Academic literature on the topic 'Metamorphic rocks New Caledonia'
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Journal articles on the topic "Metamorphic rocks New Caledonia"
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Dallmeyer, R. David, and R. Damian Nance. "40Ar/39Ar whole-rock phyllite ages from late Precambrian rocks of the Avalon composite terrane, New Brunswick: evidence of Silurian–Devonian thermal rejuvenation." Canadian Journal of Earth Sciences 31, no. 5 (May 1, 1994): 818–24. http://dx.doi.org/10.1139/e94-075.
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Several variably deformed and metamorphosed, late Precambrian volcanic–sedimentary successions have been recognized within the Avalon composite terrane exposed in the Caledonian Highlands of southern New Brunswick. Whole-rock samples of metasedimentary phyllite and phyllitic metatuff from the oldest (ca. 600–635 Ma) Avalonian succession display similar, internally discordant 40Ar/39Ar age and apparent K/Ca spectra. Intermediate-temperature gas fractions were experimentally evolved solely from very fine grained, cleavage-aligned white micas. These yield apparent ages between ca. 430 and 410 Ma, and are interpreted to closely date a static Late Silurian – Early Devonian thermal rejuvenation.Evidence for a Silurian – Devonian thermal event has not been previously documented in Avalonian rocks of the Caledonian Highlands (Caledonia assemblage). However, a thermal overprint of similar age (ca. 400 Ma) is recorded by metamorphic muscovite in high-grade gneisses and platformal metasedimentary rocks (Brookville assemblage), which are in tectonic contact with the low-grade Caledonia assemblage. These potentially correlative thermal overprints may provide minimum age constraints on the juxtaposition of these contrasting tectono-stratigraphic assemblages, which are likely to have been palinspastically separate tectonic elements during the earliest Paleozoic.
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Maurizot, P., B. Sevin, S. Lesimple, J. Collot, J. Jeanpert, L. Bailly, B. Robineau, M. Patriat, S. Etienne, and C. Monnin. "Chapter 9 Mineral resources and prospectivity of non-ultramafic rocks of New Caledonia." Geological Society, London, Memoirs 51, no. 1 (2020): 215–45. http://dx.doi.org/10.1144/m51-2016-9.
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AbstractThe mineral resources of the non-ultramafic rocks of New Caledonia and its Exclusive Economic Zone can be classified according to their host rocks. The metallic mineral resources are essentially associated with volcanic and magmatic activity. Non-economic volcanogenic massive sulfide deposits with Cu and Au are located in the Late Carboniferous Koh Ophiolite and in the Late Cretaceous Poya Terrane. Base metals, Au and Ag of the sedimentary–exhalative type are present in the metamorphic Diahot-Panié Metamorphic Complex, associated with syn-rift volcanism. An Au–Sb metallogenic province is associated with the post-obduction Late Oligocene granitoids and co-genetic hydrothermal silica–carbonate (listwanite) zones in the Peridotite Nappe; Au is disseminated in the granites and Sb occurs as lodes in the silica–carbonate. Among the non-metallic mineral resources, barite, gypsum, magnesite, phosphate, clays, dimension stones, limestone for use as cement and as a neutralizer, and aggregates are all present. Gemstones such as jade and chrysoprase are only used locally. Late Cretaceous coal, which was briefly exploited in the past, is now considered to be a source rock for an offshore potential oil and gas system. Petroleum prospectivity is currently focused on the Fairway Basin. Several low-enthalpy thermo-mineral springs with a weak geothermal energy potential are known on Grande Terre.
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Ghent, E. D., J. C. Roddick, and P. M. Black. "40Ar/39Ar dating of white micas from the epidote to the omphacite zones, northern New Caledonia: tectonic implications." Canadian Journal of Earth Sciences 31, no. 6 (June 1, 1994): 995–1001. http://dx.doi.org/10.1139/e94-088.
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An 40Ar/39Ar study of white micas from high-pressure metamorphic rocks of northern New Caledonia yielded cooling ages of 37 ± 1 Ma for both epidote and omphacite zone samples. Whole-rock samples from the lawsonite zone yielded ages in the range 44–51 Ma with complicated age spectra, probably reflecting both detrital and newly grown micas. The areal extent of the mica samples, over 300 km2, suggests that the epidote and omphacite zone rocks cooled through the muscovite closure temperature, about 350 °C, as a coherent cooling unit. Simple thermal modeling suggests that these rocks could have closed at similar times if the unroofing rate were greater than 2–10 mm∙a−1. Lawsonite zone rocks occur structurally within about 0.5 km of garnet–omphacite rocks, suggesting the possibility of major postmetamorphic tectonic displacement.
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Maurizot, P., D. Cluzel, S. Meffre, H. J. Campbell, J. Collot, and B. Sevin. "Chapter 3 Pre-Late Cretaceous basement terranes of the Gondwana active margin of New Caledonia." Geological Society, London, Memoirs 51, no. 1 (2020): 27–52. http://dx.doi.org/10.1144/m51-2016-11.
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AbstractThe basement under the Late Cretaceous unconformity in New Caledonia consists of three amalgamated terranes. They are all oceanic, arc-related and developed offshore from the eastern Gondwana active margin during periods of marginal basin development. Téremba Terrane is composed of deep sea Permian to Mesozoic arc-derived volcanic rocks and greywackes. The Koh–Central Terrane includes at its base an ophiolite with island arc tholeiites and boninites (Koh Ophiolite) of Late Carboniferous to Early Permian age overlain by a thick sequence of greywacke (Central Range Volcaniclastic Rocks) of Permian to Late Jurassic age. The Téremba Terrane and the Koh–Central Terrane may be part of the same forearc basin, with the rocks from the Koh–Central Terrane deposited in a deeper environment. The Boghen Terrane is a metamorphic complex composed of schists, broken formations and mafic–ultramafic mélange, derived from mixed terrigenous and volcanic sources. The overall fine grain size and laminar bedding suggest deep sea and more distal deposition than the other terranes. The maximum depositional ages from detrital zircons suggest deposition during the Early Jurassic to Early Cretaceous. The terrane is interpreted as a metamorphosed subduction complex that includes blueschist and greenschist facies metamorphic rocks exhumed through the Koh–Central Terrane. At a regional scale, the nature of these three pre-Late Cretaceous terranes confirms the existing palaeogeographical reconstructions, which locate New Caledonia outboard the ocean–continent subduction that surrounded Gondwana during the Paleozoic and Early Mesozoic. A detailed analysis of these terranes and their relationship with East Australian terranes of the same age shows that a marginal basin system probably existed between mainland Gondwana and proto-New Caledonia and closed before the Late Cretaceous. A tentative detailed reconstruction of this margin during the Carboniferous–Early Cretaceous period is proposed.
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AOKI, K., B. F. WINDLEY, S. MARUYAMA, and S. OMORI. "Metamorphic P–T conditions and retrograde path of high-pressure Barrovian metamorphic zones near Cairn Leuchan, Caledonian orogen, Scotland." Geological Magazine 151, no. 3 (August 13, 2013): 559–71. http://dx.doi.org/10.1017/s0016756813000514.
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AbstractThe metamorphic P–T conditions and associated relationships of the Barrovian zones near Glen Muick were re-examined by focusing on the petrology and thermodynamics of rocks at Cairn Leuchan, where garnetite lenses and layers occur in surrounding garnet amphibolite in the highest-grade sillimanite zone. The representative mineral assemblages in the garnet-rich lenses and garnet amphibolite are garnet + quartz + clinopyroxene + plagioclase + amphibole ± epidote, and garnet + amphibole + quartz + plagioclase ± clinopyroxene ± epidote, respectively. The chemical compositions of constituent minerals are the same in both garnetite and garnet amphibolite. The metamorphic P–T conditions of these rocks were estimated by thermodynamic calculations. The results show that the rocks underwent high-pressure granulite facies metamorphism at P = c. 1.2–1.4 GPa and T = c. 770–800°C followed by amphibolite facies metamorphism at P = c. 0.5–0.8 GPa and T = c. 580–700°C. Integration of our new results with previously published data suggests that the retrograde P–T trajectory of the highest-grade Barrovian metamorphic rocks marks a temperature decrease during decompression from a crustal depth of the high-pressure granulite facies, which is much deeper than previously considered.
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MAJKA, JAROSLAW, STANISLAW MAZUR, MACIEJ MANECKI, JERZY CZERNY, and DANIEL K. HOLM. "Late Neoproterozoic amphibolite-facies metamorphism of a pre-Caledonian basement block in southwest Wedel Jarlsberg Land, Spitsbergen: new evidence from U–Th–Pb dating of monazite." Geological Magazine 145, no. 6 (September 10, 2008): 822–30. http://dx.doi.org/10.1017/s001675680800530x.
