Mid- to Late-Holocene estuarine infilling processes studied by radiocarbon dates, high resolution seismic and biofacies at Vitoria Bay, Espirito Santo, Southeastern Brazil

A Baía de Vitória é um estuário com 20 km de comprimento, morfologicamente estreito, com um regime de micromaré e, como outros estuários modernos, formado durante a última transgressão pós-glacial. A morfologia de fundo do estrato estuarino é caracterizada por um canal natural principal limitado por planícies de maré com manguezais desenvolvidos. Datações de radiocarbono originais foram obtidas para a área. Cinco idades de radiocarbono estendendo-se de 1.010 a 7.240 anos AP foram obtidas através de dois testemunhos de sedimento, representando uma sequência estratigráfica de 5 m de espessura. Os resultados indicam que até aproximadamente 4.000 anos cal. AP, as condições ambientais da Baía de Vitória eram ainda de uma baía aberta, com uma conexão livre e aberta com águas marinhas. Durante os últimos 4.000 anos a baía experimentou uma fase de regressão importante, tornando-se mais restrita em termos de circulação da água do mar e provavelmente aumentando a energia de marés. Três superfícies estratigráficas principais foram reconhecidas, limitando fácies transgressiva, transgressiva/nível de mar alto e regressiva. A morfologia do canal atual representa um diastema de maré, mostrando fácies regressivas truncadas e erodidas. Biofácies de foraminíferos, passando de ambiente marinho para ambiente salobro e de manguezais em planície de maré confirmam a interpretação sismoestratigráfica. A ausência de biofácies de mangue em um dos dois testemunhos é tambémuma indicação de ravinamento de maré atual.

Benthic foraminiferal biofacies and stable isotopic record of St. Stephens Quarry, Alabama

We integrate upper Eocene-lower Oligocene lithostratigraphic, magnetostratigraphic, biostratigraphic, stable isotopic, benthic foraminiferal faunal, downhole log, and sequence stratigraphic studies from the Alabama St. Stephens Quarry (SSQ) core hole, linking global ice volume, sea level, and temperature changes through the greenhouse to icehouse transition of the Cenozoic. We show that the SSQ succession is dissected by hiatuses associated with sequence boundaries. Three previously reported sequence boundaries are well dated here: North Twistwood Creek-Cocoa (35.4-35.9 Ma), Mint Spring-Red Bluff (33.0 Ma), and Bucatunna-Chickasawhay (the mid-Oligocene fall, ca. 30.2 Ma). In addition, we document three previously undetected or controversial sequences: mid-Pachuta (33.9-35.0 Ma), Shubuta-Bumpnose (lowermost Oligocene, ca. 33.6 Ma), and Byram-Glendon (30.5-31.7 Ma). An ~0.9 per mil d18O increase in the SSQ core hole is correlated to the global earliest Oligocene (Oi1) event using magnetobiostratigraphy; this increase is associated with the Shubuta-Bumpnose contact, an erosional surface, and a biofacies shift in the core hole, providing a first-order correlation between ice growth and a sequence boundary that indicates a sea-level fall. The d18O increase is associated with a eustatic fall of ~55 m, indicating that ~0.4 per mil of the increase at Oi1 time was due to temperature. Maximum d18O values of Oi1 occur above the sequence boundary, requiring that deposition resumed during the lowest eustatic lowstand. A precursor d18O increase of 0.5 per mil (33.8 Ma, midchron C13r) at SSQ correlates with a 0.5 per mil increase in the deep Pacific Ocean; the lack of evidence for a sea-level change with the precursor suggests that this was primarily a cooling event, not an ice-volume event. Eocene-Oligocene shelf water temperatures of ~17-19 °C at SSQ are similar to modern values for 100 m water depth in this region. Our study establishes the relationships among ice volume, d18O, and sequences: a latest Eocene cooling event was followed by an earliest Oligocene ice volume and cooling event that lowered sea level and formed a sequence boundary during the early stages of eustatic fall.

