bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bathymetry and physiography
Authors: Johnson G. L. , Grantz Arthur , Weber J. R. 
Published: April 2015

Abstract
The oceanic regions located north of the Arctic Circle are the Arctic Ocean, the Norwegian-Greenland Sea, and Baffin Bay (Plate 1). The latter is described in Keen and Williams (1990). Despite the bold isobaths in Plate 1, the bathymetry of the Arctic Ocean is still poorly known. Most of the Norwegian-Greenland Sea, on the other hand, is quite precisely charted. Exceptions are the areas east of Greenland often covered by the pack ice that exits the Arctic Ocean in the East Greenland current.
The names used for the physiographic features in this volume are those shown on Plate 1. Different names that have been applied to these features in the literature are given in Sweeney and others (this volume.)
“Zero-age” variations in the composition of abyssal volcanic rocks along the axial zone of the Mid-Atlantic Ridge
Authors: Melson William G. , O’Hearn Tim 
Published: April 2015

Abstract
The mid-ocean ridge spreading centers mark the zones where the asthenosphere comes closest to the earth’s surface. Such centers are termed accreting plate margins because the oceanic lithosphere forms along these centers. Magmas that have erupted along spreading centers are minimally modified or not modified at all by contamination with older lithosphere, compared to magmas erupted through the thicker lithosphere beneath continents and islands. Thus, their compositions presumably provide us with least-modified mantle-derived liquids. Controversy remains as to the extent that these liquids—which are overwhelmingly basaltic—represent “primitive” liquids (O’Hara, 1982).
One of the most incisive models of accreting margin magma chambers is Cann’s “cocktail-onion” model (1970, 1974). This model (Macdonald, this volume) envisions a permanent magma chamber beneath fast-spreading centers and periodic magma chambers beneath slow, rifted spreading centers. The Mid- Atlantic Ridge (MAR) belongs to the latter, rifted spreading centers.
Initial work on abyssal basalt from spreading centers revealed a remarkable uniformity in composition and their “depleted” character compared to oceanic island basalts (Engel and others, 1965) in regard to elements such as K and the light rare earth elements (LREE). Since that time, a wealth of new analytical data has revealed much more diversity and certain systematic patterns related to such factors as distance from on-ridge volcanic islands, spreading rate, water depth, and broad regional groupings. A breakthrough in this area included the discovery of systematic variations in Sr-isotopic ratios moving south from Iceland along the Reykjanes Ridge, revealing decreasingly less radiogenic ratios southward, with values
Hydrothermal activity in the North Atlantic
Authors: Edmond J. M. 
Published: April 2015

Abstract
One of the major developments in the earth sciences in the last ten years has been the recognition of the importance of hydrothermal circulation in the thermal and chemical evolution of the oceanic crust. Submarine hot springs with exit temperatures as high as 350°C have been located and sampled at several locations on the ridge systems of the Eastern Pacific (Edmond and others, 1982). Hydrothermal deposits of sulphide ores and pavements of pure MnO2 have been recovered by dredging at numerous other sites. Exploration has been facilitated at these medium and fast spreading ridges by the relatively subdued topography. Success has a high probability, given the frequency of intrusive and eruptive events and the permanent presence of shallow magma chambers (Sleep and Rosenthal, 1979). On the Mid-Atlantic Ridge (MAR), none of these circumstances obtain and the results have been correspondingly meagre, with the obvious exception of Iceland. The strongest evidence for current hydrothermal activity on the MAR comes from the TAG area (Trans-Atlantic Geotraverse) at 26°N. While small temperature and 3He anomalies have been observed in the water column in the axial valley, active venting was not observed during subsequent Alvin dives. However, there are abundant indications that hot springs have played an important role in the development of the MAR over the time-span of its existence.
Much of the evidence is for low-temperature activity of the kind observed on the Galapagos Spreading Center (GSC) in the Eastern Pacific (Edmond and others, 1979 a,b). It is known,
Imaging the ocean floor: History and state of the art
Authors: Vogt Peter R. , Tucholke Brian E. 
Published: April 2015

