The Orcadian Basin is a Devonian (Old Red Sandstone) sedimentary basin formed as a result of extensional tectonics after the end of the Caledonian Orogeny in onshore-offshore northeast Scotland. The Clair oil field lies in a smaller basin with similar types of continental sedimentation and it represents the largest remaining oilfield in the UKCS. Oil is found within Devonian-Carboniferous red beds of the Clair Group directly overlying crystalline basement rocks of the Rona Ridge. Recent work has shown that Lewisian Complex exposed in NW Scotland is excellent for assessing the nature and importance ofthe Rona Ridge basement fracture network. Here, geological evidence suggests that the Devonian rocks of the Orcadian Basin are also a suitable analogue for the Clair cover sequences to some degree and that a reappraisal of the deformation history of the Orcadian Basin is necessary to enhance the understanding of spatial and temporal characterization of structures in the subsurface. Faults, fault rocks, associated mineralization and deformation allow differentiation of three groups of structures within the Devonian Orcadian Basin: i. N-S, NW-SE, WNW-ESE trending faults showing little or no carbonate mineralisation (Group 1); ii. Metre- to kilometre-scale N-S to NE-SW trending folds and thrusts related to a highly heterogeneous regional inversion event, recognized locally throughout the field area, but especially on Orkney (Group 2); iii. dextral oblique NE-SW trending faults and sinistral E-W trending faults with widespread syn-deformational carbonate mineralisation (± base metal sulphides and bitumen) both along faults and in associated mineral veins (Group 3). Localized folds are associated with Group 3 structures due to reactivation of pre-existing faults. Crucially, these later folds are synchronous with carbonate and associated mineralisation events. Re-Os model ages of syn-deformational pyrite in two faults in the Caithness area (Dounreay) are 268.4 ± 4.9 & 266.4 ± 5.2 Ma (Permian). This is consistent with the field observation that Group 3 deformation is synchronous with the emplacement of ENE-WSW-trending lamprophyres of the Orkney Dyke Swarm (ca. 250 Ma based on K-Ar dating). Thus we suggest that Group 3 structures are synchronous with Permian rifting (NW-SE extension) which new faults and locally reactivated earlier structures. It appears that the Devonian rocks of the Orcadian basin were taken through the oil window at this time during a thermal event associated with regional alkaline basic igneous activity in Northern Britain. Scalability studies from 1D transect analysis show that fracture attributes (length and aperture)in the Devonian in Caithness (Scotland) are well described by a power-law distribution over 8 and 4 orders of magnitude. Also, 2D fracture connectivity is highly variable in the system and appears to be mainly associated with corridor structures at a large scale and on longer structures at the mesoscale. The onshore dataset shows sub-vertical fault intersections (3D) suggesting that horizontal drill orientation is favoured to vertical if these rocks were to be drilled as a reservoir.

There is developing interest in cave aerosols due to the increasing awareness of their impacts on the cave environment and speleothems. This study presents the first multidisciplinary investigation into cave aerosols and their contribution to speleothem geochemistry. Modern monitoring of suspended aerosol concentrations, CO2 and temperature in Gough’s Cave, Cheddar Gorge have presented a strong relationship with cave ventilation processes. Temporal variations of aerosol levels have demonstrated the ability of aerosol monitoring to record seasonal ventilation shifts, beyond anthropogenic influences. When used in combination with more established monitoring methods, suspended aerosol monitoring is a beneficial addition to cave environmental studies Theoretical modelling and calculations based on modern aerosol monitoring have established that aerosol contributions are highly variable. Aerosol contributions are of greatest significance under slow growth or hiatus scenarios and high aerosol deposition scenarios. Marine and terrestrial aerosol contributions have been quantified in a flowstone core from New St Michaels Cave, Gibraltar. Additionally, bio-aerosol deposits and bacterial colonisation have been identified as a potential source of trace element bioaccumulation and flowstone coloration in Yarrangobilly Caves, Australia.

