Master Thesis Structural characteristics and analysis of jardas al jarari inlier the centrai part of al jabal al akhdar ne libya

Abstract

as prominent promontory of Late Cretaceous-Tertiary sedimentary belt overlooking the Mediterranean coast. The study area is chosen in the central part of this belt as it exhibits intense structural patterns and involves one of the Late Cretaceous inlier exposed within extensive outcrops of Tertiary sediments. However, the studied structures are re-assessed based on more detailed fieldwork, analysis of different kinematic shear indicators and whether the variations of both; the type of sedimentation and thickness of strata do occur. Upper Cretaceous-Oligocene sediments cover the present area and are represented from the oldest to youngest by these Formations: Al Majahir, Wadi Dukhan, Al Uwayliyah, Darnah, and Al Bayda. Elsewhere, these Formations are unconformably younger by Quaternary deposits. During Jurassic to Early Cretaceous, Al Jabal Al Akhdar was a part of passive continental margin, it is considered as a large sedimentary basin in northeast Libya. By the end of the Cretaceous (mainly Santonian), this structure was inverted, in response of right-lateral shear, and the result was the uplift of Late Cretaceous sediments within Darnah and Al Baydah Formations (Eocene to Lower Oligocene) forming the inlier structure of Jardas Al Jarari. Late Cretaceous inversion was initiated with brittle shear deformation along E-W to WNW-ESE major dextral shear and enhanced with ductile shear forming a sequence of very tight and overturned F1 and F2 asymmetric open folds trending ENE-WSW and NE-SW respectively. At the final stage of Late Cretaceous to Early Tertiary, the whole structure is themed with array of Riedel and conjugate Riedel shears along the NE-SW to NNE-SSW sinistral strike-slip faults and NW-SE dextral strike-slip faults, finally enveloped with the formation of E-W to NE-SW trending F3 major fold.