Esmeralda Caus

A model for the palaeoenvironmental distribution of larger foraminifera based on late Middle Eocene deposits on the margin of the South Pyrenean basin (NE Spain)

Abstract On the margin of the South Pyrenean basin, the late Middle Eocene sediments represent a well preserved regressive system permitting determination of the distribution of larger foraminifera along the depth gradient. Eocene deposits are compared with distribution patterns of Recent larger foraminifera based on taxa occupying comparable positions along similar ecological gradients. Eocene taxa reveal by their test morphology a similar response to specific ecological conditions to that recorded for Recent foraminifera. Four assemblages characterise an open marine shelf; they range from the lower limit of the photic zone to the lower part of the upper photic zone. Two assemblages characterise the upper part of the upper photic zone, and indicate, respectively, two different substrates, firm or soft. Below the photic zone, no larger foraminifera exist and the foraminiferal assemblages are dominated by smaller benthic foraminifera.

Carbonate platform sequence stratigraphy in a rapidly subsiding area: the Late Barremian–Early Aptian of the Organyà basin, Spanish Pyrenees

Abstract A detailed sedimentological and stratigraphical study of the Late Barremian–Early Aptian Urgonian Carbonate platform of the Organya basin, Spanish Pyrenees, has identified four depositional sequences. The first two sequences consist of transgressive and highstand systems tracts and the last two sequences of lowstand, transgressive and highstand systems tracts. Sequence boundaries at the top of sequences OR-1 and OR-4 are type 1 boundaries with evidence of exposure and erosion. Sequence boundaries at the top of sequences OR-2 and OR-3 are type 2 with no evidence of exposure or erosion. Sand-shoal (high-energy) facies characterise the first sequence, OR-1. Sequences OR-2 and OR-3 are dominated by lagoonal facies, with an important accumulation of lacustrine facies at the base of OR-3. A succession of lacustrine, deep-platform and sand-shoal facies characterises sequence OR-4. The last sequence also contains the record of an anoxic event (OAE 1a). All these characteristics have been largely influenced by the high subsidence rate of the Organya basin (1100 m of compacted limestone deposited in about 5 Ma). However, the main global eustatic changes registered in other contemporaneous basins were also identified.

Depositional model of a Cenomanian-Turonian extensional basin (Sopeira Basin, NE Spain): interplay between tectonics, eustasy and biological productivity

Abstract The Sopeira Basin is a small extensional basin with a continuous record of sedimentation from the Late Albian to the Late Turonian. In its early stages (Late Albian-Middle Cenomanian), it formed a half-graben, bounded to the south by a low-angle normal fault. During this time, sedimentation was limited to the downfaulted block until the emerged footwall was flooded, resulting in the deposition of shallow-water limestones over a vast platform. The platform was exposed during the Middle-Late Cenomanian by a relative sea-level fall. The sedimentation up to this point was controlled by local factors (extensional tectonics), and influenced by eustatic sea-level change. Subsequently, the entire area was flooded by the Late Cenomanian transgression. During the Cenomanian-Turonian boundary interval, the basinal sedimentation was characterized by calcisphaerid limestones with black cherts and organic-rich shales, while on the platform a hiatus was produced. These sedimentary features are interpreted as having been caused by global mechanisms: changes in atmospheric CO 2 and temperature, along with an increased rate of precipitation that caused an intense primary productivity at the water surface. In the basinal sea, eutrophication led initially to an unusual development of calcisphaerids and later, to the development of opportunistic planktonic foraminifera, whereas in the platform, it affected the life of carbonate-producing organisms dramatically and sedimentation ceased. Eutrophication of marine water is thus interpreted to be the main cause of the extinction of K-strategist foraminifera and associated fauna at the end of the Cenomanian.

Stratigraphy of the Lower Cretaceous (Berriasian-Barremian) sediments in the Organyà Basin, Pyrenees, Spain

Two major sedimentary cycles in the Lower Cretaceous (Berriasian-Barremian) sequence of the Organya Basin, south-central Pyrenees, Spain, are identified on the basis of the ranges of some foraminiferal species and an analysis of the sediments. The first is Berriasian-Valanginian in age and characterized by a sequence which represents shallowing upwards from basin and/or outer platform to inner restricted platform environments. The second is of Barremian age and composed of two parts. The older section is characterized by marine deposits of high energy, the younger by low energy deposits from protected or lagoonal environments of varying salinity.

Upper cretaceous biostratigraphy of the south-central Pyrenees (Lleida, Spain)

AbstractBiostratigraphical data using larger foraminifera and planktonic foraminifera permitted us to establish the correlation between shallow platform sediments rich in larger foraminifera (Montsec and Serres Marginals thrust sheets) and deeper ones containing planktonic foraminifera (Boixols thrust sheet).Consequently, the Santa Fe limestones containing Ovalveolina-Praealveolinaassemblage represent the Cenomanian. Early Turonian ( ‘IT~ archaeocretacea and P. helvetica zones) exist in both, Montsec and Boixols thrust sheets and it is constituted by Pithonella limestones. Late Turonian (M. schneegansi zone) is only present in Boixols thrust sheet (Reguard Fm.), the Montsec thrust sheet having an erosive hiatus.Late Coniacian-Early Santonian (D. Concavata zone) is represented in the Montsec thrust sheet (Cova Limestones) and in the eastern part of the Boixols thrust sheet (St. Corneli Fm.) by two differents facies giving two different microfaunal assemblages; the firts one, characterized by Ophtalmidiidae...

