DETACH: an Excel spreadsheet to simulate 2-D cross sections of detachment folds

Abstract

Structural geologists now recognize detachment folds as fundamental structural features in many contractional settings. Several two-dimensional geometric and kinematic models exist to describe the development of such detachment folds; however, most are not available in a computer-based format that permits the forward-modeling and graphical representation of the detachment fold geometry. We developed DETACH, a Microsoft Excel™ spreadsheet, to construct simple cross sections of detachment folds using published geometric and kinematic models. DETACH allows users to assess the range of possible fold geometries and detachment depths that can be constructed using a prescribed set of fold kinematics, and to quickly evaluate and select a best-fit kinematic model for folds of known geometry. We illustrate DETACH's capabilities by modeling a two-dimensional cross section of a natural detachment fold and by constructing pseudo-three-dimensional models of detachment fold terminations with the assistance of Geosec2D™ and Gocad™ structural modeling software.