Abstract
AbstractContinental passive margins and their hinterlands in the Atlantic realm have been the locus of many Low Temperature Thermochronology (LTT) and time‐Temperature (t‐T) modelling studies that evidence pre‐, syn‐ and post‐rift episodic km‐scale exhumation and burial episodes. In this study, we integrate data from over 30 published LTT and t‐T modelling studies from Morocco and its surroundings using a three‐step workflow to obtain: (a) exhumation/burial rates, (b) erosion rates and (c) palaeoreconstructions of source‐to‐sink domains, between the Permian and the Present. Our synthesis of available t‐T modelling results predicts high exhumation rates in the Anti‐Atlas (0.1 km/Myr) during the Early to Middle Jurassic, and in the High Atlas (0.1 km/Myr) and Rif (up to 0.5 km/Myr) during the Neogene. These rates are comparable to values typical of rift flank, domal or structural uplifts settings. During the other investigated periods, exhumation rates in the Meseta, High‐Atlas, Anti‐Atlas and Reguibat shield are around 0.04 ± 0.02 km/Myr. Interpolation of the exhumation rates at the regional scale allow calculation of the volume of rocks eroded. Estimates of erosion rates are between 0.2 x 103 and 7.5 x 103 km3 (in the Meseta and the Reguibat Shield respectively). Ten erosional (quantitative, from interpolation results) and depositional (qualitative, from data synthesis) “source‐and‐sink” maps have been constructed, with emphasis on the Jurassic and Cretaceous periods. The maps integrate the extent of exhumed domains, using information from geological maps, lithofacies and biostratigraphic data from new geological fieldwork and well data from onshore and offshore basins. The results illustrate changes in the source‐to‐sink systems and allow for a better understanding of the Central Atlantic margin hinterlands evolution.
Highlights
Continental passive margins and their hinterlands (Figure 1) are the locus of a significant amount of Low-Temperature Thermochronology (LTT) studies that evidence pre, synand post-rift episodic km-scale upward and downward movements (e.g. Gallagher, Hawkesworth, & Mantovani, 1994; Green et al, 2018)
Continental passive margins and their hinterlands in the Atlantic realm have been the locus of many Low Temperature Thermochronology (LTT) and time-Temperature (t-T) modelling studies that evidence pre, syn- and post-rift episodic km-scale exhumation and burial episodes
Our results show that sediment source areas in Morocco since the Permian have varied in location and size and were not always active simultaneously (Figure 23)
Summary
Continental passive margins and their hinterlands (Figure 1) are the locus of a significant amount of Low-Temperature Thermochronology (LTT) studies that evidence pre-, synand post-rift episodic km-scale upward (i.e. exhumation) and downward (i.e. burial) movements (e.g. Gallagher, Hawkesworth, & Mantovani, 1994; Green et al, 2018). In order to quantify the volume of material that was subsequently eroded above presently exposed rocks and shallowest samples from borehole data, a temperature-to-depth conversion is applied on selected t-T results (Figures 6 and 7) This conversion is often used in t-T model to estimate exhumation rates and was already applied in some of the previous studies considered in this work Assessing the sensitivity of this study, we estimate that using such high gradient in the syn-rift would not affect greatly the obtained exhumation/burial rates, as considered t-T realizations for the rifting period in the High Atlas show a flat path fairly close to surface temperature (Figure 5b). Some shallow marine sinks developed in the North Tarfaya, southern Settat and Gharb basins, and along the Mediterranean coast in the Rif domain
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