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Continental basin margin systems are dominated by alluvial fan environments throughout basin development. As the fan is long-lived, the sediments interdigitate with contemporaneous environments of deposition in the basin centre. The facies and architectures of alluvial fan deposits are influenced by: 1) the varied environments of the fan; 2) the interactions of the fan with contemporaneous distal environments; 3) allocyclic controls on these environments; and, 4) smaller-scale, and more localised, controls of climate, tectonics, base level, and sediment supply. This work considers the Cutler Group sediments of the Paradox Basin, western U.S.A. The proximal extent of the Cutler Group comprises a well exposed continental basin margin system. This work presents generalised spatial facies models across the proximal Cutler Group to ascertain the varied environments of the fan, and the zone of interaction between the fan and the contemporaneous distal environments. Temporal facies models have been constructed to highlight how long-term allocyclic climatic changes, and localised autocyclic variations control the deposition of the Cutler Group. The identification of this cyclicity is used to cyclostratigraphically correlate through the basinal deposits. The deposits of the basin margin system have the potential to significantly impact upon basin-scale fluid migration pathways. These impacts include: 1) interconnecting isolated permeable lithologies of the distal basin; 2) creating ‘thief zones’ away from distal permeable lithologies; 3) providing a bypass route to charge the distal permeable lithologies; and, 4) introducing baffles into an otherwise productive system. Generic facies models derived from this work are applied to the sediments of the Brockram Facies, northern England: a poorly exposed arid continental depositional system dominated by alluvial fan sediments at the basin margin. The application provides significant insight into the sedimentology, geometry and connectivity of the Brockram Facies. This research provides a sedimentological framework to better understand basin margin deposits in poorly exposed basins.

No description available.

The 'Golden Quadrilateral' of W. Romania is a rich mineralised magmatic province hosting major porphyry-Cu and epithermal Au-Ag deposits. The mineralisation is associated with extensive magmatism emplaced along a series of NW-SE trending pull-part basins (e.g. Brad-Sacaramb, Rosia Montana). These basins developed during the Miocene, owing to the opposite sense rotation of the ALCAPA and Tisza-Dacia micro-continents, which facilitated extension-related melting of the subduction modified sub-continental lithospheric mantle. The largest of these basins, the Brad-Sacaramb basin contains extensive calc-alkaline, amphibole-rich, porphyritic andesite and dacite volcanics and sub-volcanic intrusions. LA-ICP-MS U-Pb analysis of zircons indicate that these magmatic rocks were emplaced during the Mid-Miocene 9.7 - 13.1 Ma. The rocks display a temporal geochemical evolution from early "normal" island arc magmatism (13.0 - 11.3 Ma) to adakite-like, characterised by high Sr/Y and La/Yb ratios, emplaced after 11.4 Ma. This shift in the geochemistry resulted from the cessation of plagioclase fractional crystalisation in the adakite-like magmas, coupled with the onset of amphibole crystalisation in the lower crustal MASH zone, which depleted the melts in MREEE-HREE. This change in the crystalising assemblage may have related to an increase in the dissolved water content of the melts. High zircon Ce/CE[sup]* (Ce[sup]4+/Ce[sup]3+) and less negative Eu/Eu[sup]* indicate that the high water content of these melts was accompanies by highly oxidising conditions. These conditions may have been important in preventing early sulfide saturation, a process considered to be unfavourable for the formation of economic Au and Cu deposits. K-Ar analysis from hydrothermal illites indicate that lo low to intermediate sulfidation epithermal and porphyry-Cu mineralisation in the Brad-Sacaramb basin occurred between 9.7 and 12.3 Ma. The epithermal deposits typcially developed < 0.5 Myrs after the cessation of magmatism in the immediate vicinity. One of the most prospective deposits in the basin is the Coranda-Hondol deposit (~4.8 Moz at 1.4 g/t Au). Coranda-Hondol is a telluride-rice, intermediate sulfidication Au-Ag deposit, hosted by a series of andesitic stocks (emplaced ~12.6 Ma) and siliciclastic sedimentary formation. The deposit displays a variety of mineralisation styles with pervasive pyrite dissemenations and base-metal sulfide and sulfosalt-telluride -rich veinlets. Microthermonetry of fluid inclusions indicate that the mineralisation was facilitated by a dilute (<10 wt% NaCl) low temperature (~250[degrees]C) fluid. Stable isotopes ([delta][sup]18O[sub]fluid: 6.1 - 9.4 [parts per thousand], [delta]D[sub]fluid: -39.8 - -74.3) support a magmatic source for the fluid which mixed with meteoric waters during the waning stages of the hydrothermal system ([delta][sup]18O[sub]fluid: -0.3 - 1.6). Boiling of the ore fluid during brecciation events triggered the precious metal mineralisation. The Au is predominately hosted within the crystal lattice of textual complex and isotopicalle light ([delta][sup]34S: -19/4 - -6.5 [parts per thousand]) colloform pyrite grains (up to ~450 ppm) developed within these boiling zones.

