The structural history of the producing fields in the Rocky Mountain region, as revealed by drilling, suggests that contemporaneous growth of local folds during sedimentation was either lacking, or of minor importance. The oil now found in these fields was generated contemporaneously with the deposition of the sediments enclosing the oil or adjacent to it. This oil was conserved in the lower or central portions of the basins of deposition and much later it accumulated in the local folds formed during the Laramide deformation.
Minor amounts of oil have accumulated in the Rocky Mountain region in lenticular sands and as the result of unconformities.
Figures & Tables
The AAPG volumes of Structure of Typical American Oil Fields preceed this book, which was written as a sequel to those, and at first conceived as a third volume of the earlier work. This book is designed to review, modify and, if possible, clarify ideas with regard to the fundamental concepts of oil geology, utilizing, for this purpose, the material presented in the two earlier data-based volumes. To conform to the original standard set for it, this book has been kept relatively free from factual data and has been compiled rather as a summation, based upon the best available evidence, of present knowledge of the science. This volume does not include a discussion of the technique of field or laboratory geology, but does include papers divided into 7 parts: History; Origin and evolution of petroleum; Migration and accumulation of petroleum; Relations of petroleum accumulation to structure; Porosity, permeability, compaction; Oil-field waters; and Subsurface temperature gradients.