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Neoproterozoic-Cambrian geodynamic history of the Anti-Atlas (Morocco) and implications for the European Alpine basement

Applicant von Quadt Albrecht
Number 156244
Funding scheme Project funding (Div. I-III)
Research institution Institut für Geochemie und Petrologie ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geology
Start/End 01.10.2014 - 30.09.2018
Approved amount 302'096.00
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All Disciplines (5)

Discipline
Geology
Mineralogy
Other disciplines of Earth Sciences
Geochemistry
Geochronology

Keywords (15)

stable isotope; Geodynamic evolution; isotope analysis; Anti-Atlas Morocco; Morocco; chemostratigraphic; Geochronology; Geochemistry; Laser-ablation; Ion microprobe; Pan-African; micro-continent; LA-MC-ICPMS; Neo-Proterozoic - Cambrian boundary; ICPMS

Lay Summary (German)

Lead
Geodynamische Entwicklung des Anti-Atlas Gebirges in Marokko zur Zeit des Neo-Proterozoikums und des Kambriums und deren Auswirkungen auf das europäische alpine Grundgebirge
Lay summary

Das Anti-Atlas Gebirge im Süden von Marokko enthält Informationen über Gebirgsbildungen im Grundgebirge und in den verschiedenen Sedimentabfolgen, die von einem passiven Kontinentalhang stammen sollen; daneben gibt es weitere Spuren von vulkanischen Gesteinen und ozeanischer Kruste in den Sedimentabfolgen. Bestehende geodynamische Modelle basieren auf den Forschnungsergebnissen des Grundgebirges und sie werden in der Literatur sehr kontrovers diskutiert, unter dem Gesichtspunkt von einer Existenz  einer oder mehrerer Subduktionszonen, beteiligten vulkanischen Gesteine und deren zeitliche Abfolge.

Unser Projekt will geologische Informationen aus den Sedimenten des Anti-Atlas Gebirges und deren Vulkaniten sammeln, bestehend aus Sandsteinen, vulkanischen Flows und Wechsellagerungen bestehend aud Sedimenten-/Vulkanitablagerungen. Dünnschliffstudien und sedimentologische Charakteristika sind wichtig für spätere Interpretationen. Im Detail sollen folgende Untersuchungen gemacht werden: a) LA-ICP-MS Datierungen an Zirkonen aus Sedimenten, um das Alter der verschiedenen Populationen zu erhalten, b) hoch-präzise U/Pb TIMS Analysen an Zirkonen aus Tuffen, um die magmatische Alter sehr exakt zu erhalten, c) Spureneelement-Charateristika an Mineralien und Gesamtgesteinen, d) stabile 16O/18O Verhältniss an Zirkonen, um magmatische und nicht magmatische Zirkone zu identifizieren, d) 176Hf/177Hf Verhältnisse, um die magmatische Quelle der Zirkone zu bestimmen (Kurste, Mantel). Die Kombination dieser Methode soll es gewährleisten, dass man am Schluss ein gutes geodynamische Modell entwickeln kann.

Direct link to Lay Summary Last update: 08.12.2014

Lay Summary (English)

Lead
Geodynamische Entwicklung des Anti-Atlas Gebirges in Marokko zur Zeit des Neo-Proterozoikums und des Kambriums und deren Auswirkungen auf das europäische alpine Grundgebirge
Lay summary

The Anti-Atlas Belt (AAB) in southern Morocco records the orogenic processes by basement and sedimentary rock suites assumed to be derived from passive margin, volcanic arc, oceanic and collisional foreland geodynamic settings. Existing geodynamic models are mainly based on results acquired from basement rocks, and they are quite controversial with respect to suggested subduction dips, presence of single or multiple subduction zones, nature of volcanic arcs (continental vs. intra-oceanic), and the timing of the processes.

The present project proposes in particular to acquire data from the associated AAB sediments and volcanics, comprising various sandstones, volcaniclastic and volcanic flow deposits. Local mapping, measured sections and tectonic structures will document sampled material. Standard thin section analysis and sedimentological interpretations are crucial criteria for further analyses, which include: i) detrital zircon laser ablation U/Pb dating for evaluating the ages of the sediment source rocks and identifying syn-sedimentary volcanic activity (maximum depostional age, respectively), ii) applying high-precision ID-TIMS zircon dating of intercalated volcanic flow/ash deposits, iii) tracing the source rocks of zircons with selected element pairs, iv) 16O/18O isotope ratios to determine the proportions of magmatic and non-magmatic zircons in the sandstones, v) 176Hf/177Hf ratios in zircons to derive the nature of the parent rocks, and vi) Hf isotope ratios to interpret crustal residence ages of the parent magmas. The combination of these methods will also certainly prove the occurrence of intra-oceanic or continental volcanic arcs.
Direct link to Lay Summary Last update: 08.12.2014

