Ostracod Zones Research Articles

Upper Cretaceous high-resolution multiple stratigraphy, northern margin of the Arabian platform, central Israel

Nineteen columnar sections of pelagic sediments, from outcrops and boreholes across central Israel, deposited at relatively moderate rates on the outer shelf and the continental slope of the Arabian margin, were correlated using lithological and electric-log markers, calcareous nannofossils, planktic and benthic foraminifera, ostracods and ammonites. Thirty-seven local correlatable datum levels, from Upper Coniacian to the end of the Cretaceous, were recognized, of which 30 are based on diagnostic fossils of Tethyan significance. These datum levels include first (FA) and/or last (LA) appearances of 13 nannofossils, 14 planktic and 9 benthic foraminifera, 5 ostracod zones and 4 ammonites, as well as 10 lithological markers of chalks, marls, cherts, phosphorites and dark bituminous shales. The biostratigraphic planes do not cross lithological boundaries and therefore both are considered synchronous events. The datum levels are used for a biostratigraphic zonation, a lithostratigraphic subdivision and a chronostratigraphic interpretation. The multi-disciplinary correlations provide a powerful high-resolution stratigraphic tool for further quantitative basin analysis and for the study of global events.

Reservoir Description From Seismic Lithologic Parameter Estimation

Modern three-dimensional (3D) seismic data assist not only in delineating reservoir geometry, but also in predicting porosity and lithology variations away from well control. This case study of an oil-producing channel sand in the Taber/Turin area, Alta., Canada illustrates the improvement in reservoir characterization achieved with an integrated approach incorporating both well and seismic information.

Combined ostracod and planktonic foraminiferal biozonation of the Late Coniacian – Early Maastrichtian in Israel

Abstract. The distribution and zonation of planktonic foraminifera and ostracods during the Late Coniacian – Early Maastrichtian succession in Israel was studied in detail from six surface sections. The combination of contemporaneous biozones led to a more accurate age determination of the local ostracod zones, according to the Tethyan planktonic foraminiferal zonation. The configuration of the biozones of both taxa presents more datum lines for stratigraphic correlation of the Senonian strata of Israel. Three new ostracod species were described from Campanian sediments: Cytherelloidea zinensis, Loxoconcha hebraica and Cristaeleberis ordinata.

Ostracode fauna, stratigraphy and definition of the Beyrichienkalk sequence

An essential clue to the uppermost Silurian in the submarine Baltic arca is the Beyrichienkalk. According to recent investigations it constitutes a glacial drift boulder sequence characterized by four ostracode associations with about sixty species. In the correlation of ostracode zones of Baltoscandia these associations form a connecting link and thus are also of biozonal character. In the terms of regional stratigraphic units (East Baltic arca). the lower stratigraphic boundary of this sequence lies approximately at the beginning of the Kuressaare beds and the top in the upper Ohesaare beds. The term Beyrichienkalk should be used for those glacial erratics that are characterized by typical ostracodes of the four associations defined here.

Chin Coulee Field--a Stratigraphic Trap in Lower Cretaceous Fluvial Valley-Fill Sandstones: ABSTRACT

Hydrocarbons, stratigraphically trapped in fluvial valley-fill sandstones, constitute some of the more important oil fields in North America. The Chin Coulee field in southeastern Alberta, Canada, has produced over 4.4 million bbl of oil since its discovery in 1960, with an estimated 1 million bbl still to be produced via secondary recovery. The field covers approximately 80 km2 with an average net pay thickness of 3 m. The hydrocarbons are stratigraphically trapped in the fluvial Sunburst Sandstone, which records the Early Cretaceous transgression of the Boreal Sea. These lower Mannville aggradational sequences accumulated in an incised drainage system in Jurassic marine shales, which provide the bottom seal for the reservoir sandstones. Following deposition of the Sunburst Sandstone, an accelerated rise in base level led to the accumulation of argillaceous limestones and calcareous shales commonly referred to as the ostracod zone. These fine-grained strata provide an effective seal above the porous sandstones. Postdepositional tilting of the strata to the west, due to subsidence in the foreland basin east of a rising orogene (Nelson uplift), resulted in migration of hydrocarbons in an easterly updip direction. Stratigraphic trapping of these hydrocarbons occurred in sandstones pinching out in the upper reaches of tributary valleys to the east of the main drainage system (Chin Coulee and Taber Southeast fields). Regional paleoenvironmental reconstructions suggest that the Sunburst Sandstone is equivalent to the Cut Bank Sandstone of the Cut Bank field area in northwestern Montana. The Cut Bank field lies along the same Late Jurassic drainage system (Fox Creek escarpment), and similar tributary valleys situated east of the escarpment may exist between these two producing field areas. This suggests the presence of additional untested hydrocarbon reservoirs exhibiting stratigraphic characteristics similar to those described in the Chin Coulee field. End_of_Article - Last_Page 300------------

