bluuebunny/crossref_metadata_2025 huggingface dataset:
Imprint of Arctic sea ice cover in North-Greenland ice cores
Authors: Della Lunga Damiano , Maria Hörhold , Twarloh Birthe , Melanie Behrens , Remi Dallmayr , Tobias Erhardt , Camille Marie Jensen , Frank Wilhelms
Published: October 2019

Abstract. Sea ice is a key component of the climate system, since it modifies the surface albedo, the radiation balance, as well as the exchange of heat, moisture and gases between the ocean and the overlying atmosphere. Hence, the reconstruction of sea ice cover before the instrumental era and the industrial times is crucial to understand the evolution of Arctic climate in the last millennium and better predict its future evolution. However, identifying relevant paleo proxies in climate archives related to sea ice cover is not straightforward. Ice cores from polar regions offer great potential to provide high-resolution records of Arctic sea ice variability from chemical impurities such as Bromine species, which were recently proposed as indicators of sea ice extent, although their variability might be modulated by regional influences. We here use Bromine and Bromine enrichment of two ice cores form North Greenland (B17 & B26) and investigate its potential as proxy to reconstruct sea ice extent over the period 1363–1993 AD. Across the instrumental period, a good correlation is observed with the Baffin Bay and the Greenland Sea for B26 and B17 respectively, with both record showing minima corresponding to known Artic warming events such as the 1420 AD (for B17) and 1920–1940 (Early century warming, B17 & B26), together with a strong decline starting in the late 19th century. We simultaneously derived a chemical classification of sea ice-related contributors of ionic species (i.e. blowing snow, frost flowers, open water) utilizing the depletion of SO42− compare to Ca2+, K+ and Mg2+ characterizing sea ice brines and blowing snow as well the excess of Br− and Cl−, characterizing frost flowers, to elucidate the evolution of the different sources. In both B17 and B26 records we observe a strong contribution of blowing snow in the earliest part of the datasets, gradually declining in recent years in favour of open water sources.
Delusion Formation through Uncertainty and Possibility-blindness
Authors: Ariso José María
Published: October 2019

Algunos autores han intentado considerar los delirios como certezas –entendidas en el sentido de Wittgenstein– debido a las similitudes que parecen existir entre sus respectivos estatus epistemológicos. Sin embargo, dicho intento ha sido criticado con agudeza, entre otras razones, porque el contenido de los delirios choca frontalmente con el contenido de las certezas, por lo que los delirios no pueden ser comprendidos debido a los cambios en las relaciones de significado. Pero es evidente que, aunque los delirios no se puedan contemplar como certezas, muchos delirios afectan de un modo u otro al sistema de certezas del paciente. Partiendo de esta base, no es descabellado pensar que dicha influencia pudiera ser también recíproca: en otras palabras, parece sumamente recomendable analizar si algunos delirios se podrían contemplar como el resultado de variaciones en certezas. En este artículo llevo a cabo dicho análisis al intentar mostrar que el origen de algunos delirios pedestres y severos puede ser hallado en lo que llamaré “ceguera a posibilidades” e “incertidumbre”, términos que he desarrollado teniendo en cuenta la obra del filósofo Ludwig Wittgenstein.
Aclaraciones hermenéuticas a la noción de «significante» en Lacan
Authors: Carmine Fasolino Ruben
Published: October 2019

El texto trata de abordar la noción de «significante» lacaniano desde una hermenéutica filosófica. Para ello se recorrerán algunos momentos clave de la elaboración de Lacan sin dar por supuesto ningún uso o definición que se promueve del término en cuestión, todo ello con la intención de subrayar aspectos como el del sentido y la vedad que desde un análisis hermenéutico-filosófico pueden ser captados en toda su profundidad.
Animals positive for Yersinia pestis in Armenia
Authors: Danielyan Ruben
Published: October 2019

Objective: The objective of this study was to determine the species composition of mammals and parasites involved in the epizootic process of plague in Armenia and their geographic distribution.Introduction: Plague was first identified in Armenia in 1958 when Y. pestiswas isolated and cultured from the flea species Ct. teres collected from the burrows of common voles in the northwestern part of the country. In the process of digitalizing archived data, a statistical and spatial analysis of the species composition of mammals and parasites involved in the epizootic process of plague between 1958 and 2016 was performed.Methods: The plague archives of the NCDCP were exploited. The geographic addresses from which strains of Y. pestis were isolated from mammals and their parasite species were analyzed and grouped into 38 administrative regions (Fig.1). For geostatistical analysis, databases were created using Microsoft Excel and converted into a ESRI Geodatabase (Fig.2).Results: Data from the especially dangerous pathogen laboratories indicate that 9329 Y. pestis strains were isolated in 27 of the 38 regions of the country with 7022 (75%) of the strains found in just four regions: Abovyan 2597 (28%), Sisian 1953 (21%), Martuni 1416 (15%) and Ashotsk 1056 (11%) (Fig.3). During this period, plague bacteria were isolated from 17 mammal species including 15 rodents, Mustela nivalis (weasel), and Neomys fodiens (shrew) (Fig.4). Y. pestis was isolated from 22 species of fleas belonging to 11 genera along with two families of ticks. Of the 9329 bacterial isolates, 6540 (70.2%) came from fleas, 2646 (28.3%) came from mammals and 143 (1.5%) were from ticks (Fig.5).Conclusions: In Armenia, the primary mammalian host for Y. pestis is the common vole Microtus arvalis from which 2600 isolates (27.9%) were taken. Flea species from which large numbers of plague bacteria have been isolated include Ct. teres-3758 (40.3%), Ct. wladimiri-1262 (13.5%) and C. caspia-667 (7.1%).
A Survey on Digital Immigrants’ Technology Usage and Practice in Teaching Digital Natives
Authors: Buragohain Dipima
Published: October 2019

