bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detachment faulting and petroleum prospectivity in the Rio Muni Basin, Equatorial Guinea, West Africa
Authors: Turner Jonathan P. 
Published: April 2008

Abstract

The change from rifting to drifting is generally signified by a characteristic end-rift, or break-up, unconformity. In the Rio Muni Basin, two such unconformities bound an Aptian-Cenomanian transitional sequence of allochthonous carbonates and clastics considered unique among the South Atlantic passive margins. The transitional sequence comprises allochthonous thin-skin ‘rafts’, up to 2500 m thick, of shallow water carbonate and clastic sediment emplaced in a relatively deepwater setting along shallow detachments. A new model for the rift to drift development of the Rio Muni Basin interprets the raft tectonics as a response to a combination of end-rift-early post-rift uplift of the basin margins and deep off-shore bathymetry
c.
1800 m. Seismic interpretations reveal spectacular hanging wall geometry in the rafts as a consequence of their movement across a geometrically complex, ramp-flat basal detachment. In places, the hanging walls of the rafts display an ‘eggbox’ topography of closely spaced anticlines, often with four-way dip closure. Information from wells and analogy with adjacent basins indicates potential source rocks in the Aptian and Turonian. Several migration paths are identified, including the juxtaposition of hanging wall reservoirs with the source-bearing stratigraphy across transverse fault zones. Raft tectonics has considerable isostatic and thermal consequences, with attendant implications for predicting the timing of potential source rock maturity. Modelling maturity at variously located wells and pseudowells indicates the principal effect of the raft tectonics to have been a very rapid episode of burial in the basin centre and isostatic rebound of the unloaded margins.
Tectono-stratigraphic evolution of the North Falkland region
Authors: Lawrence S. R. , Johnson M. , Tubb S. R. , Marshallsea S. J. 
Published: April 2008

Abstract
An interpretation of regional seismic data acquired between 1993 and 1995 has been used to establish a regionally consistent tectono-stratigraphic framework for the North Falkland Shelf. This incorporates three rift (extensional) and two post-rift sequences separated by important tectono-stratigraphic breaks representing unconformities at near-Base Upper Jurassic, near-Base Cretaceous, Mid-Cretaceous and Early Tertiary levels. In the structural framework derived from seismic interpretation two major zones are recognized. The northeast Graben Zone constitutes three tectono-stratigraphic provinces, the north-south orientated North Falkland Graben, and the Western Rift Complex and Southern Half-graben which are dominated by northwest-southeast rift trends. The Falkland Islands form part of the southwest Uplift Zone which has a tectono-stratigraphic history, shown by the interpretation of apatite fission track data, to be compatible with that of the North Falkland Shelf and southern South America. A regional northeast-southwest seismic line shows an extensional northern edge to the Falkland Plateau and no apparent westerly extension of the Agulhas-Falkland Fracture Zone. A ‘rigid’ or ‘non-rotational’ reconfiguration of southwest Gondwanaland (i.e. with no independent rotation of a Falkland Islands microplate) shows a regional consistency of Late Triassic-Mid-Jurassic back-arc and Late Jurassic-Early Cretaceous South Atlantic rift trends. This is presented as circumstantial evidence for a ‘non-rotational’ model for the break-up of southwest Gondwanaland.
Scaling systematics of vein size: an example from the Guanajuato mining district (Central Mexico)
Authors: Loriga Maria Antonietta 
Published: April 2008

