bluuebunny/crossref_metadata_2025_split huggingface dataset:
Staircase normal fault geometry in the Grès d’Annot (SE France)
Authors: Lansigu C. , Bouroullec R. 
Published: April 2008

Abstract
A normal fault geometry is observed in the sediments of the Grès d’Annot Formation. The sediments are deep-water siliciclastic deposits composed of mud-rich and sand-rich successions. This seismic- to sub-seismic scale fault system is considered as a good analogue for syntectonic basin infilling. The outcropping Grès d’Annot Formation allows small- to large-scale fault analysis coupled with stratigraphic analysis. The major faults, which have throws ranging from a few metres to hundreds of metres, belong to a tilted block succession. The mud-rich and sand-rich beds thickness range from a few centimetres to tens of metres. The characterization of the fault system and the kinematic analysis carried out show strong correlation between fault geometry and lithological discontinuities. The fault geometry is largely controlled by the rheological coupling between the mud-rich and sand-rich succession. Downdip displacement of fault blocks is accommodated by layer-parallel movement. Graben structures and synthetic fault sets are related to small-scale fault steps. The fault zone characteristics are related to these fault profile heterogeneities. Kinematic analysis of this fault system provides tools for the characterization of stress field perturbation in a multi-layer system and its consequences in terms of strain localization and hydrodynamic behaviour.
Syndepositional faulting in the Grès d'Annot Formation, SE France: high-resolution kinematic analysis and stratigraphic response to growth faulting
Authors: Bouroullec Renaud , Cartwright Joe A. , Johnson Howard D. , Lansigu Christophe , Quémener Jean-Marie , Savanier Dominique 
Published: April 2008

Abstract
The presence of syndepositional reservoir scale faulting in the Grès d'Annot Formation adds an additional level of complexity in understanding the stratigraphic architecture of these, and potentially other, deep-water reservoir successions. A series of five synsedimentary faults have been characterized in relation to the high-resolution depositional framework of the Annot deep-water sandstone, faults that were active at the time of deposition of the Grès d'Annot, influencing both stratigraphic architecture and depositional processes. The five faults have normal throw, strike NE-SW (perpendicular to the regional palaeocurrent direction), and have maximum syndepositional throws of between 5 and 30m (sub-seismic-resolution scale). To understand the nature of the synsedimentary faulting, a high-resolution stratigraphic framework was developed from six vertical sedimentary sections measured along the 600m high cliff face, and from detailed correlations along photomosaic panels. Ten lithofacies have been identified and grouped into three different architectural elements that have been used as reference units for the high-resolution kinematic analysis. Syndepositional deformation of these architectural elements indicates that the faults had a polycyclic kinematic behaviour. In the hanging wall, abrupt pinchout of sandstone bodies and unusual local variations in sandstone texture also support the influence of faulting during deposition.
Scale effects of non-uniformity on deposition from turbidity currents with reference to the Grès d’Annot of SE France
Authors: McCaffrey W. D. , Kneller B. C. 
Published: April 2008

Abstract
Turbidity current non-uniformity arises when flows experience changes in slope or degree of confinement. The phenomenon may operate across a range of scales with respect to flow size, to produce a range of characteristic depositional effects. Non-uniforrnity effects at three scales can be inferred within the Grès d’Annot exposed around the town of Annot. At the basinal scale, the very presence of sedimentary deposits may reflect a non-uniformity control. At the inferred flow scale, non-uniformity effects upon facies development can be linked to particular system geometries, for example channels or scours versus sheet systems. At the smallest scale, detailed facies heterogeneity may be linked to variability in the local sea floor topography. In poorly-exposed or subsurface systems, recognition of these effects may allow the non-uniformity regime of the parental flows to be constrained and hence permit improved prediction of the first order of sedimentary architecture away from point s of control.
Patterns of geochemical variability in relation to turbidite facies in the Grès d’Annot Formation
Authors: Garcia Daniel , Joseph Philippe , Maréchal BenoÎt , Moutte Jacques 
Published: April 2008

Abstract
The deep marine Grès d’Annot Formation is one of the best exposed analogues to sand-rich turbidite sub-surface systems. Provenance and reservoir heterogeneities have been investigated through a geochemical study of different areas and facies in this formation. Most compositions may be described as mixtures between carbonate and three clastic end-members, i.e. clay, framework grains and a subset of the heavy minerals (zircon, Tioxide, apatite, monazite). These end-members have a nearly uniform chemistry over the studied area and a granite-dominated provenance consistent with a Corsica-Sardinia source hypothesis. This rather uniform provenance makes the Annot Formation a favourable case for exploring the relationships between facies and geochemistry. Not only do different facies differ in average composition, but chemical variations at the bed scale fingerprint the depositional mechanism: archetypal (graded) turbidites and traction-dominated (over-bank) deposits display contrasting variation trends in geochemical plots. The local-scale variation patterns and the general relationship between grain size and chemistry are tentatively integrated in a single differentiation model, providing a rationale for the use of geochemistry in provenance studies, and a possible way to characterize sedimentary facies.
The Grès d’Annot as an analogue for Brazilian Cretaceous sandstone reservoirs: comparing convergent to passive-margin confined turbidites
Authors: Moraes Marco A. S. , Blaskovski Paulo R. , Joseph Philippe 
Published: April 2008

