bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tectonosedimentary evolution of the Plio-Pleistocene Sant’Arcangelo Basin (Southern Apennines, Italy)
Authors: Benvenuti M. , Bonini M. , Moratti G. , Sani F. 
Published: April 2008

Abstract
This paper describes a new tectonosedimentary model for the evolution of the Plio-Quaternary Sant’Arcangelo Basin, located in the Southern Apennines of Italy. To this purpose, we carried out a new field survey of the basin fill, closely integrating stratigraphy, facies analysis, and structural and tectonic analyses. The geological map at 1:50 000 scale of the whole basin is the first result of this work. We present a new stratigraphic framework for the Sant’Arcangelo Basin succession, which has been subdivided into five major stratigraphic groups, classified as synthems, following the recognition of major basin-wide unconformities. The synthems include smaller-scale stratigraphic units, which are classified as depositional sequences or sub-synthems. These sub-units are composed of different lithofacies assemblages recording cyclic activation of fluvial, deltaic, shallow marine and lacustrine environments throughout the evolution of the basin. Integration of facies analysis and tectonic data led to the definition of a series of palaeogeographical sketches, encompassing the Piacenzian and late Pleistocene, which mark the main steps in the evolution of the Sant’Arcangelo Basin. Basin-scale hinterland-verging thrust faults and folds controlled the development of sub-basins and the progressive isolation of the Sant’Arcangelo Basin from the Ionian foredeep. The new model presented here defines the Sant’Arcangelo Basin as a triangular-shaped basin, bounded by oppositely verging thrusts. The hinterland-verging Valsinni thrust anticline limited its eastern margin and exerted a major control on the basin evolution.
Crustal magnetism of the Southern Tyrrhenian Sea from aeromagnetic surveys
Authors: Piangiamore G. L. , Faggioni O. , Barbano M. S. 
Published: April 2008

Abstract
Aeromagnetic data from the Southern Tyrrhenian Sea have been analysed, to remove the contributions of shallow and deep sources to the magnetic anomalies by applying a processing technology that increases the informative potential of the magnetic data acquired by AGIP with great accuracy, uniform distribution and high density. The aeromagnetic anomaly field has been reduced to the bottom topographic surface by the bottom reduction method. Spectral signal analysis has been carried out to separate low- and high-frequency components. The spectral reference field (SRF), obtained from the cotransformation of low frequencies, gives information about deep magnetic structures. The high-frequency components, computed from the difference between the magnetic anomaly field and the SRF, provides the spectral anomaly field (SAF). The bottom reduced magnetic anomaly field is derived by merging the high- and low-frequency bands. The resulting map provides information about geotectonic features in the Southern Tyrrhenian area and shows the effectiveness of the adopted approach over traditional procedures.
Hinterland geology and continental margin growth: the case of the Gioia Basin (southeastern Tyrrhenian Sea)
Authors: Gamberi F. , Marani M. 
Published: April 2008

Abstract
The Gioia Basin is a small trough located in the southeastern Tyrrhenian Sea between the Aeolian island arc and Sicily and Calabria. It is experiencing a post-rift margin evolution, while tectonic deformation and high rates of vertical movement are still affecting the Sicilian and Calabrian mainland. The analysis of the evolution of the post-rift depositional systems along the various sectors of the Gioia Basin margin has been carried out through the combined interpretation of multibeam bathymetry and seismic reflection data. Two seismic units have been identified and their component geomorphological elements ascertained through the analysis of seismic facies distribution. In general, the depositional architecture of the margin, the sedimentary environments and facies and related geomorphological elements that are active in the shaping of the margin appear to be mainly controlled by the physiography of the basin itself and by the geology of the hinterland that results from the structural evolution of the adjacent land areas. An evolution from a generalized slope bypass setting to a prograding offlapping slope architecture is recognized and explained as due to the transition from an out-of-grade to a graded profile progressing from the early post-rift stage to the later margin growth stage. Along the Sicilian margin, a constructional apron, mainly consisting of channel levee deposits, makes up much of the studied sedimentary package and reflects a high sediment supply related to the large size of river catchments on land. In contrast, the northeastern Sicilian basin sector is a destructional margin that flanks a region where small river drainage systems result in a low sediment supply to the basin and a continued high uplift rate promotes slope instability; as a consequence, the basin infill is here almost completely made up of mass-wasting deposits. In the Calabrian margin, a first phase of low sediment supply probably coinciding with the filling of the further inland Gioia Tauro half-graben was followed by the establishment of the Gioia-Mesima channel-canyon system that, furnishing an effective sediment flux to the margin, allows the formation of an intraslope depositional body consisting of channelized turbidite lobes.
Sedimentary and diagenetic environments of the Wildmoor Sandstone Formation (UK): implications for groundwater and contaminant transport, and sand production
Authors: Bouch Jon E. , Hough Ed , Kemp Simon J. , McKervey John A. , Williams Geoffrey M. , Greswell Richard B. 
Published: April 2008

