bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbidite sedimentation in the northwestern Atlantic Ocean basin
Authors: Pilkey Orrin H. , Cleary William J.
Published: April 2015

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

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

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

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

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
North Atlantic Mesozoic and Cenozoic paleobiogeography
Authors: Berggren W. A. , Olsson R. K.
Published: April 2015

A decade ago there was little information on the (quantitative) paleobiogeographic distribution of fossil calcareous plankton during the Mesozoic and Cenozoic (see early reviews by Berggren and Hollister, 1974; Berggren, 1978). The intervening years, however, have seen a concentrated effort towards delineating quantitatively based distribution patterns in both calcareous plankton and benthic foraminifera and relating these patterns to the evolution of surface and deep water masses in the Atlantic Ocean (i al., Haq and Lohmann, 1976; Haq and others, 1971; Tjalsma and Lohmann, 1983; Corliss, 1981; Miller, 1982; Miller and others, 1982; Nyong and Olsson, 1984; Roth and Bowdler, 1981; Thierstein, 1981).

Mesozoic paleobiogeography based on Atlantic microfossils is still in its infancy. Abyssal distributions of benthic foraminifera have been studied by Gradstein (1983), Nyong and Olsson (1984), and Sliter (1980). Numerous papers are available on the distribution of benthic foraminifera in shelf and epicontinental environments in Europe and North America but there is little information on the paleobiogeography of these in the North Atlantic basin. The record of Early and Middle Cretaceous plank- tonic foraminifera is scanty due to poor preservation because of an elevated calcite compensation depth (CCD). Late Cretaceous distribution of planktonic foraminifera is better known but quantitative studies are lacking. Calcareous nannofossil paleobiogeography is better known through quantitative studies by Doeven (1983), Roth and Bowdler (1981), and Thierstein (1981).

Summaries by Berggren (1978) and Thunell and Belyea (1982) on Atlantic Ocean Cenozoic planktonic foraminiferal biogeography
Space systems as marine geologic sensors
Authors: Anderle R. J.
Published: April 2015

Space systems that provide measurements applicable to marine geologic studies can be divided into two categories: ground- based observations of artificial and natural satellites and stars, and satellite-borne sensors that make visual, infrared, and radiofrequency measurements of the ground and ocean. The ground- based measurements provide information on plate motion and intraplate deformation, as well as long-wavelength (> 1000 km) information about the earth’s gravity field useful in tests of hypotheses of plate motion. The satellite-borne observations provide information on short-wavelength (<100 km) variations in the gravity field that correlate with seamounts and other geologic features, observations of terrestrial lineations and other surface features, limited information about ocean depth in shallow areas, and direct observations of sedimentary plumes and plankton in surface water. Satellite-borne instruments also yield indirect data relating to sedimentary processes and plankton productivity and dispersal through observation of ocean currents and their meanders, rings, ocean surface temperature, icebergs and sea ice, surface waves and internal waves that affect these processes. Satellites also provide a valuable service in collecting and relaying data from remote fixed stations and from drifting buoys and also determine the position of buoys so that current patterns can be determined.

Long-wavelength features of the earth’s gravity field are determined from laser range or from radio frequency Doppler observations of artificial satellites. Doppler observations are an indirect form of range measurements, since the maximum rate of change of the Doppler measurements within a pass varies inversely with the range between the transmitter and receiver
Resource potential of the western North Atlantic Basin
Authors: Dillon William P. , Manheim Frank T. , Jansa Lubomir F. , Pálmason Gudmundur , Tucholke Brian E. , Landrum Richard S.
Published: April 2015

We here consider the petroleum resources only of the off shelf portion of the western North Atlantic Ocean. Very little information is available for this region; off the eastern United States, only four petroleum exploration holes have been drilled in one restricted area seaward of the shelf, off the Baltimore Canyon trough. However, by interpreting seismic reflection profiles and Stratigraphie data from the Deep Sea Drilling Project (DSDP) and other wells on the adjacent slope and shelf, we can evaluate the geologic conditions that existed during development of the basin and that might lead to petroleum accumulations.