Abstract
The Eocene deep-water sand-rich deposits of the Grès d’Annot of southern France have been used as outcrop analogues for offshore Cretaceous reservoirs of Campos Basin, southeastern Brazil. The analogy is chiefly based on the sand-rich, confined nature of the two systems. Such application can be questioned as the contrasting geological settings, i.e. convergent versus passive margin, could produce rather different depositional scenarios. Detailed comparison between the two systems permits, however, recognizing additional similarities, and also some differences, whose recognition is important to ensure the correct application of the Grès d’Annot as an analogue for this and other passive-margin reservoirs. Comparative analysis of channel dimensions, facies continuity, and three-dimensional expression suggests that confined sand-rich systems show many similarities in terms of critical reservoir heterogeneity, providing that palaeotopographic control was similar, regardless of the tectonic environment in which they were formed. In addition, contrasts found among sequences in the same tectonic setting suggest that other factors (such as, for example, sand/shale ratio of the sediment input) play an important role in defining reservoir architecture. These observations further suggest that, once similarities and differences are correctly understood, analogue data, even from quite different tectonic settings, may provide a powerful tool for improving subsurface reservoir models.
Turbidite systems influenced by structurally induced topography in the multi-sourced Welsh Basin
Authors: Smith Ru 
Published: April 2008

Abstract
The latest Ordovician and lower Silurian fill of the Welsh Basin contains a range (in terms of scale, sediment texture, stratigraphic architecture and supply configuration) of deep-water depositional systems that record the influence of basin-floor topography on sediment distribution patterns. Systems supplied from the eastern basin margin at a time of broadly rising relative sea-level are interpreted to have initially filled an inboard base of slope depression lying above a tilted basement fault block (Cerig Gwynion Grits System). An opposing slope is thought to have caused deflection of turbidity currents to run parallel with the strike of the slope. Following this fill phase, a channel-fed lobe system (Caban-Ystrad Meurig System) extended further basinwards. After flooding of the eastern basin margin, voluminous, texturally immature axial systems, supplied from the southern basin margin, developed. These systems exhibit evidence for deflection of flows to run parallel to tectonically induced slopes and probable local flow reflections in areas of obliquity between bounding slopes and incident flows. The architecture of the lateral-slope to basin-axis profile has been plausibly modelled using a geometric forward model with a low-gradient lower basin slope and basinward higher aggradation rates and sand percentage.
Spatial variability of Hurst statistics in the Castagnola Formation, Tertiary Piedmont Basin, NW ITaly: discrimination of sub-environments in a confined turbidite system
Authors: Felletti Fabrizio 
Published: April 2008

Abstract

The purpose of this paper is to investigate the potential of the use of the Hurst test as a statistical tool for quantifying the degree of clustering of high and low values of field measurements in vertical turbiditic sections within a small and confined tectonically mobile basin. The paper (1) documents the fact that significant clustering occurs in almost all sections, (2) shows that there are systematic spatial variations in the degree of clustering such that different parts of the basin have different Hurst statistics, (3) discusses the origin of those spatial trends, and (4) compares Hurst
H
with Chen and Hiscott’s Hurst
K
. The case study focuses on one well-exposed reservoir-scale turbiditic unit cropping out in the eastern part of the Tertiary Piedmont Basin (NW, Italy) and representing the lower portion of an Upper Oligocene-Lower Miocene turbidite system (Castagnola Formation). The sedimentological model that has been adopted is based on the description of 41 sedimentological logs (approximately 25–35 m apart) physically correlated bed by bed. Three variables were studied: thickness of sandstones and siltstones, grain size score, and sand and silt thickness percentage (i.e. the ratio of coarse division to overlying mudstones, in percent). The Hurst test has revealed the existence of common clustering for the three studied variables (only 2 of 41 logs failed to pass the test at the 10% significance level for all the studied variables). This clustering is associated with lateral and vertical facies variations in response to changes in depositional sub-environments within the Castagnola Basin. A geostatistical analysis has been performed in order to estimate the spatial distribution of the Hurst statistics within the studied area. The analysis makes possible predictions at unsampled locations.
Rheology of a two-phase material with applications to partially molten rocks, plastic deformation and saturated soils
Authors: Vigneresse J. L. 
Published: April 2008

