Depositional environments in the 1000–2000mthick Cambrian-Ordovician succession range from inner-shelf siltstones to fluvial sandstones. Six transgressive-regressive (T-R), low-frequency (15–25 Ma) depositional sequences have been differentiated and correlated with both northern distal (Anti-Atlas, Morocco) and southern proximal (Ahnet, southern Algeria) areas. Sequence 1 (“Lower” Cambrian?) comprises fluvial deposits truncating volcanics and deformed Panafrican basement rocks. Marine strata appeared in Sequence 2 (lower and middle part of the “Middle” Cambrian) but fluvial conditions maintained to the South. Sequence 3 (upper “Middle” Cambrian) is erosionally truncated but further develops to the south, possibly comprising “Upper” Cambrian deposits. In Sequence 4 (Lower Ordovician), fluvial deposits are no longer present and inner-shelf siltstones reached southern Ougarta. Sequences 5 and 6, upper Lower- Middle Ordovician and Upper Ordovician, develop inner-shelf conditions throughout the study area at maximum flooding. Hirnantian glacial strata form a lowstand wedge in the upper part of the Sequence 6 regressive system tract. This succession designates a first-order transgression initiating in the Cambrian. It was temporarily perturbed just before its end by the Hirnantian glaciation. The related erosion led to a discontinuity, angular at basin scale, falsely suggesting a pre-glacial tectonic event. The post-glacial transgression, very fast relative to the Cambrian-Ordovician tempo, resulted in a drastic backstepping of the shorelines that shifted drastically to the south in the early Silurian. After deglaciation, the first-order inversion trend occurred between retrograding strata of the Cambrian-Ordovician succession and the prograding Siluro-Devonian wedge. This event marks in North Africa the maximum flooding of the Lower Palaeozoic megasequence. • Key words: Cambrian, Ordovician, North Gondwana, transgression, glaciation, sequence stratigraphy.

GHIENNE, J.-F., BOUMENDJEL, K., PARIS, F., VIDET, B., RACHEBOEUF, P. & SALEM, H.A. 2007. The Cambrian-Ordovician succession in the Ougarta Range (western Algeria, North Africa) and interference of the Late Ordovician glaciation on the development of the Lower Palaeozoic transgression on northern Gondwana. Bulletin of Geosciences 82(3), 183–214 (14 figures). Czech Geological Survey, Prague. ISSN 1214-1119. Manuscript received June 25, 2007; accepted in revised form September 13, 2007; issued September 30, 2007. • DOI 10.3140/bull.geosci.2007.03.183

Jean-François Ghienne, Université Pasteur, CNRS, UMR 7517 Centre de Géochimie de la Surface, Ecole et Observatoire des Sciences de la Terre, 1 rue Blessig, 67084 Strasbourg Cedex, France; JeanFrancois.Ghienne@eost.u-strasbg.fr • Kheira Boumendjel, SONATRACH, Centre de Recherche et Développement, Av. du 1er novembre, 35000 Boumerdés, Algeria • Florentin Paris, Géosciences-Rennes, UMR 6118 du CNRS, Université de Rennes 1, 35042 Rennes-cedex, France; florentin.paris@univ-rennes1.fr • Blaise Videt, the same address as the previous author • Patrick Racheboeuf, UMR 6538 du CNRS, Université de Bretagne Occidentale, 29385 Brest-cedex, France • Hamid Ait Salem, SONATRACH, Centre de Recherche et Développement, Av. du 1er novembre, 35000 Boumerdés, Algeria