The wellknown factors that lead to oil and gas accumulations are availability of source beds, adequate maturation, and the presence of reservoir beds and seals configured to create a trap. The western boundary of the area considered in this paper, the present sloperise break, is one that has developed from the interplay of sedimentation and erosion at the continental margin; these processes are affected by variations in margin subsidence, sedi-ment input, oceanic circulation, sea level, and other factors. Thus the sloperise break has migrated over time and is locally underlain by slope and shelf deposits, as well as deepbasin facies. These changes in depositional environments may well have caused juxtaposition of source and reservoir beds with effective seals.

Several papers have been written on the hydrocarbon pros-pects of the (Jansa and MacQueen, 1978; Roberts and Caston, 1975; Dow, 1979; Hedberg, 1976; Mclver, 1975; Schott and others, 1975;
Subaerial volcanism in the western North Atlantic
Authors: Saemundsson Kristán
Published: April 2015

Three regions of subaerial volcanism occur near the eastern edge of the North America plate: Iceland, Jan Mayen and the Azores. In Iceland the ridge axis emerges above sea level, most of the volcanic pile was generated subaerially along its trace, and superimposed flank zones are situated off the accretion zone. The Azores lie on both sides of the oceanic ridge axis topping an extensive platform adjoining it. The platform was generated by excess volcanic production on the transecting ridge crest similar to the ridge formation in Iceland. The islands are stratovolcanoes formed off the ridge crest by flank volcanism. The volcanism and tectonic setting of Jan Mayen and the Azores is compared to the flank zones of Iceland, of which they appear to be close analogs.

Direct access to an active oceanic spreading axis makes Iceland particularly significant. The crust generated there suffers erosion which exposes the uppermost 1–2 km for three dimensional view.

Subaerial volcanism in Iceland’s accretion zone produces a layered igneous sequence due to a wider rift zone and extensive lateral spread of lava flows as opposed to the deep ocean ridge with a much narrower rift and outflow zone of lava. Subaerial spreading may also have been important in early rifting of the North Atlantic margins (Hinz, 1981). As a result, submerged layered extrusives with units thickening downdip towards the spreading axis and offlapping in the direction of spreading may exist near some of the North Atlantic continental margins (Tucholke and Ludwig, 1982).
Model of crustal formation in Iceland, and application to submarine mid-ocean ridges
Authors: Pálmason Gudmundur
Published: April 2015

During the early 1960s, when the idea of seafloor spreading was crystallizing out of geophysical data gathered over oceanic areas, similar ideas were beginning to take shape in Icelandic geology, but on the basis of a different kind of data. Geological studies of the structure of the eastern Iceland Tertiary lava pile led Walker (1959, 1960) to suggest that regional dips of the lavas were due to sagging accompanying lava deposition in the active volcanic zone. These ideas were further elaborated by Bodvarsson and Walker (1964), who tried to estimate the amount of crustal drift that might have accompanied the injection of dikes as observed in the eastern Iceland lava pile, taking into account the increase in dike fraction with depth in the crust. Subsequent studies of the Tertiary lava pile in other parts of Iceland have essentially confirmed a structure analogous to that given by Walker for eastern Iceland (Saemundsson, 1978).

Observations from two distinct geological regions can be brought to bear on the process of crustal accretion in Iceland. One region is the present active zone of rifting and volcanism, the axial rift zone. The other region is the flanking Tertiary lava pile where the internal structure of the uppermost well-developed crust can be observed to a depth of 1–1.5 km in valleys that have been carved into the crust by glacier action.