The widespread use of digital technologies by digital natives has put a considerable amount of pressure on their educators, who are mostly digital immigrants, to recognize the relevance of digital connectivity, learn new ways of thinking and processing information of the digital natives, and integrate it into their teaching environments. The current study looks into these aspects while discussing the technology usage and practice of digital immigrant educators in higher education. A survey was conducted with a structured questionnaire on the technology usage and teaching strategies implemented by the digital immigrant educators to teach digital natives in higher education. The findings reported that digital immigrant educators must be accustomed to the a) diverse needs of digital native students and b) use and applications of digital technologies in order to create and practice interactive and collaborative teaching environments.
Ocorrência de larvas de crustáceos na desembocadura do Complexo Estuarino de Paranaguá, Paraná (Brasil)
Authors: E outros Patricia Akemi Inoue
Published: October 2019

Ocorrência de larvas de crustáceos na desembocadura do Complexo Estuarino de Paranaguá, Paraná (Brasil) 
HINTS IN THE ER- case report
Authors: Zasadzińska Katarzyna , Kukwa Andrzej
Published: October 2019

Vertigo is a false sense of motion of either the environment or self and is diagnosed in approximately half of the patients with dizziness. Acute spontaneous onset of vertigo is called acute vestibular neuritis (AVN). It is caused by peripheral lesion and requires symptomatic treatment.
The symptoms of AVN can mimic a central pathology like cerebellar or brainstem infarction with no concomitant red-flag manifestation. Magnetic Resonance Neuroimaging with Diffusion-weighted imaging (MRI-DWI) as well as Computed Tomography (CT) scan delivers false negatives results what significantly delays stroke treatment.
HINTS is an acronym for the battery of three bedside tests of ocular motor physiology. The method is more sensitive in diagnosing posterior circulation infarct than MRI-DWI with specificity -96 %.
We present a case of a patient with vertigo who underwent two cranial CT scans and neurological examination. HINTS was worrisome. The brainstem infarct diagnosis was confirmed by MRI-DWI.
Uzyskanie standardu pasywnego
Authors: Pankanin Mateusz , Szczepański Marcin
Published: October 2019

Celem artykułu jest ocena budynku mieszkalnego w zabudowie bliźniaczej w świetle obowiązujących przepisów dotyczących energooszczędności oraz analiza czasów i kosztów jego wykonania w dwóch wariantach klasy energetycznej. W ramach analizy wyliczono bilans strat oraz zysków ciepła, na podstawie którego utworzono wskaźniki charakterystyczne. Następnie zaproponowano rozwiązania pozwalające obniżyć te wskaźniki do poziomu dopuszczalnych według obowiązujących i przyszłych przepisów dla budynków jednorodzinnych pasywnych oraz porównano koszty i czasy realizacji budynku tradycyjnego ze zmodernizowanym w kierunku klasy budynku pasywnego.
Stratigraphic Studies in the Jurassic of Northeastern Mexico: Evidence for the Origin of the Sabinas Basin
Authors: Longoria Jose F.
Published: October 2019

The Jurassic sequence of northeastern Mexico includes Oxfordian through Tithonian-aged marine sediments that were deposited in eight environments: (1) sabkha, (2) nearshore, (3) lagoonal, (4) shoal, (5) inner-shelf, (6) restricted-shelf, (7) open-shelf, and (8) pelagic. Lithologic correlations relate the sections studied with the type sections of coeval rocks described from the Sierra de Parras. Based on their lithic characteristics they are assigned to the Minas Viejas, Zuloaga, La Gloria, La Caja, La Casita, and San Angel Formations.

Three biohorizons are established: (1) the first stratigraphic occurrence of the ammonite Idoceras in the early Kimmeridgian, (2) the first appearance of calpionellids in the middle Tithonian, and (3) the first occurrence of Calpionella elliptica Cadish at the Jurassic/Cretaceous boundary. Two lowerings of sea level are identified in the sections studied, the first in early Kimmeridgian and the second in the early Tithonian. These two drops of sea level are separated by a sea-level rise in the middle Tithonian. Eustatic changes of sea level are associated with tectonism in the area.

Active transform faulting in the Gulf of Mexico region resulted in the juxtaposition of Oxfordian-Kimmeridgian shallow- and deep-water facies. The translations along transcurrent faults result in a SE-NW displacement of about 300 kilometers, which caused the formation of the Sabinas Basin of northeastern Mexico. Late Jurassic sea-floor spreading in the central Gulf of Mexico is regarded as the driving mechanism.