Abstract

A global model is presented to account for the specific rheology of a two-phase material. Examples of observations are taken from a crystallizing magma and these are applied to a partially molten rock, plastic deformation and soil liquefaction. The general behaviour of the viscosity is drawn as a function of the strain rate and the amount of solid phase. It constitutes a 3D diagram developing a cubic surface. The cubic equation is justified by thermodynamic considerations. It results from the mixing of a Newtonian (
n
= 1) and a power law (
n
= 3) type of deformation. The diagram shows two types of rheological response. At high strain rate values, the viscosity contrast between the two phases is the lowest. The resulting
en masse
behaviour is observed during tectonic activity. It manifests itself by homogeneous transport of magma during emplacement and fabric development. An equivalent medium, with average viscosity is a good proxy. Conversely, at low strain rate values, the viscosity contrast between the two phases is the highest. The two end members behave according to their respective rheology. In between, a transitional state develops, in which instability occurs depending on the strain rate and stress conditions. In the 3D diagram it appears as a cusp shape. Rheology presents continuous jumps between the liquid-like and the solid-like rheology. They result in strain localization or phase segregation. The latter preferentially develops during magma crystallization. Deformation under a constant amount of each phase is also possible, resulting in pressure dissolution-like processes. A bifurcation in the solution plane of the equation of viscous motion causes instability. It is comparable with strain softening. A similar situation should develop when mixing Newtonian and power law rheology, for example during diffusion and dislocation creep, or water-saturated sediment deformation. Owing to the continual jumps between the two types of rheology, hysteresis or memory effect may develop. Rapid cyclic deformation may drive strain to extreme straining. The effect of simple shear seems much more effective than pure shear (compaction) to separate the weak phase from its strong matrix. The development of instabilities and continuous jumps from one rheology to the other lead to discontinuous motion of the weak phase. In a molten region, it corresponds to discontinuous bursts of magma that are extracted.
A comparison of structural data and seismic images for low-angle normal faults in the Northern Apennines (Central Italy): constraints on activity
Authors: Collettini C. , Barchi M. R. 
Published: April 2008

Abstract

During the past 18 Ma extensional tectonism has migrated from the Tyrrhenian sea eastward into the Northern Apennines of Italy. The extension is due in part to lowangle east-dipping normal faults, that are now exhumed in the Tyrrhenian islands and Tuscany, while additional extension is still occurring in the Apennine chain (Umbria region,
c.
200 km eastward). This tectonic framework is an example where active extensional processes affecting the Umbria region can be studied in exhumed faults that are no longer active. Here a comparison between the Zuccale Fault (ZF), cropping out in the Isle of Elba, and the Altotiberina Fault (ATF), revealed by geophysical data, seismology and seismic profiles crossing the Umbria region, provide insights into the processes affecting low-angle normal fault development and evolution.

Recorded microseismicity suggests that the ATF is presently active under a vertical σ
1
. Structural analysis of the ZF depict a comparable scenario with fluid involvement during the activity. The comparison of these two structures suggests movements with fluid involvement along gently dipping planes under a vertical σ
1
, implying that these faults are mechanically weak.
Shear deformation of pelitic rocks in a large-scale natural fault
Authors: Casciello Emilio , Cesarano M. , Cosgrove J. W. 
Published: April 2008

Abstract
Experimental tests on simulated clay gouges and data from shear zones developed in pelitic media at convergent plate margins provide contrasting evidence regarding the hydraulic characteristics and, in consequence, the frictional properties of sheared clays. The natural shear zone analysed in this work indicates that shear strain can induce mineralogical changes in smectite-bearing sediments that imply loss of water from the smectite minerals and their replacement with anhydrous illite minerals. The extreme localization of the illitization process and its geometric characteristics allow us to argue that the reaction is initiated by stress concentration along the shear zone and, once discrete shears develop, it is accelerated by both cataclasis and the frictional dehydration of smectites. This process would generate fresh water from within the shear zone, leading to fluid overpressure build up, and can account for the observed hydraulic circulation and salinity anomalies in modern accretionary prisms.
Contrasting styles of fluid-rock interaction within the West Fissure Zone in northern Chile
Authors: Janssen C. , Lüders V. , Hoffmann-Rothe A. 
Published: April 2008