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AbstractSouthwest Spitsbergen, Wedel Jarlsberg Land, consists of two Proterozoic crustal blocks with differing metamorphic histories. Both blocks experienced Caledonian greenschist-facies metamorphism, but only the southern block records an earlier pervasive M1 amphibolite-facies metamorphism and strong deformational fabric. In situ EMPA total-Pb monazite geochronology from both matrix and porphyroblast inclusion results indicate that the older M1 metamorphism occurred at 643 ± 9 Ma, consistent with published cooling ages of c. 620 Ma (hornblende) and 580 Ma (mica) obtained from these same rocks. This region thus contains a lithostratigraphic profile and metamorphic history which are unique within the Svalbard Archipelago. Documentation of a pervasive late Neoproterozoic Barrovian metamorphism is difficult to reconcile with a quiescent non-tectonic regime typically inferred for this region, based on the occurrence of rift-drift sequences on the Baltic and Laurentian passive margins. Instead, our new metamorphic age implies an exotic origin of the pre-Devonian basement exposed in SW Spitsbergen and supports models of terrane assembly postulated for the Svalbard Archipelago.
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Aoki, K., B. F. Windley, S. Maruyama, and S. Omori. "Discussion of ‘Metamorphic P–T and retrograde path of high-pressure Barrovian metamorphic zones near Cairn Leuchan, Caledonian orogen, Scotland’." Geological Magazine 151, no. 4 (March 4, 2014): 758–63. http://dx.doi.org/10.1017/s0016756813001106.
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K. Aoki, B. F. Windley, S. Maruyama & S. Omori reply: First, we thank Viete, Oliver & Wilde for their interesting and thought-provoking comments on the timing of the high-pressure granulite facies (HGR) metamorphism recorded in metamorphic rocks at Cairn Leuchan, Scotland, published by Aoki et al. (2013). Based on new metamorphic data of garnetites and garnet-amphibolites at Cairn Leuchan and new zircon U–Pb ages of amphibolitized eclogite at Tomatin, we suggested in our publication that the HGR metamorphism was retrograde after eclogite facies before the c. 470 Ma ‘Barrovian metamorphism’. Viete, Oliver & Wilde however speculate that the HGR metamorphism at Cairn Leuchan may have occurred at c. 1000 Ma, as a result of their new U–Pb zircon age of the Cowhythe Gneiss at Portsoy and from previous studies of the geological structure and geochronology. We are grateful for this opportunity to describe, albeit in a preliminary manner, our new understanding and tectonic model of the Caledonian orogen in Scotland and western Ireland of which the Barrovian metamorphism is a key component. A reply to a comment is not the correct place to propose an entirely new paradigm for such a classic orogen, but we will present our model more fully in a future publication.
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Uruski, C., and P. Baillie. "MESOZOIC EVOLUTION OF THE GREATER TARANAKI BASIN AND IMPLICATIONS FOR PETROLEUM PROSPECTIVITY." APPEA Journal 44, no. 1 (2004): 385. http://dx.doi.org/10.1071/aj03014.
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A paradigm of New Zealand petroleum geology was that the oldest source rocks known in the region were of Cretaceous age, so any older sedimentary rocks were considered to be economic basement. Two major projects have revealed that this is not universally the case and that a Jurassic petroleum system should now be considered.Firstly, the Astrolabe 2D speculative survey, acquired by TGS-NOPEC in 2001, has revealed that a significant section underlies the traditional Cretaceous petroleum systems. Secondly, the Wakanui–1 well, drilled by Conoco, Inpex and Todd in 1999, which has recently become open-file, penetrated a Mid-Jurassic coal measure sequence.Jurassic rocks, including coal measure units, are known onshore in New Zealand, They are part of the Murihiku Supergroup, one of the basement terranes comprising the Permian to Cretaceous volcanic arc that forms the basement rocks of the present New Zealand landmass. Wherever they have been seen in outcrop, these rocks generally record low grade metamorphism and have been discounted as petroleum source rocks. Where rocks of the same age were deposited distal to the volcanic arc (and the effects of heat and pressure), however, they may form components of an effective petroleum system.The New Caledonia Basin, extending more than 2,000 km from Taranaki to New Caledonia, may have been the site of a Mesozoic back-arc basin. Jurassic coal measure successions and their equivalent marine units may be locally, or regionally important as source rocks. Implications of a Jurassic petroleum system for prospectivity of the region are investigated.
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Majka, Jarosław, Karolina Kośmińska, Stanisław Mazur, Jerzy Czerny, Karsten Piepjohn, Maciej Dwornik, and Maciej Manecki. "Two garnet growth events in polymetamorphic rocks in southwest Spitsbergen, Norway: insight in the history of Neoproterozoic and early Paleozoic metamorphism in the High Arctic." Canadian Journal of Earth Sciences 52, no. 12 (December 2015): 1045–61. http://dx.doi.org/10.1139/cjes-2015-0142.
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Geochronological studies in northern Wedel Jarlsberg Land, southwestern Svalbard (Norway), showed that the Tonian (c. 950 Ma) igneous rocks were subjected to metamorphism during the Torellian (c. 640 Ma) and early Caledonian (470–460 Ma) events. Predominant augen gneisses, derived from a Tonian protolith, are intercalated in that area, with schists comprising two distinct metamorphic mineral assemblages. The M1 (Torellian) assemblage containing garnet-I + quartz + plagioclase-I + biotite-I + muscovite-I was formed under amphibolite-facies conditions at c. 550–600 °C and 5–8 kbar (1 kbar = 100 MPa). The M2 (Caledonian) assemblage comprising garnet-II + quartz + plagioclase-II + biotite-II + muscovite-II + zoisite + chlorite crystallized at c. 500–550 °C and 9–12 kbar, corresponding to epidote–amphibolite facies conditions. The M2 mineral assemblage constitutes the pervasive Caledonian fabric of the schists that was subsequently reactivated in a left-lateral strike-slip shear regime. The subsequent c. 70° clockwise rotation of the original structure to its present position was caused by a large-scale passive rotation during the Paleogene Eurekan orogeny. The new pressure–temperature estimates suggest that metamorphic basement in the study area was consolidated during the Torellian middle-grade event and then overprinted by Caledonian moderate- to high-pressure subduction-related metamorphism. A following sinistral shear zone assembled the present structure of basement units. Our results pose a question about the possible extent of Torellian precursor to the Caledonian basement across the High Arctic and the scale of its subsequent involvement in early Caledonian subduction. In conjunction with previous studies, the results suggest a possible correlation between southwestern Spitsbergen and the Pearya Terrane in Ellesmere Island.
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POTEL, S., R. FERREIRO MÄHLMANN, W. B. STERN, J. MULLIS, and M. FREY. "Very Low-grade Metamorphic Evolution of Pelitic Rocks under High-pressure/Low-temperature Conditions, NW New Caledonia (SW Pacific)." Journal of Petrology 47, no. 5 (February 21, 2006): 991–1015. http://dx.doi.org/10.1093/petrology/egl001.
Full textDissertations / Theses on the topic "Metamorphic rocks New Caledonia"
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Bowman, Dannena Renee Steltenpohl Mark G. "Exhumation history of Caledonia eclogites in Liverpool Land, East Greenland, and comparisons with eclogites in Norway." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SPRING/Geology_and_Geography/Thesis/Bowman_Dannena_35.pdf.
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Herd, Michelle Erica June. "Continental Extensional Tectonics - The Paparoa Metamorphic Core Complex of Westland, New Zealand." Thesis, University of Canterbury. Geological Sciences, 2007. http://hdl.handle.net/10092/1425.