The Oxfordian-Kimmeridgian and late Tithonian paleogeographies of northeastern Mexico are reconstructed, and parallel lineal facies belts are envisioned which account for the sporadic distribution of the Jurassic shallow-water facies in northeastern Mexico.
Outer-Ramp Limestones of the Zuloaga Formation, Astillero Canyon, Zacatecas, Mexico
Authors: Meyer Martha G. , Ward William C.
Published: October 2019

A thick section of Zuloaga Limestone (Oxfordian) crops out in Astillero Canyon about 30 km south of Concepcion del Oro, Zacatecas, Mexico and about 50 km southeast of the type locality of the Zuloaga Formation. Here the Zuloaga Formation is predominantly a carbonate mudstone-wackestone with minor amounts of grainstone. The section is divided into the following facies, in order of their volumetric importance: (1) skeletal mudstone and wackestone, (2) pellet mudstone and wackestone, (3) pellet packstone-grainstone, (4) ooid-peloid grainstone-packstone, (5) ooid grainstone, and (6) algal boundstone. In addition, there are a few thin dolomite beds. Northward toward the Coahuila Peninsula and eastward toward the Tamaulipas Arch the Zuloaga Limestone thins and contains more grainstone and evaporite.

The Zuloaga Limestone was deposited on a carbonate ramp which sloped gently southward from the Coahuila Peninsula and westward from the Tamaulipas Arch. On the inner part of the ramp, carbonate sediment accumulated in peritidal environments. The area of Astillero Canyon was on the “outer ramp”, probably 150 km south of the southern shoreline of the Coahuila Peninsula. At this locality, Zuloaga limestones were deposited predominantly in low-energy subtidal environments. The thickness of the Zuloaga Formation indicates that this was a relatively rapidly subsiding part of the epicontinental basin, but carbonate accumulation kept up with subsidence and shallow-water regimes prevailed.

Measured sections of the Zuloaga Limestone on both limbs of the same anticline are difficult to correlate, indicating that lithic units are not laterally extensive. The vertical sequences suggest that shallow-water depositional environments frequently shifted from place to place as the epicontinental shelf continuously subsided. Thus, the Zuloaga strata at Astillero Canyon lack the predominately regressive characteristics of the age-equivalent Smackover Limestone in South Texas. Assuming that the grainstone and algal-stromatolite represent deposition in the shallowest water, the stratigraphic section at Astillero Canyon may be divided into at least eight major “shoaling-upward” sequences.
THE UPPER SMACKOVER OF THE GULF RIM: DEPOSITIONAL SYSTEMS, DIAGENESIS, POROSITY EVOLUTION AND HYDROCARBON PRODUCTION
Authors: MOORE CLYDE H.
Published: October 2019

A generalized stratigraphic framework for the upper Jurassic is suggested, in which the name Haynesville Formation is utilized, and the name Lower Cotton Valley Lime is suppressed in favor of the Gilmer, where appropriate. Eustatic sea-level fluctuations have resulted in patterns of sedimentation common to upper Jurassic sequences across the entire northern Gulf of Mexico region and hence indicate the wide applicability of this generalized stratigraphic framework.

The presently accepted model of the Smackover-Haynesville sedimentation must be modified to take into account sea-level fluctuations, subsidence, and sediment availability. The model developed here is simply one of lower Smackover basin fill during a rapid transgressive phase and upper Smackover regional shoaling during a sea-level stillstand in which sedimentation was in equilibrium with subsidence. The lower and upper Smackover are not necessarily time equivalent, but represent two separate sedimentologic sea-level regimens. The Haynesville Formation is thought to be a separate sedimentologic package that was deposited during the next sea-level rise; the Gilmer Limestone formed a shelf-margin barrier behind which the lagoonal Buckner evaporites were deposited. The evaporites graded landward into quartzose clastics.

Predictable regional porosity patterns have developed in the Smackover-Haynesville, in response to early diagenetic overprints, controlled largely by eustatic sea-level subsidence interactions. These patterns include: updip oomoldic porosity in a regional meteoric-water system developed during the upper Smackover sea-level stillstand; downdip porosity preservation under marine conditions along the shelf margin; regional dolomitization associated with reflux of evaporitive waters from the Buckner lagoon behind the Gilmer shelf-margin barrier.

Structural hydrocarbon traps associated with salt movement are the most common type of Late Jurassic trap. Buckner evaporites or Haynesville shales usually form the seals in the Late Jurassic reservoirs. Jurassic source rocks are probably lower Smackover limestones and Norphlet shales. Sourcing is generally local with migration into updip areas, particularly where regional dolomitization has occurred. The time of migration, which is a key factor in a viable Smackover exploration strategy, varies across the Gulf in response to the subsidence history of each individual basin.

Future Jurassic exploration will center on south Texas, the Gilmer shelf margin, and the updip Smackover along the bounding graben fault systems. Most production will be gas, but some oil should occur along the updip faulted fairways.
SUBSIDENCE AND TEMPERATURE HISTORIES FOR JURASSIC SEDIMENTS IN THE NORTHERN GULF COAST: A THERMAL-MECHANICAL MODEL
Authors: Nunn Jeffrey A.
Published: October 2019

