News Archive
News Archive
Congratulations to Professor Jochen Halfar
on successfully obtaining Tenure and Promotion
to Associate Professor!
Earth Science Conference and visit to the mighty falls of Iguassu, Brazil
Earth Science Conference and visit to the mighty falls of Iguassu, Brazil
From Henry Halls
In early August of this year (2010) the American Geophysical Union held a “Meeting of the Americas” conference in Foz do Iguassu, Brazil1. Included in the five day meeting was a special session on “testing paleocontinental reconstructions” and the possibility that Pangea, the last supercontinent that existed prior to its break-up starting 200 million years ago, is only the youngest one in a succession of supercontinents that have existed as far back as the rock record allows (about 3500 million years). In other words Earth history has been characterized by episodic supercontinent formation and subsequent break-up. Henry Halls (with co-authors Mike Hamilton and Steve Denyszyn) presented a paper in this symposium2, using paleomagnetic data obtained at our department’s UTM Paleomagnetism Laboratory and precise U-Pb age dates from the Department of Geology Jack Satterly Laboratory.
A key player in testing the hypothesis of supercontinent cyclicity is paleomagnetism. Paleomagnetism concerns the measurement of a fossil magnetism that is preserved, often for hundreds to thousands of millions of years in certain iron oxide minerals like magnetite and for an igneous rock like basalt it becomes frozen in or “permanent” once the basaltic magma cools below about 580°C. The direction of this ancient magnetization is parallel to Earth’s magnetic field at the time of magma cooling. Today this field is approximately dipolar and resembles the field that would be produced by a bar magnetic placed at Earth’s centre and when averaged over several thousand years it would lie parallel to Earth’s spin axis. By obtaining oriented samples in the field it is possible to measure the direction of the permanent or remanent magnetization and hence through the dipole equations to calculate the ancient paleolatitude and the paleomagnetic pole position. When looking at old rocks this pole position no longer coincides with the geographic pole but is often 10’s of degrees away from it. If rocks of different ages from the same continent also have their paleomagnetic direction measured, the pole appears to move or “wander” over the earth’s surface with time. This apparent polar wander path (APW) turns out not to be a reflection of the pole moving with respect to the geographic pole, but is caused by the continent rotating and moving over Earth’s surface.. simply because the fossil magnetization is frozen in and moves with the continent. In a simple way the matching of a polar wander path for a continent or even segments thereof, indicates that if the continents are joined in such a way that the paths can be superimposed, then it means that both continents moved as a single entity over the time represented by the matching APW segments. One of the problems that leads to ambiguity in the configuration of Precambrian continents is that the field periodically reverses. On some occasions like the present, the needle of a magnetic compass towards the north pole and we refer to this kind of magnetization as “normal”; at other times the magnetic field changes so that the compass would point towards the south pole, and we refer to this kind of field as “reversed” with respect to the present-day one (it was last in this state 700 thousand years ago). We know that throughout geological time (at least as far back as 3500 million years) the magnetic field has reversed many times. Now if we suppose that a given continent has a virtually continuous record of basaltic igneous rock formation, then a complete record of Earth’s field direction could be obtained, together with all the reversals. For the last 200 million years, for which we have magnetic stripe records from the ocean floor, we know about all the reversals that have taken placef…we know which are normal and which are reversed because we have a continuous record going from 200 million years ago to the present day. However for older Precambrian rocks there are no ocean floor magnetic stripes and because for a given continent the geological record becomes incomplete, it means that there are gaps (often lasting up to ~ 100 million years ) in the geological record with corresponding gaps in the apparent polar wander path. So for that part of the geological record which is older than a gap we have no direct evidence whether or not the field at any one time was normal or reversed because the line of communication with the present day field has been broken! ! If we do not know the polarity of the pole we are at liberty to reverse the position of the continent such that its pole now lies in an antipodal position. This has drastic implications of continental fitting, which is exacerbated because while we know the location of the pole (or its antipode) and we know the ancient latitude of the continent, we do not know the ancient longitude which means we are free in moving the continent all around Earth providing that the paleolatitude and orientation of the continent with respect to the pole remain constant.
