bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of saline fluids in sedimentary basins
Authors: Hanor Jeffrey S. 
Published: April 2008

Abstract

Subsurface saline waters in sedimentary basins can be divided into three groups based on their anionic composition and salinity: (1) Waters with anions other than Cl dominant. These include Na-HCO
3
and Na-acetate waters. Most such waters have salinities of less than 10 000 mg 1
−1
; (2) Cl-dominated, halite-undersaturated waters having salinities between 10 000 and 250 000–300 000 mg l
−1
. These include Na-Cl waters and, at higher salinities, Na-Ca-Cl waters; (3) Cl-dominated, halite-saturated waters with salinities typically in excess of 300 000 mg 1
−1
. Ca and K become increasingly dominant and Na decreases with increasing salinity.

Subaerial evaporation of marine and continental waters and the subsurface dissolution of evaporites both have the potential for producing the range of salinities and dissolved chloride concentrations observed for most subsurface brines, but not their major cation compositions. The broad systematic increase in dissolved Na, K, Mg, Ca, and Sr and decrease in pH and alkalinity with increasing salinity support the hypothesis that the approach toward thermodynamic buffering by silicate-carbonate ± (halide) mineral assemblages is a first-order control on subsurface fluid compositions, even at temperatures well below 100°C. The chemical potential of chloride or, alternatively, the aqueous concentration of anionic charge, is a master variable which ranks in importance with such other variables as pressure and temperature in driving fluid-rock exchange and controlling bulk fluid compositions. This variable is in turn controlled largely by physical processes of fluid advection and dispersion.

Dissolved organic acid anions are associated primarily with low salinity waters, but dissolved metals, such as Cu, Pb, and Zn are preferentially found in brines having salinities in excess of 200 g 1
−1
. The high chloride concentration and low pH of these saline waters may enhance solubilization of metals through chloride complexing.
An integrated approach to the study of primary petroleum migration
Authors: Mann Ulrich 
Published: April 2008

Abstract
The precise mechanism of primary petroleum migration has been elusive despite intensive investigation and discussion. There is more than one mechanism, and the pathways and efficiencies of individual mechanisms vary from case history to case history due to the variable abundances of micropores, macropores and fractures in source rocks as well as different sources for the build-up of a pressure gradient. Primary migration probably proceeds as diffusion through source rock micropores via mesopores to macropores and fractures. From there, a petroleum bulk phase develops, and moves along the macropore and fracture system, possibly together with aqueous solutions.
In fact, many parameters influence petroleum transport out of a source rock, and all of them have seldom been checked by exploration geologists as most mature source rocks are inaccessible. In order to collect information about primary petroleum migration that is as complete as possible, an integrated approach consisting of sedimentology, petrophysics, organic geochemistry and numerical modelling should furnish geologically acceptable results: (i) by sedimentological methods, all potential primary migration pathways are identified, (ii) with the help of petrophysical methods, non-effective migration pathways are separated from effective pathways and excluded, (iii) organic geochemical results provide control and direct evidence for petroleum expulsion stage and efficiency, and (iv) numerical modelling finally quantifies all observed effects within the framework of the geological situation.
Reserve assessment of a stratified deposit with special reference to opencast coal mining in Great Britain
Authors: Nathanail C. P. 
Published: April 2008

Abstract
The assessment of reserves in a stratified deposit should define the areal extent of the mineral, the spatial variation of thickness and quality and the ratio of mineral to waste. The assessment of reserves at opencast coal mines in Great Britain also involves the estimation of the extent of areas where coal is absent or of reduced quality due to old mining activity, washout, alteration by igneous intrusions, lime burning and faulting. The most appropriate estimation technique will vary from site to site and, within an individual site, from seam to seam. Conventional non-spatial statistics can be used where the extent of areas of lost coal is not definable. Area-of-influence approaches such as Thiessen polygons are routinely used to estimate the spatial extent of old workings from point observations at boreholes. The use of indicator kriging may provide a refinement to this deterministic approach. Delaunay triangulations are used by popular mine design software for area and volume calculations. Kriging may also be used to model the variation of seam thickness and quality. Whatever method of estimation is used, poor quality input data will result in poor estimates. Metadata such as how, when and by whom information was collected should be used to decide whether or not a particular piece of information should be retained. Experience shows that each site must be treated as a unique entity with techniques and software being modified to suit the site circumstances. A black box ‘expert system’ approach would fail to identify site specific features and result in misleading estimates.
Phosphate rock: factors in economic and technical evaluation
Authors: Notholt A. J. G. 
Published: April 2008

Abstract
Phosphate rock in the mineral industry refers to the marketable, usually beneficiated, product. Geologically, however, the term embraces a very wide variety of rock types, of both sedimentary and igneous origin, as well as their weathering derivatives. Phosphate deposits thus form in markedly different geological environments and ore characteristics are so varied that a combination of nearly identical factors applicable to their evaluation seldom exists. In spite of this diversity, the phosphate component in most deposits is a member of the apatite group represented by the two end members: fluorapatite, the main mineral in crustal igneous rocks, and carbonate fluorapatite or francolite, by far the most important phosphate component of commercial sedimentary deposits. The identification of the correct apatite composition is important in assessing the quality of marketable phosphate concentrates.

