| Title: |
Shell Beds in Ordovician storm- to tide-dominated deposits, Daoura (Ougarta range), Algeria |
| Authors: |
Metatla, Imene; Reynaud, Jean-Yves; Ghienne, Jean-François; Vinn, Olev; Harouz, C.; El Albani, Abderrazak; Mazurier, A.; Mahboubi, S. |
| Contributors: |
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG); Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD Ile-de-France ); Tartu University Hospital; Université des Sciences et de la Technologie Houari Boumediene = University of Sciences and Technology Houari Boumediene Alger (USTHB); Hydrogéologie, Argiles, Sols, Altérations E2 – IC2MP équipe 2 (HydrASA); Institut de chimie des milieux et matériaux de Poitiers UMR 7285 (IC2MP Poitiers ); Université de Poitiers = University of Poitiers (UP)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers = University of Poitiers (UP)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS); Université Aboubekr Belkaid de Tlemcen = University of Belkaïd Abou Bekr Tlemcen; INSU TelluS-Syster, Profas B+ |
| Source: |
ISSN: 1214-1119 ; Bulletin of Geosciences ; https://hal.science/hal-04675799 ; Bulletin of Geosciences, 2024, 99 (2), pp.149-168. ⟨10.3140/bull.geosci.1894⟩. |
| Publisher Information: |
CCSD; Czech Geological Survey |
| Publication Year: |
2024 |
| Collection: |
Université de Poitiers: Publications de nos chercheurs.ses (HAL) |
| Subject Terms: |
wave-dominated ramp; shell beds; tide-modulated shoreface; cornulitids; tempestites; Daoura; Ougarta; Algeria; Upper Ordovician; [SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy |
| Description: |
International audience ; The Ordovician wave-dominated sandstones of the Daoura (Ougarta range, NW Algeria) contain shell beds with cornulitids in an exceptional state of preservation. The objective of this study, focused on the sandstone of the uppermost part of the Hassi Chaamba Fm. (Sandbian?), is to understand the shell beds from the hydrodynamic and stratigraphic perspective with the combined approach of facies sedimentology and taphonomy. A 40-m section encompassing the shell beds was studied in detail. The shell beds are preserved as dm-scale concentrations in transgressive deposits of 5 high-frequency sequences preserved at the turnaround from a regressive to a transgressive sequence set. The biota in shell beds are dominated by brachiopods, cornulitids and gastropods, suggesting that the related ecosystem extended to the offshore. Three types of shell beds are distinguished, ranging from a conglomerate in the foreshore to a hardground in the offshore transition. In the lower shoreface, the shell beds are interstratified with fine-sand SCS infilling large-scale (up to 20 m in wavelength) troughs eroded in the foreshore by transgressive ravinement. The petrographic and tomographic analysis of a sample of these shell beds shows that cornulitids and, to a lesser extent, brachiopods of the shell beds are perfectly preserved within a matrix composed of bioclasts. This suggests that they were reworked from nearby areas and therefore were present in the foreshore. Aggregation of cornulitids in clusters of 4–5 individuals suggests an adaptation to loose grounds in a relatively high energy setting. The rhythmic alternation of shell beds and sandstones in these deposits suggests a possible role of tides in their formation |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| DOI: |
10.3140/bull.geosci.1894 |
| Availability: |
https://hal.science/hal-04675799; https://hal.science/hal-04675799v1/document; https://hal.science/hal-04675799v1/file/Metatla%20et%20al_2024_Shell%20Beds%20in%20Ordovician%20storm-%20to%20tide-dominated%20deposits,%20Daoura%20%28Ougarta.pdf; https://doi.org/10.3140/bull.geosci.1894 |
| Rights: |
info:eu-repo/semantics/OpenAccess |
| Accession Number: |
edsbas.813DDD0F |
| Database: |
BASE |