In the axial rift zones the constructional processes of extrusive volcanism, faulting, and Assuring take place as discrete but closely associated events.
Seismicity along the eastern margin of the North American Plate
Authors: Einarsson Páll
Published: April 2015

The eastern boundary of the North American Plate is marked by a narrow and continuous belt of seismic activity. The earthquake zone follows the crest of the Mid-Atlantic Ridge and its associated fracture zones (F.Z.) (Fig. 1; Plate 8A; Vogt, this volume, Ch. 12.) and is intimately related to the process of plate separation, transform faulting, and generation of oceanic crust. This part of the Mid-Atlantic plate boundary has the advantage of being relatively close to the dense seismograph networks of North America and Europe, and has therefore been the subject of more study than most other parts of the oceanic rift system. For this reason it has sometimes been taken as the type example of an oceanic rift, which can be misleading. Other segments of the ridge system, such as parts of the East Pacific Rise, have been shown to possess a distinctly different seismicity pattern (Stover, 1973), with most earthquakes occurring along the fracture zones and practically no seismicity along the ridge axes.

In this paper we will describe the main features of the seismicity of the mid-oceanic ridge system in the North Atlantic and Arctic Oceans and how it relates to the physical state and processes near the plate boundary. Intraplate earthquakes, that is events within the North American Plate, are dealt with by Zoback and others (this volume).

Because of the enormous amount of literature on the subject no attempt has been made to give complete reference to every paper. For more complete references
The Continental Margin
Authors: Haworth Richard T.
Published: April 2015

Over 80% of the continental margin of eastern Canada is underlain by a seaward-thickening wedge of Tertiary and Mesozoic sedimentary rocks, a most attractive exploration target for oil and gas. The first offshore wells were drilled on the Grand Banks in 1966, just before publication of the 1970 edition of the Geology and Economic Minerals of Canada in which a mere 2,000 words attested to the fact that “the Mesozoic record of southeastern Canada [was] scant.” By 1981, a total of 158 wells had been drilled, significant shows of gas and/or oil had been recorded in 22 of the wells, and production appeared to be imminent in the Sable Island and northern Grand Banks areas. With the contemplation of production facilities comes a requirement for extensive information regarding the nature of the seabed and its stability, environmental hazards such as icebergs and their seabed scours, and the susceptibility of the coastal environment to the pollution created by marine oil spills. Thus, economic and environmental pressures have been largely responsible for the rapid accumulation of knowledge about the continental margin of eastern Canada.

Each section of this report is a precis of each chapter of the synthesis volume, The Continental Margin: Eastern Canada. Data and interpretations will be displayed in the text on standard 1:10 million scale, page-size maps (Figs. 1, 2, 3) as background for discussion of the entire margin. A comprehensive bibliography will also be included. Contributions to the volume will be organized so as to make the clearest possible distinction between fact and interpretation, and in the latter case, present the different sides of controversial questions.
Atlantic continental margin of the United States
Authors: Grow John A. , Sheridan Robert E.
Published: April 2015

The objective of this Decade of North American Geology (D-NAG) volume will be to focus on the Mesozoic and Cenozoic evolution of the U.S. Atlantic continental margin, including the onshore coastal plain, related onshore Triassic-Jurassic rift grabens, and the offshore basins and platforms. Following multiple compressional tectonic episodes between Africa and North America during the Paleozoic Era that formed the Appalachian Mountains, the Mesozoic and Cenozoic Eras were dominated by tensional tectonic processes that separated Africa and North America. Extensional rifting during Triassic and Early Jurassic times resulted in numerous tensional grabens both onshore and offshore, which filled with nonmarine continental red beds, lacustrine deposits, and volcanic flows and debris. The final stage of this breakup between Africa and North America occurred beneath the present outer continental shelf and continental slope during Early or Middle Jurassic time when sea-floor spreading began to form new oceanic crust and lithosophere between the two continents as they drifted apart. Postrift subsidence of the marginal basins continued in response to cooling of the lithosphere and sedimentary loading.