The northern coast of the Gulf of Mexico contains major depositional basins in East Texas, North Louisiana, and Central Mississippi. Basin subsidence can be interpreted as resulting from the extension of continental crust by rifting related to the opening of the Gulf of Mexico during Late Triassic to Early Jurassic times. For example, subsidence of the North Louisiana Salt Basin, determined from well data, is consistent with crustal extension by a factor of 1.5 to 2. A seismic survey across the Central Mississippi Salt Basin also indicates crustal extension by about a factor of 1.6. The thermal-mechanical model presented here describes the subsidence and temperature histories of a continental margin, assuming that the lithosphere is stretched and thinned during rifting. The effects of thermal blanketing by overlying sediments are included. The observed position of strata and current thermal regime are used as model constraints. Subsidence and temperature histories for Jurassicage sediments predicted from this model are compared with observational data. The results of this comparison indicate that geothermal gradients were higher in the past and that thermal conditions in Jurassic-age sediments were favorable for hydrocarbon generation.
Geochemistry and Origin of Smackover and Buckner Dolomites (Upper Jurassic), Tay Field Area, Alabama - Florida
Authors: Vinet Marshall J.
Published: October 2019

The Smackover-Buckner sequence in the Jay-Big Escambia Creek area is divisible into three major lithostratigraphic units: lower Smack-over, upper Smackover and Buckner with an uppermost Smackover transitional sequence. The lower Smackover is regionally extensive, mostly high intertidal, dolomitized packstones with abundant displacive anhydrite nodules. The upper Smackover is characterized both by areas of thick oolite grainstone buildups which form the primary reservoir rock and by areas of low energy, subtidal mudstones-wackestones. The Buckner is mostly nodular mosaic anhydrite with minor amounts of dolomite mudstones-packstones. The Smack-over-Buckner contact is a transitional sequence (referred to here as uppermost Smackover) of high intertidal-low supratidal dolomitized mudstones-grainstones interbedded with nodular mosaic anhydrite layers.

A combination of stratigraphic and geochemical evidence indicate dolomites of four separate origins, three of which are early diagenetic. The dolomites of the Buckner-uppermost Smackover have supratidal stratigraphy and heavy oxygen isotopic geochemistry (means 𝔡180=+1.5‰PDB) and formed penecontemporaneously with deposition. Immediately below and separated by a sharp discontinuity in chemistry are the upper Smackover dolomitized oomoldic grainstones which were dolomitized prior to uppermost Smackover deposition. Stratigraphy, petrography and light oxygen isotopic geochemistry (mean 𝔡180= −2.0‰PDB) favor a mixed-water origin for the upper Smackover dolomites.

The lower Smackover dolomites formed in arid, high intertidal-low supratidal environments penecontemporaneously with deposition based upon petrographic similarity to those of the Buckner and trace element and oxygen isotopic values intermediate between upper Smackover and Buckner dolomite values.

Late, pore-filling saddle (baroque) dolomites precipitated under deep burial conditions.
TECTONIC EVOLUTION OF GULF COAST BASINS
Authors: WALPER JACK L. , MILLER ROBERT E.
Published: October 2019

The Gulf of Mexico formed with the rifting and breakup of Pangaea during Triassic and Early Jurassic time. Its formation and the evolution of its tectonic framework as a passive continental margin can be viewed in terms of the interplay of two factors: (1) stresses operating during the rifting of Pangaea and (2) the inherited tectonic fabric of the rifted passive margin that formed at the divergent plate boundary.

Various aspects of continental rifting are examined and evaluated in terms of the stresses operating during the rifting process. A revised model involving double indentation tectonics is proposed to explain the suturing of North and South America and the formation of the Ouachita orogenic belt, which consists of a thrusted allochthonous subduction complex, volcanic arc and forearc basins. It also explains the relationship of this belt to the North America craton, with which it collided. This orogenic belt not only frames the Gulf but forms much of the pre-rift basement of the upper Gulf Coast where segments of the volcanic-magmatic arc terrane, possibly represented in the Sabine and Monroe Uplifts and the Wiggins Arch, are now found in the accreted continental margin and appear to have controlled or at least influenced subsequent Mesozoic rifting.

The variable aspects of both these interfacing factors are discussed and their influence on the long and active tectonic and sedimentary history of the Gulf Coast and its basins is evaluated. Also the factors that govern the thermal history of the basin sediments are identified.

The Gulf of Mexico is unique among passive margins in that the mechanism which caused uplift, rifting, crustal extension, and drift—with accretion of oceanic crust at a spreading center within the Gulf—aborted and stepped southward into the Caribbean, where it formed that plate. In the Gulf, meanwhile, salt, deposited in basins initially formed and controlled by the two interfacing factors during the early opening, became the dominant tectonic mechanism in controlling subsequent sedimentation and facies distribution.

Following deposition of the evaporites, the Gulf began rapid subsidence that resulted in formation of a thick prograding sedimentary wedge of both clastic and carbonate strata around its margin. Its final shaping came with Laramide tectonism that not only rejuvenated hinterland source areas to supply voluminous sediment but transported peninsular Mexico eastward to close the Gulf and form a huge sediment trap in which vast thicknesses of Tertiary to Recent sediment were deposited.
PETROLEUM PRODUCTION AND HYDROCARBON POTENTIAL OF ALABAMA'S COASTAL PLAIN AND TERRITORIAL WATERS
Authors: Mancini Ernest A. , Mink Robert M.
Published: October 2019

With the discovery of oil in 1944 at the Gilbertown Field in Choctaw County, Alabama became an oil producing state. Since that discovery, Alabama’s coastal plain and territorial waters have become increasingly important areas for the exploration of oil and gas. The primary exploration targets have been the Upper Jurassic Smackover and Norphlet formations. However, the most productive oil field in the state continues to be the Citronelle Field, which produces from reservoirs of early Cretaceous age. Upper Cretaceous rocks productive in southwestern Alabama include fractured Selma chalk and sands of the Eutaw Formation and Tuscaloosa Group. The 1979 discovery of gas in Tertiary sands has resulted in the establishment of several Miocene gas fields in the state.

