Mediterranean Neocomian belemnites, part 4: belemnites of the Barremian stratotype section

This paper deals with the distribution of belemnites in the latest Hauterivian to early Bedoulian of the Angles Barremian Stratotype Section (ABSS). The distribution of the belemnites in the ABSS is not uniform, mainly due to the inaccessibility of certain beds. To cover this, and to compare the distribution with more proximal settings, we investigated a section to the north of Le Bourguet. The latest Hauterivian sediments mainly yield Hibolithes ex gr. subfusiformis besides some Duvalia ex gr. dilatata. The earliest Barremian sediments deliver a richer association that yields the last Hibolithes spp. The first typical Barremian belemnites occur just one bed above the Hauterivian-Barremian boundary based on ammonites. This belemnite association (BaBA1) consists of Duvalia ex gr. silesiaca-gagrica, Duvalia pontica and several species of Hibolithes. At the boundary between the Nicklesia pulchella and the Kotetishvilia compressissima zones the diversity increases and the first classical Barremian belemnites occur. These were formerly attributed to Mesohibolites (BaBA2). These species are herein attributed to a new genus Shvetsovia. Together with the duvaliids from BaBA1 they were first described from Abkhasia by Shvetsov (1913). The latest Early Barremian (BaBA3) and the earliest Late Barremian (BaBA4) show well diversified belemnite associations, with many classical species, dominated by few genera closely resembling the true Mesohibolites. Eventually, these belemnite associations are compared to more proximal sections within the Vocontian Basin, and areas outside the Vocontian Basin (chiefly Hungary and Georgia). Some differences in the frequency and abundance of several species in these different palaeogeographical settings are believed to indicate differences in natural habitat. Duvalia ex gr. grasiana appears to be more abundant in more distal sections, while juvenile Mesohibolitidae, Conohibolites and Curtohibolites appear to be more abundant in the more proximal environments. Finally, a biozonation is presented and defined based on the distribution of the belemnites in the ABSS. This biozonation appears applicable in the more proximal sections, although some biozones are diachronous. The first Mesohibolites occur in the Upper Barremian Imerites giraudi Zone. In the Barremian-Bedoulian boundary sediments, as defined in the ABSS, Neohibolites first occurs, but the latter is only dominant in the marly sediments above the "calcareous Bedoulian". In the Late Barremian-early Bedoulian seven main belemnite associations can be distinguished, viz. BaBA5, BaBA6, BaBA7, BdBA1, BdBA2, BdBA3 and BdBA4. The following new species and genera are described: Hibolithes keleptrishvilii sp. nov. (latest Hauterivian), Duvalia vermeuleni sp. nov. (Early Barremian), Curtohibolites (?) bourguetensis sp. nov. (Early Barremian), and Shvetsovia gen. nov. (late Early-early Late Barremian). Besides, the Late Barremian yields the new species Mesohibolites anglesensis. Moreover, eleven species are described in open-nomenclature.