards from the earth’s mantle, forcing the earth’s crust to thin and sag, forming a rift basin. The floor and sides of the basin continue to experience high heat flow until rifting stops. When rifting stops, the basin stops opening and subsiding because heat flow was the engine for the rifting process.

The rising heat brings magmas closer to the earth surface as well. Such magmas contain all kinds of trace elements, including metals. In the Borden Basin, cracks (faults) in the rifting basin allowed for focused release of hot chemically charged plumes, which precipitated as mounds, surrounded by some filament-building algae. These mounds are where the Lead-Zinc complex is found today.

In short: in the shallow areas of this basin, extensive Bahama-bank like ooid shoals and beaches kept piling up as the basin floor subsided; in the deeper parts of the basin, concentrated heat flow caused mounds to build-up, incorporating metals and other trace elements.

So the immediate relevance of this mapping project was to locate and understand the ore-hosting formations. As a result, earlier named geologic rock units got renamed. Three new formation names were introduced and they all have Inuktituk names: The Ikparjuk (meaning ‘pocket’) Formation contains the isolated carbonate mounds that are the host of the Lead-Zinc complex. The other new Formation names are the Nanisivik (meaning ‘place where people find things’) and Angmaat (meaning ‘flints’) Formations.

The results of this project contributed to a better understanding of the Nanisevik Lead-Zinc ore body. In addition, much was learned about the ocean-atmosphere conditions during a very old and poorly known period in earth history: a practical question led to much fundamental knowledge that can be applied to other, comparable, geological problems.

This was an important paper: it became the most cited 2009 paper in the Canadian Journal of Earth Sciences.

Additional information on the Nanisivik mine:

The Nanisivik mine produced Lead (Pb) and Zinc (Zn).

  • Lead: The global demand for Lead is still rising, despite the fact that the applications for toxic Lead are decreasing thanks to invention of substitutes. There is still significant demand for Lead in Lead-acid batteries. Read more about Lead here.
  • Zinc: the following is from the USGS minerals database: about 3/4 of all zinc used globally is applied to galvanizing metal. The remaining 1/4 is consumed as zinc compounds mainly by rubber, chemical, paint, and agricultural industries.  Zinc is also a necessary element for proper growth and development of humans, animals, and plants; it is the second most common trace metal, after iron, naturally found in the human body.

The Nanisivik mine had its own Arctic Port, which the Canadian Department of National Defence (DND) intended to upgrade and use as an Arctic fueling port.  Significant ground instabilities appear to wreak havoc with those plans.

A 2002 report on the mixed-success legacy of the Nanisivik mine on the community of Arctic Bay can be downloaded here.

References

Hahn, K and E.C. Turner, 2013, Mesoproterozoic deep-water carbonate mound lithofacies, Borden Basin, Nunavut. Geological Survey of Canada, Current Research, 2013-11, 17 p.

Turner, E.C. 2003a. New contributions to the stratigraphy of the Mesoproterozoic Society Cliffs Formation, northern Baffin Island, Nunavut. In Current research. Geological Survey of Canada, 2003-B2.

Turner, E.C. 2003b. Lead-zinc showings associated with debrites shed from synsedimentary faults, Mesoproterozoic Society Cliffs Formation, northern Baffin Island, Nunavut. In Current research. Geological Survey of Canada, 2003-B2.

Turner, E.C. 2004a. Origin of basinal carbonate laminites of the Mesoproterozoic Society Cliffs formation (Borden Basin, Nunavut), and implications for base-metal mineralisation. In Current research. Geological Survey of Canada, 2004-B2.

Turner, E.C. 2004b. Stratigraphy of the Mesoproterozoic Society Cliffs Formation (Borden Basin, Nunavut): correlation between northwestern and southeastern areas of the Milne Inlet Graben. In Current research. Geological Survey of Canada, 2004-B3.

Turner, E.C. 2004c. Kilometre-scale carbonate mounds in basinal strata: implications for base-metal mineralisation in the Mesoproterozoic Arctic Bay and Society Cliffs formations, Borden Basin, Nunavut. In Current research. Geological Survey of Canada, 2004-B4.

Turner, E.C., and Long, D.G.F. 2008. Basin architecture and syndepositional fault activity during deposition of the Neoproterozoic Mackenzie Mountains Supergroup, N.WT., Canada. Canadian Journal of Earth Sciences 45: 1159–1184.

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Granites, Glaciers and the Ocean: a hike

We hiked, the other day – a well-known coastal trail, but new to me. So much still to discover here and it’s not like we haven’t been trying. The trail is in Crystal Crescent Beach Provincial Park and takes the hiker all the way around the Pennant Point peninsula in about 4 hours.

Pennant point from Google Earth

Location of the Pennant Point peninsula, which sits as a veritable appendix off the Halifax peninsula. Inset: detail showing the tip of the peninsula (Pennant Point itself). Meaning of red star discussed below. Both images Google Earth

It’s an extraordinary beautiful area and wonderful for hiking as it hardly ever gets too hot or buggy thanks to ocean breezes and fog.  The rocks and the landscape tell a fascinating story. It’s really too bad that there isn’t a single interpretive panel at the trail head.