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Northwest Africa’s Ediacaran to early Cambrian fossil record, its oldest metazoans and age constraints for the basal Taroudant Group (Morocco)
Letsch Dominik, Large Simon J.E., Bernasconi Stefano M., Klug Christian, Blattmann Thomas M., Winkler Wilfried, von Quadt Albrecht (2019), Northwest Africa’s Ediacaran to early Cambrian fossil record, its oldest metazoans and age constraints for the basal Taroudant Group (Morocco), in Precambrian Research, 320, 438-453.
Ediacaran glaciations of the west African Craton – Evidence from Morocco
Letsch Dominik, Large Simon J.E., Buechi Marius W., Winkler Wilfried, von Quadt Albrecht (2018), Ediacaran glaciations of the west African Craton – Evidence from Morocco, in Precambrian Research, 310, 17-38.
A pioneer of Precambrian geology: Boris Choubert’s fit of the continents across the Atlantic (1935) and his insights into the Proterozoic tectonic structure of the West African Craton and adjacent area
LetschDominik (2017), A pioneer of Precambrian geology: Boris Choubert’s fit of the continents across the Atlantic (1935) and his insights into the Proterozoic tectonic structure of the West African Craton and adjacent area, in Precambrian Research, 294, 230-243.

Datasets

Northwest Africa’s Ediacaran to early Cambrian fossil record, its oldest metazoans and age constraints for the basal Taroudant Group (Morocco)

Author Letsch, Dominik; Large, Simon J.E.; Bernasconi, Stefano M.; Klug, Christian; Blattmann, Thomas M.; Winkler, Wilfried; von Quadt, Albrecht
Publication date 01.01.2019
Persistent Identifier (PID) 10.1016/j.precamres.2018.11.016.
Repository Appendix A. Supplementary data


Ediacaran glaciations of the west African Craton – Evidence from Morocco

Author Letsch, Dominik; Large, Simon J.E.; Buechi, Marius W.; Winkler, Wilfried; von Quadt, Albrecht
Publication date 01.06.2018
Persistent Identifier (PID) 10.1016/j.precamres.2018.02.015
Repository Appendix A. Supplementary data


Collaboration

Group / person Country
Types of collaboration
Prof. J. Berger (University Paul Sabatier-Toulouse) France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Prof. W. Winkler (ETH Zurich) Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Profs. D. Vance and M. Schönbächler (same institute at ETH Zürich) Switzerland (Europe)
- Research Infrastructure
Prof. N. Ennih (University Chouaib Doukkali, El Jadida Morocco (Africa)
- in-depth/constructive exchanges on approaches, methods or results
Dr. A.-S. Bouvier (University of Lausanne) Switzerland (Europe)
- Research Infrastructure

Associated projects

Number Title Start Funding scheme
134739 Spätpaläozoische Geodynamik des Zentralasiatischen Orogens in der südlichen Mongolei 01.04.2011 Project funding (Div. I-III)
116693 Metal transport and ore deposition: Quantitative modelling of magmatic-hydrothermal systems 01.04.2007 Project funding (Div. I-III)

Abstract

This proposal combines detailed fieldwork with (1) high-precision geochronology, and (2) detailed petrography and geochemistry to investigate the Neoproterozoic - Cambrian geodynamic history of the Anti-Atlas (Morocco) and implications for the European Alpine basement units. The project aims at developing and discussing improved geodynamic models for the northern margin of the West African Craton during the Neoproterozoic and Cambrian. This timespan corresponds to the assembling of Gondwana Supercontinent by the Pan African orogeny. There is also a strong link envisaged to Alpine research, because similar rocks later form part of the basement of the Alpine orogenic cycle.The Anti-Atlas Belt (AAB) in southern Morocco records the orogenic processes by basement and sedimentary rock suites assumed to be derived from passive margin, volcanic arc, oceanic and collisional foreland geodynamic settings. Existing geodynamic models are mainly based on results acquired from basement rocks, and they are quite controversial with respect to suggested subduction dips, presence of single or multiple subduction zones, nature of volcanic arcs (continental vs. intra-oceanic), and the timing of the processes.The present project proposes in particular to acquire data from the associated AAB sediments and volcanics, comprising various sandstones, volcaniclastic and volcanic flow deposits. Local mapping, measured sections and tectonic structures will document sampled material. Standard thin section analysis and sedimentological interpretations are crucial criteria for further analyses, which include: i) detrital zircon laser ablation U/Pb dating for evaluating the ages of the sediment source rocks and identifying syn-sedimentary volcanic activity (maximum depostional age, respectively), ii) applying high-preicision ID-TIMS zircon dating of intercalated volcanic flow/ash deposits, iii) tracing the source rocks of zircons with selected element pairs, iv) 16O/18O isotope ratios to determine the proportions of magmatic and non-magmatic zircons in the sandstones, v) 176Hf/177Hf ratios in zircons to derive the nature of the parent rocks, and vi) Hf isotope ratios to interpret crustal residence ages of the parent magmas. The combination of these methods will also certainly prove the occurrence of intra-oceanic or continental volcanic arcs.
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