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Cretaceous continental extension was accommodated by the development of the Paparoa Metamorphic Core Complex, resulting in the separation of New Zealand from Gondwana. High grade (Lower Plate) and low grade (Upper Plate) rocks are separated by the Ohika and Pike Detachment Faults. The two detachment faults have distinctly different histories, with greater exhumation along the Pike Detachment Fault. The onset of crustal extension is proposed to have commenced along the Pike Detachment Fault at 116.2 ± 5.9 Ma (Rb/Sr dating). Both geochemical and geochronological approaches are adopted for this thesis, through the in situ analysis of oxygen and hafnium isotope ratios, trace metals and U-Pb content. Chemical changes are tracked during the petrogenesis of the Buckland Granite, with mafic replenishment observed in the later stages of crystallisation. Crystallisation temperatures of the Buckland Granite are calculated using zircon saturation thermometry, with an average Ti-in-zircon temperature of 697℃ (upper-amphibolite facies). Inherited zircons in Lower Plate rocks show distinct age peaks at c. 1000, 600 and 300 Ma, illustrating the incorporation of heterogeneous local crust (Greenland Group and Karamea Batholith). Model ages (TDM) are calculated for inherited zircons of the Lower Plate rocks, which record the time at which magma bodies (zircon host rocks) were extracted from the mantle. Maximum and minimum model ages for the Buckland Granite average at 3410 Ma and 2969 Ma, with the maximum TDM value of 3410 Ma coinciding with the proposed major crustal formation event of the Gondwana supercontinent at c. 3.4-3.5 Ga. Two distinct U-Pb zircon age peaks are observed in the Buckland Granite at 102.4 ± 0.7 and 110.3 ± 0.9 Ma. The 110.3 ± 0.9 Ma age is interpreted as the crystallisation age of the pluton, while the 102.4 ± 0.7 is proposed to represent a younger thermal (magmatic?) event associated with the 101-102 Ma Stitts Tuff.
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TEDESCHI, Mahyra. "Geodynamic evolution of the Southern Brasilia orogen, SE Brazil: new petrochronological insights from UHT and HP metamorphic rocks." reponame:Repositório Institucional da CPRM, 2018. http://rigeo.cprm.gov.br/jspui/handle/doc/19382.
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Jeanpert, Julie. "Structure et fonctionnement hydrogéologiques des massifs de péridotites de Nouvelle-Calédonie." Thesis, La Réunion, 2017. http://www.theses.fr/2017LARE0047/document.
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Le fonctionnement et la structure hydrogéologiques des aquifères de socle des granites et des gneiss sont aujourd'hui relativement bien compris. En revanche, dans cet ensemble, les aquifères dans les péridotites sont très peu étudiés et mal compris. Dans ce contexte, les massifs obductés de Nouvelle-Calédonie présentent un laboratoire naturel exceptionnel pour améliorer la connaissance de cet hydrosystème original en contexte tropical. Ainsi l'objectif du présent travail de thèse est d'approfondir la connaissance de la structure et du fonctionnement hydrogéologiques de ces massifs. L'analyse porte d’abord sur le manteau d'altération constitué de la cuirasse, des latérites, des saprolites grossières et du saprock. Plus de 60 essais hydrauliques sont menés sur les massifs de péridotites et les résultats sont compilés aux données existantes. La conductivité hydraulique moyenne des latérites est évaluée à 1.10-7 m/s et celle des saprolites grossières et du saprock à 8.10-7 m/s. L'hétérogénéité de cet horizon altéré est marquée par une gamme de variation de la conductivité hydraulique sur six ordres de grandeur et l'analyse piézométrique met en évidence des connexions hydrauliques avec le substratum fracturé profond. Le substratum est ensuite considéré. L'étude de la fracturation est réalisée à partir de mesures structurales sur affleurement et de la description de près de 1000 m de carottes de forages. L'analyse de la fracturation met en évidence l'importance du réseau serpentineux par sa densité d’une part, et par son lien avec l'altération supergène d'autre part. De plus, il est vérifié que la conductivité hydraulique du substratum diminue avec la profondeur. Cette variation est liée à la diminution de la densité de fractures altérées. Ainsi, à l'issue de ces analyses, la structure des massifs de péridotites est définie. Un réseau primaire de fractures d’espacement décimétrique lié au réseau serpentineux préstructure les péridotites. Sur ce réseau se surimpose un réseau de fractures dont l'espacement est décamétrique et caractérisé par une altération supergène. Les fractures altérées présentent localement de fortes conductivités hydrauliques, de l'ordre de 10-5 m/s. En profondeur l'espacement des fractures est hectométrique et les fractures sont majoritairement fermées, scellées par les minéraux néoformés ou par l'effet de la pression lithostatique. Les réseaux de fractures déca et hectométriques, visibles également sur l'effet d’échelle de la conductivité hydraulique, sont majoritairement verticaux, développés par instabilité de dissolution lors des processus d’altération. Cependant, des structures à faible pendage existent également et permettent la percolation du réseau. Enfin, à partir de ces nouveaux résultats et de l’intégration de l'ensemble des données acquises sur les différents massifs, un modèle de structure et de fonctionnement hydrogéologiques est proposé à l'échelle du massif. Ce modèle comprend l'horizon des latérites qui constitue un aquitard homogène sous lequel se développe l'aquifère dont l'épaisseur est de l'ordre de cinquante mètres. Le substratum est discrétisé en trois couches dont la conductivité hydraulique décroît de 2.10-7 à 2.10-8 m/s entre 50 m et 250 m environ sous le mur de l'aquifère. Les modèles numériques construits permettent de valider le modèle conceptuel unitaire et montrent que l'état de saturation des massifs est contraint par leur géomorphologie. Au terme de ce travail, plusieurs aspects doivent encore être approfondis. Le rôle hydrogéologique de la cuirasse doit être précisé et considéré dans le modèle hydrogéologique. Enfin, compte tenu du développement possible de structures très perméables, voire pseudo-karstiques, la connaissance de la distribution des structures drainantes doit être améliorée. Les résultats appliqués de ce travail de recherche sont exposés dans un rapport final et un guide méthodologique livrés dans le cadre du projet CNRT « HYPERK »Water resources of hard-rock (gneisses or granites) aquifers have significantly been studied in the past two decades. The hydrogeological behavior and structure of these aquifers are thus relatively well understood. On the other hand, aquifers in mantle-type basements, such as peridotites, are poorly studied and understood, mainly because they are not common and of limited extent. In this context, New Caledonia is a great laboratory offering unique opportunity to improve the knowledge of these original types of hydrosystems in tropical climate. Thus, the objective of this thesis is to improve the knowledge of these aquifer systems within weathered peridotites. Firstly, the study focuses on the characterization of the weathered layers of the peridotites composed of, from top to bottom, iron oxides/ferricrete, laterite, coarse saprolite and saprock (ie. top of the bedrock, with up to 20 % of weathered material). More than 60 hydraulic tests are performed and results were compiled with existing data. Mean hydraulic conductivity (K) of laterites is estimated around 1.10-7 m/s while mean value in coarse saprolites and saprock is around 8.10-7 m/s. Heterogeneity of this altered layer is high; K varies between six orders of magnitude and hydraulic head data analysis reveals a hydraulic connection with the deep fractured bedrock. Secondly, the fresh rock part of peridotites is studied. Fracture network analysis is derived from outcrop structural measurements and from the description of about 1000 m of cumulated borehole cores. This work highlights the importance of serpentine network, because of its high density and its critical impact on weathering. Moreover, the observations reveal that hydraulic conductivity decreases with depth within the substratum, due to the vertical decrease of weathered fractures density. These new results allow defining a structural framework of the massifs. It is characterized by a primary decimetrical fracture network closely related to the serpentine network. This network is overprinted by a secondary weathering network which reveals decametric spacing (ca. 30 m) and in places K values of 10-5 m/s. At depth, spacing is hectometrical and fractures are sealed by lithostatic pressure and/or subsequent mineral precipitations. These deca- and hectometric fracture networks, which are also visible on the scale effect of hydraulic conductivity, are primarily vertical and are the result of dissolution instabilities occurring during weathering processes. However, low- angle fractures do occur and allow the percolation of the network. Finally, on the basis of these new results and the integration of all existing data from different massifs a new hydrogeological conceptual model is proposed at the scale of a massif. The model includes a homogeneous lateritic aquitard and a coarse saprolite and saprock aquifer which is about 50 m thick. The bedrock is subdivided into three layers whose hydraulic conductivity decreases from 2.10-7 m/s to 2.10-8 m/s, respectively 50 and 250 m below the aquifer base. Numerical modelling validates this unitary conceptual model and reveals that the saturation of the massifs depends on their morphology. At last, several aspects require further research. The role of the ferricrete layer must be specified and considered in the hydrological model. Moreover, distribution of the fracture network remains to be fully addressed and should be studied with care given the potential development of highly permeable structures that could conform to pseudo-karstic drains. The applied results of this work are available in a “Technical guide” and a “Technical report” of the “HYPERK” CNRT Project
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Brown, Julie Louise. "The deep sulfur cycle : insights from sulfide metamorphism in blueschist and eclogite, NE New Caledonia." Phd thesis, 2007. http://hdl.handle.net/1885/109781.