The peninsula is exposed in striking almost-white granites and granodiorites (igneous rocks). They are peraluminous, meaning that their proportion of Aluminum oxide is relatively high compared to other granitic rocks. These granites are part of a large intrusive body, called the South Mountain Batholith. A batholith is a rock body that solidified from a molten magma as it cooled and moved upward towards the earth’s surface. A batholith consists therefore always of igneous rock and most batholiths are members of the granite family. Because of the excess Aluminum, peraluminous granites look very white, hence ‘leuco’ (meaning ‘light’).

SMB simplified

Simplified map showing the extent of the South Mountain Batholith in Nova Scotia. Black arrow points to Pennant Point Peninsula. Total length of Nova Scotia is about 550 km. 

The South Mountain Batholith rose and cooled in the Devonian, ca. 375 million years ago, a result of colliding continental fragments that pushed the Appalachian mountains upward. The batholith would still have been deep below the surface at that time, overlain by other rocks that formed significant relief, possibly up to 2000 m (Nova Scotia’s southern mainland is barely higher than 200 m today). These subsequently eroded away, exposing these beautiful granites.

The official geologic map of Nova Scotia shows that there are two types of granites here but these are indistinguishable to the casual observer:

Peninsula geology

Detail of official geologic map of Nova Scotia (MacDonald, 2001). The southern part of the Pennant Point peninsula is exposed in Monzogranites (legend M-L Dbmg), subtly different from the leucomonzogranites (M-L Dlmg) of the northern part of the peninsula, which are the same as those at iconic Peggy’s Cove

Another striking characteristic of the granites of the South Mountain Batholith is that they contain lots of xenoliths. A xenolith is – literally – a ‘foreign stone’ (ancient Greek), a rock fragment torn from the rocks that surrounded the magma body as it rose, cooled, and solidified. Because that surrounding rock formation may have eroded away after emplacement of the batholith, xenoliths provide key clues about the area’s geologic history. Xenoliths can range in size from millimeters to tens of meters, as in Portugese Cove, a few kilometers northeast of Pennant Point

photo

Xenolith (dark spherical rock fragment) in Pennant point granites. The white, somewhat aligned flecks are aluminum-rich feldspars that give the granite its distinctive light (‘leuco’) colour. 

The South Mountain Batholith became exposed to the surface the several million years ago, so that it became subjected to the forces of Pleistocene glaciations. Several directions of ice movements are detected along these shores, but, in general, the ice moved away from ice domes situated over major land masses towards the sea (which stood on average 100 m below that of today). The ice caps, a kilometer or more in thickness, had tremendous erosive power. They smoothed the rock surface, and rock fragments that scraped the rock at the base of the ice cap left long grooves in the granite, indicative of the direction of ice flow.

pennant point highlighted striae

Granite outcrop at Pennant Point with glacial grooves (called ‘striae’) indicating the direction of the ice flow (look close: they are parallel to the added red line). The ice cap both smoothed and scratched the rock surface

When the ice melted away, many of rocks that were incorporated in the ice flows, were left stranded. These are called ‘erratics’. While most erratics in this area consist of the same granite as the outcrop, erratics may have traveled hundreds of kilometers, thus leaving important clues for reconstructing the origin and direction of Pleistocene ice flows.

photo 17

Glacially smoothed granite surface with glacial erratics (same granites) at Pennant Point.

photo 1

Along the eastern side of the Pennant Peninsula

Then came the people

Sadly but not surprisingly, we found an immense amount of sea-borne trash on our hike. Other than the usual macerated lobster traps, buoys, gasoline cans and fishing lines, the most impressive piece was a massive 30ft piece of a wharf that rested at the red star at the top of the lake in the Google Earth image, nearly 100 m from the water edge. There was a lot of other trash around the perimeter of the little lake in the image (a.o. a Canadian Coast Guard buoy that was spilling styrofoam mini-pellets), but this was definitely the biggest piece. The assembly of trash and their location clearly shows that this lake and its boulder-rubble seaward edge is a classic storm washover feature, created by repeated battering and overwash from massive storms and hurricanes. Somewhere is a community with a big repair bill. Everywhere are all of us, “planet earth astronauts” (thank you Chris Hadfield) with an even bigger repair bill: that of the maintenance and repair of our fragile and only home.

wharf blown in at Pennant Point   Pennant point itself

30 ft piece of a wharf, resting at the red star in the Google Earth image. Red dashed line indicates washover feature. Other washovers can be seen on the left (W) side of the point. Red star is nearly 100 m from the sea  

 

References

Clarke, D.B. and S. Carruzzo, 2007, Assimilation of country-rock ilmenite and rutile in the South Mountain Batholith, Nova Scotia, Canada.  The Canadian Mineralogist, v. 45, pp. 31-42.

MacDonald, M.A., 2001, Geology of the South Mountain Batholith, southwestern Nova Scotia. Nova Scotia Department of Natural Resources, Open File Report ME 2001-2

Posted in General geoscience, Nova Scotia | Tagged , , , , , , , , , , , | 1 Comment

The graphic artist M.C. Escher and his connections with geology

Mobula Rays by Eduardo Lopez Negrete National Geographic    E41-MC-Escher-No-41-Two-Fish-1941

Left: Mobula Rays off Baja California by Eduardo Lopez Negrete / National Geographic. Right: “Two Fish” by M.C. Escher, 1941 from Escher official website

The left-hand photograph circulated on Twitter a few weeks ago and someone commented that “it looks Escheresque”. I found that fascinating: an apparently random natural phenomenon reminded someone of the mathematically composed artwork of the great M.C. Escher.