Geophysical surveys and oil-exploration drilling along the U.S. Atlantic continental margin during the past 5 years are beginning to answer many questions concerning its deep structure and stratigraphy and how it evolved during the rifting and early sea-floor-spreading stages of the separation of this region from Africa. Earlier geophysical studies of the U.S. continental margin used marine refraction and submarine gravity measurements. Single-channel seismic-reflection, marine magnetic, aeromagnetic, and continuous gravity measurements became available during the 1960s.
The Gulf of Mexico Basin
Authors: Salvador Amos , Buffler R. T.
Published: April 2015

The accumulation of abundant geologic and geophysical information about the Gulf of Mexico Basin during the last few decades has contributed significantly to the understanding of the geologic history of this important geologic province—its birth during Late Triassic-Jurassic time, and the subsequent geologic events that have given the basin its present configuration.

Much of this information has been the product of extensive surface and sub-surface geologic studies, geophysical surveys, and drilling around the periphery of the basin, mainly in connection with the exploration for oil and gas. More recently, invaluable data have been obtained in the previously little-known central part of the basin by regional geophysical surveys—particularly seismic reflection and refraction—and the results of the Deep Sea Drilling Project. The geophysical surveys were conducted by academic institutions, the U.S. Geological Survey, and the petroleum industry.

The results of these geophysical surveys have shed much light on the seismic nature of the crust underlying the Gulf of Mexico Basin—“oceanic” in the deep central part and “transitional” around the periphery of the deep basin. (The term “transitional” is applied to crust intermediate in thickness between oceanic and continental crust, possibly the result of stretching during episodes of rifting or pull-apart.) The surveys have also for the first time contributed information concerning the distribution, thickness, and structural configuration of the extensive salt deposits, as well as of the thick sedimentary column that fills the central part of the basin.

This large volume of geologic and geophysical information is now scattered throughout the extensive literature on the Gulf of Mexico Basin.
The Caribbean Region
Authors: Case J. E. , Dengo Gabriel
Published: April 2015

The Caribbean region has been an attractive area of the world since Columbus rediscovered it in 1492. In colonial times the Caribbean was an area of settlement, economic exploitation, and intense competition between the powerful nations of Spain, England, France, and Holland. Geological interest in the region, in a sense, started with the search for gold, silver, and precious stones, and the quest for the sources of the El Dorado legend. Many accounts of exploration during the conquest not only mention fabulous mines but also describe volcanoes, thermal springs, and the effects of earthquakes. It was only natural that in the initial days of modern geology the region should be intriguing to earth scientists. Thus, geologic accounts appear in the writings of such naturalists as von Humboldt, Karsten, De La Beche, Montessus de Ballore, and others. Within a global context, the first attempt to portray the geology of the region was by Suess in 1885.

In the early part of the 20th century, scientific interest, and the construction of the Panama Canal and exploration for oil greatly advanced geologic knowledge of the region. Many European scientists worked in the Caribbean during their Wanderjahren. Much of this knowledge was masterfully summarized by Schuchert (1935), and for the Central American part by Sapper (1937). Until that time, scientific contributions were mostly by geologists residing in countries outside the region; only a few indigenous geologists conducted Caribbean research, but some of their contributions were outstanding.

Long-range scientific programs were initiated shortly before World War II by Utrecht and Princeton Universities, but the work of both institutions was interrupted during the war years.
The Midcontinent Province
Authors: Sloss L. L.
Published: April 2015

Although Charles J. Mankin, Peter R. Vail, and L. L. Sloss constitute the group charged with planning, guiding, and expediting preparation of a volume titled The Midcontinent Province: United States for the series, The Geology of North America, this paper is a highly personal document put together without benefit of input from Mankin and Vail; they cannot be held responsible for the many sins of commission and omission that are recorded in the pages that follow.

