Along strike behavior of the Tizi n’ Firest fault during the Lower Jurassic rifting (Central High Atlas Carbonate basin, Morocco)

• Published in: International journal of earth sciences : Geologische Rundschau Vol. 107; no. 6; pp. 2209 - 2231
• Main Authors: Sarih, S., Quiquerez, A., Allemand, P., Garcia, J. P., El Hariri, K.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2018; Springer Nature B.V; Springer Verlag
• Subjects: Accommodation; Basins; Biostratigraphy; Carbonates; Earth and Environmental Science; Earth Sciences; Geochemistry; Geology; Geophysics/Geodesy; Jurassic; Life span; Migration; Mineral Resources; Original Paper; Rifting; Sciences of the Universe; Sedimentology; Structural Geology; Tectonics; Morocco; Syn-rift; Normal fault; Accommodation; Morocco; Lower Jurassic; Along-strike
• ISSN: 1437-3254; 1437-3262
• DOI: 10.1007/s00531-018-1596-8

The purpose of this study is to document the along-strike early syn-rift history of the Lower Jurassic Carbonate basin of the Central High Atlas (Morocco) by combining sedimentological observations and high-resolution biostratigraphy. Six sections, each from the Sinemurian to the Upper Pliensbachian, were investigated along a 75 km-long transect at the hanging wall of a major fault of the Lower Jurassic Basin (i.e. the Tizi n’ Firest fault). Depositional geometries of the early syn-rift deposits were reconstructed from the correlation between eight main timelines dated by biochronological markers for a time span covering about 6 Ma. Depocentre migration was examined and accommodation rates were calculated at the sub-zone timescale to discuss the along-strike-fault behavior of the Lower Jurassic basin formation. The early stages of extension are marked by contrasted along-strike variations in depositional geometry thickness, depocentre migration and accommodation rates, leading to the growth of three independent sub-basins (i.e. western, central, and eastern), ranging in size from 30 to 50 km, and displaying three contrasted tectono-sedimentary histories. Our results suggest that, during the early rifting phase, tectonic activity was not a continuous and progressive process evolving towards a rift climax stage, but rather a series of acceleration periods that alternated with periods of much reduced activity. The length of active fault segments is estimated at about 15–20 km, with a lifespan of a few ammonite sub-zones (> 2–3 Ma).