bluuebunny/crossref_metadata_2025_split huggingface dataset:
The transgression of an erg — sedimentation and reworking/soft-sediment deformation of aeolian facies: the Cretaceous Troncoso Member, Neuquén Basin, Argentina
Authors: Strömbäck Anna , Howell John A. , Veiga Gonzalo D. 
Published: April 2008

Abstract

The Cretaceous Troncoso Inferior Member of the Huitrín Formation comprises fluvial and aeolian facies that form a drying-upwards succession within the Neuquén Basin. The basal fluvial sandstones were deposited as braided river deposits and lie unconformably on top of either the deep-marine Agrio Formation or, locally, the shallow-marine Chorreado Member (Huitrín Formation.). In places, the fluvial sandstones are interbedded with remnants of aeolian deposits recording an arid environment and ephemeral flows. In the study area the upper section is predominantly aeolian and was controlled by northerly winds with both linear and transverse dune types being deposited. The depositional system was rapidly flooded and dune topography (relief ranging between 2 and 35 m) was preserved on its top surface. In addition to dune topography, the Troncoso dunes also show evidence of reworking and
in situ
soft-sediment deformation related to the flooding. The principal aim of this paper is to document the soft-sediment deformation and preservation of topography associated with the flooding of the dune field.

Within the soft sediment deformed and reworked sediments at the top of the Troncoso Inferior Member spatial and temporal relationships indicate that they formed in a specific sequence. Initially, water-escape processes created convolutedly folded and dish structures that were concentrated in areas of slightly higher preserved dune topography. Secondly, the convolutedly folded and dish facies were eroded and reworked by wave undercutting and migrating three-dimensional dunes in a shallow-marine environment. This subaqueous reworking resulted in an interbedded massive and cross-stratified unit. With further deepening of the water, the topography became stabilized and the uppermost part of the interval (0.1–0.3 m) was reworked by waves across most of the basin. In the topographic lows between dunes, liquefaction-induced sediment gravity flows deposited massive-flatlaminated facies.
The reworked and soft-sediment deformed aeolian dune topography is overlain by the evaporites of the Troncoso Superior Member. The distribution of flood-related facies and the amount of preserved dune topography (2–35 m) indicates that the transgression must have been rapid but of low energy.
Geochemistry and petrology of a Middle Tithonian limestone-marl rhythmite in the Neuquén Basin, Argentina: depositional and burial history
Authors: Scasso R. A. , Alonso M. S. , Lanés S. , Villar H. J. , Laffitte G. 
Published: April 2008

Abstract

The Middle Tithonian Los Catutos Member (Vaca Muerta Formation, Neuquén Basin), is lithologically and geochemically similar to limestone-marl alternations from the Late Jurassic of the northern hemisphere. Both marls and limestones are pelbiomicrites and biopelmicrites principally composed of pellets, radiolaria, forams, ostracods, equinoids, spicules of sponges and gastropods, cemented by several generations of calcite cement. Smectite and interlayers are the major epiclastic components of the fraction below 2 μm, reflecting pedogenic processes developed on volcanogenic source rocks. More abundant kaolinite in some marls reflects stronger humid conditions in the source area and enhanced terrigenous supply. Al
2
O
3
content is demonstrated to be a reliable indicator of clastic input. The same is not true for silica, often related to high biogenic productivity of siliceous organisms. Rocks show total organic carbon (TOC) contents up to 1.95% and constitute regular to good sources for hydrocarbons, although thermally immature. Rhythmites formed gently sloping mounds accumulated in a distal submarine ramp under low-energy and poorly oxygenated open-sea conditions. Sedimentation rates were high due to high productivity on the sea surface, and supply of terrigenous and carbonate sediments transported by suspension plumes originated in shallow, photic areas. δ
13
C values correspond well with the published curves for the Tithonian sea water and with other records from Tethyan limestones. A preliminary analysis of negative excursions of δ
13
C point to a productivity crisis or a mixture of water layers in a stratified sea with a periodicity of 400 ka, which could be a result of changes in the orbital eccentricity of the Earth. Light isotopic composition of O in bulk rocks is the result of diagenetic neomorphism and cement precipitation. Calculated palaeotemperatures from δ
18
C are consistent with those derived from measured vitrinite reflectance (
Ro%
) and burial history reconstruction. Data indicate initial burial during the Tithonian extending up to the Lower Cretaceous, a short period of uplift (Intravalaginian tectonic phase), and renewed uplift during the Cenomanian followed by significant Late Cretaceous sedimentation and Pliocene thrusting.
Hemipelagic record of orbitally-induced dilution cycles in Lower Cretaceous sediments of the Neuquén Basin
Authors: Sagasti Guillermina 
Published: April 2008