(Table DR1) Biofacies, percentages of important benthic foraminifera and isotope data at ODP Site 758

The Indian monsoon system, as recorded by ocean-floor biota (benthic foraminifera) at Ocean Drilling Program Site 758 in the eastern equatorial Indian Ocean, has varied dramatically over the past 5.5 m.y., long after the onset of the monsoons at 10-8 Ma. Benthic foraminifera that thrive with high productivity year-round were common before the formation of Northern Hemisphere continental ice sheets ca. 3.1-2.5 Ma, indicating that the summer (southwest) monsoon had high intensity and long seasonal duration. Ca. 2.8 Ma benthic faunas became dominated by taxa that flourish with a seasonally strongly fluctuating food supply, indicating that the northeast (winter) monsoon, during which primary productivity is relatively low, increased in duration and strength to form a system similar to that of today. The change occurred coeval with the initiation of the Northern Hemisphere glaciation, documenting a close link between the development of the Indian monsoon and Northern Hemisphere glaciation.

High-resolution correlation of coastal cliff sections in the Lagos- Portimao Formation (Lower - Middle Miocene, central Algarve, Portugal)

This paper describes a high-resolution stratigraphic correlation scheme for the early to middle Miocene Lagos-Portimão Formation of central Algarve, southern Portugal. The Lagos Portimão-Formation of central Algarve is a 60 m thick package of horizontally bedded siliciclastics and carbonates. The bryozoan and mollusc dominated biofacies is typical of a shallow marine, warm-temperate climatic environment. We define four stratigraphic marker beds based on biofacies, lithology, and gamma-ray signatures. Marker bed 1 is a reddish shell bed composed predominantly of bivalve shells in various stages of fragmentation. Marker bed 2 is a fossiliferous sandstone / sandy rudstone characterized by bryozoan masses. Marker bed 3 is also a fossiliferous sandstone with abundant larger foraminifers and foliate bryozoans. Marker bed 4 is composed of three distinct layers; two fossiliferous sandstones with an intercalated shell bed. The upper sandstone unit displays thickets of the bryozoan Celleporaria palmate associated with the coral Culizia parasitica. This stratigraphic framework allows to correlate isolated outcrops within the stratigraphic context of the Lagos-Portimão Formation and to establish high resolution chronostratigraphic Sr-isotopic dating.

Facies, depositional environment, and palaeoecology of the Middle Triassic Cassina Beds (Meride Limestone, Monte San Giorgio, Switzerland).

The Ladinian Cassina beds belong to the fossiliferous levels of the world-famous Middle Triassic Monte San Giorgio Lagerstatte (UNESCO World Heritage List, Canton Ticino, Southern Alps). Although they are a rich archive for the depositional environment of an important thanatocoenosis, previous excavations focused on vertebrates and particularly on marine reptiles. In 2006, the Museo Cantonale di Storia Naturale (Lugano) started a new research project focusing for the first time on microfacies, micropalaeontological, palaeoecological and taphonomic analyses. So far, the upper third of the sequence has been excavated on a surface of around 40 m(2), and these new data complete those derived from new vertebrate finds (mainly fishes belonging to Saurichthys, Archaeosemionotus, Eosemionotus and Peltopleurus), allowing a better characterization of the basin. Background sedimentation on an anoxic to episodically suboxic seafloor resulted in a finely laminated succession of black shales and limestones, bearing a quasi-anaerobic biofacies, which is characterized by a monotypic benthic foraminiferal meiofauna and has been documented for the first time from the whole Monte San Giorgio sequence. Event deposition, testified by turbidites and volcaniclastic layers, is related to sediment input from basin margins and to distant volcanic eruptions, respectively. Fossil nekton points to an environment with only limited connection to the open sea. Terrestrial macroflora remains document the presence of emerged areas covered with vegetation and probably located relatively far away. Proliferation of benthic microbial mats is inferred on the basis of microfabrics, ecological considerations and taphonomic (both biostratinomic and diagenetic) features of the new vertebrate finds, whose excellent preservation is ascribed to sealing by biofilms. The occurrence of allochthonous elements allows an insight into the shallow-waters of the adjoining time-equivalent Salvatore platform. Finally, the available biostratigraphic data are critically reviewed.

Colaniella, foraminifère index du Permien tardif téthysien: propositions pour une taxonomie simplifiée, répartition géographique et environnements