But of course we know that there is a lot less that is “random” in the natural world than we thought there was roughly half a century ago. M.C. Escher (1898-1972) died before Mandelbrot published his work on fractal mathematics in 1979. Mandelbrot demonstrated that much of the apparent randomness that we observe in nature is the result of relatively simple mathematical relations, controlled by what’s called a ‘strange attractor’. The best treaty on fractal mathematics and chaos theory for non-mathematicians is James Gleick’s ‘Chaos’. I read ‘Chaos’ more than 20 years ago and it completely changed my view on my work, my career and subsequently my life.

For many centuries before Mandelbrot people wondered “only” about symmetry in nature. Everyone observes symmetry and its exceptions, beginning with our own body which appears symmetrical but isn’t: two legs, arms, eyes, ears, lungs, kidneys but one mouth, esophagus, heart, liver, spleen, pancreas, bladder.

The foundations of crystallography and mineralogy are mandatory in every geoscience degree. We learn about molecular lattice structures and resulting crystal form. Depending on molecular lattice structure and resulting crystal structure, some minerals appear perfectly symmetrical, such as a cubic pyrite. At the other extreme is e.g. triclinic plagioclase, which is symmetrical in a more complex way.

pyrite   Albite_-_Crete_(Kriti)_Island,_Greece

Left: cubic pyrite. Right: triclinic plagioclase. (Wikimedia)

Maurits Cornelis (“Mauk”) Escher was fascinated, or maybe obsessed by ‘the systematic compartimentalization of space’ (in Dutch: “regelmatige vlakverdeling” as he wrote in a letter to his nephew Rudolf, a composer).

Mauk’s half brother was Berend Escher (1885-1967), an iconic professor of geology at Leiden University in the Netherlands, whose specialization was crystallography, mineralogy and vulcanology. Berend Escher was also the sole author of the next-to-last Dutch-language introductory geology textbook. The annual MSc-thesis prize, awarded by the Royal Netherlands Geological and Mining Society is named in his honour (full disclosure: I initiated the prize and was chair of its first jury but I didn’t name it).

photo 1

‘Grondslagen der Algemene Geologie’ (Foundations of Introductory geology) by B.G. Escher, 1948 (my copy).

Berend Escher’s textbook doesn’t contain a chapter on crystallography nor one on mineralogy. As an expert in that field, he decided that this subject was too big for just a few chapters in a textbook and in 1950 he published a separate textbook entitled: “Algemene mineralogie en kristallografie” (“Introductory mineralogy and crystallography”). I don’t have a copy of that book nor have I ever seen it.

Did Berend and Mauk exchange thoughts on crystallography and mineral structure? I bet they did. I bet they wrote letters to each other, but if they did, I don’t know about them. We do know that Mauk was a letter writer, because I have a fascinating book with a collection of letters between Mauk and his nephew (Berend’s son) Rudolf Escher, a composer.

Escher 2

Rudolf Escher and M.C. Escher “Beweging en metamorfosen, een briefwisseling” (‘movement and metamorphosis, an exchange of letters). 1985 - my copy

Mauk designed an ‘ex libris’ book stamp for his brother Berend, paying homage to his expertise on vulcanoes.

Escher woodcut volcano for Berend

Mauk Escher explored symmetry in an illusionary manner his whole artistic life. This is not a treatise on that subject, which is too big for one blog post. I include only one illustration here. It is highlighted in “From 2D to 3D: I. Escher drawings crystallography, crystal chemistry and crystal defects” by Peter R. Buseck of Arizona State University, a downloadable 12-page document. Peter Buseck used Escher’s images to teach about symmetry by designing puzzles about them. Here’s one

Escher BrYeBlfishes fishes and lattice lattice 1

Left: M.C. Escher, 1942, Pattern #55 “Fish”. Centre: with lines indicating symmetry (drawn by me). Right: symmetry lines only, immediately showing 3-dimensionality.

I took crystallography and mineralogy at Groningen University in the Netherlands from professor Perdok, who impressed on us (among other things) “that a 2-dimensional space cannot be filled by pentagrams except by M.C. Escher”.

Mauk Escher’s oldest George was an engineer and moved to Canada early in his life. He donated his personal collection of his father’s works to the National Gallery of Canada, giving them one of the largest Escher collections in the world. At that occasion, he talked about his father. His two younger sons became geologists, Arthur in France and Jan in Switzerland.

Why do we continue to be so fascinated by Escher? For one thing, I think that it’s because he shows us something that science alone cannot show us in the same manner: beauty, wonder and unpredictability.

Which is why we always need more Art in Science.

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#Mywritingprocess blog tour: clicking “publish” is exhilarating

thinking of Ellen Gilchrist

This post is not about Earth science, it’s about me. This is part of a relay race: an exploration into how and why people blog about science. Search for #mywritingprocess on Twitter and you find hundreds of bloggers who have tackled this relay.

The idea is to answer a few questions and pass the baton.

I would not have participated in this exploration if I had not been handed a baton, and – in a moment of sheer madness – accepted it. So now I must do my part and pass it on.

Step 1 – who tagged me?

