Tectonic Structures and Their Consequential Nontectonic Deformations —The Case of the Friable Lower Cretaceous Sandstones in Jordan

Abstract

The post Paleogene tectonic activities in the Levant comprising emergence of the Levant area from the Tethys Sea (epirogenic uplifts), the continuous drifting apart of the Arabian Plate from the African Plate along the Red Sea, and the taphrogenic movements (graben-tectonics) along the Jordan Rift Valley accompanied by uplifts of the Jordan Rift Valley eastern and western Shoulder Mountains have created a variety of major structures such as grabens, horsts, faults, strike slip faults, and flexures. Along these structures, and in their surroundings, nontectonic structures have developed with a variety of implications to the local and regional geologic set-up and topography. Such structures include formation of large topographic depressions, local faulting, block tilting, and flexuring, fine material flow channels along fractures and joints, dike fillings, density inversions, Local litho-stratigraphic pressure readjustments, and convolute bedding among others. This paper discusses the major regional tectonic structures in Jordan and their roles, together with other factors, in the formation of some nontectonic structures and the latter geologic, topographic and engineering geologic implications. After discussing the above issues, the article concludes that the exposure of the friable and easily erodible Lower Cretaceous sandstone along the major structures has created zones of geologic and topographic instability producing many types of nontectonic structures with a variety of consequences to land stability, topography, groundwater flow patterns, and fates of aquifers.