The Ordovician of the Condroz Inlier, Belgium: Trilobites from the southeastern margin of Avalonia

详细信息    查看全文

• 作者：Robert M. Owens ; Thomas Servais
• 关键词：Trilobites ; Ordovician ; Avalonia ; Condroz Inlier ; Belgium
• 刊名：Palaeogeography, Palaeoclimatology, Palaeoecology
• 出版年：2007
• 出版时间：7 March 2007
• 年：2007
• 卷：245
• 期：1-2
• 页码：272-294
• 全文大小：2142 K

文摘

During the Early Palaeozoic, Belgium was located in the eastern part of the microcontinent of Avalonia, which moved from high to low latitudes during the course of the Ordovician. In the Belgian Condroz Inlier (“Bande de Sambre-et-Meuse”), Ordovician trilobites have been reported from four formations: the early Llanvirn Huy Formation, the Caradoc Sart-Bernard and Oxhe formations, and the Ashgill Fosses Formation. These assemblages are some of the easternmost occurrences of trilobites in Avalonia, and they include aspects that are particularly interesting from a palaeobiogeographical standpoint.

The trilobite faunas of the Huy and Sart-Bernard formations are revised in detail, while the others are discussed more briefly, having been redescribed in recent years. The Huy Formation belongs to a biofacies characteristic of the outer shelf/upper slope, and its faunas are typically Avalonian, almost identical to those recorded from the Skiddaw Group of northern England, and from the Ebbe and Remscheid anticlines in the Rhenish Massif, Germany. Pricyclopyge binodosa, which is inferred to be mesopelagic, is common to all these areas, and also occurs in Bohemia and Armorica. Placoparia cambriensis has a remarkably wide distribution in the early Llanvirn, and has been recorded from a range of biofacies across Avalonia, Armorica, Morocco and Bohemia. It is suggested that this species may have been epipelagic. Re-examination of the trilobites from the Sart-Bernard Formation has confirmed that all are conspecific with, or compare closely with Bohemian taxa. The trilobite assemblages of the Oxhe Formation are typical eastern Avalonian faunas, while the Ashgill Fosses Formation assemblage has much in common with those of other parts of Armorica, as well as with Baltica and Bohemia, attesting to the increasing proximity of Avalonia, Baltica and the Prague Basin during the latest Ordovician.