Date of this Version
Mendoza, M. C. (2019). Basal Salt Deformation and Associated Penetrative Strain Captured in Analog Models. Undergraduate Honors Thesis. University of Nebraska-Lincoln.
Compressive forces occurring in orogens create shortening in their associated layers in several forms, including macroscale structures such as thrusts and faults. Shortening that is lost in other forms is known as penetrative strain. Utilizing models generated by a sandbox apparatus, researchers can simulate real-world and idealized conditions to study the interactions between deformation sequences and corresponding properties of induced penetrative strain. This research project is an extension of previous work done by Lathrop and Burberry (2016). This project expands on said previous research by investigating the effects of varying basal salt layer thicknesses of analog models on the distribution of penetrative strain in idealized models. Nine models were run at varying thicknesses of basal salt and degrees of shortening. Models with silicon thicknesses of 1 cm, 1.5 cm, and 2 cm were run to 5%, 10%, and 15% shortening, respectively. Each model consisted of a silicon layer overlain by three fine grained sand layers with a grid imprinted on the surface to illustrate deformation in the foreland system. The primary structures found in cross sectional views of these models include box folds, hinterland-verging folds, and fault and thrust folds. Upon restoring models to original horizontality, between 15.7%- 83.8% of shortening is accommodated by penetrative strain. In thick décollement settings, penetrative strain is found to increase with increasing depth and 1.5 cm silicon models are found to have the greatest variability in penetrative strain over the course of increasing total shortening.