Gravity Lexicon

Gravity & Magnetics

Exploration Lexicon

Acquisition

Processing

Interpretation

Imaging

Serguei A. Goussev and John W. Peirce

GEDCO

#1200, 815 – 8th Avenue S.W., Calgary, Alberta, CANADA, T2P 3P2

PREFACE

Authors who write texts on exploration applications often declare their sincere desire to fill certain gaps in knowledge and experience. We are no exception to this rule, but our task is a little different—we are trying to fill a gap by organizing the terminology accumulated by theory and practice in the fields of gravity and magnetics. In the preparation of this Lexicon, we were motivated by the idea of making a book of gravity and magnetic definitions with supporting references, which would be helpful in everyday use for both specialists and non-specialists. We believe that this Lexicon will also contribute to better communication among gravity and magnetic specialists, as well as between two principal players in the exploration process: clients (exploration and production companies) and contractors/consultants (companies involved in acquisition, processing and interpretation of the gravity and magnetic data).

Many improvements and innovative developments have occurred in the fields of gravity and magnetic exploration during the last five to ten years. For this reason, even such an excellent reference as the latest (1997) edition of the Encyclopedic Dictionary of Exploration Geophysics by Robert E. Sheriff cannot embrace all the numerous terms that accompany these recent developments.

In compiling this Lexicon, we tried to keep the style of an "extended entry," wherein most definitions are provided with more or less detailed explanations given in a language that would be acceptable for potential field geophysicists, and clearly understandable by other professionals in the exploration business.

Here we have not invented terms of our own. All of them are taken from the original sources, sometimes almost directly and sometimes paraphrased, and we have attempted to provide a comprehensive reference list. Terms within definitions, indicated by italics, are themselves defined elsewhere in the Lexicon. For cross-reference purposes, most of the definitions are provided with other terms related to similar concepts.

There is inevitably a personal bias in the selection of entries. We tried our best to find such terms and definitions that represent both fundamentals and the latest developments in gravity and magnetic exploration. At the same time, we clearly realize that omissions are also inevitable. We apologize in advance for such omissions and ask that readers submit their suggestions for additional entries to be included in the next edition.

A few basic geological terms are also defined herein when they are particularly relevant, because the structural-geological interpretation is the final product of gravity and magnetic acquisition and processing.

We also understand that the scope of the task and continuing development of new techniques and concepts make this work an open-ended project, and there are always opportunities to improve some definitions as well as add more entries. We would greatly appreciate all corrections, remarks, and additions to this Lexicon and ask that you send them to the authors at the following address:

Many persons provided us with their consulting assistance and encouragement. Our special thanks to Robert A. Charters, Hassan H. Hassan (GEDCO), Erwin A. Ebner (ELS Consulting), Bill Gumert (Carson Services, Inc., U.S.A.), Alberto Cementon (DFA, Australia), Phill Houghton (ARK Geophysics, U.K.), Jeff MacQueen (FUGRO-LCT), and others, whose constructive criticism and careful review contributed greatly to successful completion of this text. We are also indebted to Lesley Walker and Maria Alvizurez for all their efforts to turn our ideas into a clean manuscript.