Abstract

The lower Valanginian-lower Barremian Agrio Formation in the Mendoza region of the Neuquén Basin (Argentina) accumulated in a hemipelagic outer ramp/basin setting. The formation records the alternation of periods of fine-grained carbonate accumulation and periods of fine-grained clastic deposition, which resulted in a strongly rhythmic succession in which dark clastic hemicycles alternate with light carbonate hemicycles. Clastic and carbonate hemicycles show distinct geochemical signatures that reflect cyclic fluctuations in terrigenous influx to the basin. Clastic hemicycles have relatively high percentages of Fe, Al and K, and less than 60% CaCO
3
, whereas carbonate hemicycles contain relatively low quantities of detrital elements (Fe, Al and K), and more than 60% CaCO
3
. Fluctuations in terrigenous supply to the basin occurred in response to the alternation between two contrasting climate regimes and resulted in the formation of dilution cycles. Warm temperate (winter-wet) climate conditions led to the accumulation of clastic hemicycles, whereas arid conditions promoted the deposition of carbonate hemicycles. The ultimate mechanism that controlled the alternation of the dark and light intervals was orbital forcing, as the latitudinal shifting of climate zones was driven by the
c
. 21 000 years precessional cycle.
Jurassic marine reptiles of the Neuquén Basin: records, faunas and their palaeobiogeographic significance
Authors: Gasparini Zulma , Fernández Marta 
Published: April 2008

Abstract
The largest diversity of Jurassic marine reptiles from Gondwana has been recorded in the Neuquén Basin. Although the Early Jurassic records are limited, the records from the Middle Jurassic, especially the early Bajocian plesiosaurs and ichthyosaurs, are unique in the world. The highest abundance and taxonomic diversity is recorded from the Late Jurassic (Tithonian). Pleurodiran (Notoemys) and cryptodiran turtles (Neusticemys), ichthyosaurs (Ophthalmosaurus, Caypullisaurus), pliosaurs (Pliosaurus, Liopleurodon) and crocodilians (Geosaurus, Metriorhynchus, Dakosaurus) are members of this rich marine herpetofauna. Except for Notoemys, the other reptiles are pelagic. Their habits and large size (Caypullisaurus, Liopleurodon, Dakosaurus) suggest that they entered the sheltered Neuquén Basin occasionally, possibly for reproduction in protected areas. The model of a protected basin, open to the Pacific Ocean through gaps in an emergent by island-arc complex, fits well with the ecological requirements inferred for most of the pelagic reptiles. The Caribbean Corridor may also have played a significant role as a seaway at least during the Middle Jurassic and probably before. New findings in Tithonian and Berriasian sediments of the Neuquén Basin suggest that there was no massive extinction among the marine herpetofauna at the Jurassic-Cretaceous boundary.
Lithofacies, palaeoecology and palaeoenvironments of the Agrio Formation, Lower Cretaceous of the Neuquén Basin, Argentina
Authors: Lazo Darío G. , Cichowolski Marcela , Rodríguez Débora L. , Aguirre-Urreta M. Beatriz 
Published: April 2008

