STRUCTURAL STYLE AND SEDIMENT DISPERSAL IN AN ACTIVE FOLD-AND-THRUST SALIENT, SULAIMAN RANGE, PAKISTAN

Map pattern and GIS analyses were utilized in the investigation of drainage system evolution and sediment dispersal in the actively deforming Sulaiman Range, central Pakistan. The range is a product of ongoing collision between the Indo-Pakistani plate and the Eurasian plate, while the overall shape of the salient is consistent with previously published evidence for transitional crust underlying the lobe. The range is subdivided into four structural domains based on lithology and structural style. The Northern Sulaiman Range is flysch-dominated and seismically inactive. The other three domains are seismically active passive roof duplex systems in a westward-thickening wedge of Paleozoic-Mesozoic miogeoclinal sediments. The Eastern Sulaiman Range is bound to the west by the Kingri tear fault and is defined by NNE trending structures with greater topographic and structural relief than the rest of the salient. The Main Sulaiman Range consists of low relief W-E trending structures. The Sibi syntaxis is defined by the distinct convex-northward recess in the deformation front. At the domainal-scale of the salient, there is an inverse relationship between the density of transverse drainages and the density of individual structures. In the Sibi syntaxis and the Eastern Sulaiman, where topographic and stratigraphic relief is greatest for the Sulaiman region, structural density is low and transverse drainage density is high. Conversely in the Northern and Main Sulaiman, relief is comparatively low, structural density is high, and transverse drainage density is considerably lower. Domainal-scale drainage characteristics impact the range-scale drainage pattern by deflecting the main outlets to the east and west of the salient. These findings support a structurally controlled lateral sediment dispersal pattern resulting in northeast and southwest segmented foreland depocenters. This illustrates the interconnections between structural and fluvial systems that are responsible for sediment routing systems in active fold-and-thrust-belts. In inactive fold-and-thrust belt salients, such as western Wyoming and the Helena Salient, similar patterns of structurally controlled lateral sediment dispersal resulted in major Late Cretaceous-Paleocene depocenters in recesses adjacent to salients.