I was tagged by Sarah Boon, who blogs on blogging, nature writing, snow hydrology, mental health and photography. Sarah’s blog is also part of Science Borealis (in fact, Sarah is the genie behind Science Borealis), where this blog humbly also finds a home. I have never met Sarah in person, but we have built up a friendship of sorts in virtuality and I enjoy her writing and admire her frankness.

Step 2 – Answer Four Questions:

a) What do you generally blog about?

The title of my blog pretty much defines its content: Earth, Science and Society. I am a sedimentary geologist, but am more interested in where earth science intersects with societal issues than in the science itself (I was a prof once, but Academia was not for me: I resigned from a tenured position). I find that too much writing on the management of our one and only planet uses humanity as the vantage point instead of the planet itself and that irk has been with me pretty much since grade 8. One of the quotes in my school diary that year (I don’t remember the author) went something like this: “nature scoffs at human suffering and only considers her own greatness”. I suppose it was only logical that a child growing up in an outdoorsy family of avid readers would be interested in earth science and writing. My life long fascination with that quote motivates my writing.

Occasionally I take a side road and write about women in (earth) science or about science and art (stay tuned – my next post will take you there).

b) how does your blog differ from others’ blogs in the same genre?

I really don’t have a good answer to that question. Most earth science bloggers that I follow a bit use their blog in the context of their work, as for example Dave Petley, Matt Hall and Evan Bianco at Agile, or the Deep Sea Discovery teams on the JOIDES Resolution. I suppose each blog is pretty unique, because blogging is more personal than any other form of publishing. I am not going to dare a comparison.

c) why do you write what you do?

My professional career is winding down.  Way back when I was a student, I had dreams of being a science journalist, inspired by the superb weekly science special of my favourite newspaper. Then I became utterly fascinated by my own profession, realized that writing was very very hard and that I didn’t have a natural ability for it. Next I moved to the US and had to learn to write scientific papers in my second language. Simultaneously with all that came the parent phase. But now life is balanced and I have time. If you have learned something, you must share it (thank you, Maya Angelou). I have learned a lot, so I am trying to go back to that dream. There is no excuse – the blogosphere is out there.

d) how does your writing process work? how do you decide what to blog about? What is blogworthy to you?

I aim to write two blog posts per month and that turns out to be a tall order. One monthly post is on whatever hits me, the other one is part of a series of reviews under the header “Canadian Earth Science for @PMHarper”.  The argument for writing this series is here. My aim is to cover the breadth of Canadian Earth Science both in terms of content and authors. It should run for another year or so. Selecting an article is not very spontaneous, I keep a spreadsheet of topics and authors to help me map my progress.

I think a long time about how to tackle an issue and where to start. It takes me forever. Without the structure that I dictated to myself, I think I would quickly give up. Too hard! But I do want to. Clicking “publish” is exhilarating.

I have never taken a writing class, but I have had some very tough editors. I write in my second language. These are two distinct disadvantages. I do hope to enroll in a science writing course some time in the not too distant future. Writing is incredibly hard, but I want that challenge.

Step 3: Tag another writer or 2 to answer the questions the week after you. Give a one-sentence bio of each, and link to their websites

I am tagging Graham Young of Ancient Shore, the other Canadian earth science blogger on Science Borealis. He is curator of geology at the Manitoba Museum.

 

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Canadian Earth Science for @PMHarper 6 – Would CO2 storage in deep saline aquifers carry an environmental risk for shallow aquifers?

The preamble to this series is here. All reviews are stored in the category “Canadian Earth Science for @PMHarper” (see right hand column).

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Lemieux, J.-M., 2011, (Review:) The potential impact of underground geological storage of carbon dioxide in deep saline aquifers on shallow groundwater resources. Hydrogeology Journal, v. 19, p. 757-778. DOI 10.1007/s10040-011-0715-4

The world is warming up and humanity is the cause: we have become a geologic force, and have brought in the age of the Anthropocene. As President Barack Obama stated so eloquently in his commencement address at the University of California at Irvine last week “the question is not whether we need to act; the overwhelming judgement of science, accumulated and reviewed over decades, has put the that to rest. The question is whether we’re willing to act.”

There are numerous possibilities for action, depending on technology and political will.

The carbon dioxide content of our atmosphere now stands above 400 ppm (parts per million) and even if we all had the best intentions and started to intervene tomorrow, we simply can’t stop burning fossil fuels right away, so atmospheric CO2 will continue to rise for a long time to come.

What if we captured some of that carbon dioxide at the source (i.e. industry) and put it back in the ground before it reaches the atmosphere, thus slowing down the rise in atmospheric CO2? This process, known as Carbon Capture and Storage (CCS) – has been tackled by scientists and engineers for only just over 20 years, i.e. ever since the risk of global warming first began to be taken serious by a handful of people. Imagine that everyone had been a climate-change skeptic back then, we wouldn’t have known anything about this subject today! Here is the official (and excellent) Canadian CCS site.

Over the years, I have heard more than one climate-concerned citizen say that we should ‘just put all that CO2 back where it came from’. If only it was that simple, the process would have been routine now, pretty much like taking lead out of gasoline or CFCs out of spray cans.

This article reviews the State of the Art of our knowledge about CCS in deep saline aquifers. That knowledge is impressive but also discouraging. There are still so many unknowns!

