A. Le Hérissé

Ordovician and Silurian cryptospores and miospores from southeastern Turkey

Ordovician and Silurian samples from southeastern Turkey have yielded a large number of well-preserved palynomorphs including cryptospores and miospores, which are described here. Two new species are described (Segestrespora burgessii Steemans, Le Herisse et Bozdogan sp. nov. and Velatitetras anatoliensis Steemans, le Herisse et Bozdogan sp. nov.), two new combinations are proposed (Velatitetras retimembrana Steemans, le Herisse et Bozdogan comb. nov. and Velatitetras rugosa Steemans, le Herisse et Bozdogan comb. nov.), and two genera are emended (Dicryptosporites and Segestrespora). The morphon concept is used for the species with very close morphologies (Van der Zwan, 1979). Using these sporomorphs, four Oppel zones are erected and compared with other similar studies. Ordovician samples contain biostratigraphically useful chitinozoans and acritarchs which precisely correlate the level of appearance of the oldest trilete miospore Morphon Ambitisporites avitus—dilutus with middle to upper Ashgillian.

New palynological data from the Gramscatho Group at the Lizard Front (Cornwall): palaeogeographical and geodynamical implications

Palynological investigation of the terrigenous Gramscatho Group Formations dates the uppermost part of the Porscatho Formation (lower Gramscatho) as being of Frasnian age. This suggests a late Devonian age (Famennian?) for the chaotic Meneage Formation (mid-Gramscatho) which overlies the dated fossiliferous levels. During the Upper Devonian, the parautochthonous Gramscatho basin thus appears as a fault controlled basin which registers, by both a chaotic sedimentation and a volcanic activity, the earlier Variscan tectonic events active in more southern internal zones. The presence of reworked Ordovician acritarchs, in some lower Gramscatho horizons, constitutes a valuable tool for the palaeogeographical evolution pattern of the Devonian of this Cornwall area.