IGCP 421 - North Gondwana Bioevent\Biogeography Patterns in Relation to Crustal Dynamics : SDS at Errachidia- Rabat (Morocco). 23 April-1-May 1999

The 5th international meeting was held in Morocco by the Department of Geology, Scientific Institute, Mohammad V Agdal University, Rabat, the Faculty of Sciences, Moulay Ismail University, Errachidia, and the Geological Survey of Morocco (Midelt Regional Centre) under the overall guidance of Prof. Ahmed El Hassani of the Scientific Institute, Rabat. Associated with the meeting of IGCP 421 was a meeting of the IUGS Subcommission on Devonian Stratigraphy (SDS).
The meeting consisted of a one-day transect from Rabat across the Middle and High Atlas to Errachidia, followed by a one- day scientific meeting (24 April) at the Hotel de Ville in Errachidia during which 36 scientific papers were presented orally or as abstracts to an audience of 91 local and foreign participants. The 40 foreign participants were from Germany (9), France (9), USA (6), Italy (5), Australia (2), Czech Republic (2), Belgium (1), China (1), Iran (1), Pakistan (1), Poland (1), Spain (1) and U.K. (1). A 7-day formal excursion then ensued (25 April-1 May) during which colleagues from various institutions in Morocco and Europe demonstrated sequences of regional and global significance in the Tafilalt and Meseta regions of Morocco.
The Tafilalt region is of prime signficance for IGCP 421 because of its superb sequences displaying conodont and ammonoid biostratigraphy through Devonian time, and also because of elegantly displayed sedimentary signatures for the Kacak, Chotec, Taghanic, and Lower and Upper Kellwasser events. The Kellwasser events are also well displayed in the western Meseta though in seemingly allochthonous slabs and differing in detail sedimentologically from the same intervals in the Tafilalt region. Sections through the above 5 global event-intervals demonstrate that none of them were instantaneous; all have a "historical component" involving a significant interval of time. Of special interest for IGCP 421 is the emerging realization from provinciality of Devonian faunas between the Tafilalt and Meseta regions - including the pelagic goniatite faunas that one might assume to display little or no provinciality - that the South Atlas Suture between the two regions has undergone major displacement, conceivably more than 1,000 km.
The following sample of oral and poster contributions will convey an impression of the scope of the meeting: Condensed pelagic carbonates of the Harz Mountains, Germany (Hünecke - poster prize); Comparison of the Rabat-Tiflet zone of Morocco with coeval strata in Bohemia (Hünecke & Krienke); Dislocation of the Moroccan Meseta carbonate platform (Chakiri

& Tahiri); Extensional tectonics with respect to Devonian reef building in the northern Meseta (El Kamel & El Hassini); Hercynian deformation-evolution of the Carnic Alps (Pondrelli et al.); Mid-Palaeozoics of Pakistan (Talent et al.); Early and early Middle Devonian of the Anti-Atlas (Ziegler et al.); Mid-Palaeozoic anoxic, eustatic and reef episodes (House et al.); Magnetosusceptibility stratigraphy (Ellwood); Magnetosusceptibility stratigraphy of the Anti- Atlas compared with other Gondwanan and non-Gondwanan sequences (Crick et al.); Rock magnetic characterization of the Frasnian-Famennian boundary (Bucholz & Rolf); Emsian conodont succession of NW Morocco (Benfrika & Bultynck); Late Emsian- early Givetian conodont succession in the Tiflet area of Morocco (Gouwy et al.); Goniatite zonation of the Pharciceras Stufe (House & Becker); Famennian ammonoid succession of the S MaÕder (Becker etal.), Famennian ammonoid succession of the Anti- Atlas (Korn); Pragian conodont zonation (Slavik); Emsian-earliest Eifelian succession in the conodont genus Polygnathus (Bultynck); Conodont biostratigraphy of the Late Silurian of Sardinia (Corradini et al.); Silurian-Early Devonian pioneer plant communities (Douglas); Mid-Givetian trilobites and the Taghanic extinction (Feist & Orth); Middle Devonian stromatoporoids from North Africa (Mistiaen);Tabulate coral biogeography of Spain and Morocco (Fernandez-Martinez); Silurian-earliest Devonian Bohemian type bivalves from the Carnic Alps (Kriz); Carboniferous brachiopods from Mali (Legrand-Blain); Asteropygid trilobites from North Africa (Morzadec); Devonian and Carboniferous crinoids from Iran (Webster et al.); Placoderms from the Late Devonian of E Iran (Yazdi et al.); Conodonts from black shale facies of Appalachia (Over & Kirchgasser); Biogeography of crinoid columnals (Le Menn); Palaeozoic sharks as facies indicators (Ginter).
The formal meeting and excursion were noteworthy for excellence of preparation and enthusiasm of the excursion leaders. The various administrative authorities were memorably kind and courteous.

Two publications conference:

were

produced

for

the

1. R. Feist, J.A. Talent & B. Orth (eds), Abstract Book Errachidia Meeting SDS-IGCP 421 (April 23rd-May 1st 1999), 48 pp. Institut des Sciences de l'Evolution, Université de Montpellier II, France.

2. A. El Hassani & A. Tahiri (eds), Excursion Handbook, Pt I: Tafilalt and Maïder (eastern Anti Atlas) (p. 1-107); Pt II: The northwestern Moroccan Meseta, (p. 107-158).. Institut Scientifique (Rabat), Faculté des Sciences et Techniques (Errachidia) & Centre Régional de Géologie (Midelt), Morocco.