So what, exactly, are the challenges?

First: there are only a few possible properly contained subsurface reservoirs for CCS: 1) depleted oil and gas fields, 2) unminable coal beds and 3) deep saline aquifers. This review focuses on this last and preferred option.

Why not the first two options? CCS would be the most efficient and effective if every major (energy) industry (a ‘point source’) could inject CO2 in the subsurface. But not all of Canada’s heavy industry nor its powerplants are located above oil and gas fields or unminable coal seams. Some depleted oil and gas fields are already filled with re-injected CO2 as part of the process of producing the field (a process called ‘well stimulation’). So while those first two options are heavily researched and tested (see for example here and here), it would be better if we could access a rock compartment that is pretty much present everywhere.

Deep saline aquifers are present just about everywhere and are therefore the preferred choice.

Let’s take a look.

CCS

This diagram shows the different possible natural reservoirs for CO2 storage (source of figure). There is no vertical scale indicated, but deep saline aquifers are located at close to 1 km depth, far below the aquifers from which we draw water for human use. 

It is important to note that CO2 occurs naturally in deep saline aquifers (and has been plentiful in such aquifers for millions of years) so that re-injecting it in such an environment mimics a natural process. Naturally occurring chemical reactions (given the right temperature and pressure) in such an environment may turn CO2 into limestone and/or related minerals , but because pressure in these aquifers is very high (because they occur at great depth), CO2 often stays dissolved in the water.

CO2 (or any other gas) will only stay in the aquifer-reservoir that reservoir is properly sealed. The seal is provided by surrounding rock that is impermeable. A typical example of impermeable rock is salt or gypsum. But even such rocks have cracks and/or are broken up by faults. Cracks and faults can lead to leakage from the reservoir rock. This also is a completely natural process, but if we want to store CO2, we want it to stay in the reservoir and not leak back to the atmosphere.

Cheveriepoint Windsor_gypsum2

Gypsum outcrop, riddled with smaller and larger cracks. Yet gypsum is most of the time an excellent reservoir seal.

Another potential risk is that dissolved CO2 can change the acidity of the deep aquifer. A different acidity may cause certain trace elements, such as the toxic elements lead and arsenic, to become mobilized and travel to the shallow aquifer (which is what we use for drinkwater and irrigation). We don’t want that either.

Also, you must be able to take into account that certain effects of CO2 injection will only be noticable far away from the injection site, whereas other effects are realistic near the injection site. The difference is explained by the the architecture of the subsurface. “Architecture” refers to the manner in which the rocks are layered, tilted, folded, faulted and (re)cemented. Each rock formation has a completely unique architecture (this is what keeps geoscientists busy). These effects are called ‘near-field’ and ‘far-field’ effects.

Kentucky outcrop 1 696-9641_IMG

Examples of different archecture in rocks. Left: ‘layer-cake’ beds. Right: complex folding 

If we store CO2 in the deep subsurface, we want it to stay there ‘forever’. How long is forever? Not a single geologic formation stays unchanged forever, but some experience millions of years of utter boredom. Can we predict the rock formation with the most boring future? Keep in mind that the earth cannot things boring forever. Our planet bubbles and burps and sighs and heaves according to the 2nd law of thermodynamics, which dictates that every system always turns to maximum randomness. In the end, any sort of reservoir will come undone.

Long term geologic processes can affect deep groundwater flow significantly, a concern that has affected the research on deep storage of nuclear waste to the point where that has just about become a dead end. And – really weird question, but let’s face it: if we would be able to take significant amounts of CO2 out of the atmosphere, do we want to be able to put it back when the next ice age hits (if humanity is still around)?

It’s these sort of questions and uncertainties that have been the topic of intense research and it’s this research that is reviewed in this article.

How do you research this? Ideally, you should sample and research the reservoir itself, but that’s more or less impossible because it’s so deep. There are two other ways: 1) carry out experiments, in a lab or in super-controlled natural situations and 2) through numerical modeling and simulations (thank goodness for ever more powerful computers). This research is complicated and expensive. The real-world experiments have to run a long time before yielding data that can be understood and extrapolated.

This is what makes this article both discouraging and impressive: such fantastic research and yet so many remaining questions. The author has defined a number of knowledge gaps. He begins by stating that the state of understanding is very immature because quantitative research is no more than 10 years old. Laboratory experiments that study the interaction of minerals and CO2-saturated brines are few and far between. Most numerical models are still very simplistic (that’s mostly determined by not having sufficiently sophisticated computers, we still need better ones, yes we do).

But he ends on a positive note: despite the above, the possible environmental impacts of geologic storage of CO2 in deep saline aquifers on shallow groundwater resources appear to be low. Given proper understanding of the reservoir, leakage of harmful elements or of CO2 itself, can be minimal.

So: while more research is needed, the technology is promising. Let’s hope it will take off.

Currently, CO2 is injected in deep saline aquifers in a number of experimental sites: Sleipner (offshore Norway), Weyburn (Saskatchewan, Canada), Frio (Texas, USA), Midwestern States (USA).

Writing a review article is a big job. The job that led to this article was commissioned by the Geological Survey of Canada. The result is a body of work that serves the interest of all Canadians.