Readers, especially those who are asked to consider individual regions within the Midcontinent province, should exercise an appropriate degree of compassion where outright errors of fact are found; such mistakes are inevitable when one person attempts to cover the Phanerozoic record of a major part of a continent, but all recognizable errors require early identification and correction. It should be noted further that the stratigraphie classification and correlation implicit in this preliminary treatment are not integrated with COSUNA (Correlation of Stratigraphie Units of North America) charts; these will be available shortly(?) and will be the framework for final texts.
Quaternary geology of Canada
Authors: Fulton R. J.
Published: April 2015

The objective of this volume is to synthesize the Quaternary geology of Canada. In essence, it is an update of “Quaternary Geology of Canada“ (Prest, 1970), which synthesized knowledge of the Quaternary geology of Canada up to 1965. This volume will present current knowledge, ideas, and concepts, with particular emphasis on limits of glaciation, concepts of ice-sheet dynamics, nature of surface materials, and the interaction between Quaternary geology and the activities of man. The volume will be in two parts, one dealing with fundamental Quaternary geology and stratigraphy and the other dealing with aspects of Quaternary geology related directly to man and land use.
Innuitian Orogen and Arctic Platform
Authors: Trettin H. P.
Published: April 2015

The outline presented and discussed in this paper is preceded by a brief introduction to the geology of the region that explains the proposed organization of geological topics. This introduction is restricted to Canada because several important reports on the geology of northern Greenland are currently in press or preparation. The summary is based mainly on the framework established by Thorsteinsson and Tozer (1970) with modifications necessitated by a large amount of more recent work.
Geology of the Canadian Appalachians
Authors: Williams Harold
Published: April 2015

The Appalachian orogen in Canada is a northeast-trending belt of upper Precambrian and Paleozoic rocks that were deformed in late Precambrian (Avalonian), Middle Ordovician (Taconian), Devonian (Acadian), and Permian-Carboniferous (Alleghanian) times. The Canadian Appalachians lie southeast of the Canadian Shield and Interior Platform of North America, and the system is bounded to the east by the Atlantic Ocean (Figs. 1 and 2). Toward the southwest, its rocks can be traced through the southeast United States to Alabama. Toward the northeast, its submerged offshore extensions are covered by Mesozoic and Cenozoic sediments of the Atlantic continental margin. Syntheses of the orogen and its offshore extensions in Canada and the United States are keyed to a similar format, using many of the same maps and illustrations for purposes of continuity and clarity.

Rocks and structures like those of the Canadian Appalachians reappear on the opposite side of the Atlantic Ocean in the British Caledonides and extend northward to East Greenland and Scandinavia. An overview of the East Greenland Caledonides will be included in the Canadian Appalachian volume, because these rocks are a natural extension of those along the west flank of the Appalachian orogen and because of contiguity with the North American continent.

The present stratigraphic and tectonic analysis of rocks of the Canadian Appalachians is based on both a temporal and spatial breakdown. Temporally, its rocks can be subdivided into four broad categories: those of late Precambrian-early Paleozoic age, those of middle Paleozoic age, those of late Paleozoic age, and those of early Mesozoic (Triassic) age.
The Appalachian/Ouachita Orogens
Authors: Hatcher Robert D. , Viele George W.
Published: April 2015

The Appalachians and Ouachitas are Paleozoic orogens developed along the eastern and southern Precambrian continental margins of North America. Their histories record considerable diversity in stratigraphic, deformational, metamorphic, and plutonic events. Our purpose here is to outline the various subdivisions of the orogens and comment upon what we know of their history at the present time.

The Appalachian orogen, as presently exposed, extends from Newfoundland to Alabama in eastern North America (Fig. 1). The Ouachita orogen extends from Arkansas to north-central Mexico (Fig. 2). The connections between these two orogens are buried beneath the Mississippi Embayment of the Gulf Coastal Plain; consequently, details of that region may never be precisely known.

