Original paper

Eine Paläogeographie des Devons auf der Iberischen Halbinsel

Puschmann, Horst

Kurzfassung

Zusammenfassung Eine Paläogeographie zur Zeit des Devons auf der Iberischen Halbinsel wird entworfen. Die Zeitabschnitte des Unter-, Mittel- und Oberdevons werden gesondert betrachtet und die Gebiete mit gleichartiger Fazies zu Fazieszonen zusammengefaßt. So lassen sich im Norden und Süden der Iberischen Halbinsel je ein Sedimentationsbecken mit etwa ost-westlicher Erstreckung erkennen, die mit geringen Veränderungen das ganze Devon hindurch bestehen. Dazwischen liegt ein "mittel-spanischer Gürtel" ohne nachweisbare devonische Sedimente. Das Faziesmuster zeigt, daß die für die devonische Sedimentation zuständigen Abtragungsgebiete auf der Iberischen Halbinsel selbst zu suchen sind. Solche Abtragungsgebiete gibt es in Form kleiner Inseln oder Schwellen, die anscheinend über die ganze iberische Geosynklinale verteilt waren und vielleicht im inneriberischen Raum ihr Maximum an Häufigkeit und Sedimentproduktion erreichten. Für "Festlandsmassen" größeren Ausmaßes gibt es jedoch keine Anhaltspunkte.

Abstract

A palaeogeography of the Iberian Peninsula during the Devonian has been developed. The periods of Lower, Middle and Upper Devonian are considered separately and the areas with equal facies are regarded as facies zones. In the Lower Devonian the following facies types are distinguished: 1. a sandy, Rhenan facies with predominately rhenish faunas; 2. a limy-marly facies with predominately rhenish faunas and hercynian faunal elements; 3. a limy or argillaceous, Hercynian facies with predominately hercynian faunas. The terms "Rhenan" and "Hercynian" facies are used here also to describe facies types of the Middle and Upper Devonian in order to obtain a more contrasting picture. The limy-marly facies type of the Lower Devonian can be neglected during the Middle and Upper Devonian. The resulting facies pattern indicates two great sedimentary basins with approximately E-W axes situated north and south of the Iberian Peninsula. In the inner part of the basins the Hercynian facies is found, accompanied by the Rhenan facies on both sides. Between the northern and southern basin, a "middle Spanish belt" exists with a maximum width of nearly 300 km, where no Devonian Sediments can be proved. Small islands and ridges are assumed to be usually the areas which supplied the clastic sediments found in the inner part of the Iberian Peninsula. Such areas of erosion are known from the Sierra Morena and the Cantabrian Mountains. But there is no evidence of an extensive continental block. In the "middle Spanish belt" geosynclinal sediments are found until the Silurian. This region seems to have been subdivided in basins and ridges. Because important orogenetic movements near the Silurian/Devonian boundary are unknown, the conditions existing in the Silurian are supposed to have continued into the Devonian. The Devonian Sediments are thought to have been eroded later.