News: Earthworks in progress
It is now 50 years since Alan Smith and Tony Hallam published in Nature their classic paper on Gondwana reconstruction (Smith & Hallam, 1970). Here is a link to a video of Alan talking about this work in 2012 [link]. Smith and Hallam applied the same contour-fitting algorithm used in Bullard, Everett and Smith (1965) to fit the 500 fathom (914 m) bathymetric contours for South America, Africa, Madagascar, India and Australia to each other and to the 1000 m isobath for Antarctica. The result has withstood well the test of time. The figure at the bottom of this piece presents the fit resulting from current research (available on this website) alongside the original Smith & Hallam (1970) fit.
The most recent developments to the Earthworks Gondwana dispersal model have been used to derive two series of high-resolution images that are released today [here]. The model, CR20ABAW, incorporates the most recent thinking on the early opening of the South Atlantic Ocean, the articulation of Patagonia by closing the Early Cretaceous rift basins there and the refinement of movements along the Agulhas fault zone off the coast of South Africa and its newly-defined conjugate in South America. The rationale will be explained in a future Research Update. Meanwhile, the main points will be set out in a poster presentation at the Netherlands Earth Science Congress [nacgeo.nl/] in Utrecht, March 12-13. The abstract accepted for the poster presentation is given below and the poster itself in an A4 version may be accessed [here]. The poster was shown shortly before the congress was cut short by measures to contain coronavirus. The geology shown in the accompanying figure is courtesy of the Gondwana Map Project (IGCP-628).
2020 February 27
updated 2020 March 25
The Kalahari occupies an exceedingly flat tableland taking up much of the central part of southern Africa. When the national gravity survey of Botswana was mooted in 1970, absolute heights above seal level for this remote, dry and thinly-populated area were unavailable and precision primary levelling was still in progress. Earlier levelling work in pursuit of potential engineering work on river courses (Du Toit, 1926; Brind, 1955) had proved inconclusive. A by-product of the national gravity survey (Reeves & Hutchins, 1976) was the first rough topographic contour map of Botswana dervied from about 2500 heights determined by barometric altimeters tied to the few available reliable datum points. The lowest point in the inland drainage basin in the Makgadikgadi salt flats was determined as 903 (+/- 5) metres. Almost all of northern Botswana lay below 1000 m with the only escape for water from the annual flooding of the Okavango delta in the NW of the country at about 930 m, located near the administratrive centre of Maun.
The 18th in a series of annual conferences on the petroleum geology of Africa was held at the London Olympia, October 1-2. The series, organised by the Petroleum Exploration Society of Great Britain (PESGB) and the Geological Society of Houston, alternates between these two cities. The Olympia meeting was attended by over 500 delegates who followed two days of presentations, posters and an industry exhibition. Colin Reeves presented his most recent work on a plate-tectonic model for the dispersion of the other Gondwana continents from around Africa. A new discovery is the plate-tectonic role of a coast-to-coast Mwembishi shear zone stretching 3200 km from Namibia to Tanzania, passing through parts of seven African countries. It was active as a dextral strike-slip feature in Early Cretaceous time (135-129 Ma).
With advancing years one is inclined to reflect on a career. Few geophysicists have done so as effectively as Norm Paterson. His new book tells the story of how the now-familar techniques of geophysics in mineral exploration got started in the 25 years following the end of the second World War. It is a fascinating history of scientific and technical creativity. Creative because no one knew for sure what would and would not work - in theory or practice - but the ultimate goal of finding hidden mineral deposits for a resource-hungry world was rather obivous. Canada was centre-stage for the innovations that emerged, a situation that has survived another half century.
Project IGCP-628 - the Geological Map of Gondwana - nears completion. A workshop to review the remaining issues and discuss the path to completion was held at the State University of Rio de Janiero (UFRJ) March 19-21.
Earthworks brought an end to its status as a 'besloten venootschap' (BV) at the end of 2018, marking another stage in the transition to purely curiosity-driven research. In 2019, the main thrust of this will be directed towards the new Gondwana map project, IGCP-628, and improved models for Gondwana dispersal.
The work of refining the model of Gondwana break-up and dispersion is on-going. New, improved data for the magnetic isochrons in the Indian Ocean greatly reduce the level of uncertainty in the paleo-positions of Antarctica and Madagascar against Africa. This, in turn, reduces the uncertainty in the position of India once it was able to move independently of either Antarctica or Madagascar. The most recent model is used in the new animation on the Gondwana page of this website.