The subdivisions outlined below for the Appalachians, and to some degree for the Ouachitas, represent a time-space categorization that we hope will serve to break down the classic geographic subdivisions that have historically dominated our descriptions of the Appalachians. These subdivisions provide a means by which the history of the orogens may be more easily described and related to the constructive processes that built them on the margins of North America during Paleozoic time. These subdivisions reflect the likely plate tectonics history of the orogens and the manner in which the present southern and southeastern continental margins of North America evolved throughout Paleozoic time.
Precambrian of the Conterminous United States
Authors: Reed John C. , Sims Paul K. , Houston Robert S. , Silver Leon T. , Rankin Douglas W. , Reynolds Mitchell W.
Published: April 2015

Precambrian rocks are at or near the surface in only about 10 percent of the conterminous United States, but it can reasonably be inferred that they comprise the continetal crust beneath about 90 percent. They are missing or unrecognized in the exotic terranes along the Pacific margin of North America, but they probably form significant parts of the crust in exotic terranes or continental fragments accreted to the eastern part of the continent during Paleozoic time. Thus, the total area of Precambrian rocks to be considered in this volume is comparable to that of the exposed Precambrian of the Canadian Shield. It is important to remember that in spite of the enormous lateral extent of the craton the volume of the continental crust is almost insignificant. The width of the North American craton is more than half the radius of the planet, but the thickness of the continental crust is less than one hundredth of the planetary radius (fig. 1). The volume of the crust is less than 2 percent of the volume of the mantle beneath the U.S. part of North America.

Precambrian rocks contain the only available record of the assembly and evolution of the fragile continental raft that we know as North America during more than four fifths of geologic time. Of the areas of exposed Precambrian rocks in the conterminous United States, about half have been covered by modern reconnaissance geologic mapping (scale 1:250,000 or larger); less than a quarter have been covered by detailed modern mapping (scale 1:62,500 or larger).
Geology and tectonic evolution of Alaska
Authors: Plafker George , Jones D. L.
Published: April 2015

The last major synthesis of the geology of Alaska was Areal Geology of Alaska (P. S. Smith, 1939, U.S. Geological Survey Professional Paper 192). Up to that time, less than half of what was then the Territory of Alaska had been surveyed by geologists, even by the crudest exploratory standards. As a consequence, Professional Paper 192 was concerned primarily with the general spatial distribution, lithology, and relative ages of rock units and Quaternary deposits in Alaska with incidental mention of structure, metallic mineral deposits, and coal resources.

Since 1939 there has been a vast increase in the amount and diversity of earth science research in Alaska. The initial impetus was during World War II when expanded studies of mineral resources, surficial deposits, and Aleutian Arc volcanoes were undertaken throughout Alaska. In the post-war years there has been an explosive expansion of geologic and geophysical mapping and research both onshore and offshore. This accelerated effort was spurred on by the emergence of Alaska as a major petroleum producer, by the discovery of major metallic mineral deposits at various localities in the state, and by the extensive systematic helicopter-supported mapping and resource appraisals that have been carried out mainly by government agencies as part of the requirements for Alaska land classifications. In addition, the great 1964 earthquake stimulated intense interest in neotectonic activity and geologic hazards state-wide. As a result of work since 1939, modern geophysical and geologic data are now available for much of Alaska, and few areas remain unexplored.
The Cordilleran Orogen
Authors: Gabrielse H. , Yorath C. J.
Published: April 2015

The Canadian Cordilleran Orogen comprises the mountainous region of western Canada and includes the adjacent Pacific offshore area to the foot of the continental slope. Because the evolution of the orogen is linked directly to the dynamics of the nearby interacting lithospheric plates of the eastern Pacific Ocean, the Cordilleran volume deals with the oceanic region as far west as the spreading centres bounding the Juan de Fuca plate and the Queen Charlotte transform fault. (In this text, “Cordillera” implies “Canadian Cordillera” unless otherwise specified.)