Evaluation usually begins with a detailed mineralogical, petrographical, and chemical study of a representative sample of prospective phosphate ore to determine the principal constituents in the ore and their mode of occurrence. The data obtained establish the grade (P
2
O
5
content) of the rock and its chemical quality and, hence, the method and degree of beneficiation required to provide a commercially acceptable phosphate concentrate. Beneficiation technology is such that often the most difficult ore types (e.g. siliceous, dolomitic and Fe-Al-rich) can be upgraded satisfactorily, but the problems become more acute when impurities occur as substitutions in the apatite lattice. Quality rather than grade is often the deciding factor in determing the viability of a given deposit, in addition to other technical and economic factors.
Evaluation of grade estimation techniques
Authors: Bell T. M. , Whateley M. K. G. 
Published: April 2008

Abstract
A sample set was simulated from an exhaustive data set of silver values derived from blast holes of the 5220 bench. The sample set was used to estimate the ditribution of grade for the 5220 bench using a variety of estimating techniques. The estimating processes were controlled by the knowledge of the statistical and spatial distribution of the exhaustive data set. This approach was used to test the accuracy and precision of the different estimation techniques. The results from the simpler estimation methods (linear interpolation and triangulation) compared most closely to the blast hole samples. The more complex techniques (inverse distance and kriging), using weighting factors, were found to exaggerate the variance and smooth the interquartile range.
A review and evaluation of the costs of exploration, acquisition and development of copper and gold projects in Chile
Authors: Gorman Patrick 
Published: April 2008

Abstract
In recent years Chile has become the focus of activity for many multinational mineral resource companies. Undeniably they are attracted by the geological potential, business/investment rules and lifestyle, all of which are excellent by most standards.

In view of the continued interest in Chile a detailed profile of 36 gold and 27 copper projects and advanced prospects was prepared from a number of public sources of data. From this list a representative selection of about 10 projects was made and the costs associated with those projects were reviewed and evaluated. Based on the data a modest reserve containing 31 tonne (1 M oz) of gold might be discovered in Chile at a cost of US$ 225 kg
−1
Au (US$7 oz
−1
) or acquired for US$ 772 kg
−1
Au (US$24 oz
−1
) and then a mine constructed for US$ 1522 kg
−1
Au (US$ 47 oz
−1
). The total average cost taken from initial reconnaissance to start-up of the mine is equivalent to US$ 25 723 kg
−1
gold per year (800 oz
−1
Au per year). Historically a medium-sized copper deposit in Chile containing 1 M t of fine copper might have been discovered for US$ 6.5 t
−1
Cu (0.3 US cents lb
−1
) or acquired for US$ 10.3 t
−1
Cu (0.5 US cents lb
−1
) and then constructed for US$ 64 t
−1
Cu (2.9 US cents lb
−1
) Cu). The total cost to mine start-up is equivalent to US$ 3969 t
−1
Cu per year (US$ 1.80 lb
−1
Cu per year). The recent purchases by Emablos/Minorco of one-third of Collahuasi and Placer of 500f Zaldivar have increased the prices paid to acquire copper resources to US$ 60 and US$ 93 t
−1
Cu
in situ
(2.7 to 4.2 US cents lb
−1
) respectively. On the basis of the above figures, the cost of acquiring a gold project in Chile is typically equivalent to US$ 24 oz
−1
or 7.30f the price of gold at US$ 330 per ounce. Copper project acquisitions previously averaged the equivalent of 0.50f the price of copper at 95 US cents per lb, but this has reached 4.5% with the price paid for Zaldivar. These guideline values have been prepared to give explorationists, acquirers and developers useful empirical guidelines to help them to decide whether they have the budget to consider entry to Chile or whether to look elsewhere.
Volcanism associated with extension in an Oligocene—Miocene arc, southwestern Viti Levu, Fiji
Authors: Wharton M. R. , Hathway B. , Colley H. 
Published: April 2008