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One aspect of sulfide petrology that has received very little attention is the prograde
metamorphism of sulfide minerals in exhumed fragments of a subduction zone. 'Normal'
approaches to studying sulfur transfer in subduction zones look at sulfur in arc magmas, tracing
the su lfur pathway using isotopes. Sulfur is removed from the slab during the release of water-rich
fluids associated with metamorphism to eclogite facies. Nevertheless, New Caledonian blucschist
and eclogite preserve as inclusions in porphyroblastic minerals, a record of sulfides present during
prograde subduction processes. Significantly, these inclusion sulfides have not been retrogressed
by later fluids, as in the case of matrix sulfides in these rocks. This is a study of sulfides trapped
by blucschist through to eclogite facies silicate minerals, providing data on the behaviour of
sulfides during subduction.
Most studies in regional metamorphic terranes ignore sulfide minerals. This is somewhat
understandable, as they equilibrate an order of magnitude faster than silicate minerals (Barton
1970), and so may not necessarily reflect the origi nal equilibrium assemblage formed at the peak
conditions of metamorphism. During retrogression, sulfide structure and composition is not only
susceptible to rapid changes induced by cooling, but also by fluids, whose influx in New
Caledonia has been facilitated along greenschist facies shear zones. Therefore it is likely that
matrix sulfide minerals have re-equi librated.
However, sulfide mineral inclusions in prograde porphyroblasts (lawsonite, spessartine garnet, and
almandine garnet) are effectively armored against such retrogression or fluid influx. Cu-Fe sulfide
inclusions have been found across metamorphic grade within the lawsonite, omphacite, and
hornblende metamorphic zones, spanning a crustal profile of - 30km. Many of these inclusions
show evidence of isochemical unmixing of original monosulfides during cooling, and bulk area
scans were done to determine the original compositions. The area scans represent both binary and
ternary mixing lines between exsolution products. Careful interpretation of this data enables the
back-calculation of original equilibrium rnonosulftde phases. However, the interpretation of
sulfide chemistry is complicated. Most inclusions are in the order of I μm in size. The
determination of high P Cu-Fe-S phase relations relies not only on sulfide composition, but also on
the interpretation of co-existing mineral phases identified in larger inclusions. The results differ
significantly from the low pressure (1 atm) experimental topologies. In this way, high pressure mineral inclusion compositions provide insight into the effect of subduction pressure on Cu-F~S
internal phase relations as well as silicate sulfide equilibrium.
Despite a concentrated effort, prograde sulfide inclusions were not found in the intervening
'epidote' metamorphic zone. The absence of sulfide in the epidote zone is likely related to
fluctuating fluid fs2 - f02, which precluded sulfide and garnet being stable together at that time.
High pressure theoretical ca lculations of Cu-Fe-S equilibria support the assessment of natural
sulfide specimens, and permit the determination of high P phase relations in this system.
Chalcopyrite stability is P-dependent, and is not a stable mineral phase for much of the blu eschisteclogite
facies metamorphism in New Caledonia.
Common fsrfo2 buffers containing magnetite are irrelevant in blueschist eclogire terranes; garnet
occurs in mafic rocks at the expense of plagioclase, accompanying the breakdown of magnetite
(Green and Ringwood J 967). Magnetite-bearing redox equilibria have been extensively studied
experimentally and theoretically (e.g. Shi 1992) and are widely applied to evaluate redox
conditions in the crust and mantle. However, as magnetite is not present in eclogites, such
equilibria are deemed metastable. Therefore, it is important to determine which phase equilibria
are appropriate for subduction zone environments, on the basis of silicate-sulfide-oxide
relationships. The importance of silicate-sulfide equilibria during subduction is demonstrated by
garnet-forming sulfide-feldspar reactions, which contribute to the total garnet budget. For
example: 2CaAl₂Si₂O₈ + 2FeS + Fe₃O₄ + 2SiO₂ = 2CaFe₂Al₂Si₃O₁₂ + 2FeS₂
Anorthile Pyrrhotite Magnetite Quartz Garnet Pyrite
Such reactions can occur because of the ability of iron to behave as both a chalcophile and
lithophile element.
The prevalence of copper sulfides is characteristic of subducted sulfide. This is not due to high
copper content in these lithologies per se, but is in fact a record of prograde sulfide-sil icate
reactions in which iron behaviour changes from chalcophile to Jithophile. This results in the
concentrating of copper in the remaining sulfides, as copper retains its chalcophile character
during subduction.
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Spandler, Carl. "The geochemical and petrological evolution of subduction zones : insights from blueschist to eclogite-facies rocks from New Caledonia and high-pressure hydrothermal experiments." Phd thesis, 2004. http://hdl.handle.net/1885/146119.
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McCoy, Stephane Guy. "The dynamics of Gymnostoma maquis on ultramafic soils in New Caledonia." Phd thesis, 1998. http://hdl.handle.net/1885/110396.
Full textAbstract:
Ultramafics cover extensive areas of New Caledonia and present a
variety of unique nutritional and metal toxicity problems for plant growth.
The flora of these substrates is highly diverse and occurs as vegetation types
ranging from a low sclerophyllous maquis (heath) to rainforest. These
substrates have been the focus of intensive nickel mining over the last
century and are often devoid of vegetation for several decades. This lack of
plant establishment is a major environmental concern in New Caledonia
and has been the focus of revegetation research. The genus Gymnostoma
has received particular attention because of its nitrogen fixing association
with Frankia and dominance in vegetation types which might be
interpreted as a reflecting successional progression after fire. An
understanding of the mechanisms surrounding these successional patterns
might assist in solving practical issues of mine site revegetation with native
species.
This thesis set out to firstly determine whether vegetation types
containing Gymnostoma are successional communities, secondly to
examine certain key processes which appear to be driving vegetation
patterns, and thirdly, to identify the role of Gymnostoma in ultramafic
vegetation. Key processes associated with vegetation were examined
experimentally to determine their influence on plant growth on a range of
ultramafic substrates.
Field surveys exammmg vegetation patterns and processes were
carried out on three ultramafic soil types supporting Gymnostoma
vegetation: iron crust oxisol, eroded oxisol and hypermagnesian soil. These
three soil types have distinct chemical and physical properties which may
affect plant growth. Floristic records from each soil type were firstly
examined using MDS to determine floristic associations and subsequently
with a successional index constructed from a PCA ordination of vegetation
structure. The successional indices explained much of the variation on
MDS axes which suggested that ultramafic vegetation patterns primarily
reflects a post-fire succession. Fire records, annual growth rings of fire
sensitive Dacrydium araucarioides and demographic trends in species
composition also support a post-fire succession pattern. The succession
pattern was found to be composed of an early successional group of maquis species which either (i) decline or (ii) persist, and (iii) a late successional
group of forest species. Another important pattern revealed in surveys is
that early ultramafic successional stages progress more slowly than tropical
vegetation on other soil types. More importantly, certain processes appear
to be critical at early successional stages and predetermine later successional
development.
Surveys of abandoned mine sites set out to determine what processes
appear to be influencing plant establishment at early successional stages.
The evidence implies that most species are dispersal limited and show an
abrupt decline in abundance away from adjacent vegetation. Primary
colonist establishment is more abundant on crevice sites which trap seed,
and seedlings show higher rates of survival in such areas. The primary
colonists eventually generate a micro-environment providing shade and
litter which supports all of the subsequent colonisation of bare ground.
Shade and litter levels were regarded as important factors driving succession
on ultramafics and their effects at both the community and plant level were
examined.
Measures of light regimes in successional vegetation indicated that
light (PAR) declined with the development of vegetation cover over time.
These changes in incident solar radiation effect the community composition
depending on species light requirements for photosynthesis. Chlorophyll
fluorescence measurements of plants in natural vegetation and in field
experiments indicated that seedlings on bare ultramafic soil experienced
chronic photoinhibitive stress from a combination of high light and
substrate conditions. Seedlings under shade cloth and underneath tree
canopies potentially received less light for photosynthesis but exhibited less
stress indicative of photoinhibition. Therefore, shade may be crucial for
seedling survival at early successional stages. Furthermore, plant species
responded to high light conditions depending on their successional status.
Maquis species generally overcame photoinhibitive effects of bare ground
environments once they attained a certain age. In contrast, forest species
continued to exhibit photoinhibitive stress on bare ground environments.
Measures of soil and litter nutrient content indicate that N, P, Kand
Ca content increased with successional progression. Gymnostoma plays a
key role in the development of later successional phases by providing a
major source of nitrogen through its Frankia association. This nitrogen is
released along with other nutrients as an abundant litterfall that gradually increases soil nutrient pools over time through slow decay. Glasshouse
experiments indicated that leachates arising from slow cladode decay had no
allelopathic effect on plant growth. However, litter build up in late maquis
phases physically excluded large seeded species from establishing.
