Dip-Profile Method of Constructing Structural and Stratigraphic Cross Sections: ABSTRACT

Abstract

Dip profiles are graphs that show apparent dip as a function of distance along selected horizontal, vertical, or inclined lines on cross sections. Such profiles not only serve to integrate structural control of all kinds (surface dips, dipmeter dips, and dips derived from contour maps and migrated seismic sections) into a single numerical package, but they also provide a foundation for sophisticated geometric constructions based on the concepts of curvature trajectories and dip isogons. A curvature trajectory is a smooth line that connects points on a cross section where the bedding curvature has a distinctive property not shared by points on either side. (The trace of an axial plane is a familiar example.) Eight kinds of curvature trajectories (of which two relate to dip slip faults) occur in nature. Each kind is distinguished on dip profiles by a specific, mathematically-defined special point. A dip isogon is a smooth line that connects points of equal apparent dip on those parts of a cross section where the bedding is curved. (The trace of a crestal plane is a familiar example.) Reliable procedures for extrapolating and interpolating curvature trajectories and dip isogons (based on the known or deduced tectonic style) can be used to establish a network of primary and secondary dip profiles--thereby insuring structural and stratigraphic interpretations that are statistically and End_Page 898------------------------------ geometrically consistent with all observed data. The methods described are especially useful for resolving sparse or erratic data and predicting subtle traps and deep structures from shallow control. End_of_Article - Last_Page 899------------