One way to combat the polarity problem is to try and precisely date a reversal and to see if one of the same age occurs on another continental fragment. A fit between the two continental fragments then can be made unambiguously at least in terms of polarity.
The best material for this kind of study turns out to be basaltic dykes which represent feeder systems to basaltic lava flows. Dykes have several key properties: They occur frequently throughout the geological record in swarms, cover regions of thousands of square kilometres and represent the failed arms of hot spots that once initiated continental rifting. These failed arms extend for many hundreds, even thousands, of kilometers into continental interiors and therefore escape the deformation and alteration that subsequent continental collisions have wrought around continental margins. In their distal regions from these collision zones the swarms are therefore mineralogically very fresh and yield excellent primary paleomagnetic , geochronological and geochemical data. Their full dimensions can be readily seen from aeromagnetic maps because they tend to be magnetically stronger than the surrounding host rocks.
The geodynamic potential of dyke swarms, described by Halls in 1982, is beginning to approach fruition, as more and more paleomagnetic and geochronological laboratories worldwide are engaged on dyke studies. Together with geological mapping the dykes are being used as one of the major lynchpins in the piecing together of continental fragments in the Precambrian. At present they form more than half of the paleomagnetic studies of Precambrian rocks and there is now a consortium of mining and petroleum companies who recognise the importance of assembling the Precambrian continental jig-saw puzzle and that the precise dating of dyke swarms is a vital element in this undertaking.
In the last ten years or so tremendous strides have been made in U-Pb radiometric age dating, whereby the rare mineral baddeleyite (a zirconioum oxide) which is found in basaltic rocks, and considered highly retentive of its parent and daughter isotopes, can be dated for Precambrian rocks to less than 1 million years at two sigma. Many single polarity epochs last for several to tens of millions of years, so that in principle a given reversal can be placed within narrow age limits.
In Brazil, Henry Halls lectured on the paleomagnetism of a 1.63 billion year old dyke swarm that runs for over a 1000 km, all the way down the western coast of Greenland, and the possibility that it once connected with an igneous province in Scandinavia which has the same age1. The joining of the Baltic Shield with the north American one during the middle and early Precambrian time has been a subject of controversy, the current model fitting the east coast of Greenland onto the northern side of the Kola Peninsula in Russia. With the new results, by which a reversal has been precisely dated, a fit is made that reverses the currently accepted orientation of North America so that now the southern end of Greenland points towards the Scandinavian igneous province.
The hypothesis is made that the dykes have been fed laterally for about 2000 km from this source, the supportive evidence being that in Scandinavia dykes of a similar composition to those in Greenland and associated with the Scandinavian igneous activity, can be followed westwards for at least 100 km and one is about 1 km wide! This testifies to the ability of the Scandinavian igneous province to rapidly produce copious amounts of basaltic magma, which therefore could be available to feed even longer dykes. That basaltic magma can travel laterally in the subsurface for thousands of kilometres has been recognized both in Canada and in Antarctica. If Halls et al. are correct in their interpretation, the Greenland dykes should also be found along the southeast coast of Greenland if the feeding of the swarm from the south is to have any credibility. No dykes of 1.63 billion years have been reported but GooglearthTM shows that dykes of an orientation that are on line with those along the west coast are present. It now only remains for an intrepid geologist to collect samples from them for U-Pb dating, but the terrain is mountainous and ice-covered and very difficult (and expensive!) to access.