A fire susceptibility index was constructed from litter and vegetation
properties of successional vegetation. It indicates that Gymnostoma may
raise the susceptibility of maquis because its open canopy allows litter beds to
remain dry and flammable. However, Gymnostoma deplancheanum and
G. chamaecyparis are able to persist on their respective soil types even at
high fire frequencies because rocky terrain reduces fire spread and protects
patches of vegetation. In contrast, G. intermedium appears to have been
excluded from early successional vegetation on eroded oxisol by a
continuous cover of woody sedge maquis which is highly flammable. The
eventual dominance of broad leafed vegetation at later succession forest
stages decreases the fire susceptibility of these communities.
Results of field experiments indicate that slow maquis species growth
is primarily due to the low nutrient status of ultramafic soils. Plants which
received low doses of fertiliser and/ or litter showed a significant positive
response in terms of height and relative shoot growth. Fertiliser
applications also raised the total Frankia nodule weight per plant, indicating
that Frankia responds positively to slight increases in phosphorus. Contrary
to expectation, lime applications had no effect on maquis species shoot
growth. Lime additions resulted in fewer Frankia nodules and more
extensive root systems in Gymnostoma seedlings by reducing the
availability of other nutrients.
In summary, it is concluded that Gymnostoma dominated maquis
represents a post-fire succession. Colonisation at early successional stages is
dispersal limited and highly dependent upon the availability of crevices.
Once pioneer plants have established, litter and shade levels become crucial
factors in facilitating further succession. The relative abundance of
Gymnostoma determines the rate and direction of this successional change.
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Cornelius, Nina Kaarina [Verfasser]. "UHP metamorphic rocks of the Eastern Rhodope Massif, NE Greece : new constraints from petrology, geochemistry and zircon ages / Nina Kaarina Cornelius." 2009. http://d-nb.info/99383566X/34.
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Millonig, Leo Jakob. "The Neoarchean and Palaeoproterozoic metamorphic evolution of the Limpopo Belt’s Central Zone in southern Africa. New insights from petrological investigations on amphibolite to granulitefacies rocks." Doctoral thesis, 2009. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-36516.
Full textAbstract:
Die vorliegende Doktorarbeit präsentiert neue petrologische Untersuchungen an hochgradig metamorphen Gesteinen des Beit Bridge, Mahalapye und Phikwe Komplexes, welche gemeinsam die Central Zone des Limpopo Belt im südlichen Afrika bilden. Die Ergebnisse liefern detaillierte Informationen über die pro- und retrograde Druck-Temperatur-(P-T)-Entwicklung der drei Komplexe und bilden, in Einklang mit geochronologischen Daten, die Grundlage für die Erstellung eines einheitlichen geodynamischen Modells der Bildung der Central Zone des Limpopo Belt. Die abgeleiteten P-T Pfade wurden anhand detaillierter Untersuchungen an quartzgesättigten und - untersättigten Metapeliten bis Metabasiten erstellt, wobei sechs Sillimanit-Granat-Cordierit Gneisse, vier (Granat)- Biotit-Plagioklas Gneisse, zwei Granat-Orthopyroxen-Biotit- Kalifeldspat-Plagioklas Gneisse, ein Granat-Cordierit-Orthoamphibol Fels, ein Granat-Biotit Amphibolit und ein Granat-Klinopyroxen Amphibolit untersucht wurden. PT Punkte und P-T Entwicklungen wurden mit Hilfe von konventionellen Geothermobarometern und quantitativen Phasendiagrammen in den Systemen Na2O - CaO - K2O - FeO - MgO - Al2O3 - SiO2 - H2O - TiO2 - O(NCKFMASHTiO) und MnO - TiO2 - Na2O - CaO - K2O - FeO - MgO - Al2O3 - SiO2 - H2O (MnTiNCKFMASH) berechnet und abgeleitet. Die Phasendiagramme wurden mit den Programmen THERMOCALC und THERIAK-DOMINO berechnet. Petrologische Informationen, speziell solche, die durch den Vergleich von beobeachteten/gemessenen mit thermodynamisch berechneten Mineralparagenesen, -zonierungen, -zusammensetzungen und Modalgehalten erhalten wurden zeigen, in Kombination mit neuen und bereits existierenden geochronologischen Daten, dass Gesteine der drei untersuchten Komplexe geringfügig unterschiedliche P-T Entwicklungen zu verschiedenen Zeiten durchliefen. Proben aus der Gegend des Bulai Plutons (Beit Bridge Komplex) belegen ein hochgradig metamorphes Ereignis im Neoarchaikum um ~2.64 Ga (M2), mit peak-metamorphen Bedingungen von ~850°C/8-9 kbar und einer retrograden Dekompression mit gleichzeitiger Abkühlung zu ~750°C/5-6 kbar. Diese metamorphe Entwicklung erfolgte vermutlich im geodynamischen Umfeld eines Magmatischen Bogens. Im Gegensatz hierzu dokumentieren Proben des Mahalapye und Phikwe Komplexes metamorphe Entwicklungen im Paläoproterozoikum um ~2.03-2.05 Ga (M3), die sich zudem im prograden Verlauf der Metamorphose voneinander unterscheiden. Metamorphe Gesteine des Mahalapye Komplexes kennzeichnet eine Hochtemperatur- Niedrigdruck-(HT-LP)- Metamorphose mit schwacher prograder Dekompression von ~650°C/7 kbar nach ~800°C/5.5 kbar, die mit der Platznahme von ausgedehnten granitischen Intrusionen um ~2.06-2.02 Ga einherging. Metamorphe Gesteine des Phikwe Komplexes hingegen zeigen eine gleichzeitige Druck- und Temperaturzunahme von ~600°C/6 kbar nach ~750°C/8 kbar, die nicht mit Magmatismus im Paläoproterozoikum assoziiert war. Es wird gefolgert, dass die HT-LP metamorphe Entwicklung des Mahalapye Komplexes ihre Ursache in dem magmatischen „Underplating“ heisser mafischer Schmelzen, als Ergebnis südost- erichteter Subduktion während der Kheis-Magondy Orogenese, und/oder der zeitgleichen Aktivität von Mantel Plumes, in Zusammenhang mit der Bildung des Bushveld Komplexes, hat. Im Gegensatz hierzu belegen die Gesteine des Phikwe Komplexes eine prograde Druck- und Temperaturzunahme, hervorgerufen durch eine fortschreitende Krustenstapelung um ~2.03 Ga. Diese Stapelung ist bereits für zahlreiche andere geologischen Einheiten des Limpopo Belt belegt. Sie wird als eine Folge der endenden Annäherung/Kollision zwischen dem Kaapvaal und Zimbabwe Kraton interpretiert, welche durch südost-gerichtete Kompression im Zuge der Kheis-Magondy Orogenese zw. ~2.06 und 1.90 Ga hervorgerufen wurdeThis study presents new petrological results obtained from high-grade metamorphic rocks of the Beit Bridge, Mahalapye and Phikwe Complexes, which constitute the Central Zone of the Limpopo Belt in southern Africa. These results provide detailed information about the prograde and retrograde pressure-temperature (P-T) evolution of the three investigated complexes and, in concert with geochronological data, form the basis for the development of a coherent geodynamic model for the evolution of the Limpopo’s Central Zone. The P-T paths were inferred by the thorough investigation of silica-saturated and silica- undersaturated metapelitic and metabasic rocks, comprising six sillimanite-garnet-cordierite gneisses, four (garnet)-biotite-plagioclase gneisses, two garnet-orthopyroxene-biotite-Kfeldspar-plagioclase gneisses, one garnet- cordierite-orthoamphibole fels, one garnet-biotite amphibolite, and one garnet-clinopyroxene amphibolite. P-T points and P-T evolutions were derived by the application of conventional geothermobarometers, and quantitative phase diagrams in the systems Na2O - CaO - K2O - FeO - MgO - Al2O3 - SiO2 - H2O - TiO2 - O (NCKFMASHTiO), and MnO - TiO2 - Na2O - CaO - K2O - FeO - MgO - Al2O3 - SiO2 - H2O (MnTiNCKFMASH) - using the computer software THERMOCALC and THERIAK-DOMINO. The petrological information, in particular those obtained by comparison between observed and thermodynamically calculated mineral assemblages, zonations and modes, in combination with new and existing geochronological data provide evidence that rocks from the three investigated complexes underwent slightly different P-T evolutions at different times. The samples from the Bulai Pluton area (Beit Bridge Complex) provide evidence for a Neoarchean high-grade metamorphic event at ~2.64 Ga (M2), with peak P-T conditions of ~850°C at 8-9 kbar, and a decompression-cooling path to ~750°C at 5-6 kbar. This metamorphic evolution perhaps took place in a magmatic arc setting. In contrast, samples from the Mahalapye and Phikwe Complex document a Palaeoproterozoic event at ~2.03-2.05 Ga (M3), and were subject to different styles of prograde metamorphism. Metamorphic rocks from the Mahalapye Complex experienced a high-temperature low-pressure (HT-LP) metamorphic overprint, accompanied by the emplacement of voluminous granite bodies between 2.06 and 2.02 Ga, and provide evidence for a slightly prograde decompression from ~650°C/7 kbar to ~800°C/5.5 kbar. In contrast, the metamorphic rocks from the Phikwe Complex provide evidence for a simultaneous pressure and temperature increase from ~600°C/6 kbar to ~750°C/8 kbar, in the absence of significant Palaeoproterozoic magmatism. The HT-LP metamorphic evolution of the Mahalapye Complex is interpreted to be initiated by the underplating of hot mafic melts, either formed in response to SE-subduction during the Kheis-Magondi orogeny, and/or by contemporaneous mantle plume activities related to the formation of the Bushveld Complex. In contrast, the prograde pressure and temperature increase reflected by the rocks from the Phikwe Complex rather reflects successive crustal stacking at ~2.03 Ga. This stacking, which is also reported from many other units throughout the Limpopo Belt, is interpreted to result from the final convergence between the Kaapvaal and Zimbabwe Cratons, perhaps caused by SE-directed compression in response to the Kheis-Magondi orogeny between ~2.06 and 1.90 Ga
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Millonig, Leo Jakob [Verfasser]. "The neoarchean and palaeoproterozoic metamorphic evolution of the Limpopo Belt's Central Zone in southern Africa : new insights from petrological investigations on amphibolite to granulite facies rocks / vorgelegt von Leo Jakob Millonig." 2009. http://d-nb.info/1003787878/34.
