Showing papers on "Foraminifera published in 1972"

Late Cenozoic Ostracoda of the South Aegean Island Arc

Abstract: A detailed study has been made of Late Cenozoic ostracodes from closely sampled sections and some isolated samples on the Aegean islands of Gavdos, Crete, Karpathos and Rhodos. The stratigraphic position of the studied lithostratigraphic units has been determined by means of the evolutionary trends in Planorbulinella and in uniserial Uvigerina, and by planktonic Foraminifera (Chapter II). For a paleoecologic interpretation a method is introduced for evaluating depth of deposition and salinity, and major trends in the development of the depositional environment (Chapter III). Based on the three major realms for ostracode life reflected in the assemblages (a brackish water, a shallow marine and a deeper marine environment) some tentative assemblage zones are proposed (Chapter IV). Comparisons with the ostracode assemblages of Neogene stratotypes show that most of the biozones can be recognized outside the Aegean area (Chapter V). The systematic part of the study deals with over 200 different taxa. Three new subgenera are proposed. In total 24 new species are described. Because of primary homonymy two species are renamed (Chapter VI).

Sedimentation and Erosion on Horizon Guyot

Abstract: A small part (300 km 2 ) of the 2-km-deep summit of Horizon Guyot, a flat-topped submarine ridge at the eastern end of the Mid-Pacific Mountains, was surveyed in detail with a deeply towed instrument package. This followed up the work of several earlier Scripps Institution of Oceanography expeditions to the same feature. Three hundred and fifty stereo pairs of bottom photographs were taken, intensive coring and rock dredging were carried out, and near-bottom current meters were deployed. The summit cap of Tertiary nannoplankton ooze has truncated horizons, including Eocene chert layers, which crop out at its margins. Continuing erosion has winnowed away the fine components of the sediment, while bed-load transport of the remaining foraminiferal sand creates regular trains of ripples and dunes. All three current meters recorded currents faster than 15 cm/sec within 12 m of the sea floor. Analysis of their records indicates that scouring and sediment redistribution is performed by locally accelerated tidal currents. Net movement of sand is upslope. Hard-rock terraces underlying the pelagic sediment are exposed at the margins of the summit platform. They are probably deposits of highly mobile hyaloclastite flows, rather than relict erosional forms. Some accessory basalt clasts within the pyroclastic rocks have cracks containing an Albian (Lower Cretaceous) fauna of planktonic Foraminifera.

Deep Sea Carbonates: Dissolution Facies and Age-Depth Constancy

Abstract: DEEP sea drilling1 has shown the presence in many parts of the seafloor of a complex sequence of carbonate sediments showing various degrees of dissolution. On the present sea-floor, dissolution of carbonate increases with depth, leading to increasingly poorly preserved carbonate assemblages with increasing depth of deposition, until finally all carbonate is dissolved, leaving a residue of pelagic clay. This relationship between depth and dissolution has been used to interpret the carbonate profiles in drill sites in two contrasting ways. First, assuming that the present distribution of dissolution with depth was constant through time, poorly preserved carbonate skeletons and pelagic clay indicate great depth of deposition, whereas well preserved skeletons and pure chalk indicate a shallow ocean bottom2; second, neglecting tectonic movements, as well as redeposition, the distribution of age versus ocean depth of foraminifera, nannofossils and clay defines the rise and fall of solution levels3,4, such as the calcite compensation depth (CCD) and the (whole test) foraminiferal compensation depth (FCD) somewhat above the CCD.

Cretaceous biostratigraphy and planktonic foraminifera of Libya

Abstract: Sixty-nine species, Hedbergella libyca, Praeglobotruncana hilalensis, new species, Globotruncana concavata cyrenaica, new subspecies, correlation with Middle East, paleogeographic interpretation does not support existence of late Cretaceous seaway connecting Mediterranean Sea with Atlantic Ocean

Amino acid composition of the test as a taxonomic character for living and fossil planktonic foraminifera

Abstract: Sixteen species analyzed for 17 amino acids, multivariate analysis indicates that amino acid composition varies in a systematic way which parallels morphology, Miocene, Holocene, Atlantic Ocean

Phenotypic variation and oxygen isotope ratios in Recent planktonic foraminifera

Abstract: Distribution of species; kummerforms, bullae, saclike final chambers and symmetry related to oxygen isotope ratios; Atlantic Ocean, Pacific Ocean, Indian Ocean

Origin and Development of Globorotalia (Turborotalia) Pachyderma (Ehrenberg)

Abstract: Planktonic foraminifera, morphology indicates species derived from G. (T.) continuosa in Neogene (upper N12)

Cretaceous Foraminifers—Depth Habitats and their Origin

Abstract: UPPER Cretaceous foraminifers, both planktonic and benthic, seem to have been depth distributed in a similar way to modern species. This hypothesis, examined primarily in terms of Upper Cretaceous foraminifera along the eastern North Pacific margin, explains the distribution patterns observed in Cretaceous shelf and slope foraminifers, the correlation of these faunas to modern assemblages, and the agreement of the patterns with the hydrographic conditions envisioned for Cretaceous oceans1. Here I show that these depth patterns originated in the mid-Cretaceous during the earliest of two periods of Cretaceous continental fragmentation and ocean floor spreading.