Une classification simplifiee du genre Colaniella LIKHAREV est proposee: Colaniella ex gr. parva, Colaniella ex gr. lepida, Colaniella ex gr. minima. Elle correspond a la division du taxon en trois groupes morphologiques. La repartition geographique de ce taxon est inventoriée de meme que les environnements sedimentaires et les microfaunes associees. Les nouvelles decouvertes de C. ex gr. parva dans Ie Permien superieur des coupes de Mesagros (ile d'Egine, Grece), d'Emarat (N Elbourz, Iran) et du Wadi Wasil dans les montagnes centrales d'Oman sont decrites en detail. L'importance des Colanielles dans la biostratigraphie du Permien superieur tethysien est analysee et clarifiee au vu des travaux recents et Ie problème des migrations est abordé. A simplified taxonomic classification in 3 groups of the genus Colaniella LIKHAREV is proposed: Colaniella ex gr. parva, Colaniella ex gr. lepida, Colaniella ex gr. minima. The repartition of the eight main Colaniella biofacies is given and the paleogeographic distribution of this genus is presented on a late Permian map configuration. New late Permian localities with Colaniella ex gr. parva have been found: Aegina island (Greece), Emmarat in the northern Alborz (Iran) and Wadi Wasit in the central Oman Mountains. The stratigraphic range of Colaniella ex gr. parva is much longer than previously accepted even by specialists. This range begins in the early Midian (Abadehian) and ends in the late Changhsingian (Dorashamian), very close to the range of the genus. For environmental reasons and slow eastward migration we have apparent shorter ranges in the Eastern part of the Tethyan domain.

Foraminíferos calcáreos bénticos de la plataforma continental del norte peruano

A partir de 36 muestras de sedimento superficial, obtenidas en la zona norte del mar del Perú, frente a los puertos de Pimentel (6°45 'S a 7°19 'S), Salaverry (8°11 'S a 9°01 'S) y Huarmey (10°05 'S a 10°25 'S), durante cruceros realizados entre 1976 y 1982, se estudió la composición y al distribución de la biofacies de foraminíferos bentónicos recientes, determinándose un total de cincuenta y dos especies. En base a los análisis de similaridad y el uso de índice biológico se determinó que la biofacies del área estudiada está caracterizada por Bifarina hancocki, Bolivina costata, Bolivina piclata, Bolivina seminuda var. humilis, Cassidulina auka, Epistominella pacifica, Hanzawaia concentrica, Robulus rotulatus, Uvigerina striata, Valvulineria inflata y una especie no identificada de Bolivina.

A unique Permian-Triassic boundary section from the Neotethyan Hawasina Basin, Central Oman Mountains

In the Wadi Wasit area (Central Oman Mountains), Dienerian breccias are widespread. These breccias consist mostly of Guadalupian reefal blocks, often dolomitised, and some rare small-sized blocks of lowermost Triassic bivalve-bearing limestones. A unique block, with a size of about 200 m(3), including Permian and earliest Triassic faunas has been studied in detail. The so-called Wadi Wasit block consists of three major lithological units. A basal unstratified grey limestone is rich in various reef-building organisms (rugose corals, calcareous sponges, stromatoporoids) and has been dated as Middle Permian. It is disconformably overlain by well- and thin-bedded light grey to yellowish coloured limestones rich in molluscs. Two major lithologies (Coquina Limestone respectively Bioclastic Limestone unit) characterise the shelly limestones, their contact seems gradual. These two units are well-dated; they are of Griesbachian age and contain three conodont zones, the Parvus Zone, the Staeschei Zone and the Sosioensis Zone, and two ammonoid zones, the Ophiceras tibeticum Zone and an 'unnamed interval'. The third unit consists of a grey marly limestone containing Neospathodus kummeli (basal Dienerian). It is the first record of well-dated basal Triassic sediments in the Arabian Peninsula. The Coquina Limestone is dominated by the bivalve Promyalina with some Claraia and Eumorphotis. This bivalve association is interpreted as a pioneering opportunistic assemblage. Towards the top of the Bioclastic Limestone unit, the faunal diversity increases and contains probably more than 20 taxa of bivalves, microgastropods, crinoids, brachiopods, ammonoids, echinoid spines, ostracods and conodonts. The generic diversity of this biofacies exceeds by far any other Griesbachian assemblage known. Our data give new evidence for the geodynamical history for the distal carbonate shelf bordering the Hawasina Basin. A break in the sedimentation characterises the Late Permian. The basal Triassic shows a steady transgression and the breccias may record a distinct gravitational collapse of platform margins linked with sea-level low stand at the end of Induan time (late Dienerian-basal Smithian). delta(13)C(carb) isotopic analyses were performed and yield typical Permian values of around 4parts per thousand for the Reefal Limestone, with a strong negative shift across the Permian-Triassic boundary. During the Griesbachian values shift positively from 0.5 to 3.1parts per thousand parallel to an increase in faunal diversity and probably primary productivity. The detailed faunal analysis and the discovery of an unexpected diversity give,us a new understanding of the recovery of the Early Triassic marine ecosystem.

