Published 1995 as part of Memoir 62
Copyright © 1995 The American Association of Petroleum Geologists.  All Rights Reserved.

Geologist, teacher, and explorer.
 
 

Jeremy Tankard, 1994, watercolor, gouache, ink and charcoal, 38 X 41 cm

Before plate tectonics, there was continental drift, a concept pioneered largely by Alfred Wegener. He showed that the geometric reconstruction of the supercontinents was more than the fortuitous parallelism of the coasts on either side of the Atlantic. He also explained in an elegant way the distribution of mountain belts, stratigraphy, and middle Paleozoic ice age deposits.

The reaction to these ideas was lukewarm at best in Europe and decidedly hostile in North America. The geologists of southern Africa and South America were, however, more enthusiastic. Prominent among these were Alex du Toit of South Africa and Juan Keidel of Argentina.

Juan Keidel provided some of the supporting evidence for the contiguity of Africa and South America within Paleozoic Gondwana. His contributions are acknowledged by Wegener in his classic book Die Entstehung der Kontinente und Ozeane (1915). Keidel demonstrated the relationships between the Carboniferous-Permian Sauce Grande glacial deposits of Argentina and the Dwyka tillites of South Africa, as well as the nature of their encapsulating stratigraphies. Only in a reconstructed Gondwana did these glaciers have a rational distribution. The apparent continuity of the Cape fold belt and the Sierra de la Ventana was noted. In his seminal paper of 1921, Keidel recognized how widespread this Permian-Triassic deformation really was, forming a series of cordilleras from Ventana to the Andean foothills. To describe these ancient cordilleras, he coined the name Gondwanides. These interpretations were supported by field work on the Ventana System in the province of Buenos Aires and by surveys in the western and northern Precordillera of Mendoza and San Juan. This was also the start of his association with Alex du Toit, who visited Argentina in the early 1920s.

Field expeditions took Keidel to the Andes, Patagonia, and Neuquén. In the Neuquén basin, he was involved with the first oil well.

Juan Keidel was born in Gross Stoeckheim, Germany, in 1877. He studied at the Institute of Mining in Berlin and completed a doctorate at Freiburg under Professor Steinmann. Dr. Keidel was appointed the first head of what was to become the Geological Survey of Argentina. Subsequently, he taught geology at the University of Buenos Aires. Keidel published more than 50 papers in an illustrious career.

We dedicate this book, Petroleum Basins of South America, to the memory of Juan Keidel.

This memoir addresses the geology and dynamics of the principal petroleum basins of South America from Venezuela to Argentina. Our understanding of the way these sedimentary basins formed has advanced immensely in the last decade. This reflects improved data quality, a different way of looking at the data, a new integrated approach to basin analysis, and a new generation of geologists. A wide variety of papers reviews the tectonic framework, comparative structural styles, sequence stratigraphy, and the way these are interrelated. These basins were a long time in the making. Most have evolved by repeated reactivation of preexisting fabrics. The structural development, its timing, and the way sedimentation responded to this activity is of paramount importance to oil and gas exploration. Intentionally we do not review in any detail the Mesozoic basins of the Atlantic margin because a subject so vast would require space of its own.

We are grateful to the following people for their generous assistance in many ways, for being there when we needed them: Peter Aukes, Hugo Belotti, Nora Cesaretti, Miguel Cirbián, Al Ferworn, Silvia González, Gary Howell, Bob Meneley, Luis Spalletti and Graciela Suárez Marzal de Spalletti, Anne Thomas, Gustavo Vergani, and members of the AAPG staff. We thank Edgar Ortiz and Jeremy Tankard for the paintings prepared especially for this volume. Copyediting and layout were done by Kathy Walker. We are also grateful to Perez Companc for its support.

Anthony Tankard

Ramiro Suárez Soruco

Herman Welsink