Observations on the Lower Cretaceous Ostracode Zone of Alberta

ABSTRACT A biostratigraphically useful assemblage zone, dominated by ostracodes, has been recognized for many years by geologists working Lower Cretaceous outcrops and well sections throughout much of central and southern Alberta. This study reviews the biostratigraphic and paleoecologic value of the faunizone, as determined from the available literature and examination of five well sections. In the Foothills of Alberta, the Ostracode Zone is coincident with the calcareous member of the upper Gladstone Formation (lower Blairmore Group), while in the Plains it occurs in the upper part of the McMurray Formation (lower Mannville Group). The ostracodes inhabited the freshwater and brackish environments that flanked the southward-transgressing Moosebar-Clearwater Sea. Spatial variations in assemblage composition and lithology suggest a diversity and mixture of coastal environments, such as lakes, rivers, swamps, lagoons and estuaries. Temporal variations within sections could similarly signify alternating environments and salinities. This biozone is a facies-controlled unit which appears to be diachronous; its over-all age is probably Aptian to early Albian. Regardless of previous claims to the contrary, it appears that all the Blairmore-Mannville ostracode species are endemic to the northern Rocky Mountain region. OBSERVATIONS SUR LA ZONE A OSTRACODE CRETACE INFERIEUR DE L'ALBERTA RESUME Une zone contenant principalement des ostracodes est utilisee depuis longtemps comme horizon-repere biostratigraphique par les geologues travaillant sur le Cretace inferieur du centre et du Sud de I'Alberta. Cette etude examine la valeur biostratigraphique et paleoecologique de cette faunizone a partir de la litterature disponible et de donnees issues de cinq puits. Dans les Foothills de I'Alberta, la zone a ostracode coincide avec le membre calcaire de la partie superieure de la formation Gladstone (groupe Blairmore inferieur), tandis que dans les plaines elle apparait dans la partie superieure de la formation McMurray (groupe Mannville inferieur). Les ostracodes vivaient dans les zones a eau douce et saumatre bordant la mer Moosebar-Clearwater, qui s'avancait transgressivement vers le Sud. Les variations spatiales de la lithologie et de la composition de I'horizon-repere suggerent des variations similaires des environnements cotiers, tels que lacs, rivieres, marecages, lagunes et estuaires. De la meme facon, les variations temporelles a l'interieur d'une meme section pourraient resulter de l'alternance de salinites et d'environnements differents. L'occurrence de cette biozone est controlee par le facies et apparait etre diachrone; l'age global est probablement aptien-albien inferieur. Contrairement a de precedentes interpretations, il apparait que toutes les especes d'ostracodes du group Blairmore-Mannville sont endemiques pour la region du Nord des Montagnes Rocheuses. Traduit par B. L. Collot.