Abstract
The Wainimala Group rocks of southwestern Viti Levu, Fiji, represent part of an Oligocene-Miocene island arc. Some of the early volcanism in this arc took place on a substrate of Eocene-Oligocene frontal-arc crust. Mainly andesitic, transitional calcalkaline lavas were erupted from major subaerial volcanic edifices, while elsewhere tholeiitic magmas formed low-lying basaltic lava fields and small felsic volcanic centres on the seafloor. The intrusion of a dense bimodal basalt-dacite dyke swarm into the underlying frontal-arc crust indicates that significant crustal extension accompanied the eruption of the inter-edifice lavas.
Geochemical variations within the Wainimala volcanic suite are thought to have been generated through fractional crystallisation processes. While relatively slow ascent and mixing of magmas took place beneath the major edifices, efficient shallow-level fractionation and rapid ascent of magmas occurred in the areas between them. The contrasting styles of volcanism may reflect the interaction of ascending magmas with pre-existing heterogeneities in the frontal-arc substrate.
Neogene volcanoes of Chios, Greece: the relative importance of subduction and back-arc extension
Authors: Pe-Piper G. , Piper D. J. W. , Kotopouli C. N. , Panagos A. G. 
Published: April 2008

Abstract
The Aegean area has experienced both extension and subduction throughout the Neogene and Quaternary. Small volcanic centres with a wide range of rock types occupy a ‘back-arc’ position with respect to the subduction zone, but their geochemistry and chronological correlation with local basin subsidence indicates that their origin is primarily the result of extension. The position of voluminous andesite-dacite volcanism in the modern south Aegean arc relative to the seismically defined Benioff zone is similar to that of other active subduction zones, although the timing of vigorous volcanic activity correlates with periods of most rapid basin subsidence. The voluminous early Miocene intermediate igneous rocks of the northeast Aegean also appear closely related to subduction. Variations in subduction-related products through time are correlated with changes in the rate and direction of subduction inferred from regional tectonic data.

The island of Chios, in the eastern Aegean Sea, has several small, mid-Miocene (14–17 Ma) volcanic centres containing high-Mg calc-alkaline (adakitic) andesite, ne-normative basalt, and alkaline and calc-alkaline rhyolite. Both the ne-normative basalt and calc-alkaline andesite have Pb isotopic compositions similar to other Neogene volcanic rocks in the central Aegean region. The small size of the calc-alkaline centres (<10
−1
km
3
) distinguishes them from the nearby voluminous (1000 km
3
), 17–22 Ma, calc-alkaline to shoshonitic volcanic centres of Lesbos and Karaburum.

The minor volcanism on Chios occurred near the site of earlier voluminous arc volcanism. The rapid decrease in the rate of subduction in the mid-Miocene reduced both the production of slab-derived volatiles and silicic melts, as well as the volume of mantle wedge from which arc-type magma was extracted. At the same time, extension resulted in decompression of the lithosphere and the generation of small-volume partial melts. Volcanic products are not found near the major extensional centres: rather, they are associated with minor basin subsidence, which provided brittle pathways for magma flow.
A high-strain rift model for the southern Gulf of Suez (Egypt)
Authors: Bosworth William 
Published: April 2008

Abstract
Extensive exploratory and development drilling have documented the large extension produced during Miocene rifting in the southern Gulf of Suez. Basement fault blocks are commonly rotated > 40°, with maximum dips of 65°. Early fault planes along the rift axis now dip 23–35° NE, with later extension shifting to complex arrays of rider blocks. Multiple well penetrations show that some fault planes are gently listric between basement hanging wall and footwall cut-offs. Stratigraphic and structural relationships show that deformation shifted between several basin-bounding faults during a complex history of basin evolution and progressive sub-basin abandonment. One low-angle normal fault has been identified in outcrop and a detachment model can explain the Miocene structural development of the rift. Post-Miocene deformation and subsidence focused along the basin axis, with extension probably occurring on a new system of planar normal faults. Restoration and balancing of regional and local cross-sections indicate that the southern Gulf has been extended by 56–62%, and that total separation between Sinai and Africa was 34–36 km. Average regional β factor for the central basins of the rift is 1.9–2.0. These new extension estimates are in agreement with subsidence models and crustal thickness estimates for the Gulf, and help quantify plate reconstructions between Sinai, Africa and Arabia. They also indicate that the southern Gulf of Suez is one of the most highly extended, failed continental rifts preserved in the rock record. As such, it provides an important conceptual link between more numerous low-strain continental rifts and successful oceanic basins.
Stratigraphic response to basin formation: Jeanne d’Arc Basin, offshore Newfoundland
Authors: Driscoll Neal W. , Hogg John R. 
Published: April 2008