Soft-sediment remobilization and fluid flow processes and their products such as sand injectites, mud volcanoes, pipes, pockmarks and authigenic carbonates constitute a key, but under-appreciated component of sedimentary basins. The structures are evidence of and provide focused fluid pathways bypassing the stratigraphic and structural framework and thus have numerous implications for hydrocarbon exploration and production by influencing sediment and fluid distributions. Recent advances in subsurface imaging using high-resolution 3D seismic data, integrated with well data, geochemical data and outcrop data have greatly improved the understanding of subsurface sediment remobilization and fluid flow processes in sedimentary basins. This study presents substantial new results from the description, analysis and interpretation of products of subsurface remobilization processes and fluid flow based on all available data from the Northern North Sea and the Nigeria Transform Margin. The studied intervals, which encompass the entire Cenozoic and Cretaceous succession, have undergone repeated, large-scale remobilization and deformation of sediments through time. The North Sea is the archetype Giant Injected Sand Province (GISP) with kilometre-scale sandstone intrusions observed within multiple stratigraphic intervals, but this is the first time the northern North Sea has been systematically studied on a regional scale. Seismic-scale sandstone intrusions are well documented along the Atlantic Margin from the South Viking Graben, Outer Moray Firth, Norwegian-Danish Basin, Faroe-Shetland Basin and Barent Sea but primarily emplaced during one or two episodes. Results from the NNS show evidence for five major episodes of emplacement. These sandstones, believed to be sourced from different stratigraphic levels, have intruded thick polygonally-faulted, diatomaceous and smectite-rich mudstones; probably facilitated by hydrocarbons and diagenetically-released water in spatio-temporally varying proportions. The Cenozoic section of the Nigeria Transform Margin comprises up to 2 km of sediments, including recurrent mass transport deposits ranging between a few to tens of kilometres in length and constituting up to 25 % of the stratigraphic section. A series of fluid flow features such as pockmarks, pipes, bottom simulating reflections, polygonal faults and mound have been interpreted on the seabed and in the overburden; all of which provide evidence of focused fluid movement in the subsurface becoming more abundant towards the Niger Delta. Our study provides details on the geometries, scale, spatial distribution, potential causative mechanisms and implications of these soft-sediment remobilized and fluid flow products; as well as their relationships with other depositional and structural elements within the basin. It also reveals the extent by which sedimentary basins can be affected by these processes and therefore be incorporated into present stratigraphic frameworks and improve reservoir models.