Abstract
The lithofacies and macrofossil guilds of the Agrio Formation (Upper Valanginian—Lower Barremian) have been analysed using evidence from sedimentological, taphonomic and palaeoecological studies. The study area is Agua de la Mula and adjacent regions in central Neuquén. Seven lithofacies have been recognized in the field, which indicate that the Agrio Formation was deposited in an open-marine, ramp depositional system under storm influence. Lithofacies indicate conditions that range from low-energy basin to high-energy inner ramp. Outer and mid-ramp deposits are the most abundant. Macrofossils have been grouped into 16 guilds based on tiering, life habit and feeding category. The guilds indicate normal benthic oxygen level, normal salinity, and soft—firm muddy and sandy bottoms. Suspension-feeders are more common than deposit-feeders suggesting the predominance of suspended food particles over deposited food resources. A low input of siliciclastics and, possibly, other palaeoceanographic conditions allowed the development of oolitic facies in the inner ramp and coral patch reefs in the upper mid-ramp for a limited period of time.
Surface topography and internal strain variation in wide hot orogens from three-dimensional analogue and two-dimensional numerical vice models
Authors: Cruden Alexander R. , Nasseri Mohammad H. B. , Pysklywec Russell 
Published: April 2008

Abstract
The post-accretionary deformation of wide, hot orogens is characterized by pure-shear or transpressional shortening of relatively weak lithosphere (the orogen) between converging stronger blocks (the vice). We report on a series of analogue vice models and compare the resulting three-dimensional strain fields and surface topographies to equivalent two-dimensional numerical experiments. In the analogue models a rheologically stratified (frictional/viscous) weak orogenic lithosphere overlying a viscous asthenosphere is squeezed between converging strong lithospheric blocks. Ductile lower crust and mantle in the weak lithosphere is free to flow laterally, parallel to the orogen. The Argand number describes the model dynamics and strongly controls both the orogenic relief and the degree of lower crustal orogen parallel stretching in the analogue models. Cross sections of numerical and analogue experiments display consistent geometries in which upper crustal deformation is characterized by upright folding compared to apparently decoupled horizontal strains in the lower crust. The relative buoyancy and degree of orogen parallel flow in the lower crust of the analogue models has a dramatic influence on three-dimensional strain fields and the kinematics of upper crustal curvilinear shear zones. The analogue and numerical results demonstrate the importance of three-dimensional effects in determining the structure of natural orogens and compare favourably to field and geophysical observations of large hot orogens in the geological record.
Inversion of a symmetric basin: insights from a comparison between analogue and numerical experiments
Authors: Panien M. , Buiter S. J. H. , Schreurs G. , Pfiffner O. A. 
Published: April 2008

Abstract
We use both analogue and numerical experiments to study the inversion by shortening of a symmetric sedimentary basin. The combination of the two modelling techniques uses the strengths of each method to provide insight into basin-inversion processes. The experiments start with a pre-existing basin filled, in part, with weak layers simulating weak sedimentary rocks. Both footwall and hanging wall can deform freely. The physical properties of the materials used in the analogue experiments (sand and microbeads) and the numerical experiments are appropriately scaled to represent upper crustal rocks. We present a systematic study of the effects of basin infill, basin width and basin location and a sensitivity analysis to understand the effects of the boundary conditions. The results of both methods show that the graben fill accommodates most shortening. Weak layers play an important role in localising shortening with limited reactivation of pre-existing (but weakened) faults. In general, forward thrusts and back thrusts nucleate at the lateral contrast of strong and weak materials and cut across the graben-bounding faults. Weak basal detachments are required to transfer shortening to the basin region. The overall evolution of the analogue and numerical models is encouragingly similar.
Recent advances and current problems in modelling surface processes and their interaction with crustal deformation
Authors: Braun Jean 
Published: April 2008