Abstract

Using seismic reflection and exploratory well data, the stratigraphic response of the Jeanne d’Arc Basin to early Cretaceous extension was examined. The Jeanne d’Arc Basin, located
c.
300 km east-southeast of St John’s, Newfoundland, is a large asymmetric half-graben, which trends north-northeast. The border faults delineating the western limit of the basin are eastward dipping. The structure and geometry of the border faults and transbasinal faults engendered by the early Cretaceous extension influenced the drainage and therefore, the sedimentation patterns in and around the Jeanne d’Arc Basin. In order to assess the stratigraphic response to basin formation and its spatial variation, it was necessary to establish a chronostratigraphic framework with which to examine the effects of the extensional deformation on the preserved stratigraphy. Time surfaces determined by sequence stratigraphy in conjunction with detailed palynology from wells have allowed correlation of time-equivalent coarse-grained proximal facies to the fine-grained distal facies within the Jeanne d’Arc Basin. Correlations among seismic reflection, sedimentological and biostratigraphic data reveal that the stratigraphic response to extensional basin formation varies spatially on both a local and regional scale. The local response was controlled by the small-scale basin architecture (i.e. border/transfer fault interaction) whereas the more regional response was governed by the pre-existing axial drainage networks that enter the basin along the southern basin-bounding transfer zone. The locally-derived sediments were allowed access to the basin near the transfer zones that segment the border faults possibly because of the diminished footwall uplift. These locally derived sandstone units correlate with prograding seismic reflectors that downlap onto the late Barremian rift-onset unconformity producing a wedge-shaped geometry. The wedge is thickest near the border fault and tapers basinward. Away from these locally-derived prograding wedges (i.e. fan delta deposits), the late Barremian rift-onset unconformity, defined from stratal patterns in seismic reflection data, correlates to a flooding surface within the basin depocentres where marine sandstones onlap on to restricted marine/lagoonal and non-marine subaerially-exposed shales. These shales are iron-stained and commonly contain abundant root structures, evidence for pedification, and sideritic concretions. The overlying marine sediments predominantly sourced from the southernmost transfer zone, infilled the basin longitudinally, are more regionally persistent, and onlap onto the locally-derived prograding wedge. Exploratory well data from the Jeanne d’Arc Basin suggest that the regionally derived sediments that infill the basin longitudinally are better hydrocarbon reservoirs than the locally-derived prograding wedges because of better sediment sorting and greater regional extent.
Neotectonics, drainage and sedimentation in central Greece: insights into coastal reservoir geometries in syn-rift sequences
Authors: Collier Richard E. Ll. , Gawthorpe Rob L. 
Published: April 2008

Abstract
The modern analogue of Greek environments was used to provide insights into the prediction of coastal syn-rift architectures. Sediment flux into rift basins reflects the drainage response to slope changes induced by normal faulting. The present day Greek drainage network reflects syn-rift modification of catchments draining the Alpine-Hellenide mountain chain. On a local scale, drainage around individual fault blocks commonly exploits transfer zones. Uplift and cannibalization of earlier sequences in the footwall of new normal faults also has a marked effect on sediment dispersal. Thus, consideration of catchment areas and their evolution offers an improved understanding of potential reservoir distribution and volumetrics within the stratigraphy of any given basin.
Quantitative data on modern fault displacements and on rates of climatically forced, sea- and lake-level changes allow the prediction of relative base-level change at different localities around a half-graben or graben. Maximum rates of tectonic subsidence exceed all but the most rapid rates of glacio-eustatic sea-level fall (such as have occurred in the late Pleistocene). These data indicate it is inappropriate to apply, without some modification, sequence stratigraphic models that have been developed from areas with relatively simple subsidence histories (e.g. post-rift megasequences on passive margins) to syn-rift successions. Spatial variation in subsidence/uplift rates around rift basins is clearly demonstrated in central Greece, where coastal half-grabens show the resulting spatial and temporal distribution of systems tracts and sequence boundaries, and stratal geometries developed on a parasequence and sequence scale. Broad patterns of sequence stacking in deltaic and paralic facies are shown to be predictable, despite the apparent complexity of syn-rift successions. The fundamental control upon differential subsidence is the displacement history on individual normal fault segments. Patterns of relative base-level change and predictable sequence architectures are therefore scaled to the length of the fault segment.
Newly developed techniques to determine proportions of undersized (friable) coal during prospective site investigations
Authors: Harris Ian H. 
Published: April 2008

Abstract
Site investigations to date have been unable to determine the presence of friable (undersized) coal within areas of extreme tectonic deformation. This is especially important in the northwest of the South Wales coalfield, where most of the coal extracted is for the smokeless fuel domestic market, which requires a consistent grade size. Coal in the proximity of the deformation zone is unlikely to be suitable for its intended market due to its small grain size.
The deformation process and fracture styles which contribute to the development of friable coal are discussed and a remote method utilizing the drilling parameters of speed of advance, thrust and torque is investigated to ascertain its suitability in determining the amount and position of friable coal within a prospective coal site. If areas and volumes of friable coal can be determined before the extraction stage of an opencast coal site, site boundaries can be amended so that they do not contain large volumes of the friable product.