Abstract
Bathymetry is the science and technology of ocean depth measurement. In the narrow and traditional sense, the objective of bathymetry is to define the seafloor topographic surface, h(x, y). Most bathymetric studies also interpret the depth data— usually displayed in contour charts or profiles—in terms of undersea geomorphology and, in concert with other geophysical data, as a constraint on sub-seafloor geologic structure. In many parts of the ocean, bathymetry is about the only type of geological information available. Thus, compared to land, seafloor topography necessarily plays a larger role in geologic interpretations.
The North Atlantic Ocean covers an enormous area (4 × 107km2) with diverse and numerous geomorphic features at many scales. Bathymetric control is very uneven in distribution and quality. Some areas have been surveyed by overlapping swaths of multibeam bathymetry with reliable mapping of features less than 1 km apart, while other areas of 103 or 104km2 have no soundings, particularly in the equatorial latitudes. Unlike many previous studies, this chapter does not offer a systematic guided tour of the submarine topography. (See Holcombe, 1977 for a glossary of ocean-bottom land forms.) Recent syntheses of Atlantic bathymetry include Vogt and Perry (1982) and Emery and Uchupi (1984). Instead, the potential of seafloor “imaging” is evaluated over a large range of spatial scales, approximately ten orders of magnitude from the form of the entire Atlantic basin down to the size of grains in seafloor sediments (Fig. 1). Under “submarine imaging” are included 3-D (stereoscopic) descriptions of bottom
Gravity anomalies in the western North Atlantic Ocean
Authors: Rabinowitz Philip D. , Jung Woo-Yeol 
Published: April 2015

Abstract
The first accurate gravity measurements in the deep ocean were made in 1923 by Vening Meinesz with pendulum apparatus onboard submarines (Vening Meinesz, 1932). Since that time, and up until the late 1950s, many pendulum stations were occupied in order to obtain information about the earth’s gravitational field over the vast oceanic regions. Though these measurements were accurate (generally 3 or 4 mgal; Ewing and others, 1957) and yielded valuable information concerning the earth’s crust, upper mantle, and isostatic processes, the measurements were discrete and separated by large distances. For this reason, the construction of detailed gravity contour maps of large oceanic areas was virtually impossible. In 1958, continuous gravity measurements at sea aboard surface ships were initiated onboard, U.S.S. Compass Island (Worzel, 1959). Subsequently, gravity measurements have been routinely collected by several of the academic oceanographic institutions and industrial and government agencies.
During the 1960s, major technological advances enhanced the reliability of shipboard gravity measurements. These advances included the development of the satellite navigation system (Guier, 1966; Talwani and others, 1966a) to more reliably compute the Eötvös correction and theoretical gravity values, the development of cross-coupling and off-leveling computers to measure errors resulting from shipboard accelerations (Talwani and others, 1966b), the design of reliable temperature control systems for vibrating string instruments (Bowin and others, 1972), and the modification of the LaCoste-Romberg gravity meter for mounting on a stabilized platform (LaCoste, 1967). Accompanying these technological advances, computer systems were developed for rapid
The relationship between depth and age and heat flow and age in the western North Atlantic
Authors: Sclater John G. , Wixon Lewellyn 
Published: April 2015

Abstract
There are two simple models, compatible with the theory of plate tectonics, that can account for the observed relations between depth and age and between heat flow and age for oceanic crust. The first is the cooling plate model (Langseth and others, 1966; McKenzie, 1967; Sclater and others, 1971), which has been best matched to the depth and heat flow observations by Parsons and Sclater (1977). The second is that of a growing boundary layer (Turcotte and Oxburgh, 1967; Parker and Oldenburg, 1973) that has been matched to the depth and heat flow data by Davis and Lister (1974) and Lister (1977). Both models give good agreement with observations in the range 0–80 Ma. At greater ages the observations of average depth and mean heat flow are best matched by the plate model.
The models are similar in that thermal cooling is the dominant mechanism. The difference between them results from concentrating on two different aspects of the observations. In the plate model, emphasis is placed on matching the exponential decay of heat flow and depth at older ages, whereas the boundary layer model was developed to explain the relation between subsidence and the square root of time on young ocean floor. Though the predictions of the plate model best match the average observations there is a problem with this model in that the constant temperature bottom boundary condition is physically unrealistic. Parsons and McKenzie (1978) have reconciled the two models and also developed
Structure of basement and distribution of sediments in the western North Atlantic Ocean
Authors: Tucholke Brian E. 
Published: April 2015