Abstract
Fractals have been applied to vein systems to assess whether they have an organized and systematic structure. Understanding vein systematics allows realistic interpolation and extrapolation from available data by accurate prediction of the numbers and sizes of veins within a target volume. Vein geometries were measured from the Guanajuato epithermal Ag-Au field (Mexico) with vein attributes ranging from the millimetre to metre scale. Ores occur as mineralized quartz-calcite veins and stockworks in Tertiary sedimentary, volcanic and acid intrusive rocks. Mineralization is controlled by north-northeast-south-southwest regional extension. 1D sampling was found to be the most objective and effective way to compare the different data sets. Vein thickness distributions indicate an underlying power-law, with the scaling exponent varying between −0.66 and −0.88 over two orders of magnitude. When combined, the data maintain the same relationship over four orders of magnitude and are characterized by a slope of −0.75. Outcrop data, however, display higher densities within the stockwork. The agreement in scaling exponents between the various data sets suggests that they belong to the same overall structure and are most likely related to the same growth process.
Discrete fracture network modelling applied to groundwater resource exploitation in southwest Ireland
Authors: Jones Mark A. , Pringle Alec B. , Fulton Iain M. , O’Neill Shane 
Published: April 2008

Abstract
A discrete fracture network model has been applied to increase the probability of sinking a successful groundwater production borehole at a well-field in Carboniferous rocks in southwest Ireland. The model employs the FracMan software to explicitly represent fractures. Model construction is based on a synthesis of data from a variety of geological and hydrogeological sources. The model is verified and calibrated against borehole measurements and multiborehole pumping tests. The process of model construction indicates that the intensity of flowing fractures is controlled primarily by fracture zones running through the well-field, and that there is also a relationship between flowing fractures and zones of weathered dolomite. Simulations allow the optimal orientation of any production borehole to be determined, and suggest that the most favourable orientation increases the mean number of flowing fractures intersected by up to 30%. The likely yield for different borehole locations can be assessed by conducting flow simulations. Within fracture zones, the probability of a successful production well is high. Flow simulations are also used to quantify the degree of hydraulic interference between boreholes. The results of the modelling can be used to assess the most significant uncertainties and develop a programme of future site characterization that addresses them.
Prediction of static and dynamic fluid pathways within and around dilational jogs
Authors: Connolly Peter , Cosgrove John 
Published: April 2008

Abstract
The distribution of stresses around a fault controls the development of second order fractures and influences fluid migration pathways. This paper demonstrates how the regions of enhanced fracture-induced permeability and fluid migration pathways, in both static and dynamic situations, can be predicted for dilational jogs subjected to simple shear. Mean stress is one of several key factors influencing the migration of fluids through a system. By combining mean stress data with second order fracture predictions obtained from experimentally determined stress trajectory and differential stress data around fault geometries, it is possible to derive predictions for the fluid pathways associated with a static (homogenous) system. Superimposing the mean stress states obtained for the same jog at different applied loads enables the changes in mean stress (and hence fluid migration) associated with the cyclical loading of a fault during stick-slip faulting to be studied. In addition, the mean stress patterns associated with successive stages in the jog’s evolution have been studied and the variations in these patterns, and therefore of the associated fluid migration pathways, mapped in order to track the change in these pathways that occurs as the overlap of the jog-defining faults increases.
Carboniferous basin evolution of central Ireland — simulation of structural controls on mineralization
Authors: Lewis Helen , Couples Gary D. 
Published: April 2008

Abstract
Much is known about the Carboniferous-hosted, hydrothermal, Zn-Pb deposits of central Ireland, including temperatures, geochemistries and fluid properties at the mineralized sites. However, this knowledge is insufficient to force a unique genetic interpretation of the palaeohydrogeological system responsible for mineralization. Two hypothetical flow systems survive previous mass-balance testing: a deep, topographically driven, regional flow, and deep, convective flow systems local to each deposit. In order to develop models of these flow systems a 4D, Early Carboniferous restoration of basin development in central Ireland has been created. The structural style is one of tilted fault blocks of the pre-Carboniferous ‘basement’; the Carboniferous sedimentary rocks are deposited in the accommodation space created by movement of the basement. Fluid and heat flow simulations based on the geological restorations show that most of the rising, hot flows are focused on faults. The 4D restorations suggest that such faults are at active, syn-depositional, fault-block corners. Buoyancy driven convective flow systems, operating within both the fractured basement and its sedimentary cover, are a viable mineralization system that agrees with the geological interpretation. Topographically driven flow systems developed from the geological interpretation do not reproduce the important characteristics of hydrothermal flow as deduced from evidence at the deposit sites.
Gravity lineaments and Carboniferous-hosted base metal deposits of the Irish Midlands
Authors: O’Reilly B. M. , Readman P. W. , Murphy T. 
Published: April 2008