A new national airborne geophysical coverage (aeromagnectis and gamma-ray spectrometry) of Malawi was completed in 2014. A contract to interpret the results was awarded to the Geological Survey of Finland (GTK) working in cooperation with BRGM (France) and brought to completion early in 2018. Some of the highlights of this work were presented at a two-day meeting held in Zomba, Malawi, January 18-19 this year. A much larger project, GEMMAP, led by BRGM, is now underway to improve the geological mapping and mineral potential mapping of the country. The first year results of GEMMAP formed the main focus of the Zomba meeting.
A short symposium was held in the Department of Earth Sciences in Cambridge on Friday February 9 this year. The theme was to honour the memory of Alan Smith and some of the many ways he contributed to teaching, research and scientific progress over his career The event was held the day before his memorial service in St John's College Chapel and was followed by a meal attended by Alan's daughter, her family and some of Alan's many friends in a Cambridge restaurant that evening.
The meeting dedicated to the East Afric Margin, held at the Geological Society in London in April 2016, has led to a dedicated volume of the journal Petroleum Geoscience. The contribution by Colin Reeves is entitled The development of the East African margin during Jurassic and Lower Cretaceous times: a perspective from global tectonics. This paper was released recently online under the doi http://doi.org/10.1144/petgeo2017-021.
The paper includes all the Euler rotation parameters for the reconstruction model, including revisions made up to October 2017, model CR17AAHH. This model is illustrated by the animation accessible on the Gondwana page of this website.
The abstract of the paper appears below where it is followed by a single frame from the animation at 90 Ma (Turonian).
2017 December 15
Every three years, those with scientific interests in the geology common to all parts of Gondwana meet to discuss developments. In November 2017 it was the turn of Bangkok and the Thai Department of Mineral Resources to host the meeting of 300 participants from 20 countries at a convenient downtown location. Talks were spread over four days and addressed many aspects from geodynamics to palaeontology but with an emphasis on the terranes that were early-leavers of Gondwana, migrating north to form what is now SE Asia while the core of Gondwana remained intact.
Ian MacLeod, chief technologist at Geosoft Inc., was recently honoured with the Cecil Green Entreprise Award from the Society of Exploration Geophysicists. The award took place at the SEG's annual convention, held this year in Houston in September.
The Petroleum Exploration Society of Great Britain held its 16th annual 'Africa' conference in London from August 28 to September 1, as usual in collaboration with the Geological Society of Houston. The event kicked off with an evening lecture at the Geological Society at Burlngton House when Colin Reeves spoke on 'Gondwana re-assembled: challenges for making the new map and insights for exploration'. In it he reported on progress with the new geological map of Gondwana and the most recent deveopments in trying to understand the precise geometry of re-assembled Gondwana and its dispersal, starting in the Jurassic. The latest animations were also available to delegates on the conference CD.
Dr Alan Smith passed away in Cambridge on August 13, aged 80. Alan was a pioneer in the early days of plate tectonics, working with Edward Bullard and Jim Everett at what was then the Department of Geodesy and Geophysics at Cambridge on the first computer-generated fits of the continents around the Atlantic Ocean. The first fit was published in the Proceedings of the Royal Society in 1965, at a time when many respected authorities - such as Harold Jeffreys at Alan's Cambridge college - disputed that continental drift was at all possible.
Eleven former staff members of the ITC location in Delft (that closed in 2001) got together in Delft for a lunch to mark Colin Reeves' 70th birthday.
Colin Reeves will give the plenary session talk on the final day of the Brazilian Geological Congress. The congress will be held in Porto Alegre, Brazil from October 9th to 13th. The congress marks the 70th anniversary of the foundation of the Geological Society of Brazil.
Clear skies over The Netherlands gave the perfect opportunity to view the transit of the planet Mercury across the face of the sun yesterday.
A model of the evolution of the Indian Ocean that has been under development for many years has now been published. The digital version was released on February 27 under doi number http://doi.org/10.1144/SP431.12 with the title Insight into the Eastern Margin of Africa from a New Tectonic Model of the Indian Ocean. The contribution is part of Geological Society Special Publication No. 431: Transform Margins: Development, Controls and Petroleum Systems (eds Nemčok, M., Rybár, S., Sinha, S.T., Hermeston, S.A., & Ledvényiová, L.).
On Saturday January 16 Geosoft celebrated its 30th anniversary with a Gala Evening at the Royal Conservatory in Toronto. Colin Reeves was invited to take part as one of the founders of the company. About 150 employees and spouses attended the evening with many receiving awards for long service to the company.
A celebration of the pioneering marine gravity work of Dutch geophysicist Professor F.A. Vening Meinesz more than 80 years ago was recently held in Delft. The symposium took place in the Mekelzaal of the Science Centre in Delft (space formerly occupied by the mineralogical museum) and was organised by the Hollandse Cirkel, an organisation dedicated to the history of geodesy in The Netherlands.
