The people, science and technology behind discovery

At home in the field

by Graham Chandler on December 10, 2013 community

The AfricaArray field school is helping to prepare geoscience students for work in Africa and the rest of the world. Shown above: students use a Geometrics Walkmag to collect ground magnetic data.

Students are introduced to five different geophysical techniques, software, geology and safety. They use forward modelling software and cost estimates to design a survey and work flow.

Launched in 2004, the AfricaArray program is enabling students in Africa and America to develop their field experience and share valuable knowledge about the geosciences.

AfricaArray was founded by Penn State, the University of the Witwatersrand (Wits), and South Africa’s Council for Geoscience. The program is committed to supporting the geosciences in Africa by funding postgraduate studies, facilitating student exchange between the two universities, setting up a pan-African research “seismic network”, as well as funding and supporting an annual field school.

The field school, which Geosoft has supported for more than five years, takes on between 20 and 25 students from Africa and the U.S. each summer. Included are fourth-year Wits students, for whom field school work is compulsory. Other African students include postgraduate students, lecturers, and geological survey employees.

African students have been sponsored by the Society of Exploration Geophysicists (SEG) for eight years, the United Nations Educational, Scientific and Cultural Organization (UNESCO) and the International Union of Geological Sciences (IUGS), while U.S. students have been sponsored by the Opportunities for Enhancing Diversity in the Geosciences program of the National Science Foundation (NSF). The NSF students are selected by Penn State as part of an REU program (Research Experience for Undergraduates) on merit from under-represented groups in the geosciences. They also receive pre- and post-field school training at Penn State.

The AfricaArray program runs for three weeks at Wits, explains Stephanie Enslin, senior instructor. In the first week, Wits graduate students and staff give lectures which introduce undergraduates to five different geophysical techniques, software, geology and safety. Another first-week task is to help students prepare for the job market. This involves creating a real-world “request for bid,” as if the students were submitting a bid to a mining company to carry out a geophysical survey. They use forward modelling software and cost estimates to design a survey and work flow.

The second week takes place in the field at South Africa’s Bushveld Complex, a large igneous intrusion with the largest platinum reserves in the world. This year, Enslin and fellow students went to the eastern part of the Complex and carried out a survey where sponsor Anglo Platinum hopes to develop open-cast mining of the Merensky Reef. Students were divided into groups which rotated through different geophysical methods each day. Graduate students and staff supervised the work, which included reflection and refraction seismics, resistivity, gravity and differential GPS, magnetics, EM, and ground-penetrating radar. In the evening, the day’s data were downloaded and processed, and at 7:30 the following morning the results were presented.

Says Enslin: “Students also spend time looking at borehole cores, measuring densities and susceptibilities, so that they can have realistic values for the geological models they create in the third week. We were lucky enough this year to visit a new nearby open-cast mine; which gave the students some perspective as to what conditions are actually like 20 metres under the surface, all the way down to bedrock.”

Susan Webb, director, and Stephanie Enslin, senior instructor with the the AfricaArray field school test a new Scintrex CG5 Gravity Meter.

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Geosoft software is used during field work to create geological and aeromagnetic maps overlain with the grid on which the students are working.

Geosoft software is used during this second week to create geological and aeromagnetic maps overlain with the grid on which the students are working. This helps to keep track of where they have surveyed and to make sure there is overlap between the geophysical methods used.

The field location is important in AfricaArray. In the Bushveld, for example, students are in a real mining environment working on a real project. Dykes in the area cause “loss of ground,” and variations in overburden directly affect the cost and safety of an open-cast project. “The mine actually selects the region in which we work,” explains Susan Webb, director of the field school, “with the caveat that the goal is to train students, not do a consulting job. The mine obviously gets the data; and we are able to work out of an exploration camp.” 

The third week is back at Wits, where students choose geophysical methods with which to work. Each student in each group works on a different method. Then, together, they organize and process the data. “This is where Geosoft has been most useful,” says Enslin. “Students import their data into databases which are used to display profile data. They also use Geosoft to create grids and maps which they can then overlie the profile data on to. These grids are essential when it comes to correlating features detected by different techniques, as well as correlating with the geology and terrain maps.”

Webb says the loss-of-ground factor provides an excellent opportunity for students to fully utilize the Geosoft platform. “Geosoft provides an integrated toolset that allows the students to understand the importance of planning through to final interpretation. They can see where the dykes are and they can also see how the ground magnetic data radically improve the imaging.” In short, the capabilities help the students visualize the data in the field context.

Students then model the data, correlating the different data sets as well as borehole data to create as accurate a geological model as possible.

On the Friday of that third and final week, the groups present their interpretation. The Wits students go on to submit individual reports combining all these data while each of the U.S. students presents on a different method back home.

Webb says the program is essentially two-tier: “The participating students learn about planning and about collecting, interpreting and integrating the data, while the graduate student instructors learn about software, maintaining equipment, logistics, data quality (for example, making sure the data are of consistent quality across five different groups), and how to interact with people from divergent backgrounds with varying understandings of geophysics.” 

Students take what they learn in the field and apply it to their work back home. As an example, Webb cites one of this past year’s students who has equipment at his home institution in Cameroon and is now setting up a field school for a ground water program he’ll be teaching. Another example is Ester Mutari, who has started her own field school in her native Kenya.

Notes Webb: “Ideal candidates [for AfricaArray] are junior faculty members in departments that have access to equipment but limited field experience.”

The resounding success of the field school is echoed in the response of this year’s participants:

“We managed to get a general idea of what the pyroxenite package, which includes the Bastard and Merensky Reefs, looks like below the overburden and also where it’s situated,” says Kirsten Stephens, a fourth-year honour’s students in the Wits geophysics program. She speaks enthusiastically about the field school program in general: “It was great to have so many different countries and cultures coming together to learn about geophysics. I also made valuable connections with people for future research opportunities.”

Stephens notes that Geosoft proved especially helpful in the survey work. “We were able to display results, say from magnetics and gravity, and then overlay those results onto different images to aid with interpretation. Simply overlaying the gravity over an image of the field area with the proposed outcrop of the Merensky Reef helped us piece the whole geological model together.”

For fellow field-school student Henry Mukasa, a graduate geologist from Makerere University in Kampala, Uganda, the school was “that single opportunity that would help me pursue my ambitions.” His experience with AfricaArray will certainly add a new dimension to his current work as a junior geologist with Auranda Minerals in Entebbe. “It was my first time putting geophysics theory into practice, and I was given the opportunity to handle and control most of the field data. For me, this was like a dream come true.”

Sponsors of this initiative include: Society of Exploration Geophysicists, International Union of Geological Sciences, United Nations Educational, Scientific and Cultural Organization, Council for Scientific and Industrial, Research, TGS, Anglo American, Anglo American Platinum Limited, Geosoft Inc., Dr. D.H. Loke, GEOTOMO Software, Professor Gordon Cooper, Head of Geophysics, University of the, Witwatersrand, Geometrics, National Research Foundation, National Science Foundation Council for Geoscience, theUniversity of the Witwatersrand and the Pennsylvania State University.

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