Exploration Geophysics

https://doi.org/10.1016/B978-0-12-409548-9.12536-9Get rights and content

Abstract

Geophysics is a science that studies the structure and dynamics of the Earth by making measurements of its gravitational, magnetic, electrical and electromagnetic fields, radioactivity and the passage of elastic waves. It studies phenomena such as earthquakes and volcanoes, the movement of continents, and the formation of mountains and ocean basins. Geophysical measurements are used to determine the distribution of various physical properties within the Earth, such as bulk density, magnetization, magnetic susceptibility, electrical conductivity and elastic moduli. In turn, these properties are used to deduce the distribution of different types of rocks and minerals within the Earth, and information about their state, for example their temperature, strength or fluid content. Exploration geophysics applies geophysical methods to search systematically for valuable resources contained in the Earth's crust such as precious and base metals, industrial minerals, and coal, oil, and gas. This article reviews the principles of the main geophysical methods, and the acquisition, processing and interpretation of data. The application of geophysics to various phases of exploration is illustrated by three case studies—first, the use of teleseismics and magnetotellurics to identify regions that could host diamondiferous kimberlite pipes; second, the use of aeromagnetic surveys to find stratiform copper-silver deposits buried beneath desert sands; and third, the use of reflection seismics to image the geological structure of a layered igneous complex containing chromite and platinum group elements ores.

References (0)

Cited by (0)

Raymond Durrheim (PhD, Witwatersrand, 1990) holds the South African Research Chair in Exploration, Earthquake and Mining Seismology at the University of the Witwatersrand, Johannesburg. He is co-Director of the AfricaArray research and capacity-building programme, was co-leader of the Japanese-South African collaborative project “Observational studies in South African mines to mitigate seismic risks” (2010–15), and is a principal investigator of the International Continental scientific Drilling Program (ICDP) project “Drilling into seismogenic zones of M2.0–M5.5 earthquakes from deep South African gold mines” (DSeis, 2016–present). He is the author or co-author of more than 120 refereed articles published in journals, conference proceedings and books and co-author of the article that received the Society of Exploration Geophysicists award for the best paper published in Geophysics in 2012. He was president of the South African Geophysical Association (SAGA) in 1995/96 and was awarded SAGA's highest honor, the Krahmann Memorial Medal, in 2015.

Musa Manzi is an Associate Professor and a Director of the Reflection Seismic Research Centre in the School of Geosciences, University of the Witwatersrand (South Africa). He holds a BSc degree in Maths and Physics (2007), BSc Honors degree (2008) and PhD degree (2013) in geophysics from the University of the Witwatersrand. His research interests involve practical and theoretical aspects of seismic imaging, mainly focussing on near-surface applications, deep mineral and hydrocarbon exploration. He received an award for the best paper published in “Geophysics” journal in 2012 from the Society of Exploration Geophysicists (SEG), and the 2016 Africa Award for Research Excellence in Earth and Oceans Science from the American Geophysical Union (AGU).

Susan Webb is an associate professor of geophysics in the School of Geosciences at the University of the Witwatersrand. She received a B.S. in geophysics at the State University of New York–Binghamton (SUNY) in 1986 and an M.S. in geophysics from Memorial University of Newfoundland, Canada, in 1992. She moved to South Africa to take up a position at Gold Fields as an explorationist, and 4 years later joined the School of Geosciences at the University of the Witwatersrand as a lecturer. She completed a Ph.D. there in 2009 and became a senior lecturer in 2010. Her research is focused on applying geophysical methods to investigate Earth processes at multiple temporal and spatial scales, from determining the geometry of the mineral-rich Bushveld Complex to investigating the magnetic effects of lightning in Lesotho. She is passionate about involving students in research. She directs the AfricaArray Geophysics Field Program and served on the Board of Directors of the American Geophysical Union. In 2014 she received the Society of Exploration Geophysicists (SEG) Outstanding Educator Award.

View full text