1 Foz do Iguassu is a town of about 40,000 people that lies within a few kilometers of the mighty Iguassu Falls. The highest fall is similar to Niagara but the width of the falls, which are often in two cascades, extends for several kilometres along a river which marks the border between Brazil and Argentina. It is truly one of the natural wonders of the world and can be viewed from both Brazil and Argentina with the latter holding the upper hand in terms of scenic splendour. After the five day AGU meeting was over Henry stayed on for a short holiday, choosing the five star hotel Cateras (the only hotel in the National Park) and overlooking the falls. A true five star hotel in every way. It is not often one can sleep in a room with the window wide open letting in the roar of a nearby falls! My visit to the falls themselves was punctuated by treks along jungle paths to view wildlife. This included several kinds of toucans, a black red-crowned peacock-like bird, an exotic woodpecker with a yellow crown, alligators and a tarantula, plus of course a whole host of smaller birds. The hotel refused to allow me out at night because of the danger from jaguars! The short movie clip of the falls is from the Brazilian side.
2 A paper on this topic has been recently accepted for publication:
Halls, H.C., Hamilton, M.A. and Denyszyn, S.W. 2011. The Melville Bugt dyke swarm of Greenland: a connection to the 1.5-1.6 Ga Fennoscandian Rapakivi granite province? Accepted for publication in Precambrian Research Special Volume of the 6th International Dyke Symposium, held in Varanasi India, February 4 to 7, 2010.
Professor Halls Guest of Honour at Indian International Conference
In early February Professor Henry Halls (ERS) attended the 6th International Dyke Conference (IDC) in Varanasi, India. These meetings are held every five years, the first being organized by Professor Halls in 1985 at UTM. Since that time the meetings have been held in Australia, South Africa, Israel, Finland and now India. Dykes represent the conduits or fissures along which basaltic magma breaks through the Earth's crust in response to the separation of Earth's lithospheric plates(the current eruption on Iceland is being fed from just such a fissure!). Ultimately after the volcanism has ceased magma is stranded in the fissure, and will solidify to form a dyke.
Dykes of the same trend and age can occur in their hundreds together to form what is known as a Dyke Swarm. Dykes are a common, if not the most ubiquitous, feature of continental rifting throughout geological history.
The oldest recognized dykes are more than 3 billion years old. Due to a recent breakthrough in our ability to precisely date basaltic rocks, a precision of one million years on the U-Pb age of a dyke swarm several 100's to 1000's of million years old, can now be achieved! Basaltic dykes are also excellent recorders of fossil magnetism that dates from their original cooling and solidification. The direction of the fossil magnetization can be measured at UTM's Paleomagnetism Laboratory, which gives information on the ancient latitude and location of the Geographic pole at the time the dyke was formed. From this information an "Apparent Polar Wander Path" for a particular continent can be constructed from pole positions obtained on dyke swarms of different ages. These paths and the orientation and age of the various dyke swarms can then be used to reconstruct past continental configurations throughout geological time. The idea, that continents undergo a global amalgamation (to form a "Supercontinent") and then a dispersal appears to have happened several times, leading to the concept of a "Supercontinent" cycle with a period of about 700 million years!
At the dyke conference several papers were presented, including one of using dyke ages as a sort of "barcode" to identify continents that have had common histories and which therefore may have been in proximity to one another.
Professor Halls presented a paper linking Greenland to Scandinavia 1600 million years ago. He was the Guest of Honour (as the founder of the IDC
events) at the Opening Ceremony which was attended by several luminaries in Indian Geology. A consortium of scientists, with financial backing from oil and mining companies, has recently been formed to precisely date dyke swarms on a global basis, with the ultimate target of reconstructing the history of continental movement for the last three million years! Professor Halls has recently been awarded a three-year NSERC grant to pursue paleomagnetic research related to the project and will be part of a Symposium on the topic to be held in Argentina in August.
Gunning Research Graces Cover of "Organic and Biomolecular Chemistry"
The article describes the controlled, sequential functional group decoration of a potent anion recognition scaffold using a modular and highly efficient synthetic route. Calorimetric screening showed one of the derivatives to be a highly potent and selective sensor for inorganic phosphate.
Novel asymmetrically functionalized bis-dipicolylamine metal complexes: peripheral decoration of a potent anion recognition scaffold Joel A. Drewry, Steven Fletcher, Haider Hassan and Patrick T. Gunning, Org. Biomol. Chem., 2009, 7, 5074.
