Testing of Permian - Lower Triassic stratigraphic data in a half-graben/tilt-block system: evidence for the initial rifting phase in Antalya Nappes

摘要

Testing of Middle Permian - Lower Triassic stratigraphic data from the Antalya Nappes in a half-graben/tilt-block system has revealed the presence of episodic rifting events separated by periods of tectonic quiescence. Following a period of uplift during the Permian (Late Artinskian to Roadian), the basement rocks have been activated by displacement faults and several depocenters in half-graben-like asymmetrical basins began to be filled with Roadian to Wordian continental clastic deposits intercalated with coal and marine rocks. The Early Capitanian time was a period of tectonic quiescence. The second event occurred in Middle to Late Capitanian times and produced basaltic volcanic rocks intercalated in the shallow marine fossiliferous carbonate successions. Following the Lopingian (Wuchiapingian and Changhsingian) and Permian-Triassic boundary interval representing a long tectonic quiescence, the last rifting episode started with an abrupt facies change in the late Griesbachian. Variegated shales, limestones, volcanics, talus breccia, and debris flow deposits were laid down in a half-graben/tilt-block system. As normal faulting has become active, the deposition continued on the subsiding hanging wall side. The stratigraphic gap increased in magnitude as the erosional truncation has incised deeply the footwall side. This initial rifting phase in the Antalya Nappes is prior to the onset of a stronger and more continuous rifting event that occurred in the Anisian-Carnian interval including a variety of deepwater clastic and carbonate deposits, radiolarites containing sometimes blocks and clasts derived from the basin margins, and volcanic rocks carrying intraoceanic setting character.