Carbon-isotope stratigraphy of the Liesberg Beds Member (Oxfordian, Swiss Jura) using echinoids and crinoids

The Liesberg Beds form the transition between the lower Oxfordian dark coloured marls (Renggeri Member and the Terrain a Chailles Member) and the middle Oxfordian reefal limestones (St-Ursanne Formation). Both lithofacies and biofacies are diverse and evolve rapidly up-section. Stable isotope studies of whole-rock samples are therefore excluded. In search for a convenient isotopic marker, we measured carbon isotope compositions of several fossil groups and chose crinoid stems of Millericrinus spp and echinoid spines of Paracidaris spp because of their abundance throughout the section and the small variations of delta(13)C within one fossil and between fossils from the same stratigraphic level. The delta(13)C values of echinoderms largely reflect earliest diagenetic conditions at the seawatersediment interface. The porous stereome structure secreted of high Mg-calcite by echinoderms has a high reactive surface/volume ratio, which triggers the precipitation of very early syntaxial cements. In the four studied sections reproducible carbon isotope shifts were observed both for Millericrinus spp stems and Paracidaris spp spines. A negative delta(13)C shift of 1-1.5 parts per thousand was observed near the base of the section, just above the transition from Terrain a Chailles Member, where the first corals occur. In the middle and upper part of the four sections, characterised by a stepwise increase of corals and the macrofossils, a positive delta(13)C Shift of about 2 parts per thousand was observed. Despite the highly variable lithologic composition of the Liesberg Beds;Member, carbon isotope shifts seem to be consistent and warrant an interpretation as an original signal, controlled by the isotopic composition of dissolved carbonic acid in seawater. We explain the heavy delta(13)C values (approximate to 2-2.3 parts per thousand) in the lower Liesberg Beds as a transition from an oxygen-limited environment (Terrain a Chailles Member) to the Liesberg Beds Member. The lowest delta(13)C values (approximate to 1-1.5 parts per thousand) correspond to a large input of dissolved nutrients to the platform under oxidizing conditions. The ensuing positive shift (between 2.5 and 3.5 parts per thousand), however, seems to correspond to a general trend of opening up of the platform and connection to open marine waters. Positive delta(13)C values in the upper Liesberg Beds is interpreted as a result of important accelareted extraction of organic carbon from the ocean reservoir, that occurred possibly during periods of warm and humid climate.

Sedimentology and taphonomy of storm-generated shell beds from the Verulam formation (Ordovician), Lakefield and Gamebridge quarries, Southern Ontario, Canada /

The Verulam Formation (Middle Ordovician) at the Lakefield Quarry and Gamebridge Quarry, southern Ontario, is comprised of five main lithofacies. These include shoal deposits consisting of Lithofacies 1, winnowed crinoidal grainstones and, shelf deposits consisting of: Lithofacies 2, wackestones, packstones, grainstones, and rudstones; Lithofacies 3, laminated calcisiltites; Lithofacies 4, nodular wackestones and mudstones; and, Lithofacies 5, laminated mudstones and shales. The distribution of the lithofacies was influenced by variations in storm frequency and intensity during a relative sea level fall. Predominant convex-up attitudes of concavo-convex shells within shell beds suggest syndepositional reworking during storm events. The bimodal orientations of shell axes on the upper surfaces of the shell beds indicates deposition under wave-generated currents. The sedimentary features and shell orientations indicate that the shell beds were deposited during storm events and not by the gradual accumulation of shelly material. Cluster and principal component analysis of relative abundance data of the taxa in the shell beds, interbedded nodular wackestones and mudstones, and laminated mudstones and shales, indicates one biofacies comprised of three main assemblages: a strophomenid (Sowerbyelladominated) assemblage, a transitional mixed strophomenid-atrypid assemblage and an atrypid (Zygospira-dominatQd) assemblage. The occurrence of the strophomenid, the strophomenid-atrypid and atrypid assemblages were controlled by storm-driven allogenic taphonomic feedback.