Alabama should remain an excellent region to explore for oil and gas in the years ahead. Much of Alabama's coastal plain and territorial waters remain untested. Petroleum exploration will probably continue to be concentrated on Upper Jurassic Smackover and Norphlet prospects; however, the Haynesville Formation and Cotton Valley Group have petroleum potential in southwestern Alabama. With renewed interest in the Upper Cretaceous in the onshore northern Gulf of Mexico area, the Cretaceous in Alabama should also see additional hydrocarbon exploration. The Miocene shallow gas discoveries in coastal Alabama have demonstrated that hydrocarbons are present in Tertiary strata in the state. Other prospective Tertiary units include upper Paleocene and lower Eocene sands and Oligocene carbonates. The keys to successful prospecting in the region for Upper Jurassic and Cretaceous objectives are the delineation of petroleum traps associated with salt movement and the recognition of favorable lithofacies. Identification of favorable stratigraphy is critical to defining prospective Miocene reservoirs.
GAS COLUMNSVS.DEPTH IN TEXAS-LOUISIANA GULF COAST BASIN RESERVOIRS
Authors: WHEELER JOE O. , DAVIS JAMES M.
Published: October 2019

A plot of Gulf Coast Tertiary-Pleistocene gas columns vs. depth of burial shows that on average, columns are greater in deep reservoirs than in shallow reservoirs. Further, the plot suggests that for a given depth of burial, there is a maximum attainable gas column. Analysis of the data permits the construction of a set of probability curves, plotting depth of burial vs. gas column, which are statistically significant.
DEPOSITIONAL ENVIRONMENT OF THE QUEEN CITY FORMATION (EOCENE) IN THE HAGIST RANCH FIELD, DUVAL AND McMULLEN COUNTIES, TEXAS
Authors: SPETSERIS JERRY J.
Published: October 2019

The Queen City Formation in South Texas has been described as a progradational wave-dominated delta system. Within this system is included a prodelta shelf and mud facies, lagoonal mudfacies, meander-belt sand facies, and stacked coastal barrier sand facies. In South Texas, Eocene deposits typically demonstrate cyclic successions of transgressive, inundative conditions followed by episodes of regression. Eocene episodes were in response to variation in relative rates of sediment supply and basin subsidence or sea level rise. Genetically related terrigenous Queen City sediments and their marine equivalent comprise a thick, regressive deltaic pulse that overlies the top of Carrizo fluvial-deltaic series of the Wilcox group. The transgressive Weches Formation, consisting of prodelta and shelf deposits, in turn overlies the Queen City section. Examination of core, thin sections, and wireline logs in the Hagist Ranch Field indicates an overall storm-dominated shelf succession. Depositional response indicates a mixture of progradational and aggradational infilling. The Queen City section is characterized by a coarsening upward sequence of very fine to fine-grained glauconitic sandstone separated by fossiliferous marine mudstone. Some sandstone intervals are quartzose, well sorted, and thinly cross-stratified. Other intervals are composed of intensely burrowed, rippled sandstones and siltstones which exhibit mixed bedding. The sandstones contain transported organic debris and exhibit wave and current-induced primary sedimentary structures, possibly as a result of combined flow. These include scour surfaces, ripples, and low-angle cross-stratification. In many instances, ripples and cross-stratification exhibit truncation surfaces. The presence of glauconite and fossiliferous mudstone suggests an open marine setting. Several feet of sand were possibly deposited rapidly, by storm activity, then followed by a period of deposition characterized by quieter conditions and intense burrowing. These sandstone units were stacked successively to create amalgamated sheet sandstones, 20 to 100 feet (6.1-30.5 m) in thickness. Overall, the Queen City section is interpreted as having been deposited in an inner shelf setting where surface waves and currents were the dominant agents.
HABITAT OF OIL AND GAS IN THE MIDDLE FRIO (OLIGOCENE) HACKBERRY
Authors: Curtis Doris M. , Echols Dorothy J.
Published: October 2019

This paper reinterprets the stratigraphic position, depositional environments, and depositional systems in the middle Frio (Oligocene) Hackberry, and their relation to hydrocarbon accumulations. This stratigraphic unit is present in the subsurface of southeastern Texas and southwestern Louisiana, in an area known as the Hackberry embayment. The unit consists of a lower Hackberry sandstone-shale sequence, overlain by middle and upper Hackberry marine shale (the Hackberry shale “wedge”).

The lower Hackberry sandstone sequence overlies a truncated lower Frio section, but in some interdomal areas and in downdip locations, lower Hackberry sediments rest conformably on lower Frio Nonion struma beds. Planktonic foraminifers indicate that the erosional surface between lower and middle Frio coincides with a worldwide relative sea level fall approximately 30 million Ma, in planktonic foraminiferal zone P 21. Dip-oriented submarine channel systems related to this erosional surface contain lower Hackberry reservoir sands in downdip positions.

The marine shale wedge that overlies the lower Hackberry sandstones was deposited during a relative sea level rise, when rates of subsidence exceeded rates of deposition. Some strike-oriented discontinuous marine sand reservoirs are present within the shale wedge.

