Showing papers on "Foraminifera published in 1968"

Palaeoclimatic Data from Speleothems

Abstract: DEVELOPMENT of the technique for obtaining palaeotemperature data by measuring the ratio of 18O/16O (refs. 1 and 2) in the calcium carbonate of foraminifera from deep sea sediments3 has led to the confirmation of geological and biological evidence that the Pleistocene glacial cycles were accompanied by fluctuations in global temperatures. Unfortunately, because of the slow rate of deposition of deep sea sediments, the time resolution of the 18O/16O data from these deposits does not enable detailed temperature profiles throughout a glacial cycle.

Upper Cretaceous Foraminifera from southern California and northwestern Baja California, Mexico

Abstract: 9 Family Hormosinidae Haeckel, 1894 43 INTRODUCTION 9 Subfamily Hormosininae Haeckel, 1894 43 STRATIGRAPHY 10 Genus Reophax Montfort, 1808 43 BIOSTRATIGRAPHIC ZONATION AND AGE 11 R. globosus Sliter, n. sp. 43 Globotruncana rosetta Zone 13 R. prolatus Sliter, n. sp. 43 Globotruncana mariei Zone 14 Family Rzehakinidae Cushman, 1933 43 Rugoglobigerina rugosa Zone 14 Genus Rzehakina Cushman, 1927 43 PACIFIC COAST CORRELATION 15 R. epigona (Rzehak) 43 INTERREGIONAL CORRELATION 18 Genus Silicosigmoilina Cushman & Church, BIOFACIES AND PALEOECOLOGY 22 1929 43 Shelf assemblage 22 S. californica Cushman & Church 43 Bathyal assemblage 23 Family Lituolidae de Blainville, 1825 43 Faunal diversity 25 Subfamily Haplophragmoidinae Maync, 1952 .. 43 PALEOZOOEOGRAPHY 25 Genus Haplophragmoides Cushman, 1910 43 LOCALITIES 39 H. excavatus Cushman & Waters 44 SYSTEMATIC PALEONTOLOGY 39 H. sp. cf. H. famosus Takayanagi 44 Superfamily Ammodiscacea Reuss, 1862 39 H. frascri Wickenden 44 Family Astrorhizidae Brady, 1881 39 H. kirk! Wickenden 44 Subfamily Rhizammininae Rhumbler, 1895 39 Genus Cribrostomoides Cushman, 1910 44 Genus Bathysiphon M. Sars, 1872 39 C. cretaceus Cushman & Goudkoff 44 B. brosgei Tappan 39 C. trifolium (Egger) 45 B. californicus Martin 40 Subfamily Lituolinae de Blainville, 1825 . ...... 45 B. varans Sliter, n. sp. 40 Genus Ammobaculites Cushman, 1910 .... ... 45 B. vitta Nauss 40 A. alexanderi Cushman 45 Subfamily Hippocrepininae Rhumbler, 1895 .... 41 Genus Haplophragmium Reuss, 1860 45 Genus Hippocrepina Parker in G. M. Dawson, 1870 41 H. lueckei (Cushman & Hedberg) Subfamily Placopsilininae Rhumb ler, 1913 45 45 H. sp. cf. H. barksdalei (Tappan) 41 Genus Placopsilina d'Orbigny, 1850 45 Genus Hyperammina Brady, 1878 41 P. sp. 45 H. erugata Sliter, n. sp. 41 Family Textulariidae Ehrenberg, 1838 46 Family Saccamminidae Brady, 1884 41 Subfamily Spiroplectammininae Cushman, 1927 46 Subfamily Saccammininae Brady, 1884 41 Genus Spiroplectammina Cushman, 1927 46 Genus Saccammina M. Sars, 1869 42 S. chicoana Lalicker 46 S. complanata (Franke) 42 S. laevis (Roemer) 46 Family Ammodiscidae Reuss, 1862 42 S. sigmoidina Lalicker 46 Subfamily Ammodiscinae Reuss, 1862 42 Family Trochamminidae Schwager, 1877 46 Genus Amn2odiscus Reuss, 1862 42 Subfamily Trochammininae Schwager, 1877 .... 46 A. cretaceus (Reuss) 42 Genus Trochammina Parker & Jones, 1859 46 A. glabratus Cushman & Jarvis 42 T. boehmi Franke 46 Genus Amtnodiscoides Cushman, 1909 42 T. pilea Sliter, n. sp. 47 A. lajollaensis Sliter, n. sp. 42 T. sp. cf. T. ribstonensis Wickenden 47 Superfamily Lituolacea de Blainville, 1825 43 T. texana Cushman & Waters 47