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Canada’s Geoheritage Surge: Geoscience Heritage, Geoparks, Geosites, Geotourism

FIRST POSTED June 4, 2014. Updated June 10, 2014

IMG_2530  Sudbury shatterconesLeft: A fossil tree at the Joggins Fossil Cliffs UNESCO World Heritage Site (NS, Canada). Right: 1.8 billion year old shatter cones (result of an asteroid impact) at Sudbury (ON, Canada – photo Andy Fyon)

Here is a commonly heard complaint: “most citizens don’t know anything about earth science, because it’s not taught in school (and – in extension – therefore citizens don’t know the first thing about earth materials, natural hazards, climate change – fill in the blanks). I don’t buy that. A lot of subjects are not taught in school and most people are not completely ignorant about those (criminal law, orthopedic surgery, etc.).

There is earth science in the secondary school curriculum in Canada, although not a lot. I would love it if there was more, but then other subjects would have to give, and I ask you which ones? Imagine the endless battle that would ensue.  Not worth the energy. An unproductive exercise.

But why makes this a problem? We have the whole planet for a lecture room! Just stick your nose out the door, and there is something to learn about the earth, no matter where you live or travel. Put up a sign, build a trail, an interpretation centre, write a book or develop an app.

And that’s exactly what’s been happening slowly but surely over the last 15 years or so. I call it the Geoheritage surge. I’m not going to write its biography, but I thought it might be useful to list what we have in Canada. And – please! – if you see an omission, tell me and I’ll happily add it!

Also – I don’t really care what we call it. The term “Geoheritage” is popular here in Nova Scotia, because the province is in the process of creating a list of sites, which they call a Geoheritage list (more about it further below). Elsewhere in Canada people prefer the term “Geoscience Heritage” to treat the concept in parallel with built Heritage. “Geosites” is used somewhere else again – simply indicating a place where worthwhile earth science can be observed.  A “Geopark” is an area that meets certain criteria of the Global Geopark Network (more about this also below), etc.

Really, it doesn’t matter. Any initiative that celebrates places that teach citizens about earth history and earth materials, about the history of dealing with the earth and its materials (historic mines for example), it doesn’t matter. Any site that can be a destination for a field trip.

So here goes:

Canadian organizations that do earth science outreach 

The Canadian Geoscience Education Network (CGEN) “is the education arm of the Canadian Federation of Earth Sciences (CFES). CGEN is concerned with all levels of geoscience education in Canada and encourages activities designed to increase public awareness of geoscience”. CGEN is 100% volunteer-run and they are particularly focused on school teachers. CGEN has also developed the “Careers website” and the “Where Challenge” and coordinates EdGeo. EdGeo is responsible for organizing 1-week workshops and field trips for science teachers in the summer across Canada.

This special 2009 issue of the “Geoscience Canada”, the Journal of the Geological Association of Canada, on geoscience outreach pioneer Ward Neal is open access (as are all their issues prior to 2011)

And here is a 2012 report on Canada’s Geoheritage efforts from one of Canada’s geoheritage champions, published in a CFES newsletter (a wonderful publication that seems to have expired).

Museums and interpretive centers: Fifteen museums and natural heritage centres cooperate and communicate efforts in the Alliance of Natural History Museums of Canada. In addition, there is: the Royal Tyrrell Museum in Drumheller (dinosaurs!) – see below.

Globally recognized Canadian sites

The UNESCO World Heritage designation is one of the world’s most prestigious. There are cultural and natural World Heritage sites. Canada has 17 UNESCO World Heritage Sites, of which 9 are natural sites and 8 are cultural sites. Of the natural sites, no fewer than 6 have been designated largely or exclusively because of their Geoheritage. These are:

  1. Canadian Rocky Mountain Park (AB/BC), which includes the late Precambrian Burgess Shale site and the dramatically fast retreating Athabasca glacier complex                                                                                                                     629-2902_IMG  629-2944_IMG Left: Mt Wapta, the site of the Burgess Shale Quarry in the distance. Right: the toe of the Athabasca glacier (in 2005) with a marker indicating its position 13 years earlier.    
  2. Dinosaur Provincial Park, home of the amazing Royal Tyrrell Museum – your best destination for cutting edge knowledge on Cretaceous dinosaurs. Tyrrell Albertosaurus  Tyrrell museum area _  Horseshoe Canyon  badlands Left: Albertosaurus model at the Royall Tyrrell Museum. Right: Horseshoe canyon near the Royal Tyrrell Museum: quick erosion helps to uncover Cretaceous fossils.                    
  3. Gros Morne National Park, which includes the official Cambrian-Ordovician Boundary at Green Point and the Precambrian Woody Point and Table Mountain ophioliteGSSP Green Point
  4. Joggins Fossil Cliffs, “the Coal-Age Galapagos” – a complete early Carboniferous coastal plain ecosystem that includes upright fossilized trees (picture at the top of this blog page).
  5. Miguasha National Park, representing the Devonian “Age of Fishes”.
  6. Kluane/Wrangell-St.Elias/Glacier Bay/Tashenshini-Alsek National Park, an impressive collection of modern glaciers on the Canada-US border.