Abstract
During the past 20 years the morphology of the seafloor has become relatively well known along the crest and shallow flanks of the Mid–Atlantic Ridge through echo sounding and seismic reflection profiling (see Plate 2). In this area sediment cover is so thin, rarely more than 50–100 m, that high frequency echo sounding (12 kHz) essentially maps the surface morphology of oceanic crust. Although our knowledge of this crustal morphology still is far from being detailed or complete, the observed patterns and spacing of fracture zones and crustal blocks provide a general model that can be used to understand the basement morphology in more thickly sedimented regions away from the ridge crest. Structure contours on basment for most of the western North Atlantic recently have been compiled by Tucholke and others (1982) and Tucholke and Fry (1985). Their mapping used the crustal “template” of the mid-ocean ridge together with data from all available seismic reflection profiles in the western Atlantic basins. With some additional mapping, I have extended these structure contours to cover the area from the Mid–Atlantic Ridge crest west to the continental margin between about 8°N and 70°N (Plate 5).
Until the basement morphology is completely masked by sediments, it exerts strong control on how sediments are distributed in the ocean basin. Gravity-controlled mass movements such as debris flows and turbidity currents deposit their sediment load in the deepest accessible basins; consequently, thick ponded sediments often are observed in fracture-zone troughs (Plate 5, Profile F; Plate 6,
Subduction of Atlantic lithosphere beneath the Caribbean
Authors: Westbrook G. K. , McCann W. R. 
Published: April 2015

Abstract
The Caribbean Plate lies between the North American and South American plates and moves relatively eastward with respect to them. The interior of the plate is predominantly oceanic in origin, but along its margins there are island arcs and continental fragments. The plate’s boundaries are often diffuse and ill- defined, especially that with South America.
The boundary between the Caribbean and North American plates exhibits great variety. In the Cayman Trough at the western end of the boundary, a small spreading center (Holcombe and others, 1973) links two major systems of transform faults that extend westward along the southern margin of the trough and eastward along its northern margin and also, less clearly, on its southern margin. The eastward transform faults develop into a complex zone of strike-slip faults in the region of Hispaniola which may also have a component of subduction/underthrusting (Bracey and Vogt, 1970), before passing into a zone of oblique subduction at the Puerto Rico Trench (Fig. 1). Some proportion of the motion across the boundary zone is distributed along the southern margin of Hispaniola and Puerto Rico, with associated deformation of sediments in the Muertos Trough (Ladd and Watkins, 1978). As the plate boundary curves round east of the Lesser Antilles island arc, normal subduction becomes predominant, with active volcanism in the Lesser Antilles. Somewhere along the Lesser Antilles segment of the Caribbean plate boundary, probably at about 14N, lies the triple junction between the Caribbean and the North and South American plates.
Plate kinematics of the central Atlantic
Authors: Klitgord Kim D. , Schouten Hans 
Published: April 2015

Abstract
Opening of the central Atlantic Ocean basin during the past 200 Ma separated North America from Africa and created a classic example of plate tectonic divergent motion and associated geologic features (LePichon, 1968; Morgan, 1968). The entire history of relative motion of these two plates is preserved in the fabric of sea-floor spreading (SFS) recorded by magnetic lineation and fracture zone (FZ) patterns (Fig. 1) (Vine and Matthews, 1963; Heezen and Tharp, 1965) on both flanks of the Mid-Atlantic Ridge. Age calibration of the SFS magnetic anomaly pattern (Cox, 1973; Harland and others, 1982; Kent and Gradstein, this volume) enables us to treat SFS lineations as isochrons of sea-floor crustal ages. FZs mark the path of spreading center offsets (transform faults) through time, providing an approximate flowline trace of the motions that separated the North American and African plates.
Reconstruction poles of rotation and stage poles of motion can be determined from the SFS lineation and FZ data sets (Bullard and others, 1965; McKenzie and Parker, 1967; McKenzie and Sclater, 1971; Harrison, 1972). The kinematic history described by these poles provides a framework for examining major tectonic events, anomalous plate behavior, geologic phenomena, paleooceanographic events, etc. (e.g., Vogt and others, 1969; Tarling and Runcorn, 1973; Dewey and others, 1973; Vail and others, 1977; Sclater and others, 1977; Pitman, 1978; Rona and Richardson, 1978; Schwan, 1980; Kerr and Fergusson, 1981;
Turbidite sedimentation in the northwestern Atlantic Ocean basin
Authors: Pilkey Orrin H. , Cleary William J. 
Published: April 2015