Fig. 8. Facies and sequence stratigraphic interpretations in the Cambrian-Ordovician succession of the Ougarta Range
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Fig. 9. Dating of the Cambrian-Ordovician succession in the Ougarta Range
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Neritopsis represents the only surviving genus of an ancient group of the Neritimorpha that has no internal dissolution of its shell walls. While the two known living species have lecithotrophic early development without larval shell, Neritopsis aqabaensis n. sp. from the Gulf of Aqaba, Jordan, has a planktotrophic veliger. These living species of the genus differ in their protoconch shape as well as teleoconch morphology and ornament from the Triassic species that can be considered related to Neritopsis. Neritopsidae with the modern Neritopsinae is distinguished from the Triassic Cassianopsinae n. subfam. based on the genus Cassianopsis n. gen. with three species by features of their protoconch as well as the different characters of the operculum. Zardiniopsis n. gen. differs from these by higher shell shape and a smaller more complexly ornamented protoconch. Fossariopsis has a more angular shell shape. Colubrellopsinae n. subfam. with Colubrellopsis n. gen. resembles Cassianopsis n. gen. in respect to protoconch and features of the aperture of the teleoconch, but the former has rounded whorls and an ornament of axial ribs. Among the Fedaiellidae n. fam. with smooth shells two species of Fedaiella are redefined. The characters of the inner lip of their aperture connect them with the Neritopsidae, whereas the operculum in the Fedaiellidae with concentric structure on the outside distinguishes them from neritopsids.
In distinction to the groups of the Neritopsoidea members of the Dephinulopsidae have a smooth inner lip of the aperture. Here Delphinulopsinae and Platychilininae n. subfam. differ from each other in the shape and ornament of their teleoconch. Schwardtopsis n. gen. resembles a juvenile Delphinulopsis grown to a larger size. The large concave callus of the inner lip and almost open coiling defines Delphinulopsis. Rows of nodes, low initial shell and rapid growth in shell diameter to an almost limpet shape characterises Platychilina, and lamellar growth increments on an almost limpet-like shell with flat initial part is present in Marmolatella. The Palaeonaricidae n. fam. contains two species of Palaeonarica, which have a Nerita-like shell with simple aperture.
The Naticopsidae of the Carboniferous and Permian has its continuation in the Ampezzonaticopsinae n. subfam. of the Triassic, being connected to each other by the sinuous ornament of ribs on their larval shells. The genera are distinguished by teleoconch shape and differences in the ornament of their larval shell. Ampezzonaticopsis n. gen. has whorls well separated by deep sutures, Cortinaticopsis n. gen. has a simple aperture and a callus covering the umbilicus. The Hologyrinae n. subfam. with Hologyra have a ridge in the columellar furrow and an operculum that resembles that attributed to Carboniferous Naticopsis. Their protoconch has a characteristic chevron ornament on its larval whorls.
The new family Tricolnaticopsidae is proposed to hold Tricolnaticopsis n. gen. with a smooth shell and convex inner lip and color pattern of dots. Into the aperture an operculum of bean-like shape may be fitted and this operculum has quite independent characters. It would also fit with Pachyomphalus with shallow sutures and two species, one with short rounded conical shape and the other with elongate shell. Both resemble Tricolnaticopsis n. gen. as does Rinaldopsis n. gen. with its wide flat inner lip. Laubopsis n. gen. has an open umbilicus and has no clear connection with similar species.
The new family Scalaneritinidae is based on Scalaneritina n. gen. with an elongate shape and axial ribs. The protoconch is rounded with its larval shell having an ornament of low, fold-like collabral ribs. Ladinaticella n. gen. has three species: two have similar shell shape, in one case with a few strong ribs as ornament, while in another case there are many, and a third has a more rounded apex. In the case of Lancedellopsis n. gen., the shell is low, has a rapid increase in diameter and a low tooth in its aperture. Its relation to the other Neritimorpha remains undetermined.
Among the species of Neritoidea from St Cassian Formation the members of the Neritariidae are arranged into the genera Neritaria, Ruganeritaria n. gen., Dentineritaria n. gen., Oncochilus, and Cassianpisulina n. gen. The genus Neritaria has a complexly ornamented protoconch, and the related Ruganeritaria n. gen. differs by the protoconch having only axial ribs. The operculum has the general shape of that found in modern Nerita and its relatives. Dentineritaria n. gen. has a central tooth on its inner lip and its protoconch is relatively large with straight axial ribs. The Oncochilinae is distinguished notably by projections of the inner lip into the aperture, which are two in Oncochilus and single larger one in Cassianpisulina n. gen. The latter is defined and compared with modern Pisulina. The Trachineritariinae n. subfam. with Trachyneritaria n. gen. is distinguished by characters of the teleoconch that has the inner whorls dissolved. Its relation to Trachynerita remains problematic. • Key words: Gastropoda, Neritimorpha, Triassic, Tethys, Italy, Jordan, new taxa (fossil, living).