Middle Ordovician (Whiterockian-Chazyan) trilobites from the Sunblood Formation, District of Mackenzie

The Middle Ordovician Sunblood Formation in the South Nahanni River area, District of Mackenzie, comprises mainly limestones and dolostones of intertidal and shallow subtidal origin as indicated by the presence of desiccation polygons, fenestral fabric, and oncolites. The study of well preserved, silicified trilobites from low diversity, Bathyurus-dominated, Nearshore Biofacies faunas of Whiterockian and Chazyan age collected in six stratigraphic sections through the Sunblood Formation permits the recognition of three new Whiterockian zones, and two previously established Chazyan zones. The Bathyurus mackenziensis, Bathyurus sunbloodensis, and Bathyurus margareti zones (Whiterockian), together with the Bathyurus nevadensis and Bathyurus granu/osus zones (Chazyan) represent the Nearshore Biofacies components of a dual biostratigraphic scheme that considers both temporal and spatial distribution patterns, and are compositionally distinct from faunas in correlative strata around North America that represent other biofacies. Twenty-six species belonging to eighteen genera are described and illustrated. Ludvigsenella ellipsepyga is established as a new bathyurine genus, in addition to four new species of Bathyurus : Bathyurus mackenziensis, Bathyurus sunbloodensis, Bathyurus margareti and Bathyurus acanthopyga. Other genera present are: Basilicus, Isote/us, ///aenus, Bumastoides, Fail/eana, Phorocepha/a,Ceraurinella, Acanthoparypha, Xystocrania, Cydonocephalus, Ectenonotus, Pseudomera, Encrinuroides, Calyptaulax, Amphilichas and Hemiarges.

Patterns of faunal change at an upper Cambrian trilobite extinction event, Nolichucky Formation, Tennessee and Virginia

During the Upper Cambrian there were three mass extinctions, each of which eliminated at least half of the trilobite families living in North American shelf seas. The Nolichucky Formation preserves the record of one of these extinction events at the base of the Steptoean Stage. Sixty-six trilobite collections were made from five sections In Tennessee and Virginia. The lower Steptoean faunas are assigned to one low diversity, Aphelaspis-dominated biofacies, which can be recognized in several other parts of North America. In Tennessee, the underlying upper Marjuman strata contain two higher diversity biofacies, the Coosella-Glaphyraspis Biofacies and the Tricrepicephalus-Norwoodiid Biofacies. At least four different biofacies are present in other parts of North America: the Crepicephalus -Lonchocephalus Biofacies, the Kingstonia Biofacies, the Cedaria Biofacies, and the Uncaspis Biofacies. A new, species-based zonation for the Nolichucky Formation imcludes five zones, three of which are new. These zones are the Crepicephalus Zone, the Coosella perplexa Zone, the Aphelaspis buttsi Zone, the A. walcotti Zone and the A. tarda Zone. The Nolichucky Formation was deposited within a shallow shelf basin and consists largely of subtidal shales with stormgenerated carbonate interbeds. A relative deepening is recorded In the Nolichucky Formation near the extinction, and is indicated In some sections by the appearance of shale-rich, distal storm deposits above a carbonate-rich, more proximal storm deposit sequence. A comparable deepening-upward sequence occurs near the extinction in the Great Basin of southwestern United States and in central Texas, and this suggests a possible eustatic control. In other parts of North America, the extinction IS recorded In a variety of environmental settings that range from near-shore to slope. In shelf environments, there is a marked decrease in diversity, and a sharp reduction in biofacies differentiation. Although extinctions do take place in slope environments, there IS no net reduction in diversity because of the immigration of several new taxa.

Trilobites of the Upper Cambrian (Marjuman) Pika formation of the Southern Canadian Rocky Mountains

The Upper Cambrian Pika Formation in the southern Canadian Rocky Mountains forms a complete lithologic Grand Cycle. The overall pattern of deposition is one of shallowing upwards from a subtidal, muddy, storm-influenced basin to a shallow carbonate bank. The Pika passes gradationally into the overlying inter- to supratidal siliciclastics of the Arctomys Formation. This transition probably reflects a fall in relative sea level. 2 Twenty seven collections from three sections yielded trilobites. The faunas are assigned to two low-diversity biofacies: the Marjumia - Spencella Biofacies and the GZyphaspis - menomoniid Biofacies. In contrast to biofacies of deeper, open-shelf environments, such as the Wheeler and Marjum formations of Utah, the Pika biofacies lack agnostid trilobites. Consequently, agnostid-based zonations defined elsewhere in North America cannot be applied to the Pika and a new sequence of three zones and one informal fauna is proposed for use in inner shelf facies. Eleven species belonging to six genera are described and illustrated. The species Marjumia bagginsi is new. Other genera present are: Bolaspidella, Knechtelia, GZyphaspis and Spencella, in addition to a number of indeterminate forms