Full textBooks on the topic "Metamorphic rocks New Caledonia"
1
Wobus, Reinhard A. Changes in the nomenclature and stratigraphy of Proterozoic metamorphic rocks, Tusas Mountains, north-central New Mexico. Washington: U.S. G.P.O., 1985.
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2
Grapes, R. H. X.R.F. analyses of quartzo-feldspathic schists and metacherts, Franz Josef-Fox Glacier area, Southern Alps of New Zealand. [Wellington]: Victoria University of Wellington, 1985.
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3
Hutton Symposium on the Origin of Granites and Related Rocks (2nd 1991 Australian Academy of Science). Second Hutton Symposium on Granites and Related Rocks, Canberra 1991: Plutonic, volcanic and metamorphic rocks of the New England Batholith : excursion guide, 29 September - 4 October 1991. Canberra: Bureau of Mineral Resources, Geology and Geophysics, 1990.
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4
Nyman, Matthew William. Petrology and geologic relationships of metagabbro shear zones, southeastern Adirondack Mountains, Whitehall/Ft. Anne, New York. 1987.
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5
New stratigraphic subdivisions and redefinition of subdivisions of late Archean and early Proterozoic metasedimentary and metavolcanic rocks of the Sierra Madre and Medicine Bow Mountains, southern Wyoming. Washington: U.S. G.P.O., 1992.
Find full textBook chapters on the topic "Metamorphic rocks New Caledonia"
1
Worliczek, Elisabeth. "Naturally Occurring Asbestos: The Perception of Rocks in the Mountains of New Caledonia." In Environmental Transformations and Cultural Responses, 187–214. New York: Palgrave Macmillan US, 2017. http://dx.doi.org/10.1057/978-1-137-53349-4_8.
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2
Ozdemir, Adil, and Yildiray Palabiyik. "A New Method for Geochemical Prediction of the Existence of Petroleum Reservoirs in Magmatic and Metamorphic Rocks." In Proceedings of the 2021 International Petroleum and Petrochemical Technology Conference, 694–702. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-9427-1_64.
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Baird, Graham B., Fawna J. Korhonen, and Kevin R. Chamberlain. "Pressure-temperature-deformation-time path for the Seve Nappe Complex, Kebnekaise Massif, Arctic Swedish Caledonides." In New Developments in the Appalachian-Caledonian- Variscan Orogen. Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2554(12).
Full textAbstract:
ABSTRACT The Seve Nappe Complex in the Scandinavian Caledonides records a range of peak metamorphic conditions and timings. To better understand pressure-temperature-deformation-time differences throughout the complex and possible tectonic scenarios, metamorphosed mafic rocks within the Tarfala Valley of the Kebnekaise Massif (Sweden) were investigated using integrated petrologic and geochronologic techniques. Thermodynamic modeling of two samples using domainal and whole-rock compositions integrated with mineral chemistry, mineral textures, and titanite and zircon U-Pb geochronology constrained a portion of the pressure-temperature (P-T) path. Peak metamorphic conditions of 590–660 °C and 9.7–10.5 kbar were followed by near-isothermal decompression or a subsolidus clockwise P-T path. Amphibolite units in the valley record retrograde conditions at 450–550 °C at less than 7.5 kbar, although mineral modes and textures are most consistent with pressures <4 kbar. The majority of titanite growth occurred due to the introduction of hydrous fluids during cooling and following exhumation to midcrustal levels. U-Pb ages of retrograde titanite define a spread from ca. 480 to 449 Ma, and the oldest age is interpreted to constrain the timing of retrogression following exhumation. This interpretation is supported by a U-Pb zircon crystallization age of 481 ± 7 Ma for a metamorphosed intermediate to felsic synkinematic dike hosted in one of the amphibolite units. These results indicate that the Kebnekaise region records Early Ordovician deformation and metamorphism that was of lower grade compared to other Seve Nappe Complex locations to the south. The tectonic history of these rocks includes metamorphism and exhumation during the Cambrian–Ordovician pre-Scandian event, followed by thrusting of the Seve Nappe Complex and neighboring rocks onto Baltica during the Silurian Scandian orogeny.
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Hollocher, Kurt, Peter Robinson, Maria Van Nostrand, and Emily Walsh. "The Blåhø Nappe, central Norwegian Scandinavian Caledonides: An oceanic arc–back-arc assemblage distinct from the Seve Nappe Complex." In New Developments in the Appalachian-Caledonian- Variscan Orogen. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2554(13).
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ABSTRACT The Scandinavian Caledonides have a complex latest Proterozoic–Early Devonian history, but they were finally assembled during the Silurian–Devonian (Scandian orogeny) collision between Baltica and Laurentia. Their dominant structural components are the Lower (Baltican margin), Middle (Baltican and farther outboard), Upper (Iapetan arcs), and Uppermost (Laurentian margin) Allochthons. This study examined the Blåhø Nappe, a complex unit of metamorphosed, intensely deformed igneous and sedimentary rocks assigned to the Middle Allochthon. Metamorphic grades are regionally amphibolite facies, but granulite- and eclogite-facies rocks are locally found. Although most metamorphic ages span a range from Middle Ordovician to Devonian, Blåhø eclogite and other high-pressure rock ages are exclusively Scandian. We analyzed 95 samples of Blåhø Nappe metamorphosed igneous rocks, which were mostly mafic rocks, composed of a minor arc-derived set and a major set transitional between arc and depleted to enriched mid-ocean-ridge basalt (MORB), a range characteristic of back-arc basins. Historically, the Blåhø Nappe has been assigned to the Seve Nappe Complex, the upper part of the Middle Allochthon as mapped in western Sweden and easternmost Norway. In contrast to the Blåhø Nappe, eclogites and other high-pressure rocks in the Seve Nappe Complex have yielded exclusively pre–Scandian orogeny Cambrian and Ordovician ages. Additionally, post–mid-Proterozoic igneous rocks of the Seve Nappe Complex are overwhelmingly dike swarms that were emplaced during the latest Proterozoic breakup of Rodinia, which have rift and MORB-type chemical signatures rather than arc and back-arc signatures, as has the Blåhø Nappe. We hypothesize that the Blåhø Nappe precursors formed on the upper plate, above a west-directed, late Cambrian to Ordovician subduction zone off the Baltican margin. Subduction of the Baltican margin, and possibly rifted fragments on the lower plate, produced the older Seve Nappe Complex eclogites and thrust the Blåhø and Seve Nappe Complex materials onto Baltica. This left the Blåhø Nappe and Seve Nappe Complex precursors on the lower plate during Scandian subduction and collision with Laurentia, allowing exclusively Scandian eclogite formation in the Blåhø Nappe. The Blåhø Nappe and Seve Nappe Complex thus seem to have distinct origins and should not be correlated with one another.