Global Geopark Network

stonehammer logo           geoparks logo    Left: The logo of Stonehammer Global Geopark, located around Saint John, NB. Right: the logo of the Global Geoparks Network

The Global Geopark Network was initiated under the umbrella of UNESCO but is not a UNESCO Program. It goes too far here to explain the difference. The important thing is that Geoparks are becoming popular venues for attracting tourists to geoheritage sites worldwide but not (yet) in North America where the only recognized Global Geopark is Stonehammer Geopark in the area of Saint John (NB).

Stonehammer Global Geopark was officially recognized in 2010. Efforts to create more Canadian Geoparks (there are a few more underway!) are coordinated through the National Geoparks Committee. The Global Geopark Conference will take place in Saint John in September of this year. Keep your fingers crossed because that’s when the vote will take place for the next Canadian Geopark.

Provincial Geologic Highway maps

NS Geologic Highway Map

Geologic Highway maps are designed especially for the general public. They feature a (simplified) geologic map of the jurisdiction with the main highway system and notable stops with lots of explanation. They are still only in paper (or downloadable) format and badly deserve to be morphed into apps:

Geologic Landscapes highway maps of Northern and Southern British Columbia

What is the Yukon Territory made of? A wonderful publication – free downloadable pdf!

The Geologic Highway Map of Alberta can be ordered here

The Saskatchewan Geologic Higway Map can be ordered here

A geologic highway map for Manitoba is in the making

A geologic highway map for southern Ontario can be downloaded here and the one for northern Ontario is here.

The New Brunswick Geologic Highway map is out of print (I have one, it dates back to 1985 and really really deserves a new edition).

The Nova Scotia Geologic Highway map (pictured above) is a gem and can be ordered from the Atlantic Geoscience Society.

The Traveller’s guide to the Geology of Newfoundland and Labrador can be ordered here.

I could not find a geologic highway map or similar publication for Quebec, the NW Territories, Nunavut or Prince Edward Island. I hope that’s me – tell me!

Individual examples of geoheritage initiatives and communication across the country

British Columbia: Tumbler Ridge Dinosaur trackway and museum

Yukon: The Yukon Beringia Interpretive Centre and The Dawson City / Klondike Gold Rush National Historic Site

Alberta: The Earth Sciences Department of the University of Alberta has an outdoor rock interpretation garden

Ontario:

The Ottawa Gatineau Geoheritage Project promotes greater public knowledge and appreciation of the geology and related landscapes in and around Canada’s National Capital Region.

The Carleton University Department of Earth sciences has an active outreach coordinator: lots of information and events in and around Ottawa. The department’s emeritus professor Allan Donaldson has been active in geoscience outreach for a long time and started Friends of Canadian Geoheritage.

The Ottawa Riverkeeper website pays attention to Geoheritage

The Ontario highlands website has reams of Geoheritage activities, one of which is the iconic Metcalfe geoheritage park

Science North’s Dynamic Earth Centre, home of the iconic ‘Big Nickel’ in Sudbury is an amazing place to explore and learn about the Sudbury area geology and mining.

Greater Sudbury-20111109-00160_elisabeth_kosters_mia_boiridy_Dynamic_North_sudbury_Nov0911          Sudbury Phoenix                                Left: Examining mineral samples under the microscope with Dynamic Earth director Mia Boiridy (photo Andy Fyon). Right: Inside the Phoenix capsule in Dynamic Earth’s own mine! This is the capsule that was used to rescue the 34 miners in Chile in 2010

Book: “Ontario Rocks” is a well-researched treaty on three billion years of geologic history of Ontario, written for the general public.

Nova Scotia: The Department of Natural Resources (home of the ‘mineral resources division’ = geological survey) is working on a Nova Scotia Geoheritage list – work in progress.                                                                                                                                         The world famous light house at Peggy’s Cove is built on a unique granite outcrop and there are interpretation panels there. You can order the brochure here                                    The Fundy Geological Museum in Parrsboro celebrates the local geology, but especially focuses on the oldest dinosaur fossil site nearby (Wasson’s Bluff), which also features in PBS’s ‘Your Inner Fish’, the documentary based on the same book by American Paleontologist Neil Shubin (see also my post on Nova Scotia’s Blue Beach).

The Maritimes: Published by the Atlantic Geoscience Society in 2001, “The Last Billion Years” is “a geologic history of the Maritime Provinces of Canada”. This book was a national non-fiction National best-seller that year and hasn’t been out of print since. It serves as a model for  “Four Billion Years and Counting: a Canada’s geological heritage”, which is expected to be available later this year (stay tuned).

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A totally unique and separate case: 

The International Appalachian Trail celebrates geoheritage along the entire length of the Appalachian mountain belt – yes, all the way into Europe!

 

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Canadian Earth Science for @PMHarper – 5: refining seismic risk assessment in Canada

The preamble to this series of reviews is here. All reviews can be found under the category “Canadian Earth Science for @PMHarper”

Atkinson, G.M. and K. Goda, 2011, Effects of Seismicity Models and New Ground-Motion Prediction Equations on Seismic Hazard Assessment for Four Canadian Cities. Bulletin Seismological Society of America, v. 101, no. 1, p. 176-189.

If only we could predict earthquakes as well as we can predict the weather for the rest of the week. But we can’t. That is, we know where earthquakes can strike but we don’t know when they will happen. In other words, we can predict them in space, but not in time.