In general terms the geology of this region can be related to rifting that formed the western margin of ancestral North America, subsidence and sedimentation along the resultant passive continental margin and, finally, its interaction with allochthonous terranes that produced the varied tectonic styles, regional metamorphism, the various plutonic and volcanic suites, and controlled the physiographic evolution leading to the present landscape. Current concepts on plate-tectonics play an important role in interpretations of the evolution of the Cordillera and, therefore, the integration of geophysical, structural, stratigraphic, and sedimentological data from studies underway in the Pacific offshore region is particularly cogent to an understanding of the ancient history of the orogen. These concepts are stressed by organizing the volume into chapters dealing with assemblages of rocks deposited or emplaced in environments that for the most part have modern-day plate-tectonics analogues.

This is an ideal time for an updated synthesis of Canadian Cordilleran geology. Since the last synthesis in 1970, a great deal of data have been collected and analyzed in the light of the revolutionary plate-tectonics concepts.
Geology of the Grand Canyon
Authors: Spamer Earle E.
Published: April 2015

The first annotated bibliography on Grand Canyon geology, this splendidly organized and detailed bibliography is designed as a research guide to existing literature. It is an annotated compilation of Grand Canyon research projects as developed and accumulated to date. It is a synthesis of many hundreds of observations and conclusions drawn from them and is intended to expedite the use of data in future research. Because of the many different fields of specialization represented, this remarkably detailed and pain stakingly thorough accumulation of literature, titles, and annotations should prove a tremendous boon to future progress in the accumulation of the geological literature of Grand Canyon.
Mineral Resources of China
Authors: Ikonnikov A. B.
Published: April 2015

Published in 1975 on microform, this 555-page volume provides an overview of the mineral resources of China. It contains chapters devoted to the structural geology of China; coal; oil and gas; iron ore; heavy metals; light, noble, and rare metals; and numerous maps. An introductory chapter provides a brief history of the geological exploration of China, beginning with von Richtofen’s 1870 survey.
Geology of the Grand Canyon
Authors: Spamer Earle E.
Published: April 2015

Volume 1 of this guide was published in 1990 as Geological Society of America Microform Publication 21, complemented by the four volume series, Geology of the Grand Canyon: an Annotated Bibliography (GSA Microform Publications 13, 14, 17, and 20, published in 1983, 1984, 1988, and 1990, respectively). The present volume is complemented by volume 5 of the annotated bibliography, also a GSA Microform publication. All of these volumes cover the entire history of Grand Canyon geological literature, from the first geological note of the canyon in 1857. They will soon be complemented by a companion publication (The Grand Canyon Fossil Record, presently in preparation for publication) that will provide a complete guide to the paleontological literature for the Grand Canyon. At that time, the basic research guides to all of the Grand Canyon geological literature will be complete.
Questions on Geologic Principles
Authors: Reyer Eduard
Published: April 2015

The appearance of this translation of Eduard Reyer's Geologische Prinzipienfragen (1907) is as timely as John Biram's English translation of Alfred Wegener's Die Entstehung der Kontinente und Ozeane (1912, 4th rev. ed., 1928, Dover, 1966). Both translations mark a general revival of interest in the historical growth of two major geodynamic concepts: gravity tectonics and continental drift. In a way, these two aspects of geodynamics are complementary. Reyer, who lived from 1849 to 1914, drew attention to the potential energy created by vertical crustal movements; Wegener, who lived from 1880 to 1930, stressed the importance of great horizontal displacements. Wegener's book appeared to achieve a real breakthrough for continental drift, an idea that had been ripening since the seventeenth century, but most geoscientists rejected his proposals because of the preconceived opinion that crustal rocks were too strong and that the proposed driving forces too weak for such a process. An entirely new branch of geonomy paleomagnetism had to be developed before enough diagnostic facts were gathered to prove that continental drift did, nevertheless, occur in the Phanerozoic. Similarly, Eduard Reyer developed a clear concept of glide tectonics (Gleitfaltung) through observation and experimentation, but his ideas conflicted with the prevailing contraction theory which was then strongly supported by his teacher and later colleague Eduard Suess (1831-1914). Custom, inertia of thinking, and authority caused a rejection of Reyer's ideas by most of his contemporaries. Disappointed, Reyer devoted his later years to social reform, to the founding of public libraries, and to various philosophical problems. Only once, because he was deeply convinced of the correctness of his ideas, did he turn his efforts and his genius to the fundamental problems of geology. Geologische Prinzipienfragen, his last book on geology, has now been translated into English: it represents a matured concept of geology at the beginning of the twentieth century. Reyer's book is of great value for two major reasons: first, it contains many examples of unbiased observation, clear inductive thinking, and verification by means of experimental tests. Secondly, by stressing the role of gravity as a driving force, it marks a milestone in the development of structural geology.
Return to sport after hip surgery for femoroacetabular impingement: a systematic review
Authors: Casartelli Nicola C , Leunig Michael , Maffiuletti Nicola A , Bizzini Mario
Published: April 2015

