Colloquy: Exploration Fabric of Africa

Colloquy: Editor’s Column

Nina RachThe American Association of Petroleum Geologists (AAPG) has developed a new African exploration GIS database, as the Edward G. Purdy Memorial Project, honoring the late geologist (b. 4 December 1931, d. 13 October 2009) who left a rich legacy of carbonate research and made significant contributions to the understanding of African geology.

In 1989, Purdy published maps of the “Exploration Fabric of Africa” and “African Basins,” based on regional geology, tectonic framework and exploration-oriented information from a variety of sources, at scales of 1:5 million and 1:10 million. Since those maps were published, there have been major discoveries in deepwater West Africa, Nile Delta, transform margin, the East African Rift Valley, and East Africa offshore.

African Exploration GIS

In April this year, AAPG released the latest updates of Purdy’s original maps within the context of modern GIS. The original Purdy data was fully vectorized and attributed, and two other geology datasets were added: USGS 1997 data and digital data derived from 1968 UNESCO maps, as well as faults and sediment thicknesses from the CGMW Tectonic map of Africa (2010) and image data showing the age of the seafloor around Africa, based on Dietmar Muller’s work [EFA v. 3.2].

The ArcMap project has hyperlinks to relevant DSDP and ODP drill sites. The layers show the location of deepsea drilling sites and contain hyperlinks to archived data stored at NOAA and Texas A&M University. Final GIS version EFA v. 3.2 includes revised basin locations, ages, classification; revised sediment thickness; and revised depth-to-basement.

EFA is a joint industry project, sponsored by: AAPG, Afren, BHP, BP, CGG-Veritas, Chevron, Faroe Petroleum, Fugro, Hanno Resources, Hess, HRT Canada, ION, Lynx Information Systems, Maersk, Marathon, Moyes & Co., Murphy, Nexen, Nippon, Ophir Energy, PGS, Rift Energy, RWE, Sapetro, Sasol, Serica, Shell, Sipetrol, Statoil, Svenska, TGS, The Geological Society, Total, and Tullow Oil.

AAPG will publish the EFA Interactive Internet map, hardcopy maps and other digital output. EFA GIS data is only available to sponsors and to certain designated universities. See:

Who was Purdy?

Edward George Purdy was a carbonate and petroleum geologist who published widely. He earned a BSc. in agriculture from Rutgers University in 1956 and a Ph.D in geology from Columbia University in 1960. His doctoral studies in the Bahamas were funded by Humble Oil & Refining Co., Gulf Research & Development Co., Shell Development Co., and the American Petroleum Institute.

Beginning in 1959, he taught for 6 years at Rice University in Houston, first as Assistant, and then as Associate Professor of Geology, concentrating his research on British Honduras (now Belize).

In 1965, he joined Esso Exploration in Houston.

From 1979 to 1983, Purdy was the Geological Manager for Esso Exploration Europe-Africa Division. In 1986, after 21 years, he took early retirement from Esso and founded the international petroleum exploration consultancy, PetroQuest International Inc., based in Weybridge, Surrey. He continued to work for more than two decades, publishing the Africa maps in 1989.

From 1992-1995, Purdy was a visiting professor at Imperial College, and at Royal Holloway, University of London. From 2002-2004, he was a guest scientist and invited lecturer at Goethe-University in Frankfurt am Main, Germany.

In 1998, Purdy received a Special Commendation Award from the AAPG “for pioneering research on carbonate sediments and reefs, a seminal role in exploration worldwide, and for teaching and mentoring young geologists.”

His self-described “last contribution to science” was a review and analysis of University of Chicago paleontologist Jack Sepkoski’s taxonomic diversity database, which Purdy related to sea-level change and strontium isotope data throughout the Phanerozoic, published in 2008.

In April 2010, SEPM’s carbonate research group started their annual meeting with a Memorial to Ed Purdy, “a phenomenal carbonate geologist and person.”

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