New data on the Eocene/Oligocene boundary in the Romanian Carpathians

In the Romanian Carpathians the boundary between Eocene and Oligocene stratigraphic sequences may be examined in three geological provinces: (1) the east Carpathians, (2) the Getic Depression (these two units containing exclusively detrital-terrigenous sediments), and (3) the northwestern sector of the Transylvanian Basin (which contains an epicontinental sequence). 1. (1) In the East Carpathians, the boundary occurs between the zones Globigerina corpulenta-gortanii + Ericsonia subdisticha (Priabonian) and Pseudohastigerina micra + extinction to Cyclococcolithus formosus (Rupelian). From a lithostratigraphic point of view, the boundary lies between the lower Fusaru sandstone (internal facies) or the Lucacesti sandstone (external facies) and the overlying mainly non-marine bituminous formations (marls with fetid opal-cherts). 2. (2) In the Getic Depression, the Priabonian is represented by the upper section of a pseuoflysch (Olanesti beds) with Globigerina corpulenta, G. officinalis (P 17) and a heterogeneous nannoplankton assemblage. The gritty-conglomerate and ingressive Lower Oligocene (Corbi or Cheia Beds) yields G. tapuriensis (P 18) and Helicopontosphaera reticulata (NP 22) assemblages. 3. (3) In the Paleogene epicontinental area of the northwestern part of the Transylvanian Basin, the formation across this boundary are represented by the Brebi marls (with bryozoans) (Upper Priabonian-Henisian). The equivalence of the (northern) Lattorfian to the upper part of the (Mesogean) Priabonian has recently become accepted. On the basis of the evolution of marine microfaunas (nannoplankton, ostracods and foraminifera), the Eocene/Oligocene boundary has been determined at a few metres below the top of the Brebit marls, at the junction of zones NP 21 and NP 22 (the extinction of Cyclococcolithus formosus is considered as a marker for the upper boundary of the Ericsonia subdisticha zone). The same boundary delimits two ostracod zones (those of the Eocene Phlyctocythere eocaenica and of the transition Eocene/Oligocene species Paijenborchella tricostata) and two zones with Mesogean planktonic foraminifera (P 17 with G. cerroazulensis and P 18 with G. ampliapertura + Pseudohastigerina micra).

Micropalaeontological evidence for land near Cirencester, England, in Forest Marble (Bathonian) times: a preliminary account

SummaryAnalysis of a Bathonian ostracod fauna and the microflora from a claypit at Tarlton, Gloucestershire, strongly suggests that land was then nearby. Among the non-marine Ostracoda are cypridacean species similar to lacustrine forms from the French Bathonian. Such an assemblage has not previously been recorded from Britain. The clay is assigned to Bate's revised Bathonian ostracod zone 6, and a palaeogeographical interpretation is offered in terms of recent reconstructions of British Bathonian landmasses.

Lower Jurassic biostratigraphy and ostracods of the Danish Embayment

The Lower Jurassic sequence and ostracods from 36 borings within the Danish Embayment are analysed and described.Hettangian, Sinemurian and Pliensbachian are demonstrated on the basis of extensive ostracod faunas, whilst only weak indications of Aalenian have been found.The following ostracod zones are defined as a basis for a biostratigraphical subdivision of the Lower Jurassic series in the Danish Embayment:The Ogmoconchella adenticulata - Nanacythere (Nanacythere) simplex Zone (Upper Pliensbachian).The Ogmoconchella danica Zone (Upper Sinemurian and Lower Pliensbachian).The Gramannella apostolescui - Kinkelinella (Klinglerella ) foveolata Subzone (Lower Pliensbachian).The Progonoidea reticulata Subzone (lowest Upper Sinemurian, Lias Beta-1a).The Cristacythere betzi - C. crassireticulata Zone (upper Lower Sinemurian).The Ogmoconchella aspinata Zone (Hettangian and lower Lower Sinemurian).The chronostratigraphical subdivision of the Lower Jurassic sequence in the Danish Embayment is presented, based upon the ostracod faunas described here and upon previous investigations of sediments, foraminifera and megafossils.The conditions prevailing in the basin are discussed, with descriptions of the sedimentary and faunal developments, and an evaluation of the relationships with other parts of the Northwest European area.124 ostracod species are described; 23 are described as new, whilst 30 species which cannot be referred to any known species are described with open nomenclature owing to limited or badly preserved material. The remaining 71 species have all been described previously and are more or less well-known. The 124 species fall into 27 genera or subgenera, of which 2 genera (Pseudomacrocy pris and Cristacythere) and 1 subgenus (Nanacythere (Goniocythere)) are established as new.A subdivision is made of the described Lower Jurassic "Procytheridea". The genus Klinglerella Anderson, 1964 is placed as a subgenus under Kinkelinella Martin, 1960. Pleurifera Gramann, 1962 and Progonoidea Gramann, 1962 are regarded as independent genera placed together with Kinkelinella and the new genus Cristacythere.The family Healdiidae is regarded as being represented by only three genera in the Lower Jurassic: Ogmoconcha, Ogmoconchella and Pseudohealdia. The Ontogenetic development of the muscle scar area in Ogmoconchella is shown to be a development from a simple muscle scar of the Pseudohealdia-type to a typical Ogmoconchella-scar.ree genera in the Lower Jurassic: Ogmoconcha, Ogmoconchella and Pseudohea!dia. The Ontogenetic development of the muscle scar area in Ogmoconchella is shown to be a development from a simple muscle scar of the Pseudohea/dia-type to a typical Ogmoconchella-scar.