Abstract
The Wildmoor Sandstone Formation, proved in three boreholes drilled at Birmingham University, is dominated by fine- to medium-grained sandstones deposited in a braided river environment, within which channel lag, channel fill and abandoned channel facies are recognized. Minor proportions of aeolian sandsheet are present, as are dolocretes, not previously reported in the formation.
The sandstones are feldspathic and lithic arenites, and typically are clay-poor. Early dolomite dominates the diagenetic overprint, and is preferentially developed in channellag deposits. Burial diagenetic effects are minor. Late calcite occurs as a pore-filling phase and within fractures.
Minor fractures and granulation seams are oriented parallel to the NE-SW Birmingham Fault. ‘Conventional’ granulation seams, with comminution of detrital material, and more complex seams containing comminuted dolomite cement with a millimetre-wide halo of dolomite cement are present, the latter implying that the sandstone was dolomitecemented at the time of fracturing.
Several scales of heterogeneity will affect groundwater solute transport. The palaeosols and abandoned channel mudstones may act as barriers to vertical flow at the decimetre scale. Dolomite-cemented channel-lag deposits may act similarly at smaller scales. Granulation seams have permeabilities of two-three orders of magnitude lower than their host sandstones, but their limited occurrence may limit their impact on larger scale flow. Matrix permeability is controlled by grain size and dolomite cement.
The fines in the fine-grained, ripple cross-laminatied sandstones were extensively washed out during coring, and this lithology may be a source of sand yields in some sandstone boreholes. Although no enhancement of particle yields was seen during packer testing, the possibility remains that more comprehensive failure may occur at higher pumping rates.
Non-reactive solute movement through saturated laboratory samples of undisturbed stratified sandstone
Authors: Bashar Khairul , Tellam John H. 
Published: April 2008

Abstract
There has been much recent work on developing models of non-reactive solute migration in saturated stratified porous media. Almost all experimental results against which the models have been tested have been obtained using artificial media. The aim of the present study is to test the models against data from naturally stratified media. In this paper we report the results of the experiments carried out on samples of laminated, intact, saturated Triassic sandstone from the UK. Column experiments were performed at steady flow rates using samples with flow either parallel or perpendicular to the lamination. For flow parallel to the lamination, the breakthrough curves were asymmetrical. They were generally characterized by early breakthrough and tailing. Asymmetry and tailing increased with increasing flow rate. Column experiments in which flow was interrupted showed the presence of physical non-equilibrium. For flow perpendicular to the lamination the breakthrough curves were symmetrical. Simultaneous use of bromide and amino-G-acid, conservative tracers having very different diffusion coefficients, demonstrated the significance of diffusion particularly when the flow is parallel to the lamination. Thinsection analysis, dye staining and positron emission projection imaging (PEPI) techniques were used to study the spatial variations in hydraulic properties in the samples. Thinsection analysis indicated that the thickness of individual layers, each of different porosity and grain size, varies from less than 1 mm to several millimetres and occasionally exceeds 1 cm. The dye and PEPI experiments also identified stratification of flow when the flow is parallel to the lamination, but in the latter case the most obvious stratification was at a larger scale than for the former. No preferential flow was found for samples with flow perpendicular to the lamination. It is concluded that the dominant process in solute migration in the sandstone samples is stratification that is, at least, at two scales, a process which will result in a fractionation where two solutes of different diffusion coefficient are present.
Compositional changes in a fumarolic field, Vulcano Island, Italy: a statistical case study
Authors: Buccianti A. , Tassi F. , Vaselli O. 
Published: April 2008

Abstract
The identification of compositional changes in fumarolic gases of active volcanic areas is one of the most important objectives in monitoring programmes. Together with information from seismic data and deformation, it provides key data to the formulation and management of emergency plans for populations living near active volcanoes.

Chemical data obtained from different fumaroles collected at Vulcano Island (Sicily, southern Italy) between 2000 and 2004 have been analysed statistically. The methodology has identified parameters able to elucidate the structure of the complex fumarolic field of Vulcano in the investigated span of time, notwithstanding the high data variability. The southern portion of the Tyrrhenian Sea was affected by an earthquake (
M
= 5.8, 40 km NE of Palermo) in December 2002. Abrupt outgassing on the island of Panarea occurred in November 2002 and Stromboli was significantly active from December 2002 to July 2003. The great geological instability of the area is thought to have had an influence on the variability shown by the data.

