LOCHKOVIAN (LOWER DEVONIAN) CONODONT BIOTIC EVENTS AND GLOBAL CORRELATIONS

Many biotic events have been registered in the Lochkovian conodont record of key areas in Perigondwana regions (Spanish Central Pyrenees, Bohemia, Carnic Alps, Celtiberia) and Euramerica (Western and Arctic North America). They are the best tool for intercontinental and interfacial detailed correlations.

Innovation and Radiation Events of the main Lochkovian conodont groups are the basis for subdividing this stage in zonal or even smaller units and in correlating across facies and continents.

The lower Lochkovian is characterized by a radiation of icriodids that can be used to correlate between neritic and pelagic facies in perigondwana sections of Europe. In the upper part of the lower Lochkovian an innovation Event, the entry of Ancyrodelloides, is a global Event of great correlation potential.

The middle Lochkovian coincides with the Innovation Event of Lanea. The subsequent radiation of Ancyrodelloides and its quick evolutionary rate provides one of the best tools for subdividing the middle Lochkovian into global intervals lasting less than 500 ky. Further radiation events within Lanea and the Innovation events of Flajsella and Kimognathus furnished even more accuracy in correlating strata from Gondwana and Euramerica.

The upper Lochkovian follows the Innovation Event of Masaraella. A further subdivision is based on the Innovation and radiation events of Pedavis. These events are also recorded in Euramerica and Gondwana, both in neritic and pelagic facies permitting tie correlations worldwide. The radiation of Masaraella facilitates further subdivision in Euramerica.