Late Chattian larger foraminifera from the Prebetic Domain (SE Spain): New data on Shallow Benthic Zone 23

This study focuses on an Oligocene succession dominated by larger foraminifera and coralline algae in the Benitatxell Range (Prebetic Domain, southeastern Iberian Peninsula). The foraminiferal assemblage, studied in thin sections, and interpreted as Shallow Benthic Zone 23, late Chattian, includes: Austrotrillina asmariensis, Nephrolepidina spp., Eulepidina dilatata, E. elephantina, E. raulini, Amphistegina bohdanowiczi, A. mammilla, Operculina complanata, Nummulites cf. vascus, N. aff. kecskemetii, Heterostegina assilinoides, Spiroclypeus blanckenhorni, Cycloclypeus mediterraneus, Miogysinoides formosensis, Postmiogypsinella aff. intermedia, Neorotalia viennoti, Risananeiza pustulosa, and Victoriella conoidea. The Rebaldí section, a succession of late Oligocene limestones 3 km north of the Benitatxell section, shows a similar association with Peneroplis thomasi, A. asmariensis, M. complanatus, Neorotalia viennoti, N. lithothamnica, Heterostegina aff. assilinoides, Spiroclypeus blanckenhorni, Cycloclypeus mediterraneus, A. bohdanowiczi, and Risananeiza pustulosa; it is interpreted as the early part of SBZ 23. This section also contains Praebullalveolina aff. oligocenica, described from the early Rupelian of Turkey, and Schlumbergerina alveoliniformis, previously interpreted as Burdigalian-Recent. Prior to this work, Cycloclypeus mediterraneus was considered to go extinct and be replaced by C. eidae at the SBZ 22B-23 boundary. However, its presence in the Benitatxell and Rebaldí sections extends its range to the late Chattian in the Eastern Betics and indicates an asynchronous extinction in the Tethys. The presence of Amphistegina mammilla Fichtel and Moll 1798 in late Chattian deposits from the western Tethys contradicts the currently accepted hypothesis that places its origin in the Indo-Pacific province in the early Miocene, from where it would have migrated into the Parathethys during the middle Miocene. In addition, the biogeographic range of P. thomasi, A. asmariensis, and P. oligocenica is extended to the westernmost part of the Tethys.

Revision of the Maastrichtian-Palaeocene charophyte biostratigraphy of the Fontllonga reference section (southern Pyrenees, Catalonia, Spain)

The Fontllonga section is one of the best-known stratigraphic sections wordwide for the study of charophyte biostratigraphy of the Maastrichtian and lower Palaeocene. An updated proposal for the charophyte biostratigraphy of this section is presented after summarizing previous knowledge. The zone of Peckichara cancellata allows the upper Campanian–lowermost Maastrichtian to be characterised in the base of the section (La Maçana Formation). The Microchara punctata biozone represents most of the Maastrichtian (Figuerola Formation). Within this biozone, a Clavator ultimus subzone is proposed to improve characterisation of the lower and middle Maastrichtian. Both the upper and lower boundaries of the Microchara punctata biozone proposed in previous studies are modified based on new occurrences of the index species. A charophyte assemblage belonging to the Dughiella bacillaris biozone is reported for the first time from the middle of the section (Perauba Complex) and provides an age for this unit ranging from the upper Danian to lower Thanetian. A foraminifer assemblage found in the basal marine deposits above the non-marine succession of the Fontllonga section provides new biostratigraphic data to locate the upper boundary of the non-marine succession at least within the upper Thanetian

Marine and Transitional Middle/Upper Eocene Units of the Southeastern Pyrenean Foreland Basin (NE Spain)

The stratigraphic basis of this work has allowed the use of larger foraminifers in the biostratigraphic characterisation of the new Shallow Benthic Zones (SBZ). This part of the volume presents a description of the sedimentary cycles formed by the transgressive-regressive systems of the Lutetian and Bartonian in the southeastern sector of the Ebro Foreland Basin.Concerning the Lutetian deposits studied in the Amer-Vic and Empordà areas, four sedimentary cycles have been characterised. The first and second are found within the Tavertet/Girona Limestone Formation (Reguant,1967;Pallí,1972), while the third and fourth cycles cover the Coll de Malla Marl Formation (Clavell et al.,1970), the Bracons Formation (Gich,1969,1972), the Banyoles Marl Formation (Almela and Ríos,1943),and the Bellmunt Formation (Gich,1969,1972). In the Bartonian deposits studied in the Igualada area,two transgressive-regressive sedimentary cycles have been characterised in the Collbàs Formation (Ferrer,1971),the Igualada Formation (Ferrer,1971),and the Tossa Formation (Ferrer,1971). The Shallow Benthic Zones (SBZs)recognised within the Lutetian are the following:SBZ 13, from the Early Lutetian, in the transgressive system of the first cycle;SBZ 14,from the Middle Lutetian, in the second cycle and the lower part of the transgressive system of the third cycle; SBZ 15,from the Middle Lutetian, in the remaining parts of the third system; SBZ 16, from the Late Lutetian,throughout the fourth cycle.The association of larger foraminifers in the first and second cycles of the Bartonian in the Igualada area has been used as the basis for the definition of SBZs 17 and 18 recognised in the Bartonian of the western Tethys