Abstract

Geochemical data from three profiles crossing the West Fissure Zone in northern Chile were used to describe the chemical effects of fluids on faulting processes. The results document considerable differences of fluid-rock interactions between the profiles (A–C). Within the area of profile A and C fluid activities have neither led to intensive exchange reactions between fluids and rocks nor to notable changes in whole rock and mineral composition of fault rocks relative to their undeformed host rock. Investigations of stable isotopes (δ
13
C, δ
18
O) and fluid inclusions indicate infiltration of predominantly descending (meteoric) fluids and only subordinate involvement of ascending hydrothermal fluids. In the case of profile B, fluid-enhanced weakening mechanisms are dominant. Dissolution transfer has led to the formation of an alteration zone up to 400 m wide. Along profile B we have no indications for warm fluids derived from a deep source. Rather, a number of lines of evidence (e.g. δ
18
O and δD) show that fault rock alteration took place due to the infiltration of low temperature meteoric water. For this profile, all geochemical data indicate an open fluid system. Moreover, the chemical variations across the West Fissure Zone agree well with the structural variability observed at this traverse. The application of a variety of geochemical analyses of fault rocks shows the heterogeneity of large-scale continental fault zones.
Development of local orthorhombic fabrics within a simple-shear dominated sinistral transpression zone: the Arronches sheared gneisses (Iberian Massif, Portugal)
Authors: Pereira M. Francisco , Silva J. Brandão 
Published: April 2008

Abstract
The Coimbra-Cordoba shear zone (Iberian Massif), characterized by simple-shear dominated sinistral transpression, exposes several outcrops of strongly sheared peralkaline gneisses surrounded by mica schists and amphibolites. These gneisses are included in the Arronches Tectonic Unit, a thick unit of mylonitic rocks with a steep foliation and an associated gently plunging stretching lineation parallel to the fold axes. Strain partitioning is testified by widely spaced anastomosing shear bands around less-strained domains and by the existence of different shearing domains ranging from relatively ‘less-strained’ and coarse-grained mylonites to highly strained and fine-grained ultramylonites.

Three shearing domains defined by textural and structural changes resulted from progressive deformation and increasing strain, which leads to increased mylonitization of gneisses. This is revealed by the increased modal percentage of the matrix and the decreased percentage of porphyroclasts, accompanied by evolution from orthorhombic to monoclinic fabrics: Conjugate Shearing Domain (
CSD
), Intermediate Sinistral Domain (
ISD
), and Sinistral Domain (
SD
).

This contribution shows that in a simple-shear sinistral dominated transpression zone with a well-developed and widespread monoclinic fabric, it is possible to find mechanical conditions to produce local orthorhombic fabrics. In the Arronches gneisses a local strain regime exists in apparent contradiction with the bulk deformation regime.
Shear zones and metamorphic signature of subducted continental crust as tracers of the evolution of the Corsica/Northern Apennine orogenic system
Authors: Molli G. , Tribuzio R. 
Published: April 2008

Abstract

This paper focuses on new data concerning the deformation and metamorphic history of continental margins of the Mesozoic Ligurian Tethys. In the Tenda massif (NE Corsica), a slice of the European-Iberian continental margin, contractional shear zones show
HP/LT
metamorphic assemblages and top-to-the-west kinematics. These shear zones are overprinted by greenschist facies exhumation-related structures showing top-to-the-SW sense of transport and then top-to-the-NE extensional shearing. The presence of
HP/LT
metamorphism, together with the kinematics of syncontractional shear zones, supports the classic view of Cretaceous-Eocene east-vergent ‘alpine-subduction’ during the early evolution of the Corsica belt. By taking into account structural and metamorphic data on Tuscan continental units belonging to the other side (Adria margin) of the former Mesozoic Ligurian ocean, we ascribe the Corsica/Northern Apennine system to a polycyclic orogen.
Robert Stephenson (1803–1859) — the first groundwater engineer
Authors: Preene M. 
Published: April 2008

Abstract
From a humble background in the mining communities of Tyne and Wear, with little academic education, Robert Stephenson followed in the footsteps of his father, George, and became one of the foremost civil and mechanical engineers of the early 19th Century. While he is primarily associated with railways, Robert Stephenson had considerable dealings with groundwater during his professional life, applying a rational, empirical approach that would be familiar to modern practitioners. Stephenson’s approach to groundwater issues was probably shaped largely by the years spent battling water-bearing quicksands during construction of the Kilsby Tunnel near Rugby on the London to Birmingham Railway. Careful observations allowed him to conclude that local drainage by use of arrays of wells was possible, without the need to drain the whole aquifer body. Later in his career he advised on public water supplies from the Chalk for London and the Sherwood Sandstone for Liverpool. His careful observations and reasoned interpretation, allowed him to advance the concept of a ‘cone of influence’ around a pumped well and to develop tests and monitoring programmes to assess the impact of new abstractions on existing water features. Today, his work may seem basic, even obvious, but, in the days before the work of Darcy and Dupuit, there were many who disputed his findings. Stephenson preferred to let the facts to speak for themselves, but where this was not possible he vigorously publicised the benefit of applying a scientific approach to the management and control of groundwater.