The Petroleum Exploration Society of Great Britain, in collaboration with the Geological Society of Houston, hosted its 14th conference on African Exploration and Production in London, September 3 and 4. About 600 delegates attended, mostly from across the spectrum of commercial interests in petroleum exploration in Africa. There were two days of talks, an extensive poster display and a large exhibition area for commercial booths in the former Royal Agricultural Hall in Islington.
A two-week workshop around the New Gondwana Map project (IGCP-628) was held in Rio de Janiero from June 22 until July 3. There was a full programme of talks and software instruction classes and the many aspects of producing the new map were discussed by specialists from many parts of the southern continents. The following week, July 6-10, Colin Reeves gave his 'African Geodynamics' course over five days at the State University of Rio de Janiero for a group of around 20 postgraduate students.
It is with sadness that I received news of the death of David G. Hutchins on April 30 in Windhoek, Namibia.
Dave and I go back many years. For both of us our first professional experience, after gaining our MScs from the University of Birmingham, was with the Geological Survey of Botswana in Lobatse. Dave arrived there a year or two after me and together we carried out the National Gravity Survey of the whole country between August 1972 and December 1973. Between us, there were not many hot, dry corners of Botswana that we had not visited by Land Rover by the time this was complete. I think we both learned the hard way that being ‘airborne’ was the only way to make serious progress with geophysical mapping over areas as large areas as this!
Building a working model of Gondwana dispersion has reached a new horizon. A paper summarising many of the results from the past years of work on understanding the Indian Ocean has been accepted for publication and should appear in a Special Publication of the Geological Society later this year. The rotation parameters for achiveing the fit and the relative movements of Africa, Antarctica and India over time are included in the paper. A key contribution in the last 12 months has been the new understanding that has come from introducing mid-ocean ridges into the model, moving at half the angular velocity of their conjugate coasts.
At the suggestion of my son Alexander, the two of us recently took a trip back to where I first did fieldwork for the Geological Survey of Botswana, starting in 1970 - the Okavango Delta in the NW corner of the country. We flew directly to Maun from Johannesburg and, after an initial overnight camping trip by motorboat and makoro, picked up a rented 4x4. We set off NE towards Shorobe with a plan to drive all around the Okavango Delta, taking advantage of the 400 km Four Rivers Highway along the length of the Caprivi Strip (Namibia) and the tar road from the Mohembo border crossing back to Maun via Lake Ngami. Despite a number of typical bush-driving setbacks, we completed the 1433 km camping trip in seven days, about one-third of it on dirt roads.
A selection of pictures from our journey may be found here. [The original photos have been recovered but the order is no longer entirely correct. Thank you, Google.]
The Gondwana-15 conference will take place in Madrid from 14 to 18 July. Colin Reeves will be presenting two papers, one reporting recent work on the precise process by which Gondwana disrupted, the other appealing for a new cooperation between geologists and geophysicists in making a better map of the Precambrian crust of Africa as a constituent element of the new Geological Map of Gondwana (IGCP 628).
2014 June 9
There has not been much activity on this website recently but quite a lot of material has been published as extended abstracts and refereed publications in the last 18 months. These items may prove useful to those following Gondwana-related research and exploration interests. The list below summarises what has appeared. I will do my best to provide copies in response to e-mail requests.
2014 May 15
Colin Reeves contributed to a an item on Uptown Radio in New York concerning a new World Bank initiative in Africa. The plan is to raise US$ 1 billion for systematic mapping of the whole of Africa to stimulate the resource exploration sector. Many people probably find it difficult to imagine that the geology and resources of much of the continent is still largely unknown, even today. The original news report came from Reuters.
An international project to produce a new geological map of Gondwana - a successor to the de Wit et al. map from1988 - has received the support of Unesco and the IUGS under the name The Gondwana Map Project– the geological map and the tectonic evolution of Gondwana. It has IGCP Project No. 628. The project starts in 2013, has a five year duration and is led by Professor Ranata Schmitt at the University of Rio de Janiero. All those who wish to join with Earthworks in contributing to this project are invited to contact Colin Reeves directly. An excerpt from the full project proposal follows...
Colin Reeves has been appointed as a contributing editor to the Toronto-based Earth Explorer e-magazine. His first contribution is a report on the 24th Colloquium of African Geology held in Addis Abeba in January 2013. His report may be found at this web-address:
The next opportunity to follow this course will be at the SAGA meeting in Skukuza, October 2013 (see 'Read more', below). The tenth running of the African Geodynamics course was held during the 24th Colloquium of African Geology in Addis Abeba, January 11 and 12, and generated considerable interest The course is an attempt to distil the experience of more than 20 years of plate tectonic modelling into a global picture of the evolution of the African continent, its shelves, rifts and surrounding oceans throughout Phanerozoic time. The incomplete knowledge of Africa's geology is supplemented with more than 40 years experience with regional geophysical mapping in Africa, India and Australia, as well as from the record of growth of the surrounding oceans.