BANDEL, K. 2007. Description and classification of Late Triassic Neritimorpha (Gastropoda, Mollusca) from the St Cassian Formation, Italian Alps. Bulletin of Geosciences 82(3), 215–274 (14 figures). Czech Geological Survey, Prague. ISSN 1214-1119. Manuscript received April 27, 2007; accepted in revised form July 30, 2007; issued September 30, 2007. • DOI 10.3140/bull.geosci.2007.03.215

Klaus Bandel, Universität Hamburg, Geologisch Paläontologisches Institut und Museum, Bundesstrasse 55, 20146 Hamburg, Germany; klausbandel@yahoo.de

An unusual type of paleokarst carbonate sedimentary rock has been found in the Bohemian Karst, Czech Republic. This well-layered coarse-crystalline limestone is reddish in color and occurs as horizontal or slightly inclined layers filling deep paleokarst cavities within karstified faults in Early Devonian marine-limestone host rocks. Field observations confirm that these sedimentary rocks are undoubtedly younger than the polyphased Variscan folding. Petrographic and geochemical studies indicate that the studied paleokarst limestone is quite different from the Silurian and Devonian limestones, from common cave speleothems, as well as from the typical clastic Late Cretaceous and Cenozoic karst sediments of the Bohemian Karst. Carbonate δ¹³C and δ¹⁸O stable isotopic ratios of the paleokarst limestone (δ¹³C from –4.0 to –6.2 ‰, δ¹⁸Ofrom –6.2 to –8.4‰PDB), differing both from marine Silurian and Devonian limestones and Cenozoic secondary cave carbonates of the area, correspond to a non-marine depositional environment. The paleomagnetic data suggest that magnetic properties of the studied rocks were acquired during the Early to Middle Triassic, although these ages have not yet been confirmed by finds of contemporaneous microfossils. The only microfossils that were extracted using dissolution methods consist of several younger plant and faunal remains including angiosperm pollen grain specimens belonging to the family Myricaceae, likely Tertiary in age. Their sporadic occurrence is interpreted as the result of secondary infiltrations into the millimeter-wide cracks and cavities, in correspondence with the thin-section data on diagenetic successions. • Key words: Prague Synform, paleokarst sedimentary rocks, Triassic, paleomagnetic study, C and O stable isotopes, plant microfossils.

ŽÁK, K., PRUNER, P., BOSÁK, P., SVOBODOVÁ, M. & ŠLECHTA, S. 2007. An unusual paleokarst sedimentary rock in the Bohemian Karst (Czech Republic), and its regional tectonic and geomorphologic relationships. Bulletin of Geosciences 82(3), 275–290 (14 figures, 4 tables). Czech Geological Survey, Prague. ISSN 1214-1119. Manuscript received February 28, 2007; accepted in revised form June 20, 2007; issued September 30, 2007. • DOI 10.3140/bull.geosci.2007.03.275

Karel Žák, Institute of Geology AS CR, v.v.i., Rozvojová 269, 165 00 Praha 6 – Lysolaje, Czech Republic; zak@gli.cas.cz • Petr Pruner, the same address; pruner@gli.cas.cz • Pavel Bosák, the same address, and Karst Research Institute SRC SASU, Titov trg 2, 6230 Postojna, Slovenia; bosak@gli.cas.cz • Marcela Svobodová, the same address; msvobodova@ gli.cas.cz • Stanislav Šlechta, the same address; slechta@gli.cas.cz