Paleoenvironmental distribution of larger foraminifera in Upper Cretaceous siliciclastic–carbonate deposits (Arén Sandstone Formation, South Pyrenees, northeastern Spain)

ABSTRACT This study examines the distribution of larger foraminifera in an upper Campanian–lower Maastrichtian siliciclastic–carbonate depositional environment within the Arén Sandstone Formation. Three assemblages have been identified, which refer to prodelta, reef, and lagoon depositional facies. Prodelta deposits are characterized by Lepidorbitoides socialis, Lepidorbitoides aff. minor, Clypeorbis mammillata, and Siderolites cataluniensis. The reef deposit assemblage contains Siderolites calcitrapoides, Siderolites cataluniensis, Orbitoides gruenbachensis, “Orbitoides” aff. concavatus, Lepidorbitoides aff. minor, and Fallotia jacquoti. They are associated with the encrusting foraminifera Solenomeris and Haddonia. The lagoonal assemblage contains Fascispira colomi and Omphalocyclus macroporus. Among the siderolitids, the keeled saucer-shaped Siderolites cataluniensis colonized the deepest environments at the lower photic zone, whereas the canaliculate spine-bearing Siderolites calcitrapoides characterized shallower waters. The former lived on soft media of calm environments whereas the latter crawled on firmground of high-energy environments. Lepidorbitoides socialis shared with Siderolites cataluniensis and Clypeorbis mammillata the deepest, calm environments, while Lepidoritoides aff. minor adapted to a wide range of depths in low to moderate water-energy environments. Orbitoides gruenbachensis and “Orbitoides” aff. concavatus colonized the firm media in the upper photic zone, whereas Omphalocyclus macroporus was an epiphyte in soft media in areas with a moderate-energy water. The meandropsinids occupied the upper photic zone; the odd pair Fallotia jacquoti and Eofallotia simplex colonized high-energy environments, whereas their relative Fascispira colomi adapted to shallow, calm environments. The structure of the assemblages of larger foraminifera described in this paper provides a useful tool for the reconstruction of the Late Cretaceous shallow-water fauna in mixed siliciclastic-carbonate environments.

Late Cretaceous alveolinaceans (larger foraminifera) of the Caribbean palaeobioprovince and their stratigraphic distribution

Architectural analysis of the Late Cretaceous alveolinaceans of the Caribbean palaeobioprovince has made it possible to separate four genera: Praechubbina, Chubbinella gen. nov., Chubbina and Caribalveolina. The first three genera belong to the family Rhapydioninidae, while the fourth is placed in the family Alveolinidae. Two species, Praechubbina breviclaustra and P. oxchucensis sp. nov., represent the primitive genus Praechubbina, while the species cardenasensis and obesa, previously ascribed to this genus, must be reassigned respectively to Chubbinella gen. nov. and Caribalveolina. The species Chubbina jamaicensis, C. macgillavryi and C. fourcadei sp. nov. complete the inventory of Chubbina. The alveolinid genus Caribalveolina comprises two species, C. obesa and C. michaudi. Caribbean alveolinaceans include two successive assemblages. The lower assemblage is characterized by Praechubbina oxchucensis, P. brevisclaustra, Chubbinella cardenasensis and Caribalveolina obesa. The upper assemblage is represented by the genus Chubbina, with C. fourcadei, C. jamaicensis and C. macgillavryi, and Caribalveolina michaudi. The age of the lower assemblage is uncertain (probably Late Campanian–Early Maastrichtian), while the upper assemblage has been dated by strontium isotope stratigraphy as Late Maastrichtian. http://zoobank.org/urn:lsid:zoobank.org:pub:88A5CA4D-3D6F-42E9-BEE8-EF3F7B3BA85F

LEPIDORBITOIDES MINIMA DOUVILLÉ FROM MEXICO, A FORAMINIFERAL INDEX FOSSIL FOR THE CAMPANIAN

Mexican topotypes of Lepidorbitoides minima Douville, type species of the genus Orbitocyclina Vaughan 1929, exhibit an orbitoidiform architecture conditioned by an obliquely-overcrossed stolon system in only three stolon planes in the medium layer of the shell and arising from a single auxiliary chamberlet. This architecture is identical with the one observed in Campanian early species of the Tethyan genus Lepidorbitoides. Orbitocyclina is therefore placed in synonymy with Lepidorbitoides Silvestri, 1907. This opens the way for a transatlantic biozonation based on quantitative methods supported by evolutionary theory using nepionic acceleration as a measurable feature.

LEPINOCONUS CHIOCCHINII GEN. N., N. SP., A CONICAL AGGLUTINATED FORAMINIFERA FROM THE UPPER CRETACEOUS OF ITALY

A new conical agglutinated foraminifer, Lepinoconus chiocchinii gen n., n. sp. from the lower Campanian shallow-water platform deposits of the Lepini Mountains (central Apennines, Italy), is described. It has a pseudo-keriothecal wall structure, uniserial arrangement of the adult chambers and multiple apertures. The exoskeleton is constituted by beams (main and intercalary) continuous from one chamber to the next, while the endoskeleton bears pillars. The new taxon is included in the Coskinolinidae family. Lepinoconus chiocchinii gen. n., n. sp. is known from southern Italy, Greece and Albania.