Η Μεσόγειος θάλασσα είναι μια κλειστή θάλασσα που μπορεί να χωριστεί σε δυτικό και ανατολικό τμήμα. Η ανατολική Μεσόγειος είναι μεγαλύτερη σε μέγεθος από την δυτική και παρουσιάζει έντονο γεωλογικό ενδιαφέρον σε διάφορους τομείς. Συγκεκριμένα η νοτιοανατολική Μεσόγειος με την παρουσία της Μεσογειακής ράχης, της Λεκάνης Λεβαντίνης, του αβυσσικού πεδίου του Ηροδότου, του κώνου του Νείλου και του ηπειρωτικού μπλοκ του Ερατοσθένη αποτελεί ένα μεγάλο πεδίο ερευνών. Ένας τομέας ερευνών που τα τελευταία χρόνια παρουσιάζει μια έξαρση είναι η ύπαρξη πεδίων υδρογονανθράκων στην περιοχή. Το μεγαλύτερο ενδιαφέρον εστιάζεται στη γεωλογική εξέλιξη δυο λεκανών, της Λεβαντίνης νοτιοανατολικά της Κύπρου και του Ηροδότου νοτιοδυτικά της Κύπρου. Οι δυο αυτές λεκάνες σχηματίστηκαν την ίδια γεωλογική περίοδο ως λεκάνες προχώρας λόγω της καταβύθισης της Αφρικανικής πλάκας κάτω από την Ευρασία. Φιλοξενούν το ίδιο περίπου πάχος ιζημάτων όπως και ίδιους τύπους ιζημάτων. Έχουν διαφορετική γεωμετρία με την λεκάνη του Ηροδότου να είναι βαθύτερη και διπλάσια σε έκταση από την λεκάνη της Λεβαντίνης. Για την λεκάνη της Λεβαντίνης υπάρχουν αρκετά στοιχεία για την στρωματογραφία της, και τη δυνατότητα της να αναπτύξει πεδία υδρογονανθράκων, καθώς και πιστοποιημένα αποθέματα πετρελαίου και φυσικού αερίου. Μέσω αυτών των στοιχείων και γνωρίζοντας ότι η λεκάνη Ηροδότου έχει ίδια ηλικία σχηματισμού συγκρίναμε τις δυο λεκάνες όσον αφορά την παλαιογεωγραφική τους εξέλιξη και την στρωματογραφία τους με σκοπό να εκτιμήσουμε τα αποθέματα που μπορεί να φιλοξενεί η λεκάνη του Ηροδότου. Σύγχρονα λαμβάνουμε υπόψη και το ρόλο που διαδραματίζουν στην εξέλιξη των λεκανών αλλά και της ευρύτερης περιοχής, το ηπειρωτικό μπλοκ του Ερατοσθένη και ο κώνος του Νείλου Παρουσιάζονται επίσης σεισμικά δεδομένα στα οποία φαίνονται άμεσοι δείκτες υδρογονανθράκων DHI (Direct Hydrocarbons Indicators) αλλά και άλλα στοιχεία που αφορούν την εξέλιξη των λεκανών. Αυτοί οι δείκτες συνδέονται άμεσα με σημεία στα οποία υπάρχουν διαφυγές υδρογονανθράκων, όπου πιθανά να υπάρχουν πεδία υδρογονανθράκων. Επίσης αναφέρεται ποια πρέπει να είναι τα κριτήρια ούτως ώστε να αναπτυχθούν υδρογονάνθρακες. Τέλος παρουσιάζεται ένας συγκεντρωτικός πίνακας με όλα τα συγκριτικά στοιχεία των δυο λεκανών, που μας δείχνει τα πιστοποιημένα στοιχεία της λεκάνης της Λεβαντίνης και τις εκτιμήσεις για την λεκάνη του Ηροδότου μέσα από την σύγκριση της με τη λεκάνη Λεβαντίνης. / The Mediterranean Sea is an close sea that can be divided into western and eastern part. The Eastern Mediterranean is larger in size than the west and has a big geological interest in various fields. Specifically, the southeastern Mediterranean in the presence of the Mediterranean ridge, the Levantine basin, the Herodotus abyssal plain, the Nile cone and the Eratosthenes continental block, is a large field of investigation. One of the main interesting topics is the genesis and the development of hydrocarbon fields in the area. The major focus is on the palaeogeographic evolution of two major basins, such as Levantine basin and Herodotus basin. These two basins were formed in the same geological period as foreland basins due to subduction of the African plate beneath Eurasia. Accommodate approximately the same sediment thickness and the same sediment types. They have different geometry with Herodotus basin is deeper and doubles in size from the Levantine basin. For the Levantine basin there is enough evidence for the stratigraphy, and the ability to develop oil fields and they are certified reserves of petroleum and natural gas. Through these elements and knowing that Herodotus basin formed in the same age we compared the palaeogeographic evolution and stratigraphy of the two basins with a view to assess the stocks that can accommodate the Herodotus basin. At the same time we take into account the role they played in the evolution of the basins, the Eratosthenes continental block and the Nile cone. Seismic data are also presented which show direct hydrocarbon indicators DHI (Direct Hydrocarbons Indicators) and other data concerning the evolution of the two basins. These indicators are directly linked to places where there are leaks of hydrocarbons, which are thought to be hydrocarbon fields. Finally we present a table summarizing all the comparisons of the two basins, which shows us the certified data of the Levantine basin and the estimated oil and gas reserves of Herodotus basin through the comparison of the Levantine basin.