Latitudinal variation in Globigerina pachyderma (Ehrenberg) in surface sediments of the southwest Pacific Ocean

Abstract: Planktonic foraminifera, continuous cline between New Zealand and Antarctica, three morphologic groups, statistical data, relationship to hydrologic conditions, proposed application to paleoclimatology

Shell porosity of recent planktonic foraminifera as a climatic index.

Abstract: Despite variations in pore diameter and pore concentration between 22 species of planktonic Foraminifera, shell porosites are relatively uniform for those co-occurring in the same latitudinal belts: over 10 percent for tropicalsubtropical species; 5 to 10 percent for temperate species; and less than 5 percent for subpolar-polar species. Shell porosities of fossil planktonic Foraminifera may be useful indices for interpreting Cenozoic climates.

Depth Habitats of Pelagic Foraminifera during the Pleistocene

Abstract: PLANKTONIC foraminifera, numbering about thirty modern species, have been found alive not only near the surface but as deep as 2,000 m (ref. 1). Emiliani2 analysed the O18/O16 composition of the shells of several species and concluded that different species occupy different depth habitats, with Globigerinoides ruber and G. sacculifera living very close to the ocean surface, Globigerina spp. living somewhat deeper and Globorotalia spp. occupying the deepest habitats down to about 200 m for population averages. Whereas O18/O16 analysis of the carbonate shells can only establish the depth at which average shell deposition takes place, not only for individual shells but for entire populations, recent work by Jones3, using opening and closing plankton nets, has shown that the conclusions reached by Emiliani2 are essentially correct. It therefore seems that the average depths of shell deposition are also the average depths at which the different species live.

Pleistocene Pteropods in Pelagic Sediments

Abstract: PLEISTOCENE stratigraphy of deep-sea cores has been based chiefly on fauna analysis of planktonic foraminifera1–4, or oxygen isotope measurements of palaeotemperature5–7. I describe a further method of studying Pleistocene biostratigraphy by the detailed analyses of pteropod fauna of six long cores in the Gulf of Mexico, Caribbean, Mediterranean and Red Sea (Table 1). The Pleistocene pteropod zones can be correlated with planktonic foraminifera zones, oxygen isotope analyses and 14C dating.

MICROPALEONTOLOGIA y ESTRATIGRAFIA DEL LIMITE CRETACICO-TERCIARIO EN HUANTRAI-CO (PROVINCIA DE NEUQUEN). Ostracoda. Parte 1: Cytherellidae, Bairdiidae, Pontocypridinae, Buntoniinae y Trachyleberidinae (pro parte)

Abstract: On the western side of the Cerro Huantrai-co, North of the Neuquen Province, there are outcrops from freshwater and marine strata resting upon Cretaceous continental red beds and covered by basa1tic lavas and tuffs of Tertiary age, which are faulted forming a syncline and are intruded by basaltic dikes. The studied section comprises the freshwater and marine beds; with the first, composed by olive gray clays which contain freshwater ostracoda, beggins the Upper Cretaceous transgression followed by brackish to open marine sandy cha1ks, sandy and calcareous clays strata. For this part of the section it is proposed the name Huantrai-co Formation, which is separed in a lower freshwater member (Ievels CP-25 to CP-23) and an upper marine member (levels CP-22 to CP-ll). The Huantrai-co Formation is followed by the Roca Formation composed by cha1ks and sandy chalks. The Huantrai-co Formation represent in the Cretaceous basin an outher shelf subsidence area whereas the Roca Formation, in the Lower Tertiary, was deposited in a shallow sea. The micropa1eonto1ogica1analysis, shows a sharp faunistic break between the Huantrai-co and the Roca Formations, dated as Late Cretaceous (Lower and Midd1e Maastrichtian) and Early Tertiary (Lower Danian). The age, in the Cretaceous strata, is based especially on p1anktonic foraminifera and benthonic -foraminifera and ostracoda- associations. The Lower Tertiary p1anktonic assemb1age shows an early phylogenetically development; Globoconusa daubjergensis (Bronnimann ), 1acks sutura1 openings on the spira1 side, and Globorotalia pseudobulloides (P1ummer) and Subbotina triloculinoides (P1ummer) shown smooth walls. A hiatus. which comprises the Upper Maastrichtian, is registered. In the present paper are described and figured some new ostracoda species form the Cretaceous-Tertiary section in the Huantrai-co area.