Production is found in the updip lower Hackberry in structural traps in reservoirs related to near-shore and fluvio-deltaic deposition (traction-transport systems), and, in downdip locations, in stratigraphic-structural traps in submarine channel systems (gravity-transport systems). Unexplored objectives related to submarine channel-fan systems may be present downdip below thick growth-faulted younger Frio sections.
MICROPALEONTOLOGICAL STRATIGRAPHIC FRAMEWORK FOR THE CRETACEOUS BLACK LIME WACKESTONE-MUDSTONE FACIES OF THE GULF OF MEXICO
Authors: McNulty Charles L.
Published: October 2019

One of the widespread Cretaceous units of the Gulf of Mexico is characterized by dark, megapaleonto-logically poor to barren lime wackestones and mudstones, herein referred to as the Tamaulipas. The unit forms the Gulfward component of facies sets which include reef and back-reef facies. These crop out in the Sierra Madre Oriental, have been drilled in the Coastal Plain, and apparently encircle the Gulf of Mexico. Although divisible into rock units (Taraises, Tamaulipas, Cuesta del Cura, lower Agua Nueva), the lithofacies is unified by the overriding physical properties and prevalent bathypelagic paleontological aspect. The temporal span of the facies varies from one locality to another but generally extends from earliest Cretaceous into Turonian.

In spite of difficulties resulting from a biologically eccentric biota and limitations resulting from thin-section study necessitated by induration, there has been prolonged investigation of the unit. The biostratigraphic framework is well established in some oil company laboratories and in reports, particularly by Bonet, Trejo, and Longoria, but these are not always readily available, and related literature is widely scattered. Consequently, a current summary is offered here.

The most useful taxa of the Tamaulipas are calpionellids, nannoconids, calcisphaerulids, micro-calamoidids, and planktonic foraminifers. For each of these taxa, general properties, illustrative and significant species, and important ranges are given.

The distributions of the significant forms delineate detailed zonations for intervals of (1) Berriasian to Hauterivian, based on calpionellids, (2) middle Aptian to early Albian, based on foraminifers, microcalamoidids, and calpionellids, (3) late Albian to middle Cenomanian, based on foraminifers, and (4) early Turonian, based on foraminifers.

Calcisphaerulid ranges are somewhat unreliable, but calcisphaerulids provide supporting evidence, particularly for the mid-Albian. Nannoconids are very small and typically obscure in thin sections of conventional thickness, but they often help in dating, particularly for the early Aptian. Their visibility and assistance can be improved by cutting thin sections with a tapered edge or by treating a fragment of sample with calcareous nannofossil techniques. Calcareous nannofossils are present but have not been extensively reported so far, perhaps partly because of the obscuring effect of recrystallization involved in induration.
SEDIMENTARY PATTERNS AT RIDGE AND SWALE BATHYMETRY, INNER CONTINENTAL SHELF, VIRGINIA, U.S.A.
Authors: OERTEL GEORGE F.
Published: October 2019

A computer generated three-dimensional plot of 220 sq km of the Virginia inner continental shelf revealed three distinct bathymetric zones, not detectable on navigation charts. The survey area is characterized by broad low-relief plains, “ridge and swale” regions, and “dome and swale” regions. Low-relief plains are featureless areas of the sea floor that gently dip seaward at 0.03 to 0.06 degrees. Ridge and swale regions have linear trends in bathymetry with up to 6 m of local relief and 2 to 3 degree slopes. The dome and swale regions are differentiated from the ridge and swale areas by the lack of well-defined parallel ridges. Bathymetrically high areas stand out as individual mounds or domes.

Detailed studies were made at a ridge and swale area located 30 km east of the Chesapeake Bay entrance. Three ridges in a 3.4 sq km survey area are spaced approximately 0.75 km apart and have a maximum relief of 5.5 m. Each of the ridges is transected by shallow submarine depressions that are subnormal to the trends of the ridges. As a result, the ridge crests are undulating surfaces formed by linear trending domes and the shallow depressions.

Spatial distribution of five lithosomes in the study area corresponds with bathymetrically distinct portions of the ridge and swale system. The five areas are described as dome crests (along the ridge axis), cross-ridge depressions and upper-ridge margins, lower-ridge margins, swale floors, and scour troughs. The characteristics of these lithosomes suggest that the surface deposits are not relict, but are due to active marine processes. Grain size increases between the swale floor and the ridge crest. The only exceptions to this trend are coarse deposits at scour troughs on the swale floors. Surface sediments on domes along the ridge crests contain primary sedimentary structures in a coarse sand lag. Cross-ridge depressions contain primary sedimentary structures in fine sand, indicative of both bedform migration and storm-related sand drapes. The presence of bioturbated fine sand along the adjacent ridge-face slope, between the cross-ridge depressions, suggests that these areas are relatively stable.
STRATIGRAPHIC SEQUENCE RESPONSE TO GLACIO-EUSTATIC FLUCTUATIONS IN A RAPIDLY SUBSIDING LATE CENOZOIC BASIN, SAN FRANCISCO, CALIFORNIA
Authors: CLIFTON H. EDWARD
Published: October 2019