The time-dependent variations in the components of the data have been investigated using logratios. The H
2
O-HCl-SO
2
subcomposition, for a limited set of fumaroles, has been used to check for log-contrast principal components to be considered as a monitoring tool of volcanic activity. Results obtained indicate that the compositional changes are a complex function of time, chemistry, temperature and space. ANOVA (analysis of variance) of log-ratios for which there is no time dependence has elucidated components subject to significant spatial variations across the fumarole field, due to changes in redox conditions, and components dominated by random variations.
Exploratory compositional data analysis
Authors: Daunis-I-Estadella J. , Barceló-Vidal C. , Buccianti A. 
Published: April 2008

Abstract
This paper presents the first steps that should be performed whenever the study of a compositional dataset is initiated. Centre, variation matrix and total variance of a compositional dataset are introduced. In addition the biplots are also introduced as a powerful tool to analyse and discover special features related to subcompositions. The exploratory methodology is applied to a dataset consisting of the major, minor and trace elements composition of soil samples from several places in Tuscany (Italy). The structure of the data, collected from three different known country rocks of ophiolitic nature (basic and ultrabasic rocks), represent an interesting case study for experimenting on new methodologies of statistical investigation and for pointing out differences related to parental chemistry and mineralogy as well as the nature of processes to be related to the subsequent evolution.
Rounded zeros: some practical aspects for compositional data
Authors: Martín-Fernández J. A. , Thió-Henestrosa S. 
Published: April 2008

Abstract

It is very important to realize that the well-known ‘zeros problem’ in compositional data is inherent in the nature of the data rather than in the log-ratio methodology. In a strict sense, any null value is informative itself and needs specific treatment before a multivariate method is applied. In the
rounded zero
case specific techniques of missing data should be applied as a previous step, taking into account that any of these techniques must respect the compositional nature of the data. In practice, when an imputation method is applied, then it is necessary to make a sensitivity analysis of the results from multivariate analysis. These methodological aspects are applied and illustrated using compositional data from geological samples.
Permo-Carboniferous climate: Early Pennsylvanian to Late Permian climate development of central Europe in a regional and global context
Authors: Roscher Marco , Schneider Joerg W. 
Published: April 2008

AbstractA well-justified stratigraphical correlation of continental successions and new palaeogeographic reconstruction of Pangaea reveal new insights into the northern Pangaean climate development influenced by palaeogeography, palaeotopography, glacio-eustatic sealevel changes and ocean currents. The overall Permo-Carboniferous aridization trend was interrupted by five wet phases. These are linked to the Gondwana icecap. The aridization and weakening of wet phases over time were not only caused by the drift of northern Pangaea to the arid climatic belt, but also by the successive closure of the Rheic Ocean, which caused the expansion of arid/semi-arid environments in the Lower/Middle Permian. The end of the Gondwana glaciation rearranged ocean circulation, leading to a cold, coast-parallel ocean current west of northern Pangaea, blocking moisture coming with westerly winds. The maximum of aridity was reached during the Roadian/Wordian. The Trans-Pangaean Mountain Belt was non-existent. Its single diachronous parts never exceeded an average elevation of 2000 m. The maximum elevation shifted during time from east to west. The Hercynian orogen never acted as an orographic east-west barrier, and the Inter-Tropical Convergence Zone was widely displaced, causing four seasons (dry summer/winter, wet spring/autumn) at the equator and a strong monsoon system.
Quantitative magnetic resonance imaging methods for core analysis
Authors: Chen Quan , Rack Frank R. , Balcom Bruce J. 
Published: April 2008

Abstract

The majority of sedimentary rocks have significant paramagnetic impurities, which lead to magnetic resonance signal lifetimes too short to be detected by clinical magnetic resonance imaging (MRI) methods. Quantitative information is the ultimate goal for rock-core analysis. The SPRITE (single-point ramped imaging with
T
1
enhancement) imaging technique has proven to be a very robust and flexible method for the study of a wide range of systems with short signal lifetimes. As a pure phase-encoding technique, SPRITE is largely immune to image distortions generated by susceptibility variations, chemical shift and paramagnetic impurities, unlike clinical magnetic resonance imaging methods. It enables systems with transverse lifetimes as short as tens of microseconds to be successfully visualized. Our experimental results show that most sedimentary rocks have a single exponential transverse magnetization decay for
T
*
2
, which suggests that quantitative imaging of local fluid content can be easily obtained. Some examples of MRI techniques are represented that reveal internal sedimentary characteristics and heterogeneity. In addition, the application of quantitative MRI techniques to examine flow mechanisms in rock cores is outlined.
The Janus database: providing worldwide access to ODP and IODP data
Authors: Mithal Rakesh , Becker David G. 
Published: April 2008

Abstract

In 1997, the Ocean Drilling Program began using a relational data management system and applications called Janus to store and retrieve data collected on the drill ship
JOIDES Resolution
. Since then many new web-based data access queries have been added, and some modifications to the database have been made. The database modifications were needed to allow the migration of pre-Janus data to the database, to incorporate modifications in the calibration procedures, to improve database performance, to add storage and access to various digital images, and to add access to scanned digital images of original paper data. These modifications were made by staff at Texas A&M University and reflect enhancements required by the Ocean Drilling Program (ODP) scientific community.