Background

We aimed to appraise (1) the rate of return to sport of athletes after hip surgery for femoroacetabular impingement (FAI) and (2) some aspects that may influence the return to sport.

Methods

Four databases (EMBASE, PubMed, Web of Science, Cochrane Library) were searched until 21 October 2014. Studies evaluated return to sport of athletes who underwent hip surgery for the treatment of symptomatic FAI. A validated tool was used for quality evaluation of the studies.

Results

A total of 18 case series (level of evidence IV) with moderate-to-high methodological quality were included. On average, 87% of athletes returned to sport after hip surgery for FAI and 82% returned to the same sport level as before the occurrence of the symptoms. Professional athletes seem to return to sport at a higher rate compared with recreational and collegiate athletes. Sport participation after hip arthroscopy tends to decrease for professional athletes at short-term and mid-term follow-ups. Diffuse hip osteoarthritis at the time of surgery may not allow athletes to return to sport.

Conclusions

Most athletes return to sport after hip surgery for the treatment of symptomatic FAI. The level of competition, time of evaluation after hip surgery and presence of articular cartilage lesions at the time of surgery may influence return to sport. Future studies with higher levels of evidence should describe and evaluate return to sport protocols after hip surgery for FAI.
Tracking surgical day care patients using RFID technology
Authors: Wauben L S G L , Guédon A C P , de Korne D F , van den Dobbelsteen J J
Published: April 2015

Objective

Measure wait times, characterise current information flow and define requirements for a technological information system that supports the patient's journey.

Design

First, patients were observed during eight random weekdays and the durations of actions performed at each phase of the surgical trajectory were measured. Patients were grouped into patients receiving general anaesthesia or local (or topical) anaesthesia. Second (active) Radio Frequency IDentification (RFID) technology was installed and patients were tracked during 52 weekdays. Length of hospital stay, length of stay and wait times per phase, and differences in wait times between the two types of administered anaesthesia were analysed. Third, interviews were conducted to characterise the current information flow between staff, and between staff and escorts (patients’ family/friends escorting them throughout their journey).

Results

Observations (198 patients) showed that the average duration of actions for general anaesthesia patients took longer than for local anaesthesia patients, especially at the recovery phase (general anaesthesia: 0h16, local anaesthesia: 0h01).

RFID tracking (622 patients): Significant differences were seen for wait times between general and local anaesthesia patients at: preoperative ward (p=0.014), recovery (p<0.001) and postoperative ward (p<0.001). The average percentage of wait time during the entire hospital stay ranged from 64% to 68% (with variation in groups being substantial).

Interviews (30 escorts, 9 ward nurses and 8 holding/recovery nurses): Escorts did not use the current information system and ward nurses indicated problems with exchanging information concerning bringing/picking up patients to/from the holding/recovery that resulted in unnecessary wait times for some patients (mainly local anaesthesia patients).

Conclusions

Most time spent in hospital is wait time. A Patient Tracking System was designed to automatically display the phase in which a patient is in. It provides transparency for patients and staff in the surgical trajectory and is expected to reduce intermittent communication, improve patient flow, reduce wait times and improve patient and staff satisfaction.