Abstract
Central Ireland contains an extensive carbonate succession of Courceyan-Brigantian age, deposited in fault-bounded sub-basins across the Irish Midlands. Carbonate sediments host base metal Pb-Zn deposits of mostly pre-Arundian age, with mineralization episodes controlled by syn-rift crustal extension. As the region is highly glaciated, geological structure is not well mapped. Here, it is shown that the mineralization is spatially correlated with a network of ‘Caledonian’ northeast-southwest trending and interconnecting weaker north-northeast-south-southwest and subtle northwest-southeast trending gravity lineaments. Gravity derivative maps are used to demonstrate these relationships and it is shown that the occurrence of the base metal deposits is related to the local magnitude and direction of the derivatives. The continuity of lineaments across the Carboniferous regions into older Palaeozoic terranes, where they usually correlate with mapped faults, indicates strong Caledonian basement control on Variscan tectonic development and related episodes of base metal mineralization. The reactivation of older basement fractures controlled the migration pathways of mineralizing fluids and the spatial distribution of deposits. These methods applied to densely spaced gravity data are a useful tool in understanding basement and basin-fill properties which influence ore genesis.
Tertiary-Quaternary magmatism within the Mediterranean and surrounding regions
Authors: Wilson Marjorie , Bianchini Gianluca 
Published: April 2008

Abstract

Tertiary-Quaternary magmatism within the Mediterranean and surrounding regions, including the European foreland of the Alps, the North African margin and the Eastern Mediterranean, occurs in three distinct associations:

•
anorogenic, extension-related intra-plate magmas, typically Na-rich alkali basalts, basanites and their differentiates, but locally including subalkaline basalts and potassic partial melts (e.g. leucitites) of the mantle lithosphere;

•
orogenic, subduction-related/post-collisional magma series related to plate convergence; typically with potassium-rich geochemical characteristics which may be related to subduction of continental crustal materials;

•
subalkaline basalts, similar to mid-ocean ridge basalts, formed at localized oceanic spreading centres.

The magmatism is spatially and temporally associated with the Late Cretaceous-Cenozoic convergence of Africa-Arabia with Eurasia which resulted in the progressive closure (by subduction) of oceanic basins in the Mediterranean domain and ultimately the collision of the Alpine orogen with the southern passive continental margin of Europe. Break-off of subducted lithospheric slabs may have provided an important trigger for magmatism in several localities.
The timing and geographical distribution of magmatism of orogenic and anorogenic affinity is summarized. Detailed discussion of the major and trace element and Sr-Nd-Pb isotope characteristics of the magmatism in the Central Mediterranean region provides important insights into the petrogenesis of the magmas and the nature of the main mantle source components.
Crustal structure of the North Tyrrhenian Sea: first result of the multichannel seismic LISA cruise
Authors: Mauffret A. , Contrucci I. 
Published: April 2008

Abstract
During a deep-penetration multichannel seismic cruise, the North Tyrrhenian basin was investigated. This basin has a shallow Moho along the Italian coast. Two kinds of dipping reflections were identified in the crust. The westward-dipping reflections are interpreted as Apennines or/and Alpine thrusts whereas the eastward-dipping reflections may be the seismic expression of extensional detachments. The deep part of the 10 km thick Corsica Basin is well imaged on the continental shelf. This basin was formed before or during the opening of the Balearic-Ligurian basin and is related to the collapse of the Alpine Corsica belt. We emphasize the active role of plutonic bodies that rise from a 3 km depth during the mid-Pliocene. The thinning of the North Tyrrhenian crust could be explained by a delamination of the Adriatic lithosphere that retreats towards the east.
IBS Pannonian Basin project: a review of the main results and their bearings on hydrocarbon exploration
Authors: Horváth Frank , Tari Gábor 
Published: April 2008

