Original paper
Faunenwandel oder Faunenkrise? Faunistische Untersuchung der Grenze Frasnium/Famennium im mittleren Südasien
Farsan, Noor Mohammad
published: 9/19/1986
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ArtNo.: ESP026001603001
Abstract (German)
Zusammenfassung. Eine lückenlose Sedimentation über die Grenze Frasnium/Famennium ist im mittleren Südasien mindestens in vier Lokalitäten (Rebat-e-Pai in West-Afghanistan; Ghuk im westlichen Zentral-Afghanistan; Iraq in Zentral-Afghanistan und Kalate Hadji Abdul Hossein in Ost-Albors, Iran) durch Fossilien belegt. Ein schmales Epikontinentalmeer erstreckte sich von Zentral-Afaghanistan bis nach Ost-Albors (Iran), in dem die Kontinuität der Sediment-Abfolge und die Sukzession der Fossilführung über beide Stufen gewährleistet wurde. Der Faunenwandel ist aber nur in Rebat-e-Pai (West-Afghanistan) infolge der reichen und vielfältigen Epikontinentalfauna zu beobachten. Er zeichnet sich durch allmählichen Diversitätsrückgang bei Brachiopoden, Tentakuliten und Asteropyginen im Laufe des Frasnium und sukzessive Diversitätszunahme bei den Brachiopoden im Famennium aus.
Abstract
There are only 4 localities (Rebat-e-Pai, West-Afghanistan; Ghuk, western Central-Afghanistan; Iraq, Central-Afghanistan and Kalate Hadji Abdul Hossein, East-Albors, Iran) in the Middle part of Southern-Asia in which continuous sedimentation at the Frasnian-Fammennian Boundary can be verified by means of fossils. The existence of a narrow epicontinental sea extending from Central-Afghanistan to East-Albors (Iran) led to deposition of a complete stratigraphic sequence incorporating faunal succession at the Frasnian-Femennian Boundary. The process of faunal turnover at this boundary can be demonstrated only in Rebat-e-Pai (West-Afghanistan) as the result of its rich and diverse shallow epicontinental biota. The pattern of faunal turnover shows a gradual decrease in the number of genera and species of brachiopods, tentaculites and trilobites (Asteropyginae) during the Frasnian followed by a subsequent increase of brachiopods in the Famennian. The last representatives of the trilobites, tentaculites and corals disappeared at the end of the Frasnian, while all three genera of brachiopods (Productella, Ripidiorhynchus and Cyrtospirifer) which occur in the Upper-Frasnian crossed the Frasnian-Famennian boundary unchanged. The Frasnian faunal turnover was not a single event. It was an accumulation of many short-dated successive episodes of extinctions which changed the character of the fauna. There exists no evidence for a catastrophic change at the Frasnian-Famennian boundary.