We report the development of a highly efficient, facile and modular synthetic route to orthogonally functionalized bis-dipicolylamine (BDPA) receptors.
http://www.rsc.org
Fekl Undergraduate Findings Featured in American Chemical Society's "Inorganic Chemistry" Journal
Research findings resulting from a fourth-year undergraduate thesis project (chm489; 08/09) just have been featured on the front cover of the prestigious American Chemical Society journal "Inorganic Chemistry":
The publication "Ligand-Based Reactivity of a Platinum Bisdithiolene [...]", by Kerr, Harrison, Lough and Fekl, reports on a newly discovered access to a class of compounds that could be extremely useful for the synthesis of unsymmetrical bio-active compounds:
http://pubs.acs.org/
This honour nicely highlights the quality of research performed by highly qualified personnel here at all levels, including outstanding UTM undergraduates.
In addition to Mitch Kerr's contribution, additional valuable contributions to this paper came from Dan Harrison (chemistry graduate student located at UTM) and a collaborating X-ray crystallographer (Alan Lough, St. George).
New layer...
New layer...
Early Researcher Award to Ulrich Fekl
Developing Inexpensive Catalysts for Cleaner, Sulfur-free Gasoline and Oil.
Lead researcher: Dr. Ulrich Werner Fekl
Number of researchers benefiting: 4
The crude oil used to make gasoline contains sulfur. When burned with fuel, this sulfur contributes to formation of urban smog – a major cause of pollution, premature deaths, increased hospital admissions and other illnesses. The petrochemical industry relies on special catalysts to remove much of the sulfur from crude oil. But the industry is increasingly using lower quality oil that is richer in sulphur and current catalysts are not good enough to meet the stricter environmental regulations and standards of the future. Dr. Fekl’s research aims for a better catalyst, made of small molecules, for more efficient sulfur removal.
http://www.mri.gov.on.ca/english/news/ERA081709_toronto_bd.asp
Research Contributions of Prof Henry Halls Honoured
A special session at the recent American Geophysical Union- Geological Association of Canada Joint meeting , held in Toronto, May 24-27th 2009, was organized to honour the research contributions of Henry Halls. The session was entitled “Frontiers in Precambrian Geodynamics, a tribute to the research of Henry Campbell Halls”. It ran for one and a half days and featured both oral presentations and posters. It was followed by a roast and toast during a Lake Ontario Cruise arranged by the meeting organizers and featured a summary of his research, embarrassing stories and a final speech by Henry himself. A 1982 article by Henry was also included in a “Foundations of Earth Science” list of seminal papers in the understanding of Mantle Plumes [www.mantleplumes.org/Foundations.html] where his paper appears in the same list as those by Darwin, Lyell, Hutton, Tuzo Wilson and other notables!
Front cover for Prof. Patrick Gunning
Prof Patrick Gunning got a front cover in one of the top medical chemistry journals ChemBioChem
Nicole Prent, winner of the best student presentation at CAP 2009
Biophysics graduate student Nicole Prent received the first price for the Best Student Paper Presentation (oral) in the Medical and Biological Physics (DMBP) division at the annual 2009 Canadian Association of Physicists Congress.
Appointment of Professor Peter Macdonald
To : Members of the Department of Chemical and Physical Sciences
From : Gage Averill, Vice-Principal, Academic and Dean
I am very pleased to advise you that the Agenda Committee of the Academic Board has approved the appointment of Professor Peter Macdonald to a five-year term as Chair of the Department of Chemical and Physical Sciences from July 1, 2009 - June 30th, 2014.
I am very pleased that Professor Macdonald has agreed to serve the department in this capacity. He is a highly regarded departmental and UTM citizen, respected for his commitment to UTM and for his investment in the creation of a strong physical science presence at UTM. His combination of loyalty, commitment to departmental cohesion, and experience will undoubtedly inspire and guide the department during his term. Please join me in congratulating Peter on his appointment.