Foraminifera from the Lower Cretaceous and Upper Jurassic of the Northwestern Atlantic

Abstract: During Leg 11 (Miami-Hoboken) of the Deep Sea Drilling Project, deposits of early Cretaceous and late Jurassic age were penetrated at four sites. Three of them (Sites 99, 100, 101) are situated in the BlakeBahama Abyssal Plain to the north and east of San Salvador (Bahama Islands), whereas Site 105 is near northern end of the Hatteras Abyssal Plain approximately 600 kilometers to the east of Cape Hatteras (Figure 1). For exact locations, lithologic descriptions and other details, reference is made to the individual Site Reports in this volume.

Planktonic foraminifera from the Comanchean Series (Cretaceous) of Texas

Abstract: Systematic descriptions, one new genus (Favusella) and 12 new species, two zones with four subzones, Albian-Cenomanian boundary

Paleozoogeography of Late Cretaceous planktonic foraminifera in North America

Abstract: Distribution not uniform but similar to present distribution, two faunal provinces; Tethyan, species-rich, restricted species, 30 degrees -40 degrees N. latitude; Pacifican, low species diversity, cosmopolitan species, high latitudes, Cenomanian-Maestrichtian

The Biostratigraphy of the Tasmanian Marine Tertiary

Abstract: Tertiary marine rocks occur in small scattered outcrops around Tasmania's north and west coasts, on some islands in Bass Strait, and below sea level in Mussel Roe Bay. All occurrences except those in Mussel Roe Bay and on Preservation Island have been recorded previously. From 64 samples, about 300 categories (form, subspecies, species, genus etc,) of foraminifera have been identified. Planktonic species are generally poorly preserved, but good faunas have been identified from Fossil Bluff, Brittons Swamp and Marrawah, the latter in company with Lepidocyclina howchini Chapman and Crespin and Amphistegina lessonii d'Orbigny. All rocks are of Early and Middle Miocene age (Longfordian Batesfordian, Carter's Faunal Units 6, 8 and 9) with the possible exception of one sample from Mussel Roe Bay which may be Late Oligocene (Janjukian, Faunal Unit 5). All sediments are of shallow water origin, deposited in depths of less than 20, usually less than 10, fathoms. Water temperatures were those of the Warm Temperate to Subtropical Zones in Faunal Unit 6 time, Subtropical during Faunal Unit 8 time and Tropical during Faunal Unit 9 time. Waters may have been slightly warmer in the north-east than in the north-west during Faunal Unit 6 time. Sediments at about 100 feet below sea level in Mussel Roe Bay, and at less than 150 feet above sea level at Wynyard, King Island, Cape Grim, Mt Cameron West, Marrawah, Daisy Creek and Granville Harbour formed during a marine transgression throughout Faunal Units 5 and 6, There seems to be a Faunal Unit 7 hiatus which may represent regression. Higher level sediments (above sea level on Cape Barren and Preservation Islands) and at 170-310 feet above sea level at Brittons Swamp, Redpa, and Marrawah formed during another, more extensive transgression in the time of Faunal Units 8 and 9. Comments are made on the age of some basalts in the north-west of the State; on the relation of these outcropping sediments to those of the Bass Basin; on the common occurrence of large and planktonic foraminifera in a single sample from Marrawah; and a palaeogeographic map is presented.

