Detachment Fold Kinematic Modeling: A Breakthrough in Quantitative Descriptions of Detachment Folds

Abstract

Detachment folds are an important type of fault-related folding structures in fold-thrust belts. Although many geometric and kinematic models for detachment folds have been developed, there is no such a model that presents a quantitative relationship between fold shapes and fault kinematics as fault-propagation fold and fault-bend fold models do. Therefore, the kinematic evolution of detachment folds cannot be mathematically deciphered from the geometries of deformed folds. In this study, a series of fully quantitative models for detachment folds, named DF kinematic models, are developed on the basis of the mathematical expression of conservation of mass. Similar to trishear models for fault-propagation folds, the DF kinematic models are quantitatively described using velocity fields such that they are appropriate for forward and inverse kinematic modeling. The DF kinematic models are able to produce a variety of fold geometries and along-strike variable fold vergence that are commonly observed in nature. As compared to other detachment fold models, the DF kinematic models do not need to specify hinge migration or limb rotation, both of which are inherent in the DF kinematic models, and do not require sinking of synclines on the fold limbs to keep the area balanced.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015