Abstract
The IBS Pannonian Basin project presents a good example of fruitful joint activity between Hungarian and other European scientists, and beneficial co-operation of academia and the petroleum industry. This allowed us to achieve significant progress in the understanding of the structure, tectonic evolution, stratigraphic features and hydrocarbon generation in the Pannonian Basin.
The Pannonian region has been an integral part of the Alpine belt, and it reveals the complexity of orogenic evolution. Continental to oceanic rifting, followed by convergence, subduction and continental collision shaped the Palaeozoic-Mesozoic substrata of the region. Subsequently, two periods of basin formation (Late Cretaceous and Palaeogene) occurred, most probably in compressional setting. From the earliest Miocene large scale lateral displacement and block rotation took place in the internal domain of the orogen, together with the formation of the Pannonian Basin. This has been characterized by lithospheric extension, however, interrupted by compressional events. The modern Pannonian Basin is in an initial phase of positive structural inversion. All of these tectonic events had significant impacts on the formation and the economic value of the various petroleum systems in the area.
Late Neogene sedimentary facies and sequences in the Pannonian Basin, Hungary
Authors: Juhász E. , Phillips L. , Müller P. , Ricketts B. , Tóth-Makk Á. , Lantos M. , Kovács L. Ó. 
Published: April 2008

Abstract
Detailed sedimentological, facies and numerical cycle analysis, combined with magnetostratigraphy, have been made in a number of boreholes in the Pannonian Basin, in order to study the causes of relative water-level changes and the history of the basin subsidence.
Subsidence and infilling of the Pannonian Basin, which was an isolated lake at that time occurred mainly during the Late Miocene and Pliocene. The subsidence history was remarkably different in the individual sub-basins: early thermal subsidence was interrupted in the southern part of the basin, while high sedimentation rate and continuous subsidence was detected in the northeastern sub-basin.
Three regional unconformities were detected in the Late Neogene Pannonian Basin fill, which represent 0.5 and 7.5 Ma time spans corresponding to single and composite unconformities. Consequently two main sequences build up the Late Neogene Pannonian Basin fill: a Late Miocene and a Pliocene one. Within the Late Miocene sequence there are smaller sedimentary cycles most probably corresponding to climatically driven relative lake-level changes in the Milankovitch frequency band. Considering the periods, the estimated values for precession and eccentricity in this study (19 and 370 ka) are close to the usually cited ones. In the case of obliquity the calculated period (71 ka) slightly deviates from the generally accepted number. Based on the relative amplitudes of oscillations, precession (sixth order) and obliquity (fifth order) cycles had the most significant impact on the sedimentation. Eccentricity caused cycles (fourth order) are poorly detectable in the sediments. The longer term (third order) cycles had very slight influence on the sedimentation pattern.
Progradation, recorded in the Late Miocene sequence, correlates poorly in time within the basin. The dominant controls of this process probably were changes of basin subsidence rate and the very high sedimentation rate. The slow, upward trend of silt and sand bed thickness as well as that of the grain size also reflects the local progradation.
The present-day tectonics of the Aegean as deduced from seismicity
Authors: Hatzfeld Denis 
Published: April 2008

