Analogue Modeling of Fold and Thrust Development Above Existing Basement Structures for the PNG Fold and Thrust Belt

Abstract The Papua New Guinea (PNG) fold and thrust belt records a complex structural and tectonic evolution and contains large hydrocarbon reserves. However, the jungle-covered mountains exhibit precipitous relief in the heavily karstified and strongly deformed Miocene limestone (Darai formation). This severely limits data acquisition such that seismic data are often of poor quality or unusable. For these reasons, the internal geometry and kinematic evolution of the large anticlines recorded in this zone are poorly understood. It is postulated that the structural history has been marked by: Mesozoic-Paleogene rifting in basement, crustal scale Miocene inversion, detachment folds often above old normal faults in basement, thin-skinned thrusting along decollements in the Jurassic and Cretaceous and decapitation of inversion or detachment folds by out of sequence thrusts, (Hill et al., 2008; Hill et al., 2010). In order to validate some of the interpretations of the internal parts of fold-belt structures fourteen analogue sandbox experiments have been performed as geological forward models under a computerized X-ray tomography device. In this paper, we describe the experimental procedure and the results of these experiments, which have allowed us to test the following configurations: (i) Pure compression (different rates of deformation have been tested); (ii) Oblique compression (testing several angles of oblique compression); (iii) Inversion of normal fault (reactivation of basement fault, variation of the remobilized throw).