Ostracod Biostratigraphy of the Kimmeridgian in Northern and Western Europe

The chronostratigraphical type profile of the Kimmeridgian of Dorset is subdivided biostratigraphically into five ostracod zones. Six other areas in Northern and Western Europe with Kimmeridgian ostracods are examined. The species are listed, counted, and examined in relation to the zones of the type Kimmeridgian.In the Lower Kimmeridgian the ostracod faunas bear the impression of a relatively uniform composition between the examined areas. In the Upper Kimmeridgian two different faunal regions are developed. In the North Sea Basin in the North Western Danish Embayment and in Dorset relatively uniform faunas occur, separated from other, again rather uniform faunas occuring in the Mid-European Region, from Northwestern Poland and Scania to the Paris Basin.Stratigraphically important are species of the genera Galliaecytheridea, Mandelstamia, and Macrodentina. 19 species are given diagnoses. Two new subgenera and seven new species are established.

Marine Upper Jurassic, Eastern Wyoming

The Swift-Rierdon nomenclature of the Ellis group in Montana is applied in eastern Wyoming to formational units of the group. Indications are that the names are applicable to the marine Upper Jurassic throughout most of Wyoming and western South Dakota, but the term Sundance should be retained because of historical significance. Thickness maps indicate that the distribution of the Rierdon sediments in eastern Wyoming was influenced by a minor depositional basin, the River embayment, corresponding in general with the present Powder River Basin, and a positive-trending feature, the arch, present across north-central Wyoming during the early part of Upper Jurassic time. Micropaleontologic studies indicate the presence of two distinct Rierdon ostracode biofacies whose distribution is apparently governed by environmental factors associated with presence of the Sheridan arch. The Swift sediments are lithologically and paleontologically distinct from those of the Rierdon, but show a less definite pattern of distribution, probably because of ineffectiveness of the Sheridan arch during their deposition. For a similar reason, only a single ostracode assemblage is present in the Swift formation. Two ostracode zones are recognized in this assemblage.

Ostracodes of the Middle Devonian Onondaga beds of central Pennsylvania

Research Article| March 01, 1941 Ostracodes of the Middle Devonian Onondaga beds of central Pennsylvania FRANK M. SWARTZ; FRANK M. SWARTZ Search for other works by this author on: GSW Google Scholar FREDERICK M. SWAIN FREDERICK M. SWAIN Search for other works by this author on: GSW Google Scholar GSA Bulletin (1941) 52 (3): 381–457. https://doi.org/10.1130/GSAB-52-381 Article history received: 30 Jul 1940 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation FRANK M. SWARTZ, FREDERICK M. SWAIN; Ostracodes of the Middle Devonian Onondaga beds of central Pennsylvania. GSA Bulletin 1941;; 52 (3): 381–457. doi: https://doi.org/10.1130/GSAB-52-381 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Collections from the Middle Devonian Onondaga shale and limestone of central Pennsylvania and northeastern West Virginia have provided an abundance of Ostracoda, and the field work has also yielded much information concerning the lithologic features and the relationships of the Onondaga deposits. Descriptions are given of the Onondaga beds observed at 12 localities in Pennsylvania and 2 in West Virginia, and the stratigraphy as seen at these places is discussed.A total of 40 ostracode species has been recognized in the area. Of these, 3 were previously described, 35 are new. and 2 are represented by material too poor for specific description. The species are distributed through 11 families and 22 genera, 3 of the latter being new. For comparisons with members of this fauna, new figures and descriptions are given of 3 species from the Jeffersonville limestone of Kentucky, and of 1 from the Hamilton shale of Ontario.Four ostracode zones are recognized in the Onondaga beds near New Bloomfield, Pennsylvania. One of these is widespread; further work is needed to indicate the geographic distribution of the other three. The assemblage as a whole is not close to the known ostracodes of the Onondaga of New York, but further study of the latter will be needed before trustworthy conclusions can be drawn. The ostracodes of the Onondaga of Pennsylvania are clearly distinct from those of the Jeffersonville limestone of Kentucky, suggesting an appreciable difference in age. There are important affinities with ostracodes of the Camden chert of western Tennessee as recently studied by Bassler, but the latter assemblage includes numerous Oriskany elements and is clearly older. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.