Abstract
Turbidity currents account for much of the sediment deposited on the western North Atlantic Ocean basin floor. The most obvious expression of the importance of this sedimentation mechanism is the large area of the sea floor occupied by the abyssal plains, which are large ponds of turbidity-current-derived sediment (Plate 2). In fact the Hatteras and Sohm Abyssal Plains are among the largest active depositional basins in the world’s ocean basins. Other than the abyssal plains, the major feature of the western North Atlantic basin which is affected by turbidity current erosion and deposition is the North American continental rise. Turbidity currents are responsible for moving huge volumes of sediment off the continental shelf edge and continental slope. Some individual turbidity currents crossing the North American rise are known to exceed 100 km3 in volume (e.g. Elmore and others, 1979). Both the amount of sediment transported and the frequency of turbidity-current events are assumed to be closely related to Pleistocene sea-level fluctuations; low sea levels produce more or at least larger turbidity currents because of direct contribution of sediment to the upper slope by rivers. High sea-level stands of geologically brief duration, such as the present one, result in trapping of most fluvial sediment in estuaries.
The genetic term turbidite is defined as the deposit of a shortlived single turbidity current. The concept of turbidity currents dates back to the observations by Forel (1887) on the cold, sediment-laden undercurrent formed by the Rhone River upon entering Lake Leman. Observations by
Deep current-controlled sedimentation in the western North Atlantic
Authors: McCave I. N. , Tucholke Brian E. 
Published: April 2015

Abstract
With its multiple sources of sediment and bottom water, the North Atlantic experiences more active redistribution of sediments than most other ocean basins. North Atlantic bottom waters originate around Antarctica, in the Norwegian Sea, the Mediterranean, and the Labrador Sea. Sediment is supplied from continental land-masses, oceanic islands (notably Iceland) and from surface biological production. The water movements are controlled principally by differing densities of the water masses, and the currents tend to follow the contours of the sea floor. Where interfaces of steep density gradient intersect the seafloor, internal tides and high-frequency internal waves may also resuspend sediments. The Gulf Stream, and warm-core and cold-core mesoscale eddies with clockwise (anti-cyclonic) and anticlockwise (cyclonic) circulation, apparently contribute to the variability of current velocity at great depths and help to erode and redistribute sediments.
The most important depositional products of this current activity are the great “sediment drifts” of the region (see Plate 2). These features probably contain a detailed but as yet poorly known record of the fluctuations in bottom-current activity of the North Atlantic. They have formed principally since the beginning of the Oligocene, when strong abyssal circulation began in the North Atlantic (Ewing and Hollister 1972; Tucholke and Mountain, 1979; Miller and Tucholke, 1983). The precise relationship of the drifts to the present abyssal current regime is not clear because details of that regime are poorly known. Few long-term, deep current-meter records have been taken and most of these are not adjacent to drifts.
Seabed geotechnical properties and seafloor utilization
Authors: Silva Armand J. , Booth James S. 
Published: April 2015