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Willner, A. P., C. R. van Staal, J. Glodny, M. Sudo, and A. Zagorevski. "Conditions and timing of metamorphism near the Baie Verte Line (Baie Verte Peninsula, NW Newfoundland, Canada): Multiple reactivations within the suture zone of an arc-continent collision." In New Developments in the Appalachian-Caledonian- Variscan Orogen. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2554(09).
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ABSTRACT The Baie Verte Line in western Newfoundland marks a suture zone between (1) an upper plate represented by suprasubduction zone oceanic crust (Baie Verte oceanic tract) and the trailing continental Notre Dame arc, with related upper-plate rocks built upon the Dashwoods terrane; and (2) a lower plate of Laurentian margin metasedimentary rocks with an adjoining ocean-continent transition zone (Birchy Complex). The Baie Verte oceanic tract formed during closure of the Taconic seaway in a forearc position and started to be obducted onto the Laurentian margin between ca. 485 and 476 Ma (early Taconic event), whereas the Birchy Complex, at the leading edge of the Laurentian margin, was subducted to maximum depths as calculated by pseudosection techniques (6.7–11.2 kbar, 315–560 °C) by ca. 467–460 Ma, during the culmination of the Taconic collision between the trailing Notre Dame arc and Laurentia, and it cooled isobarically to 9.2–10.0 kbar and 360–450 °C by 454–449 Ma (M1). This collisional wedge progressively incorporated upper-plate Baie Verte oceanic tract rocks, with remnants preserved in M1 high-pressure, low-temperature greenschist-facies rocks (4.8–8.0 kbar, 270–340 °C) recording typical low metamorphic gradients (10–14 °C/km). Subsequently, the early Taconic collisional wedge was redeformed and metamorphosed during the final stages of the Taconic cycle. We relate existing and new 40Ar/39Ar ages between 454 and 439 Ma to a late Taconic reactivation of the structurally weak suture zone. The Taconic wedge on both sides of the Baie Verte suture zone was subsequently strongly shortened (D2), metamorphosed (M2), and intruded by a voluminous suite of plutons during the Salinic orogenic cycle. Calculated low- to medium-pressure, low-temperature M2 conditions in the Baie Verte oceanic tract varied at 3.0–5.0 kbar and 275–340 °C, with increased metamorphic gradients of ~17–25 °C/km during activity of the Notre Dame arc, and correlate with M2 assemblages in the Birchy Complex. These conditions are associated with existing Salinic S2 white mica 40Ar/39Ar ages of ca. 432 Ma in a D2 transpressional shear zone and synkinematic intrusions of comparable age. A third metamorphic event (M3) was recorded during the Devonian with calculated low-pressure, low-temperature conditions of 3.2–3.8 kbar and 315–330 °C under the highest metamorphic gradients (23–30 °C/km) and associated with Devonian–early Carboniferous isotopic ages as young as 356 ± 5 Ma. The youngest ages are related to localized extension associated with a large-scale transtensional zone, which reused parts of the Baie Verte Line suture zone. Extension culminated in the formation of a Middle to Late Devonian Neoacadian metamorphic core complex in upper- and lower-plate rocks by reactivation of Baie Verte Line tectonites formed during the Taconic and Salinic cycles. The Baie Verte Line suture zone is a collisional complex subjected to repeated, episodic structural reactivation during the Late Ordovician Taconic 3, Silurian Salinic, and Early–Late Devonian Acadian/Neoacadian orogenic cycles. Deformation appears to have been progressively localized in major fault zones associated with earlier suturing. This emphasizes the importance of existing zones of structural weakness, where reactivation took place in the hinterland during successive collision events.
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Maher, Harmon, Alvar Braathen, Morgan Ganerød, Per Terje Osmundsen, Tim Redfield, Per Inge Myhre, Christopher Serck, and Sara Parcher. "Core complex fault rocks of the Silurian to Devonian Keisarhjelmen detachment in NW Spitsbergen." In New Developments in the Appalachian-Caledonian- Variscan Orogen. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2554(11).
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ABSTRACT A Silurian–Devonian metamorphic core complex has recently been recognized in northwest Spitsbergen, on the northwest corner of the Barents Shelf at the junction between the Atlantic and Arctic oceans. The associated Keisarhjelmen detachment, a major, ductile-brittle fault zone, is 200–500 m thick and has a map trace >150 km. A top-to-the-north transport direction is parallel to the axis of a large-scale, shallowly north-plunging, detachment corrugation. This detachment zone separates overlying faulted Silurian–Devonian aged cover strata from underlying migmatitic rocks in the core. The detachment shows a diverse array of fault and metamorphic rocks with structural ascent, ranging from sheared migmatite, mylonite, ultramylonite, foliated cataclasite, pseudotachylite, and breccia. Footwall post-kinematic granitic intrusions occurred shortly prior to, and likely during, deposition of the older cover strata. Variably deformed, syn-kinematic granitic sheets and veins within the detachment zone are considered coeval. Thin sections show significant grain size reduction, porphyroclasts, and well-developed composite fault surfaces. Relict garnet sigma porphyroclasts associated with chlorite and sericite indicate retrogression. Feldspar porphyroclasts show significant sericite alteration, undulose extinction and limited recrystallization low in the detachment, and brittle deformation throughout. Quartz deformation textures and grain size vary considerably within and between samples. Deformation during retrogression continued into the brittle realm with the development of thick foliated cataclasites, fault breccias, and local pseudotachylites concentrated at the top of the detachment. Biotite in particular shows grain size reduction, concentration along C-surfaces, and shredding and redistribution, suggesting it played a significant role in both ductile and brittle faulting. Veins, micro-veins, and fluid inclusion planes are ubiquitous throughout the detachment, indicating substantial fault-related fluid flow. Given existing geochronologic and P-T (pressure-temperature) data from the basement rocks of the area, the kinematics, retrogression, and ductile-brittle transition are consistent with exhumation of a core complex developing by orogen-parallel extension associated with transtension during the Late Silurian and Early to Middle Devonian in northwest Spitsbergen. Remaining questions include how this core complex connects with coeval plate-scale strike-slip faults in Svalbard, and its relationship to mainland Norwegian core complexes and Devonian basins to the south.
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White, Chris E., Sandra M. Barr, James L. Crowley, Deanne van Rooyen, and Trevor G. MacHattie. "U-Pb zircon ages and Sm-Nd isotopic data from the Cobequid Highlands, Nova Scotia, Canada: New contributions to understanding the Neoproterozoic geologic history of Avalonia." In New Developments in the Appalachian-Caledonian- Variscan Orogen. Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2554(07).
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ABSTRACT Forty-three new U-Pb zircon ages from metasedimentary and igneous rock units throughout the Cobequid Highlands of northern mainland Nova Scotia, Canada, provide new insights into the Neoproterozoic evolution of this long-enigmatic part of Avalonia in the northern Appalachian orogen. Contrasts in ages and rock types resulted in the identification of fault-bounded Neoproterozoic assemblages of units forming the Bass River, Jeffers, and Mount Ephraim blocks. In the Bass River block, quartzite, metawacke, and minor calc-silicate rocks and marble (Gamble Brook Formation) with a maximum depositional age of 945 ± 12 Ma are associated with subaqueous mafic volcanic rocks, siltstone, and ironstone (Folly River Formation) and intruded by 615–600 Ma calc-alkalic subduction-related dioritic to granitic rocks of the Bass River plutonic suite. The contrasting Jeffers block forms most of the Cobequid Highlands and consists mainly of intermediate to felsic volcanic, epiclastic, and minor plutonic rocks. The western and eastern areas of that block yielded ages mainly ca. 607–592 Ma for both volcanic and plutonic rocks, whereas the central area has ages of ca. 630–625 Ma from both volcanic and plutonic rocks and inheritance in overlying Devonian conglomerate. The Mount Ephraim block forms the eastern part of the highlands and includes possible ca. 800 Ma quartzofeldspathic, semipelitic and pelitic gneiss and schist of the Mount Thom Formation, ca. 752 Ma volcanic arc rocks of the Dalhousie Mountain Formation and related 752–730 Ma gabbroic/dioritic to granitic plutons of the Mount Ephraim plutonic suite and Six Mile Brook pluton, as well as ca. 631 Ma granitoid rocks of the Gunshot Brook pluton. The pre–750 Ma high-grade regional metamorphism and deformation and 752–730 Ma subduction-related magmatism recorded in the Mount Ephraim block were previously unrecognized in Avalonia. Evidence from zircon inheritance and Sm-Nd isotopic data in igneous units suggests linkages among these now-separate areas, and comparison with other parts of Avalonia in the northern Appalachian orogen suggests similarity to southeastern New England.
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Romer, Rolf L., and Uwe Kroner. "Provenance control on the distribution of endogenic Sn-W, Au, and U mineralization within the Gondwana-Laurussia plate boundary zone." In New Developments in the Appalachian-Caledonian- Variscan Orogen. Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2554(02).