Nous avons mené cet exercice au travers d’une étude pluridisciplinaire combinant des couvertures géophysiques (gravimétrie et aéromagnétisme) réactualisées ou nouvelles, des informations géologiques acquises sur le terrain ou sur carottes de forages pétroliers et un catalogage de propriétés pétrophysiques des roches. Sur une large moitié sud du Bassin parisien, du Massif armoricain aux Vosges, nous avons : i) réalisé un schéma structural du substratum du Bassin parisien, ii) proposé une carte géologique détaillée, sous couverture, iii) réactualisé la carte de zonation de la chaîne varisque en France, intégrant de nouvelles datations sur carottes de forages ayant atteint le substratum. D’après ces résultats, la suture éo-varisque se poursuit d’ouest en est, de la partie sud-armoricaine jusqu’au nord des Vosges, le domaine nord-armoricain se prolonge jusqu’à la faille de Bray et la zone saxothuringienne est continue d’est (Vosges) en ouest (Manche). Egalement, à l’aide de modélisations conjointes de gravimétrie et magnétisme, intégrant l’information recueillie dans le forage de Couy, la nature du substratum environnant désormais mieux connu, ainsi que les contraintes pétrophysiques nouvelles, nous proposons que la source de l’AMBP soit un corps plutonique intermédiaire à acide. Pour finir, en compilant la bibliographie et nos résultats, nous proposons que ce corps se soit mis en place entre le Viséen inférieur et le Viséen supérieur, dans une ouverture NNE-SSW selon un raccourcissement maximal NNW-SSE. / Mapping the cadomian/variscan basement buried beneath the Paris basin is a key objective to improve the geological knowledge of the Variscan belt in West Europe. We address this objective using a combination of new and updated potential field data (aeromagnetic and gravity), as well as information provided by field studies and drill cores, and a library of petrophysical characteristics measured on field samples. On a large southern half of the Paris basin, from the Armorican Massif to the Vosges: i) we made a new interpretative structural sketch map under the sedimentary cover, ii) we proposed a detailed geological map of the Paris basin substratum, iii) we updated the tectonic sketch of the Variscan belt in France, supported by new geochronological determinations on deep drill cores. Altogether, these results show that the eo-Variscan suture is extended from the southern part of the Armorican Massif to the northern Vosges. Eastwards, the North-Armorican domain reaches the Bray fault; and the Saxothuringian zone is extended from the Vosges to the English Channel. In addition, based on combined aeromagnetic and gravity 2D modelling constrained by Couy deep borehole data, the PBMA source is interpreted as a deep intermediate-alkaline plutonic body. Finally, compiling bibliographic information together with our new results, we hypothesize that this magmatic body could have been emplaced in the early to late Visean period, during a NNE-SSW opening under a NNW-SSE shortening.

No description available.