More than 1,750 m of late Cenozoic deposits are exposed in a structurally continuous section in sea cliffs south of the city of San Francisco. Well-defined facies in this succession reflect deposition in the eolian dune, alluvial, freshwater pond/swamp/marsh, embayment, backshore, foreshore, nearshore and inner-, mid- and outer-shelf environments. The facies are arranged throughout the succession in alternating regressive and transgressive sequences. The most complete regressive-transgressive cycles show the following upward progression: outer-shelf, mid-shelf, inner-shelf, nearshore, foreshore, backshore/eolian dune, embayment, inner-shelf, mid-shelf, outer-shelf. In this progression, an erosional surface separates the embayment facies from the overlying shelf facies. Although many of the cycles are incomplete, the alternating upward-shallowing and upward-deepening trends are present throughout. The upward-shallowing sequences typically are continuous, whereas upward-deepening sequences contain a distinct hiatus. Nearshore and foreshore deposits do not occur in transgresssive sequences; instead, an erosional surface marks the interval at which they would be expected. The transgressions and regressions are interpreted to reflect Pleistocene glacio-eustatic sea level oscillations.

The facies sequences in this deposit differ from some of the transgressive-regressive sequences described elsewhere. Widespread erosion seems not to coincide with relative lowstands of the sea, but rather occurs with the landward translation of the shoreface during a relative sea-level rise. This situation may be due to the rapid subsidence required to develop such a thick section in a short period of time. It may also be that, because of the high frequency of sea-level fluctuation, insufficient time existed during the lowstands to allow for widespread planation. Vertical textural trends in the regressive and transgressive sequences are more complicated than the simple upward-coarsening and upward-fining trends commonly ascribed to such sequences. These complications probably result from some combination of the effects of the high-gradient and high-energy character of this coast and the rapid rate of subsidence in this tectonically active area.
CHEMICAL ALTERATION OF SMACKOVER OILS AS A FUNCTION OF MATURATION
Authors: Sweeney R.E.
Published: October 2019

The distribution of API gravities of Smackover oils is shown to be quantitatively related to the thermal maturity of the reservoirs. In addition, by comparison to the empirical limits of Waples (1980) and the theoretical limits of Quigley and MacKenzie (1988), it is shown that these maturities are too low for the thermal cracking reactions needed to produce the API gravity distribution.

The chemical composition data for 131 oils were obtained from the DOE database and correlations were made using 31 compositional parameters and the API gravity of the whole oils. Strong correlation coefficients are shown to exist between oil gravity and the composition of the higher carbon-number molecular groups. These correlations suggest that ‘in reservoir’ oil cracking reactions do occur in Smackover reservoirs. Therefore, the rate for these reactions must be enhanced (Sassen and Moore, 1988) over those predicted by laboaratory studies and considered typical for other areas.

Sassen (1988) suggests that ‘thermochemical sulfate reduction’ is the process responsible for early crude oil destruction in Smackover reservoirs. This process has been shown to significantly alter the oil composition in Paleozoic reservoirs of the Big Horn Basin (Orr, 1974). However, early crude oil destruction (i.e., high gravity oil in low maturity reservoirs) does not occur in the Big Horn Basin reservoirs. Therefore, it is concluded that the high gravity oil in low maturity reservoirs of the Smackover formation is, generally, not due to thermochemical sulfate reduction. It is suggested that the API gravity-maturity trend for the Smackover oil family is governed by kinetic parameters related to the composition of the initial ‘type’ oil, especially the frequency factor ‘A’ of the Arrhenius kinetic equation.
ORGANIC GEOCHEMISTRY OF GASES AND CONDENSATES FROM BLOCK 511A HIGH ISLAND SOUTH ADDITION OFFSHORE TEXAS, GULF OF MEXICO
Authors: WALTERS CLIFFORD C.
Published: October 2019

Chemical and isotopic data obtained on gases from High Island 511A indicate that the reservoirs contain hydrocarbons from multiple sources. A significant portion, 17 to 34 percent, of the produced methane is biogenic. Thermogenic gases were generated from a single source lying at depths greater than 16,000 feet, considerably deeper than the Pleistocene reservoir sands. Condensates coproduced with natural gas were also studied. Chromatographic analysis revealed that the condensates possess very unusual compound distributions, atypical of light petroleum fluids derived from phaseseparated crude oils or thermal cracking. Normal and branched alkanes are noticeably depleted, and cyclic hydrocarbons are enriched. Aromatic compounds are in exceptionally high concentrations. In the C9-C18 range, isoprenoid hydrocarbons are the dominant components. No one process appears to totally explain the atypical compositions of the High Island 511A condensates. A model was developed which is consistent with the compositional data and production history. Thermogenic natural gas-condensate from a single source charged the 511A Pleistocene reservoirs where biodegradation occurred to varying degrees. Hydrocarbons generated from terrestrial Type III kerogen in local immature sediments were extracted by the biogenic methane. As the biogenic methane accumulated in the sands, the extracted, low maturity thermal hydrocarbons were also added to the reservoir in roughly equal proportions as the high maturity thermogenic condensates. This resulted in condensates with a light hydrocarbon distribution characteristic of both immature and mature generation. Biodegradation and water washing may have further per-turbed the light hydrocarbon abundances. The geological situation which gave rise to the 511A immature condensates is common throughout the offshore Gulf of Mexico and may be responsible for many of the unusual light hydrocarbon distributions found in petroleums from this area.
A GEOCHEMICAL STUDY OF OILS FROM THE SOUTH PASS 61 FIELD, OFFSHORE LOUISIANA
Authors: Requejo A.G. , Halpern Henry I.
Published: October 2019

Detailed geochemical analyses of twenty-three crude oils from various reservoirs in South Pass 61 field, offshore Louisiana, indicate that the oils belong to a single family and are derived from the same source. The large variation in bulk and chemical properties (e.g., API gravity, hydrocarbon composition) can be attributed to post-generative processes, most importantly biodegradation and evaporative fractionation. A third alteration phenomenon, which was noted only in a single sample, is gas deasphalting.