Biostratigraphy of upper Cretaceous deposits in the southern eastern Carpathians near Brasov

Abstract: The lithological and microfaunal facies of the Upper Cretaceous in the southern part of the Eastern Carpathians are discussed. The characteristics of the sedimentation basin, which included high turbidity and turbulence and rapid deposition, as well as rapid fluctuation of sea level, had a strong influence on the microfaunal association. Description and illustration of four new species (Haplophragmoides herbichi, Parafissurina lageniformis, Pleurostomella dacica, Pleurostomella pseudocurta) and two new subspecies (Fissurina orbignyana inornata, Fissurina orbignyana bicornis) are also presented, along with lists of the successive foraminiferal assemblages. Biostratigraphy of Upper Cretaceous deposits in the southern Eastern Carpathians near Brasov INTRODUCTION The geological structure of the Eastern Carpathians is rather intricate both from a lithologic and a tectonic viewpoint. Rumanian geologists distinguish several tectonic units (nappes) by the extremely varied lithologic constitution of these deposits as well as by their macrofaunal and microfaunal content. Detailed micropaleontological studies are rather few due to the varied lithology, the scarceness of foraminifera in some formations, and the very intricate tectonic structure. Owing to the fact that macrofossil remains are rather scarce, workers rely more and more on data obtained from microfossils in order to establish a more judicious and detailed stratigraphy of these deposits. With this situation in mind, as subject of the thesis for my doctor's degree I was allotted the study of the Upper Cretaceous deposits in the southern end of the Eastern Carpathians. My studies have resulted in a detailed zonation of the Upper Cretaceous deposits in this region. SOURCE OF MATERIAL The material studied was obtained from the Upper Cretaceous deposits located in an area to the east of the city of Brasov that is situated between the villages of Vama Buzaului, Intorsura Buzaului, Valea Mare, Valea Dobirlau and Teliu, covering an area of approximately 190 sq. km. (text-figure 1). More than 500 samples from various outcrops exposed in the valleys crossing this area were collected and analysed in the period 1957-1964. The material has been treated in the Paleontological Laboratory of the University of Bucharest and has been deposited in its collections. GENERAL CHARACTER OF FAUNA The general microfaunal character of the Upper Cretaceous in this region is indicated by the scarcity and often the complete lack of planktonic elements and by the great abundance of agglutinated tests. I tried to use as much as possible the evidence offered by planktonic species (when they did appear), but a more important basis of my work was formed by those species or groups of species whose frequency and constancy is appreciable in the various lithologic sequences encountered. In the sequence of Cenomanian deposits, the presence of species of the planktonic genera Rotalipora, Schackoina, Praeglobotruncana and Hedbergella provided extremely valuable information. The Turonian deposits, however, on account of their marked shalysandy character with interbedded sideritic marly limestones, red clays and volcanic cinerites, are almost completely lacking in planktonic micropaleontology, vol. 14, no. 2, pp. 225-241, pis. 1-2, april, 1968 225 This content downloaded from 40.77.167.121 on Thu, 27 Apr 2017 17:49:54 UTC All use subject to http://about.jstor.org/terms

Production of pollen-sized 'microforaminifera' from 'normal' foraminifera

Abstract: Pollen-sized 9microforaminifera9 were produced from 9normal-sized9 calcareous foraminifera of the species Ammonia limnetes (Todd and Bronnimann) by the differential destruction of the test with 5 percent HC1.

Oxygen-isotope analysis of recent tropical Pacific benthonic Foraminifera.

Abstract: Analysis by the oxygen-isotope method of samples of benthonic Foraminifera, collected at different depths on the continental shelf and slope of western Cenitral America, yielded isotopic temperatures agreeing closely with the temperatures measured in the field. The validity of the oxygen-isotope method as a means of analysis of paleotemperatures is further supported.