Comment on 'Tectonic and environmental factors controlling on the evolution of Oligo-Miocene shallow marine carbonate factories along a tropical SE Circum-Caribbean' by Silva-Tamayo et al. (2017)

Silva-Tamayo et al. (2017) study the Chattian to Langhian carbonate succession of the Siamana Formation in the Cocinetas Basin (La Guajira, Colombia). They identify a change in carbonate factory from mixed photozoan-heterozoan and photozoan associations dominated by corals in the Chattian-early Burdigalian to a heterozoan rhodalgal association in the late Burdigalian-Langhian. To validate the regional scale of this shift in carbonate-producing biota along the southeastern Circum-Caribbean realm, Silva-Tamayo et al. compare the Siamana Formation with the San Luis carbonate succession in the Falcón Basin (NE Venezuela) and the Perla carbonates in the Urumaco Trough (Gulf of Venezuela). Referring to Albert-Villanueva (2016) they state that, as in the case of the Siamana Formation, the carbonates of the San Luis Formation also recorded a change in carbonate-producing biota, from a photozoan/heterozoan carbonate factory in the late Oligocene-early Miocene to a heterozoan/rhodalgal carbonate factory in the middle Miocene. Notwithstanding, Albert-Villanueva (2016) interprets the carbonate units cropping out in the Falcón Basin (San Luis and Churuguara formations) as early Miocene in age, and the passage from photozoan to heterozoan carbonate factory as a lateral change of facies within the lower Miocene carbonate platforms of the Falcón Basin

Marine and Transitional Middle/Upper Eocene Units of the Southeastern Pyrenean Foreland Basin (NE Spain)

The stratigraphic basis of this work has allowed the use of larger foraminifers in the biostratigraphic characterisation of the new Shallow Benthic Zones (SBZ). This part of the volume presents a description of the sedimentary cycles formed by the transgressive-regressive systems of the Lutetian and Bartonian in the southeastern sector of the Ebro Foreland Basin. Concerning the Lutetian deposits studied in the Amer-Vic and Empordà areas, four sedimentary cycles have been characterised. The first and second are found within the Tavertet/Girona Limestone Formation (Reguant, 1967; Pallí, 1972), while the third and fourth cycles cover the Coll de Malla Marl Formation (Clavell et al., 1970), the Bracons Formation (Gich, 1969, 1972), the Banyoles Marl Formation (Almela and Ríos, 1943), and the Bellmunt Formation (Gich, 1969, 1972). In the Bartonian deposits studied in the Igualada area, two transgressive-regressive sedimentary cycles have been characterised in the Collbàs Formation (Ferrer, 1971), the Igualada Formation (Ferrer, 1971), and the Tossa Formation (Ferrer, 1971). The Shallow Benthic Zones (SBZs) recognised within the Lutetian are the following: SBZ 13, from the Early Lutetian, in the transgressive system of the first cycle; SBZ 14, from the Middle Lutetian, in the second cycle and the lower part of the transgressive system of the third cycle; SBZ 15, from the Middle Lutetian, in the remaining parts of the third system; SBZ 16, from the Late Lutetian, throughout the fourth cycle. The association of larger foraminifers in the first and second cycles of the Bartonian in the Igualada area has been used as the basis for the definition of SBZs 17 and 18 recognised in the Bartonian of the western Tethys.This research was supported by DGICYT grant PB 98-1293, and is a contribution to IGCP 393 of the Grup Consolidat de Recerca "Geodinàmica i Anàlisi de Conques" of the Barcelona University and the Research Commission of the Generalitat de Catalunya.Peer reviewe

Geology of the Falcón Basin (NW Venezuela)

This paper presents a geological map and cross-section of the Falcón Basin based both on published and unpublished work and on new data collected in the northern and southern basin margins. The geological map covers an area of 4600 km2 at 1:100,000 scale. The cross-section is oriented NNW-SSE, traversing perpendicular to the main structures. In general, the structure of the study area results from the inversion of a graben (Oligocene-early Miocene back-arc basin), that started in the middle Miocene due to the convergence between the Caribbean and South American plates. The map, the cross-section and the observations made in the field have been used to generate a tectonostratigraphic reconstruction of the Falcón Basin. The Oligocene-early Miocene sedimentary succession mapped and described is relevant to the hydrocarbon exploration in the Caribbean and in the Gulf of Venezuela, where new hydrocarbon resources have recently been discovered (i.e. Perla gas field)

Geology of the Falcón Basin (NW Venezuela)

<p>This paper presents a geological map and cross-section of the Falcón Basin based both on published and unpublished work and on new data collected in the northern and southern basin margins. The geological map covers an area of 4600 km² at 1:100,000 scale. The cross-section is oriented NNW-SSE, traversing perpendicular to the main structures. In general, the structure of the study area results from the inversion of a graben (Oligocene-early Miocene back-arc basin), that started in the middle Miocene due to the convergence between the Caribbean and South American plates. The map, the cross-section and the observations made in the field have been used to generate a tectonostratigraphic reconstruction of the Falcón Basin. The Oligocene-early Miocene sedimentary succession mapped and described is relevant to the hydrocarbon exploration in the Caribbean and in the Gulf of Venezuela, where new hydrocarbon resources have recently been discovered (i.e. Perla gas field).</p