Reassessment of Lochkovian - Pragian conodont faunas from the Rade de Brest and the Presqu'île de Crozon (Massif Armoricain, France)
Abstract
Four informal Lochkovian-Pragian conodont faunal intervals, FI 1 to FI 4 have been recognized in Lower Devonian sections yielding in the westernmost part of the Massif Armoricain. The conodont assemblages are in general not abundant, poorly diversified, and largely dominated by icriodids. The structural constraints induced poor preservation and fragmentation of conodont elements. Most conodont taxa are endemic and show close affinities with those of the Lower Devonian of Spain, mainly Celtiberia and the Guadarrama. One of the rare, widespread conodont species, is Masaraella pandora. A new morphotype, angustoides angustoides beta, is described. The vertical range of conodont taxa and the biostratigraphic interpretation of the four faunal intervals strenghten the position for the Lochkovian-Pragian boundary as previously proposed, and allows complementary correlations between the studied sections.