Geologic Model Studies Using Trend-Surface Analysis

Abstract

Trend-surface analysis is used to study geologic structure and structural development of two areas in south-central and northwestern Kansas. Trend surfaces, simulating regional structure, are fitted to structure at different stratigraphic horizons and the gross structural patterns visually compared. Dissimilar patterns between surfaces suggest major structural "breaks." Isopachous data reveal information on structural development during the interval, and, by adding each interval one increment at a time, deformation can be seen by a series of time-sequence patterns. Trend-surface residuals generally correspond with local structural features. Residual maps are compared by noting the coincidence of like areas of structure and determining their coefficient of association. It was found that adjacent maps were most closely related and that the similarity decreases in older beds, probably reflecting increased structural complexity. The rate of change in magnitude of the residuals also gives information on the direction of the basin margins.