Abstract
This chapter presents geotechnical physical property data on sediment in the western North Atlantic in the area of 20° to 45°N, and 50° to 85°W. Available data are synthesized to characterize major physiographic regimes in terms of pertinent engineering properties of the sediment, then these properties are interpreted in relation to utilization problems that may develop because of certain sedimentary processes or unfavorable sedi- ment-deformational behavior. The data base for this synthesis, although still relatively meager in most areas, has been expanded considerably since the initial such synthesis by Keller and Bennett (1968) and the subsequent work by Horn and others (1974). In keeping with the purpose of the volume, this paper is a summary review and is not intended to exhaustively document all published and unpublished data.
Areas considered are those beyond the shelf break and include the continental slope, rise, and abyssal basin. The most abundant data are for the continental slope and rise, but studies are so concentrated locally that coverage is non-uniform. Available data for the deep-sea regime are sparse and most data are for only the upper two meters of sediment. Because of these limitations, this data base should not be used directly for particular site-specific applications. However, the preliminary generalizations resulting from this study are helpful in understanding processes and they provide a basis for planning more detailed studies.
In decreasing order of abundance, the following geotechnical data are available: water content and/or wet unit weight, grain size analysis, undrained shear strength (vane measurements),
Northwestern Atlantic Mesozoic biostratigraphy
Authors: Gradstein F. M. 
Published: April 2015

Abstract
The marine Mesozoic sedimentary and paleoceanographic history of the western North Atlantic region is buried in the 0.5–2 km thick sediments of the ocean basin and in the 2–15 km thick sedimentary wedges forming the Atlantic continental margin and the Atlantic Coastal Plain. In the Atlantic Coastal Plain itself there are outcrops of shallow marine Upper Cretaceous strata for which Olsson (1978) has provided a good biostratigraphic sum- mary. North of New Jersey, Paleozoic strata in the Appalachian orogenic belt are present along the shoreline. These Paleozoic strata form part or all of the basement beneath the shelf as far north as the Grenville Front between Newfoundland and Labra- dor (Wynne-Edwards, 1972). In a general sense, the present east- ern coastline of Newfoundland, Nova Scotia, and the New England states matches that of the late Jurassic and late Cretace- ous. This study surveys the types and distribution of Mesozoic microfossils to further our understanding of Atlantic Mesozoic stratigraphy.
Micropaleontology, the microscopic study of fossils from about 0.001 to several millimeters in longest dimension, plays an important part in the reconstruction of the geological history of ocean basins. These small fossils are recovered, unbroken, in large numbers in core samples. The types and distribution in time and space of these fossils help the micropaleontologists to determine the relative age and original environment of the rocks in which they are found, as well as to reconstruct paleoceanographic conditions.
Different types of microfossils found in the marine Mesozoic strata offshore are nannofossils
Neogene marine microfossil biofacies of the Western North Atlantic
Authors: Poag C. Wylie , Miller Kenneth G. 
Published: April 2015

Abstract
The western North Atlantic Ocean was one of the first areas to be explored by the Deep Sea Drilling Project (DSDP; Leg 1, 1968). Subsequently, Glomar Challenger returned for 17 additional Legs (2,4,11,12,37, 39,43,44,45,49,51,76,78,82,93, 94, 95; Fig. 1). In addition to deep-sea drilling, more than 200 gravity and piston cores, collected mostly by the Lamont- Doherty Geological Observatory, have sampled Neogene sediments in the western North Atlantic (Fig. 2). In the shallower water of the continental shelf, more than 100 boreholes have sampled the Neogene sedimentary section (Ascoli, 1976; Poag 1978,1985, inScholle, 1982; and Poag inScholle and Wenkam, 1982; Hathaway and others, 1979; Barss and others, 1979; see Fig. 1). This paper summarizes microfossil biofacies data chiefly from DSDP Sites as published in the Initial Reports of that project. At the time of writing, detailed data from DSDP Legs 78, 82,93,94, and 95 had not yet been published. The Initial Reports data are supplemented by a few key published syntheses. Temporal and spatial composition and distribution of deep-sea zoo- planktonic, phytoplanktonic, nektonic, and benthic biofacies (sediment assemblages) are briefly discussed and compared with data from North American continental margin sites (Fig. 1). We point out the relationships of the composition and distribution of biofacies to paleoclimates, paleoceanography, sea-level changes, and sedimentary processes. Using a narrow definition of the term Neogene, we limit our discussion to Miocene and Pliocene microfossils. For a dicussion of Quaternary microfossils, the reader should