Details of the programme may be found at this webpage: African Geodynamics
The 24th Colloquium of African Geology will be held at the United Nations Economic Commission Conference Center (UNECA) in Addis Ababa, Ethiopia from 8 to 14 January 2013 (http://www.cag24.org.et/). A session has been devoted to Regional geophysical mapping applied to exploration of the geology of Africa with convenors Jörg Ebbing and Mark Jessel. Over 20 oral presentations have been received and accepted. We should all learn more about the power of airborne geophysics in exploring the geology of Africa!
The 34th International Geological Congress in Brisbane attracted almost 6000 delegates from all over the world. Colin Reeves contributed a paper to the speical session on the role of geological surveys in the development of resources under the title: Modern technology: opportunity or threat for failing geological surveys? The talk was deliberately controversial and drew supportive reactions from African delegates who recognised the truth about the parlous state of many national geological surveys in Africa. A PDF file of the talk is available upon request to Earthworks.
The abstract of the talk appears below. A longer, illustrated text on this topic may be downloaded via the item Earthworks 2001-2011 under the News tab above.
In May 2012 Colin visited Iceland again, this time with his two sons Richard and Alexander. An earlier visit, as a student in 1966, was an early influence in his decision to study earth sciences.
The introduction of GIS methodologies to the Geological Survey of India (GSI) and other Indian geo-institutes was pioneered in the late 1990s by a project, Indigeo, that brought ITC and the Maastricht School of Management together in an initiative supported by The Netherlands government. The project was based in renovated buildings on the GSI Hyderabad campus and provided training for many hundreds of earth scientists in its five-year lieftime. In 2012, the GSI Training School will inaugurate several new buildings - an education block, auditorium and student residence blocks - to accommodate the burgeoning need for such training in India.
One of our biggest assignmemnts to date was completed at the end of 2011. Leading the team of consultants, made up of Earthworks BV, Geoexploration (Nigeria) Associates and GeoWitch of The Netherlands, supervising the new two-million line-kilometre airborne geophysical coverage of all onshore Nigeria was an assignment that extended over almost eight years. Paterson, Grant and Watson delivered their final interpretation products at the beginning of 2012.
Colin Reeves gave a lecture sponsored by the AAPG, RWE and Maersk at several locations in Europe during November and December 2011. The title of the talk was 'Some plate-tectonic thoughts on the early opening of the South Atlantic Ocean'. The venues were Geneva (Nov 30), Vienna (Dec 1), Hamburg (Dec 7) and Copenhagen (Dec 15). The abstract of the talk may be seen here.
At the request of the Geological Survey of Botswana I have retrieved a selection of 35 mm slides from my archives to tell the story of how regional geophysical surveys got started in the Kalahari. The work began with geophysical studies in the Okavango delta (gravity, seismic refraction and micro-seismicity) and later extended into a national gravity survey and aeromagnetic reconnaissance of the sand-covered regions. The slide collection may be viewed at the web-album address here.
A short descriptive text appears below.
March 2011 marks ten years since Earthworks began when Colin Reeves first became part-time with ITC. Time to reflect on ten years of projects and look forward to the future. The way we are still thinking was set out in a recent public presentation entitled Africa: Resources in Development. A PDF version of the presentation may be downloaded here.
Two new animations of continental movements are approaching completeness.
South Atlantic Ocean
The first of these is an animation of the development of the South Atlantic Ocean to accompany an invited paper in the Journal of African Earth Sciences. The animation may be viewed and downloaded here but is subject to revision during the review process.
Generations of students from around the world dedicated to map-making have passed through this building, the last of them leaving in 2000. Now the original building of ITC in Delft is no more. It was demolished in October 2010. ITC itself, now a faculty of TU Twente, will celebrate its 60th anniversary in Enschede in December 2010.
The model of Gondwana dispersal developed by Earthworks over many years has specific consequences for the sequence of events by which India's passive margins developed. These events are summarised in a new publication from the Government of India's Department of Science and Technology.
The new airborne geophysical coverage of Nigeria was completed in July 2010 with the addition of airborne gravity and magnetic survey over the region of the Niger Delta. The aeromagnetic and gamma-ray spectrometry data acquired up to July 2009 were released in January this year. The new survey now covers the whole land area of the country - over 2 million km of flying.