Understanding Mechanics of Fold-Thrust-Belt through Sandbox Modelling

Abstract

One of major challenge and complex issue in structural geology is understanding the mechanism of Fold-Thrust-Belt (FTB). Numerous authors have been worked to solve these particular subjects in the past. However, most of them are concentrated in describing internal deformation and their tectonic evolution. FTB deformation is very complex due to their natural geological parameters which control their geometries and styles. Although, in natural example often difficult to analyse this parameter using outcrops or seismic reflection data due to the poor image quality as a results of complex deformation styles particularly in the form of tight folds and steep faults. Therefore, in evaluation FTB need to generate special approach which focus in integrating result of palinspastic reconstructions trough balancing cross-sections and sandbox modelling. This paper will present results from series experiment using analogue sandbox modelling for ramification mechanics of FTB and their associated structures. The main focus of the experiment is evaluating main geological parameters in controlling geometry and fault styles of several different tectonic setting. The results of the study show the importance roles of preexisting structures or basement configuration in controlling end results of FTB deformation styles. Others geological parameter such as variation lithology governed by facies and package thickness are considered as mechanical stratigraphy which play key roles in strain distributions. In addition, their initial slope is among the important parameter which clearly influenced in the final results of deformation. Among all, basement configuration is one of the parameters seems to have major impact in fault styles such as thin-skinned versus thick-skinned FTB. Understanding these initial parameters conditions are very important in order to have the best modelling results representing natural examples. The result of this study was validated using 2D seismic data from Eastern Indonesia which consider as the main frontier exploration hydrocarbon in FTB setting.