Validating Structural Styles in the Flysch Basin Northern Rif (Morocco) by Means of Thermal Modeling

Achraf Atouabat,Sveva Corrado,Oriol Gimeno-Vives,Andrea Schito,Dominique Frizon De Lamotte,Faouziya Haissen,Geoffroy Mohn

doi:10.3390/geosciences10090325

Achraf Atouabat, Sveva Corrado + Show 5 more

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https://doi.org/10.3390/geosciences10090325

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Abstract

Vitrinite reflectance and a micro-Raman spectroscopy parameters data set have been acquired on dispersed organic matter of the Maghrebian flysch basin and the Tangiers unit across a NE-SW section in the north-western Rif belt (North Morocco). Thermal maturity shows increasing values from the hinterland to the external unit (from NE to SW). Paleo-thermal indicators show that the internal flysch basin (i.e., the Mauretanian unit) is less mature than the external one, (i.e., the Massylian unit), with Ro% and Ro eq. Raman values ranging from 0.64% to 1.02% (from early mature to late mature stages of hydrocarbon generation). 1D thermal modeling estimates the overburden now totally eroded ranging from 3.1 km to 6.0 km, and has been used as constraint to reconstruct the complete thrust wedge geometry in Miocene times. The reconstructed geometry accounts for high shortening (about 63%) due to the development of an antiformal stack in the frontal part of the wedge made up by the flysch succession. This stacking is interpreted as a consequence of the western translation of the Alboran Domain in the core of the Betic-Rif orogenic system.

Highlights

Fold-and-thrust belts are structures through which former passive margin sedimentary covers and shallow basement rocks mainly shorten because of convergence
The use of different thermal maturity indicators in the thermal model is highly recommended since it has been demonstrated that vitrinite reflectance alone can suffer several pitfalls due to the scarcity or misidentification of maceral content, or reflectance retardation/suppression phenomena [112]
Levels of thermal maturity for the outcropping successions range from early-mature to late-mature stages of hydrocarbon generation

Summary

Introduction

Fold-and-thrust belts are structures through which former passive margin sedimentary covers and shallow basement rocks mainly shorten because of convergence. The rules of their evolution both across and along the strike are well-known [1,2,3,4,5]. Uncertainty exists in defining the structural style and shortening in the Central-Western Mediterranean region, where orogens develop with typical arcuate shapes [6,7] as a result of the long-lasting tectonic evolution in between the convergence of Eurasia and Africa. The area complexity has brought the development of different and sometimes contrasting geodynamic models [12].

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