With the start of the Integrated Ocean Drilling Program (IODP) an opportunity exists to make additional enhancements to the existing Janus database. As such, two major areas are identified: developing a core description program(s) and providing data visualization tools for improved analysis. Efforts to use Java-based programs to build these enhancements are cited. Geographic information systems (GIS) technology is being explored as a viable approach to providing these enhancements.

Building an understanding of the Janus database is best accomplished by visiting the Web site
http://iodp.tamu.edu/database
. Available data can be reviewed using the online ‘Database overview’ option. A list of all queries that are available in Janus can be acquired through the online ‘Data search’ option.
Channel flow and continental collision tectonics: an overview
Authors: Grujic D. 
Published: April 2008

Abstract
The principle of channel flow as defined in fluid dynamics has been used in continental geodynamics since the 1980s. The basic equations for one-dimensional flow introduced to geologists by Turcotte and Schubert were further developed by several research groups to meet the needs of specific studies. The most substantive differences among numerical models are results of different solutions for flow in crust, developed for different boundary conditions. The concept of channel flow has met with strong opposition and criticism from geophysicists and modellers. Although it is difficult to prove unambiguously that there is an active weak channel, it is still the most successful model to explain and predict the tectonics, metamorphism and exhumation of high-grade terranes in some orogens. Moreover, the concept of channel flow has stimulated novel approaches to the study of both the tectonics and metamorphism of large, hot orogens and the interaction between tectonic and surface processes.
Mechanisms and timescales of felsic magma segregation, ascent and emplacement in the Himalaya
Authors: Scaillet B. , Searle M. P. 
Published: April 2008

Abstract

We combine field, petrological, geochemical and experimental observations to evaluate the timescales of compaction-driven and shear-assisted melt extraction and ascent in the Himalaya. The results show that melt migration via compaction and channelling is inescapable and operates on timescales of less than 1 million years and possibly as short as 0.1 million years. Field and petrological data show that such a fast and efficient melt transfer results from a combination of favourable factors, including: (1) low but constant melt viscosity (10
4.5
Pa s) during extraction and ascent; (2) grain size coarsening of the source rocks in response to prolonged heating prior to melting; and (3) high source fertility and thus high melt fraction, owing to elevated modal amounts of muscovite in leucogranite sources. All three factors dramatically increase source permeability. Calculations show that shear-assisted melt extraction had a time interval recurrence in the range 10 000–100 000 years (10–100 ka), leading to sill thicknesses of 1–30 m. Yet melts falling at the low end of the viscosity range when coupled to high shear velocities may lead to veins several hundred metres thick. The deepest structural levels (e.g. central Zanskar Range) show that
in-situ
melts formed where pure shear compaction was greatest and where simple shear was also operative. Magma extracted from migmatite leucosomes was injected along planes of weakness parallel to the ductile shear fabric, probably by some form of hydraulic fracturing crack propagation mechanism. Large High Himalayan leucogranite (HHL) bodies (e.g.
c.
5 km thick sills at Manaslu, Makalu and northern Bhutan) may thus represent inflated laccoliths assembled via dykes that tapped a 100–300 m melt layer produced by compaction of the Greater Himalayan Series (GHS). Thermal simulations show that such melt layers may have incubation times of several million years. Although transport time for magmas associated with the HHL is short, the time for assembly may take several million years for the largest HHL, as geochronological data indicate (up to 5 million years for Manaslu, Shisha Pangma). Transport of leucogranite melt from mid-crustal levels towards the surface was concomitant with active low-angle normal faulting along the South Tibetan Detachment (STD) normal fault, a structure that effectively formed the lid to the extrusion of a partially molten layer of mid-crustal rocks (channel flow). Rapid cooling of the granites emplaced at the top of the GHS implies rapid extrusion and lateral flow of GHS rocks beneath the STD during the period
c.
20–17 Ma. Weakening of the crust by partial melting is thus likely to be pulsatory in time, and future thermomechanical models should incorporate such aspects to model tectonic evolution of hot orogens.