Abstract
I present a brief summary of recent advances in the field of computational geomorphology and various attempts to couple numerical models of landscape evolution to models of crustal/lithospheric deformation. The most commonly used formulations for the various physical processes at play during surface erosion, transport and deposition are presented, as well as an outline of how they have been incorporated in a variety of numerical schemes. I also explain how the coupling between erosion and tectonics has been performed under various simplifying assumptions. Determining the rate constants for each of the proposed landforming mechanisms remains a difficult challenge that has recently been helped by the advent of new low temperature thermochronometers and exposure dating by cosmogenic radionuclides. I demonstrate how the information contained in the relationship between age and elevation can be used to provide constraints on the ‘age’ of a landscape, as well as how important rate information can be extracted from various datasets by using simple modelling techniques. This paper demonstrates why the field of computational geomorphology needs to harmonize the various parameterizations (often the legacy of empirical relationships derived from observations at the human scale), quantitative estimates of the value of the numerous rate parameters and improvement of the numerical techniques.
The deliberate search for the stratigraphic trap: an introduction
Authors: Allen Matthew R. , Goffey Graham P. , Morgan Richard K. , Walker Ian M. 
Published: April 2008

Abstract
This Special Publication draws upon contributions to a similarly titled conference ‘The Deliberate Search for the Stratigraphic Trap — Where Are We Now?’ held at the Geological Society in London during 2004. Observations in this introductory paper have been drawn from the authors’ experience, talks given at the conference and papers within this volume. Specifically it is noted that by analogy to basins which are perceived to be mature for structural traps, stratigraphic traps can have substantial remaining potential. Additionally, current exploration for stratigraphic traps seems rather restricted to areas where seismic data allow the direct assessment of fluid fill and reservoir development. It is argued that the industry is probably not doing enough to learn from established stratigraphic traps to guide future exploration for such traps. Looking forward, it is suggested that the industry faces two key challenges. Firstly, the use of all available data to assess fluid type and reservoir presence in areas of unfavourable rock physics, and secondly, the development of sufficiently sophisticated predictive models of stratigraphic trap development.
Evaluating subtle stratigraphic traps: prospect to portfolio
Authors: Binns P. E. 
Published: April 2008

Abstract
A compilation of 85 stratigraphic traps demonstrates the variety of trapping mechanisms and the scope for developing new concepts by matching geological models with features in 3D seismic volumes. However, aspects of quantitative evaluation may discourage exploration. Investors require assurance in the form of probabilistic evaluations of risk and value but information critical to the evaluation of new stratigraphic concepts is likely to be lacking. As estimates of risk and uncertainty vary with information, prospects evaluated with radically different levels of information must be ranked with care. The requirements for quantitative project ranking and portfolio optimization have to be reconciled with the need to ‘venture into the unknown’. The character of stratigraphic prospects dictates different evaluation methods from those used to evaluate structural prospects. This, together with the high degree of sensitivity of value to evaluation methodology, can also lead to inconsistencies in ranking.
Within the context of a company’s overall strategy and risk tolerance, organizational and cultural factors may influence prospect selection. In particular over-emphasis on quantitative methods may not have the intended effect. A common understanding, amongst technical and commercial disciplines and decision makers, of the background to quantification is essential.
Factors which encourage the progression of stratigraphic prospects include a dedicated geoscience effort, a separate ‘growth’ portfolio of new concepts, a formal structure for progressing these and a stable organization.
Breast screening, chicken sexing and the search for oil: challenges for visual cognition
Authors: Donnelly N. , Cave K. R. , Welland M. , Menneer T. 
Published: April 2008