Contribution a l'étude sédimentologique du plateau continental dans la'baie de biafra

Abstract: The main purpose of this sedimeniological study is the ecology of the planktonic and benihic Foraminifera. The continental shelf off Cameroons represents a special environment in ierms of hydrology, because warm waier with a poor sait content occurs above a colder, more saline wafer ut depth. A tidal current flows 10 ihe North, and iurbidity is high in coastal waters. Al1 particularities in Foraminifera species disiribution have been siudied and explained by nafure and grain-size of sedimenis and their influence on benthic species ecology. The chemical, mineralogical and lithological properiies of the sediments have been defined, as me11 as ihe distribution of oolith.es. l E.N.S.A. Rennes. ” Centre O.R.S.T.O.M. de Pointe-Noire. * l * E.P.H.E., Paris. 56 L. BERTHOIS, A. CROSNIER, Y. LE CALVEZ

Biostratigraphy of Niobrara-Equivalent Part of Mancos Shale (Cretaceous) in Northwestern Colorado

Abstract: Study of microfossils, particularly Foraminifera, from the part of the Cretaceous Mancos Shale in northwestern Colorado that is equivalent to the Niobrara Formation of the High Plains region has determined that these fossils can be used to establish biostratigraphic subdivisions and interpret paleogeographic conditions. The microfossils used in the investigation came from two surface sections and one well in northwestern Colorado and one surface section in northeastern Colorado. The microfauna contains several species in common with beds of the same age in the Gulf Coast and Great Plains areas, and also contains forms which have been reported from equivalent beds in Alberta and the Arctic Slope of Alaska. The microfossils are predominantly calcareous and represent a limited number of planktonic and benthonic forms. Samples taken throughout each of the sections were studied and plotted systematically to determine the stratigraphic distribution of the microfossils. Concentrations of larger numbers of fossils were found in the lower part of the Niobrara-equivalent strata. This lower part is characterized in both northwestern and northeastern Colorado by a variety of benthonic calcareous foraminifers, notably species of Globorotalites and Bifarina, and Pleurostomella austiniana. It is termed informally the Globorotalites interval. Further study may make possible the subdivision of this interval on the basis of the stratigraphic distribution of Globorotalites and Bifarina. The microfauna of the upper part of the section is more limited and is characterized particularly by some species of Gavelinella, notably G. talaria. This upper part is termed the Gavelinella interval. Throughout the Niobrara-equivalent section the planktonic species Heterohelix lobulosa and Hedbergella loetterlei are common, and in most samples the planktonic forms predominate. Interpretation of the environment of deposition of the northwestern Colorado beds has been based on (1) the ratio of planktonic to benthonic foraminifers, (2) modern analogues of foraminiferal genera found as fossils, (3) size and abundance of microfossils, and (4) variety of genera and species. The evidence indicates that large volumes of clay-size clastic sediment were supplied to northwestern Colorado during the deposition of the Niobrara-equivalent part of the Mancos Shale. This fine-grained clastic material diluted the population of foraminifers found as fossils in the sediment (in comparison with the living population) and may have restricted the variety of genera and species. The absence of keeled foraminifers in Niobrara-equivalent beds in northwestern Colorado indicates colder water temperatures (probably less than 20° C) in this region than in areas on the south and east at the same time. The colder water temperatures, as well as the distribution of fine-grained clastic sediment, probably resulted from a combination of a southward-directed, nearshore circulation system along the western boundary of the western interior seaway and the possible upwelling of deeper, colder water. Ratios of planktonic to benthonic Foraminifera and modern analogues of some genera indicate that the seaway was probably on the order of 200 m deep in northwestern Colorado during deposition of the Niobrara-equivalent beds.