Abstract
We present a review of the seismicity and focal mechanisms for the Aegean (historical, teleseismically and microseismically computed), which we compared with the recent active faults. A very consistent trend in the T-axes within the Aegean across blocks of different size and orientation suggests that the surface tectonics of the Aegean is controlled by the deformation of the lithosphere as a whole. Some recently active faults (mostly the NW-SE-striking faults that are located west of the Aegean sea) are not associated with seismicity, some seismicity is associated with new E-W-striking faults of modest displacement that are mostly seen in continental Greece. We suggest that, due to the important amount of internal deformation of the Aegean lithosphere and the inferred rotations, the localization of the deformation changes with time and a precise timing of the recent faults activity is necessary to correlate with present-day deformation. We also suggest that, for continental crust, the work to create new fault that strike perpendicular to the main strain direction (as deduced from focal mechanisms and GPS measurements) is less than the work to reactivate faults that strike obliquely to the strain direction. We propose that a diffuse system of normal faults or grabens starts to develop, parallel to the Gulf of Corinth, and links the western termination of the North Aegean Trough to the northern end of the Kefallinia fault.
On the origin of west-directed subduction zones and applications to the western Mediterranean
Authors: Doglioni C. , Gueguen E. , Harabaglia P. , Mongelli F. 
Published: April 2008

Abstract
West-directed subduction zones show east-verging arcs of 1500–3000 km. They are usually younger than 50 Ma and are characterized by a frontal accretionary wedge and a back-arc basin propagating together toward the east. The accretionary wedge scrapes off superficial layers of the downgoing plate (thin-skinned tectonics) whereas the back-arc extension cross-cuts the entire subduction hanging wall (thick-skinned tectonics). The slab of this type of subduction is steep to vertical and the hanging wall of the subduction has a mean elevation of 1000 m below sea level. Trenches and foredeeps are the deepest basins of the Earth and the mean depth is of 5000 m below sea level. West-directed subduction occurs both in case of the highest E-W convergence rates among plates (e.g. W Pacific examples) and no or very low convergence (e.g. Carpathians). Following Atlantic W-directed subduction examples, the W-directed subductions seem to develop along the back-thrust belt of former E-directed subduction zones, where oceanic lithosphere occur in the foreland to the east with the narrowing of the American continents. This could be applied to the onset of the Apennines subduction along the back-thrust belt of the Alpine-Betic orogen where Tethys oceanic crust was present. The Alpine orogen was stretched and scattered in the Apennines back-arc basin. The back-arc extension is internally punctuated by necks (sub-basins) and boudins (horsts of continental lithosphere). Asymmetric extension in the back-arc basin appears controlled by differential drag between the eastward mantle flow and the overlying passively transported crustal remnants. Compression in the accretionary prism may be interpreted as the superficial expression of the shear occurring between the downgoing lithosphere and the horizontally moving mantle which compensates the slab roll-back. The area of the Apennines appears lower than the area of the sedimentary cover before subduction: this favours the idea that not significant crustal slices have been involved in the Apenninic accretionary prism, and the basement thrust sheets included in the western part of the belt are mainly relicts of the Alpine-Betic orogen.
Overview of partitioning and fate of contaminants: retention, retardation and regulatory requirements
Authors: Yong Raymond N. 
Published: April 2008

Abstract

This overview study examines the principal interactions between contaminants and soil fractions responsible for contaminant partitioning, with the aim of developing a further understanding of retardation and retention processes during contaminant transport. The defining mechanisms for sorption and desorption of contaminants are generally known for many types of contaminants in interaction with specific soil fractions. However, contaminant accumulation in soil-engineered barriers or soil substrate material needs to be addressed in terms of contaminant retention or contaminant retardation as a contaminant attenuation process. This is necessary if regulatory requirements regarding
natural attenuation capabilities
are to be fulfilled. The combined processes leading to partitioning of contaminants in complex mixtures of contaminants and soil fractions have yet to be fully defined and understood. However, sufficient information exists concerning chemical and biologically mediated mass transfer to permit one to appreciate the need for distinguishing between irreversible sorption and temporary sorption processes. Failure to properly realize this can make the natural attenuation concept for clay barriers a ‘disaster waiting to happen’.