Abstract
Interpretation of images of the Earth’s subsurface is a process whereby humans perceived and categorize visual features derived from seismic data. The seismic data are presented in the form of vertical slices showing points of change in some variable being measured (e.g. acoustic impedance) and horizontal slices showing surfaces interpolated between values at a particular time or horizon across multiple vertical slices. These images are usually highly complex and their nature has been determined largely by the technical capabilities of the hardware and software of the imaging technology. Because of these constraints, we argue, images do not convey information as readily as they could. We believe that these images could be more informative if they were constructed and tailored with known properties of the human visual system. Furthermore, little or no consideration has been given to the training and selection for image interpretation vis-à-vis the fundamental psychological skills that distinguish good from poor interpreters. In this paper we argue that tailoring images to the human visual system and developing working practices that eliminate biases will improve the detection of subtle features related to hydrocarbon traps. Furthermore, establishing training procedures that enhance the visual system’s ability to detect and encode hydrocarbon traps, and creating selection procedures that select individuals with excellent visual imagery skills will also facilitate performance.
Application of a sealing surface classification for stratigraphic related traps in the UK Central North Sea
Authors: Corcoran Joel 
Published: April 2008

Abstract

Traps can be categorized by defining the relationship of the seals with respect to the reservoir/seal bounding surface(s). Two major subdivisions provide the foundation of the classification;
one-seal traps
are structures which possess closed contours at the reservoir/seal interface, whereas
poly-seal traps
are those where closed contours at the reservoir/seal(s) interface do not exist or are inadequate to entirely close the trap on a single sealing surface; thus implicating the requirement of one or more base and/or lateral seals. The nature (conformable, unconformable, tectonic, facies change, waste zone) and combination of the seals essential to contain the hydrocarbon pool with respect to the one-seal and poly-seal distinction allow for further subdivisions of each of these classes. This publication catalogues a variety of Lower Cretaceous, Upper Jurassic and Tertiary stratigraphic related traps (stratigraphic and combination) from the Central North Sea with respect to fourteen applicable sealing-surface classes.

The paper also provides a source for identifying and categorizing prospective stratigraphic related traps in accordance with documented field examples from the Central North Sea. In addition, the author demonstrates the scheme as a first-pass exploration tool to rank future portfolios of stratigraphically trapped prospects with respect to the trapping integrity/reliability of the sealing surface(s).
Pleistocene coralline algal build-ups (
coralligène de plateau
) and associated bioclastic deposits in the sedimentary cover of Cutro marine terrace (Calabria, southern Italy)
Authors: Nalin R. , Basso D. , Massari F. 
Published: April 2008

Abstract

Carbonate build-ups mainly constructed by encrusting coralline red algae are currently developing on Mediterranean soft bottoms, at depths ranging from 20 m to 160 m. They are usually referred to as ‘
coralligène de plateau
’. Few fossil examples of these bioconstructions have been described in the literature and their evolution in the context of a stratigraphic cycle has never been modelled in detail. Cutro marine terrace (Calabria, southern Italy) preserves mid-Pleistocene deposits assigned to Marine Isotope Stage (MIS) 7 or MIS 9. Extensive algal build-ups representing the deepest unit of the succession occur in the outer and central portion of the terrace, interpreted as the most distal setting from the palaeo-shoreline. Two studied sections, Vrica and Telegrafo, showed that the solid biogenic framework grew over a basal rhodolithic layer, which was stabilized by the binding activity and overgrowth of non-geniculate Corallinales (calcareous red algae). Therefore, these bioconstructions represent a rare fossil example of
coralligène de plateau
. At the Telegrafo section,
Titanoderma pustulatum
has been identified as the major rhodolith component. The build-ups are dominated by
T. pustulatum
, associated mainly with
Mesophyllum
spp. and locally with
Lithophyllum stictaeforme
. Rhodalgal bioclastic deposits are found in lateral contact with the build-ups. The two facies developed together under a hydrodynamic regime where phases of sedimentation from storm-driven currents alternated with phases of calm conditions. They were deposited during a single stratigraphic cycle beginning with the generation of a ravinement surface during the transgressive systems tract (TST) and ending with the burial of the
coralligène
by well-sorted shoreface bioclastic sands. Optimal and extensive growth of the
coralligène
took place during the highstand systems tract (HST).