Late Cretaceous planktonic foraminifera from the coastal area east of Susa (Apollonia), northeastern Libya

Abstract: Upper Cretaceous limestone, which is strikingly similar lithologically to the upper Cretaceous chalk of western Europe, is exposed along the coastal area east of Susa. These strata in the Wadi Merghes-Wadi el Atrun area have yielded diverse and well-preserved foraminiferal faunas which include more than 70 benthonic and 14 planktonic species. The planktonic foraminifers indicate that this sequence is correlative to the Globotruncana tricarinata zone of Bolli (1957) (upper Campanian-lower Maestrichtian). Specimens of Bolivinoides miliaris Hiltermann & Koch in a late stage of evolutionary development suggest further that these strata are early Maestrichtian (late Cretaceous) in age. Ratios of planktonic to benthonic specimens indicate that this limestone was probably deposited in an outer neritic or upper bathyal environment.

Lower Triassic foraminifera from the Thaynes Formation in southeastern Idaho and western Wyoming

Abstract: Approximately 600 specimens of arenaceous foraminifera have been recovered from insoluble residues of limestones from the Lower Triassic Thaynes Formation in southeastern Idaho and western Wyoming. Most of the ten species, four of which are new, belong to genera which are far-ranging in age. This is the second reported occurrence of foraminifera from the Lower Triassic in the western hemisphere.

Sedimentary Facies in Area of Mixed Terrigenous-Carbonate Deposition, Arlington Reef Complex and Adjacent Areas, Northern Great Barrier Reef: ABSTRACT

Abstract: The northern Great Barrier shelf can be divided into 3 major bathymetric zones: (1) the nearshore zone, extending to depths of 5 fm; (2) the inner shelf, extending to depths of 20 fm; and (3) the marginal shelf extending to the shelf edge at 40-50 fm. In the area studied, reef development is concentrated on the inner two thirds of the marginal shelf. Sedimentary facies in this area reflect three major influences: (1) source (terrigenous and carbonate); (2) hydrography; and (3) relic facies. On the inner shelf, nearshore terrigenous sand is succeeded seaward by dominantly terrigenous mud which transgresses two pre-Recent facies: (1) terrigenous sand in the north and (2) shell gravel in the south. Mixing of pre-Recent sediments, terrigenous mud, and modern carbonates (molluscan and foraminiferal) complicates the basic pattern. Both pre-Recent facies extend to within 1 mi of the reef with no significant dilution by modern reef-derived debris. Major interreef channels are floored by fine-grained, mixed terrigenous-carbonate sediment. The terrigenous material (30-50 percent) is dominantly silt and clay size. The identifiable, carbonate fraction is composed mainly of planktonic and benthonic Foraminifera, juvenile and larval mollusks, and skeletal debris. Most of this channel-floor sediment apparently is derived either from the inner shelf or from the open ocean; little appears indigenous. The main reef complex is built on a 16-fm platform, and encloses a central area of about 64 sq mi. Much of the interior platform is covered by low coral growth or by dead coral with a thin cover of worn, broken, and stained skeletal grains, mainly large Foraminifera, Halimeda, and coralline algae. Major sediment accumulation occurs only in the lee of the main reef where quiet-water conditions allow the deposition of carbonate mud with up to 18 percent fine terrigenous detritus. The sparse coarse fraction is molluscan, Foraminifera increasing in abundance near the reef. Reef-derived sediment is abundant only on and directly adjacent to the reefs. End_of_Article - Last_Page 551------------

Biostratigraphy of the Cretaceous-Tertiary Boundary in the East Texas Embayment Based on Planktonic Foraminifera.

Abstract: The biostratigraphic study of the topmost Cretaceous strata in the East Texas Embayment based on planktonic foraminifera, has yielded the following results. The presence of a saddle shaped arch, referred to as the Grimes-Angelina topographic high, which was undergoing erosion during Maastrichtian and Danian times. The topmost preserved Cretaceous along the trend of the topographic high ranges in age from Campanian to mid­ dle Maastrichtian. The existence of active faults at the end of the Cretaceous for portions of the Mexia-Talco fault system, is suggested by the pres­ ence of thick intervals of Midway strata containing reworked Cretaceous fossils located in two separate areas in the vicinity of Freestone and Limestone counties. In addition, at least some minor fault movement in the Mount Enterprise fault system is indicated by the presence of late early Maastrichtian age strata at the top of the Cretaceous in a well in Leon County located just south of a fault. The remainder of the East Texas Embayment appears to have had no major tectonic movements at the end of the Cretaceous. For most of the East Texas Embayment, the age of the topmost Cretaceous strata appears to be late middle Maastrichtian. CHAPTER