Sediments of the New England Continental Rise

Abstract: Sediment from short cores taken on the continental rise off Georges Banks show two facies which are best distinguished by clay mineral ratios. The green-gray material in the upper, Holocene section of the cores is carbonate and amphibole rich and has a montmonllonite/illite peak-area ratio which typically is greater than one. These characteristics serve to distinguish the upper facies from the red-brown Pleistocene sediment of the lower core section in which illite is the dominant clay mineral. The clay mineralogy of the Pleistocene facies is consistent with a source in the Permo-Carboniferous red-bed area of the Canadian Maritime Provinces. This red lutite, which acts as a tracer for bottom current movement, was entrained on the continental rise by the Western Boundary Undercurrent and transported southwestward along the regional contours. The coarse fraction of this facies probably originated in down-slope processes along the entire continental margin under a regime of lower sea level and as ice-rafted debris. The upper, Holocene facies cannot be linked o t any specific continental source, but it appears to have the sediment of the Labrador Sea as its immediate source. The montmorillonite-rich lutite is transported to the south parallel to the regional contours by the Western Boundary Undercurrent. The carbonate component consists of coarse Foraminifera which originate in the warm Gull Stream. The character of the sediment and measurement of the predominant direction and speed of the bottom currents indicate that the Western Boundary Undercurrent is a significant factor in sediment transport and deposition on the east coast continental rise. A dispersal system parallel to the regional slope is confirmed to be operative for the fine sediment.

Correlation of Lower Pleistocene Crag at depth in Suffolk

Abstract: Biostratigraphic correlation of two boreholes drilled into sediments; foraminifera and palynomorphs, England

Subsurface reproduction in foraminifera

Abstract: Gamogony in unidentified foraminifers below the water-sediment interface is believed to be evidence of their infaunal habit. IN parts of Long Island Sound and Narragansett Bay, living specimens (i.e., rose bengal stained; Walton, 1952) of certain species of Foraminifera were found below the upper centimeter of bottom sediment in such large numbers that Buzas (1965) and Brooks (1967) suggested that they may be infaunal organisms. This idea challenges the widely held view that benthonic foraminifers are epifaunal forms (e.g., "All Foraminifera live on the surface of the substratum"; Myers and Cole, 1957, p. ... ..... . : L l : . . . ......... . ...-. : . ... . ..... TEXT-FIG. 1-Microphotograph of empty abutting tests in a curved intergrain space approximately 16 mm below the water-sediment interface; X290 approx. 1075) and that their inclusion within the bottom sediments is due to accidental burial. One indication of a "natural" infaunal existence (as opposed to accidental burial) would be evidence that foraminifers can reproduce within the sediments. Examples of this have been found in a sediment core obtained from the nearshore pebbly sands of the Poquonock River estuary, Groton, Connecticut which are covered by two inches of water at low tide. Upon collection, the water in the sediment TEXT-FIG. 2-Microphotograph of abutting foraminifers with multinucleate cytoplasm attached to grain surface approximately 3.5 mm below the water-sediment interface; X290 approx.

Upper Cretaceous planktonic foraminifera from the Pondicherry area, south India

Abstract: Thirty-three species, Gublerina rajagopalani n. sp., two zones and two subzones, correlation with Globotruncana tricarinata and G. ganserri zones, Campanian, Maestrichtian

The Foraminifera and Some Associated Microfossils of Sites 135 to 144

Abstract: A total of 465 samples, all collected on shipboard, were available for examination of the foraminifera and associated microfossils. On the average, this amounts to one sample for slightly less than one meter of recovered core. Most of the washed residues were separated into two fractions (retained in the 80 mesh and 230 mesh sieves). Only a few samples were too hard for conventional washing methods and had to be studied in thin section (Site 139, Core 6; Site 144, Core 6). A set of charts showing the composition and preservation of the microfauna for each sample, with special emphasis on the foraminifera, has been prepared and is reproduced here on Tables 2 to 11. These tables also include the determinations of the zones and ages. The figures indicating the planktonic/benthonic ratios and the percentage of foraminifera (of the total fauna in the 80-mesh fraction) are in most cases estimates rather than counts. For some samples, the record of the foraminiferal species has been left incomplete or omitted altogether. Such samples are marked in the last columns ("Remarks") by the letters "P"—partially examined or "n"-not examined. Omissions of this kind will be found in monotonous sequences of rich faunas, or where an occasional sample was poorly preserved. Their purpose was to save time without losing essential data.

Permian Tethys and Indian Ocean

Abstract: Permian data, classification, paleontology, foraminifera, Mollusca, Brachiopoda, paleogeography, continental drift

The biota of the Pennsylvanian (Virgilian) Leavenworth Limestone, midcontinent region; Part 3; Distribution of calcareous foraminifera

Abstract: Eleven families represented, four foraminiferal reaction groups, related to three distinct biofacies, shallow water platform carbonate assemblage, systematics, factor analysis of distribution; for reference to part 2, see this Bibliography Volume 34, No. 1, 15 E70-04417

Foraminifera and the Holocene History of the Gulf of St. Lawrence

Abstract: Foraminifera have been utilized to interpret the response of waters in the Gulf of St. Lawrence to climatic changes during the Holocene. Sediment cores (up to 1000 cm long) from the Gulf of St. Law...