Thermal Regime and Extension of the Lithosphere in Different Tectonic Structures of the Sirte Basin, Libya

Abstract

Numerical reconstruction of burial, thermal and maturation histories are carried out for eight sedimentary sections along the profile from the Cyrenaica Platform on the eastern coast of the Sirte Basin to the Hun Graben on the western border of the Sirte paleoift. The interval of depths for temperature calculations included the sedimentary. The analysis of variations in the tectonic subsidence of the basin is used to estimate the amplitudes and duration of the events of thermal activation and extension of the lithosphere occurred during evolution of the Sirte Basin. The modeling suggests that thermal activations of the lithosphere in the Albian–Cenomanian and Oligocene–Pleistocene are common for all tectonic structures of the Sirte Basin and the Cyrenaica Platform. A relatively high temperature regime is also typical for modern state of the lithosphere in the Sirte Basin and Cyrenaica Platform. Such a regime is caused mainly by the thermal activation of the lithosphere during the last 10 Ma. The intensity of this activation is highest in the western part of the Basin, where it is accompanied by the highest erosion amplitudes. The analysis of the variations in the basin tectonic subsidence suggests that two intervals of significant extension of the lithosphere in the Upper Cretaceous and Paleocene are common for all areas within the basin. The total amplitude of the crustal extension attains 1.5 in the central part of the Sirte Basin (the Ajdabiya and Maradah troughs and Zelten and Dahra platforms), is equal to 1.3 in the Hameimat and Zallah troughs, and is minimal (1.11–1.17) in the periphery of the basin (within the Hun Graben and Cyrenaica Platform).