Triterpane and sterane biomarker distributions of the oils corroborate their common source. Maturity estimates based on sterane isomerization and alkyl phenanthrene distributions also indicate that the oils were generated at a similar level of maturity. However, the degree of sterane aromatization (% triaromatic sterane parameter), exhibits a wide range, and is not related to reservoir depth or other bulk properties of the oils. Hopane/sterane ratios also vary more than would be expected for a single family of oils. Both parameters are highly correlated with the absolute concentrations of 17α (H), 21β(H)-hopane and 5α(H),14α(H),17α(H)-ethyl cholestane (20R). The process(es) resulting in these biomarker correlations are uncertain.
A Case Study of The Preservation Potential of The Coastal Lithosomes of Small Deltaic Systems: Examples From The Holocene of The Texas Continental Shelf
Authors: Bartek Louis R. , Anderson John B. , Abdulah Kenneth C.
Published: October 2019

An investigation of the Holocene stratigraphy of the coast and inner continental shelf in the area surrounding the modem Brazos Delta indicates that overstepped wave-dominated deltas are an important element of the transgressive systems tract of high sediment yield depositional systems. It appears as though the Brazos incised valley, which was carved during the Wisconsinan eustatic lowstand, was infilled or abandoned during an interval of rapid eustatic rise and that the fluvial-deltaic system then migrated onto the adjacent interfluve. The system appears to have stabilized during the 9,000 year B.P. eustatic still stand and nucleated a delta in an area that lies approximately 15 km offshore of the modern Brazos delta. This delta was transgressed during an ensuing rapid rise and was preserved as a shelf sand body. This routine was repeated at least two more times and has resulted in the generation of three shelf sand bodies. Deltas that were transgressed during intervals when the rate of eustatic rise was high (2 cm/year) have the highest preservation potential. During the intervals of rapid eustatic rise, the deltaic deposits are rapidly overstepped and the sand body is isolated on the shelf. During this process the upper couple of meters of the delta may be reworked into a strike aligned sand body, while the lower portion (>2 meters below sea level (approximately 7 meters thick)-upper and lower shoreface equivalents) of the delta is preserved in place in its original pod-like geometry. These deltaic sand bodies lie beneath a ravinement surface, may be associated with the remains of the fluvial channel that fed them, and may be 10 meters thick. During intervals of slow eustatic rise (0.2 cm/yr) a large proportion of wave dominated deltas is reworked and less than 3 meters of the original deltaic facies may be preserved under the ravinement surface.
Evolutionary Classification of Coastal Sediments
Authors: Boyd Ron , Dalrymple Robert , Zaitlin Brian
Published: October 2019

One of the most successful ways of classifying coastal environments has been to employ the dominant coastal process variables as discriminating parameters. This approach has been previously applied to deltas and continental shelves using the three parameters of waves, tides and rivers and to tidal inlets using only waves and tides. We suggest that a three parameter triangular classification can be extended to all coastal environments and enables a division into the primary categories of deltas, estuaries, barriers and tidal flats. Although combinations of coastal processes may remain constant through time on any coast, the coast itself undergoes continuous evolution. This necessitates the inclusion of time as a fourth parameter to satisfy an evolutionary coastal classification. If we adopt a sequence stratigraphic view of coastal evolution, then we may place most coastal sediments within either the transgressive or highstand systems tracts, undergoing either progradation (regression) or flooding (transgression). If we assume that all temporal evolution between sedimentary environments within the coastal system takes place during either a regression or transgression then we can substitute regression/transgression for time as the fourth parameter. Using this approach we see that all environments may occur in the general case but that at times of (maximum) flooding, estuaries predominate and that as sediment continues to be supplied during progradation, deltas, barriers and tidal flats expand at the expense of estuaries. At any one time, each depositional environment may be further subdivided using wave, tide and river process domination.
Land Loss Rates: Louisiana Coastal Plain
Authors: Britsch Louis D. , Kemp III E. Burton
Published: October 2019

Land loss mapping and rate curve development for 62 quadrangles in the Louisiana Coastal Plain show that land loss rates vary significantly throughout coastal Louisiana. Differences in land loss rates among individual quadrangles are a function of the geologic setting, and the factors that contribute to land loss. Of the 62 quadrangles mapped, 16 show an increase in the land loss rate, 36 show a decrease, and 10 remained approximately the same. On a regional scale, the land loss rate for the entire Louisiana Coastal Plain has decreased from an average yearly rate of 41.88 square miles for the 1956-58 to 1974 period to 30.71 square miles for the 1974 to 1983 period.

The data generated during the land loss study is being combined with engineering geology, geomorphic, and subsidence data to determine the causes for land loss in site specific areas of the Louisiana coast. It will also be used to identify areas of maximum and minimum land loss so that mitigation efforts can be planned in areas where the potential for significant reduction in land loss is greatest.