Lots of research goes into attempting to make better earthquake prediction and this is of course necessary because the casualties are enormous: about 800,000 people died in earthquakes worldwide between 2000 and 2012. Many earthquake casualties occur because people are crushed in collapsing buildings and this happens especially in countries that don’t have the right building codes or where building codes were ignored. The latter usually happens due to poverty, lack of good governance and/or corruption (see my older post here).

Two regions in Canada are susceptible to earthquakes. In the west is Coastal British Columbia, which is situated on the large and active Cascadia fault (a good popular book about this feature and its associated risk is ‘Cascadia’s fault‘ by Jerry Thompson).

significant EQ canada 1663_2006 Lamontagne et al 2008 3

Figure 1. From Lamontagne et al., 2008

Eastern Canada does experience earthquakes too, although it will never experience the large earthquakes that are expected for western Canada because it’s geologically very different.

significant EQ canada 1663_2006 Lamontagne et al 2008 2

Figure 2. From Lamontagne et al., 2008

These figures show clearly that no truly large earthquake has ever struck eastern Canada, and we understand geology enough to be sure that that will never happen. However, smaller earthquakes can create all kinds of havoc and damage. As recently as 2010, an earthquake with moment magnitude 5.0 struck near Buckingham (QC) and was felt widely, also in Ottawa.

So earthquake-prone regions require the design and legalisation of building codes But how to quantify this kind of risk? And especially – how to quantify risk for something that happens rarely, such as a – mild – earthquake?

This is the focus of the article by Atkinson and Goda.

The paper is a contribution towards refining the risk of seismic hazard in coastal British Columbia (particularly Vancouver) and eastern Canada (particularly Ottawa, Montreal and Quebec City). The article does not aim to predict earthquakes in time.

The authors ask a question that can be phrased more or less as follows: “given that earthquakes of certain magnitudes occur in these regions, how large is the risk of damaging ground motion (and what implications does that have for building codes)?” To make that question a little easier to understand, you can think of the following question as an analogue: “given that about 2,000 people die in traffic accidents annually in Canada, how large is the risk for a Canadian to die in traffic?” If you wanted to answer that question, you would start collecting data over many years. You wouldn’t only count fatalities, but also age, gender, home province, type of transportation, etc.  and then do the math (Statistics Canada has done that).

It’s more complicated to estimate seismic risk, but there are methods. These methods are based on an in-depth knowledge of the geology of a certain area (which tells us where the zones of weakness in the earth’s crust are). The models also require systematic information on every earthquake that strikes: its depth, its magnitude, over how large an area it was felt, etc. This information is collected constantly. The longer we collect this information, the more precise the models.

Geophysicists have developed models that enable predictions of ground motion on the basis of such data collection. Such models characterize the expected ground motion for a given risk (=probability). They are called “Seismic Hazard Models”

The standard Seismic Hazard Model for Canada was developed by the Geological Survey of Canada  about 20 years ago. This model is the basis for our national building code. Of course, a lot more data have become available in 20 years and – just as important – insights and computer power have improved tremendously. So it’s appropriate to revisit and, if necessary, revise, improve and refine the model.

For example, a better model can improve risk estimates for soil liquefaction, a nasty ‘byproduct’ of some earthquakes: the 1988 magnitude 6 Saguenay earthquake (shown on figure 2) caused liquefaction at 25 km from the epicenter. A good 2011 CBC report discusses the risk of earthquake-induced liquefaction for greater Ottawa.

The biggest earthquake that occurred in Southeastern Canada was the 1663 Charlevoix earthquake (magnitude 7). The authors estimate that this was really a ‘clustered event’, meaning that it consisted of a series of quakes over a period of several hundred years, separated by quiet periods that may last thousands of years. This pattern is related to the geologic make-up of the region, mostly a very old fault that dates back ca. 400 million years. Such seemingly erratic activity can only be properly analyzed and modeled using advanced statistical methods.

After applying their improved methodology and incorporating new data, the authors show that the refined model results in different risk predictions for the four cities. Their model deals better with a number of uncertainties: certain risk windows become narrower. It looks like the seismic hazard for these regions is lower than the original 1995 model predicted. This would be good news (if the model is reconfirmed after additional testing) because it would save money on building codes.

There: expensive data collection and research leads – after decades of work – to improved and even cheaper building codes. Without decades of data collection, such a conclusion would not have been possible.

===

Dr. Gail Atkinson is a seismologist. She is Canada Research Chair in earthquake hazards and ground motion at the University of Western Ontario. A recent article in Time Magazine on concerns about hydraulic fracturing and earthquakes in Ohio quoted Dr. Atkinson. Many areas where hydraulic fracturing takes place do not have proper regulations for this industry in place (industry is always ahead of the law). Dr. Atkinson said: “There’s a very large gap on policy here. We need extensive databases on the wells that induce seismicity and the ones that don’t. I am confident that it is only a matter of time before we figure out how to exercise these technologies in a way that avoids significant quakes.” In other words: correlation doesn’t necessarily mean causality: not every observed earthquake in Ohio has to be caused by hydraulic fracturing and you need a lot of detailed data to do a proper analysis, after which it is possible to write proper regulations.  

Reference

Lamontagne, M., S. Halchuk, J. F. Cassidy, and G. C. Rogers, 2008, Significant Canadian Earthquakes of the Period 1600–2006, Seismological Research Letters Volume. 79, No. 2, p. 211-223. This article is free to download.

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