Abstract
Detailed sedimentological and biostratigraphical studies of successions in the eastern Anti-Atlas (SE Morocco) focused on changing depositional environments and reconstructions of sea-level changes during the late Famennian to middle Tournaisian. The investigations cover a transect from the central Maider to the easternmost and southern Tafilalt regions near the Moroccan/Algerian border. The Moroccan data are compared with the standard succession of the German Rhenish Massif and with the regional and global stratigraphic record.The results testify to high-frequency sea-level changes, including two global transgressive and anoxic events: the main Hangenberg Event (Hangenberg Black Shale level) at the top of the Wocklumeria Zone (Upper Devonian VI-E), and the Lower Alum Shale Event at the lower/middle Tournaisian (Lower Carboniferous I/II) boundary. Regionally, both anoxic intervals coincided with mass extinctions, followed by rapid radiation, especially of pelagic biota. A significant shallowing and regression occurred just below the Devonian-Carboniferous boundary at the northern margin of Gondwana and caused the sudden N/NW progradation of a large deltaic complex over 300-500. km. Thick siliciclastic successions filled fast subsiding synsedimentary troughs of the Maider and Amessoui Syncline (southern Tafilalt). Correlation with the glacial phases of southern Gondwana (South America, South Africa) indicates a glacial-eustatic origin of sea-level changes and a major sea-level fall in the scale of 100. m or more, coinciding with the main regressive phase of the extended Hangenberg Crisis interval. The new results are in accord with the hypothesis of an episode of cool-humid climate at the end of the Devonian that allowed contemporaneous glacial buildup in high latitudes and extensive clastic discharge in the middle latitudes of NW Africa.
Original language | British English |
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Pages (from-to) | 340-364 |
Number of pages | 25 |
Journal | Palaeogeography, Palaeoclimatology, Palaeoecology |
Volume | 310 |
Issue number | 3-4 |
DOIs | |
State | Published - 1 Oct 2011 |
Keywords
- Ammonoids
- Biostratigraphy
- Conodonts
- Glaciation
- Hangenberg Event
- Sequence stratigraphy