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ABSTRACT The Paleozoic plate boundary zone between Laurussia and Gondwana in western Pangea hosts major magmatic and hydrothermal Sn-W-Ta, Au, and U mineralization. Individual mineral deposits represent the results of the superposition of a series of exogenic and endogenic processes. Exogenic processes controlled (1) the enrichment of the ore elements in sedimentary protoliths via residual enrichment during intense chemical weathering and via climatically or tectonically controlled redox traps, (2) the spatial distribution of fertile protoliths, and, thus, eventually (3) the spatial distribution of mineralization. Endogenic processes resulting in metamorphism and crustal melting controlled the mobilization of Sn-W, Au, and U from these enriched protoliths and, thus, account for the age distribution of Sn-W and Au mineralization and U-fertile granites. It is the sequence of exogenic and endogenic processes that eventually results in the formation of mineralization in particular tectonic zones. Whereas the endogenic processes were controlled by orogenic processes during the assembly of western Pangea itself, the exogenic processes were linked to the formation of suitable source rocks for later mineralization. The contrasting distribution of magmatic and hydrothermal Sn-W-Ta, Au, and U mineralization on the Laurussia and Gondwana sides of the plate boundary zone reflects the contrasting distribution of fertile protoliths and the contrasting tectonic situation on these margins. The Laurussian margin was an active margin during most of the Paleozoic, and the distribution of different mineralization types reflects the distribution of terranes of contrasting provenance. The Gondwanan margin was a passive margin during most of the Paleozoic, and the similar distribution of a wide range of different metals (Sn, W, Ta, Au, and U) reflects the fact that the protoliths for the various metals were diachronously accumulated on the same shelf, before the metals were mobilized during Acadian, Variscan, and Alleghanian orogenic processes.
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Yokoyama, K., R. N. Brothers, and P. M. Black. "Regional eclogite facies in the high-pressure metamorphic belt of New Caledonia." In Geological Society of America Memoirs, 407–24. Geological Society of America, 1986. http://dx.doi.org/10.1130/mem164-p407.
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Zalasiewicz, Jan. "4. Rocks transformed." In Rocks: A Very Short Introduction, 51–65. Oxford University Press, 2016. http://dx.doi.org/10.1093/actrade/9780198725190.003.0004.
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‘Rocks transformed’ outlines the processes of metamorphism and describes the different types of metamorphism: regional, contact, and impact. Regional metamorphism is the most common form and occurs in mountain belt zones where the crust is much thicker. High pressures and temperatures result in recrystallization in the rocks. As temperatures and pressures increase, the new crystals that form are bigger. The original chemical composition of the rocks affects the resulting metamorphic rocks. Muds become slates and mica-schists, while limestones become marbles. Contact metamorphism takes place at the boundaries of magma bodies and impact metamorphism is seen when meteorites crash into the Earth’s surface.
Conference papers on the topic "Metamorphic rocks New Caledonia"
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Guerer, Derya, BÉNÉDICTE Cenki-Tok, Vasileios Chatzaras, Fernando Corfu, Julien Collot, and Pierre Maurizot. "Petrochronological and Structural Constraints on Intra-Oceanic Subduction Initiation from the Metamorphic Sole of the New Caledonia Ophiolite." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.899.
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Ward, David B. "Rubidium-strontium geochronology of Proterozoic rocks from the Pecos and Truchas metamorphic terranes, north-central New Mexico." In 41st Annual Fall Field Conference. New Mexico Geological Society, 1990. http://dx.doi.org/10.56577/ffc-41.211.
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McLemore, Virginia T., and Christopher McKee. "Geology and geochemistry of syenites and adjacent Proterozoic granitic and metamorphic rocks in the Zuni Mountains, Cibola County, New Mexico." In 40th Annual Fall Field Conference. New Mexico Geological Society, 1989. http://dx.doi.org/10.56577/ffc-40.149.
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Baker, Lindsey K., Sara V. Stotter, Christopher L. Andronicos, and Christopher G. Daniel. "TESTING MODELS OF MAZATZAL (1650 MA) AND PICURIS AGE (1400 MA) METAMORPHISM IN NEAR–GRANULITE FACIES METAMORPHIC ROCKS OF THE NORTHERN TAOS RANGE, NEW MEXICO." In GSA Annual Meeting in Indianapolis, Indiana, USA - 2018. Geological Society of America, 2018. http://dx.doi.org/10.1130/abs/2018am-320328.
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Satyana, A. H. "Ciletuh Subduction, West Java - New Findings, New Problems: Regional Implications to Cretaceous-Paleogene Convergence of Sundaland Margin and Its Petroleum Geology." In Indonesian Petroleum Association 44th Annual Convention and Exhibition. Indonesian Petroleum Association, 2021. http://dx.doi.org/10.29118/ipa21-g-29.
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Ciletuh, southwest Java has been well known as one of the places in Java where pre-Tertiary basement rocks are exposed (Verbeek and Fennema, 1896; Duyfjes, 1940; van Bemmelen, 1949; Sukamto, 1975). In plate tectonic point of view, Ciletuh has been known as place outcropping melange complex related to pre-Tertiary oceanic plate subduction (Thayyib et al., 1977). Ciletuh subduction regionally has been linked to the Cretaceous subduction zones of Luk Ulo/Karang Sambung (Central Java) and Meratus Mountains (South Kalimantan) (Hutchison, 1973; Asikin 1974; Hamilton, 1979). Ciletuh subduction however, has not been dated using metamorphic rocks formed in its subduction zone. Its link to Luk Ulo and Meratus subduction zone only based on the presence of melange, which also lacks of data Meanwhile, subduction zones of Luk Ulo and Meratus have been dated and analysed. We herewith present the results of new field studies and various analyses carried out in the last five years of the Ciletuh subduction complex. The indication of Cretaceous subduction has not found from the date measurement, Ciletuh shows Eocene related subduction. Most of the ophiolites were island-arc tholeiitic or island-arc basalt formed in supra-subduction zone. The overlying olistostrome deposits were younger than previously considered and lasted until early/middle Miocene. Some of the basaltic pillowed lava is considered as part of the ophiolite, while the ones at Gunung Badak is more likely a part of the early Miocene Jampang volcanism. Link of Ciletuh to Early Cretaceous subduction of Luk Ulo is not supported by geochronological data. The new knowledge of Ciletuh subduction implies the pre-Tertiary and Paleogene geology of Java, and petroleum prospectivities of the Paleogene objectives of southern West Java. New problems arise and need more field data and analyses to find out the answers.
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Ganev, Valentin. "THE NEW LA-ICP-MS LAB FACILITY IN THE GEOLOGICAL INSTITUTE AT BULGARIAN ACADEMY OF SCIENCES � FIRST RESULTS FROM TRACE ELEMENTS DETERMINATION AND U-PB AGE DATING OF METAMORPHIC ROCKS." In SGEM2011 11th International Multidisciplinary Scientific GeoConference and EXPO. Stef92 Technology, 2011. http://dx.doi.org/10.5593/sgem2011/s01.139.
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Darling, Robert S. "Felsic Mineral Inclusions in Zircon from the Port Leyden Nelsonite, Western Adirondack Highlands, New York: A Product of Magma Mixing?" In Northeastern GSA Section Meeting. Geological Society of America, 2016. http://dx.doi.org/10.1130/abs/2016ne-272695.
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The Port Leyden nelsonite is small magnetite-apatite-ilmenite ore body occurring in Mesoproterozoic metapelitic gneiss on the western margin of the Adirondack Highlands. It is unusual in that no compositionally adequate parent magma (e.g. jotunite or oxide-apatite gabbronorite) has been identified in the area (Darling and Florence, 1995).The nelsonite typically contains elevated levels of Zr (1400 to 2500 ppm) largely present in abundant modal zircon. The Zr abundances are considerably higher than normal levels of Zr solubility in non-peralkaline melts and suggests that some of the zircon modal fraction is inherited (Hanchar and Harrison, 2003).The zircon grains display both euhedral, oscillatory zoned cores (interpreted as igneous) and anhedral, irregular, compositionally homogeneous rims (interpreted as metamorphic or igneous). The oscillatory zoned cores contain small (2-10 micrometer), solid inclusions that have energy-dispersive X-ray spectra (EDS) consistent with quartz, K-feldspar, plagioclase, biotite, and apatite. Remarkably, no low-silica mafic mineral inclusions (e.g. orthopyroxene, clinopyroxene, olivine) were observed in zircon.Felsic mineral inclusions in zircon from an igneous rock that has mafic magma affinities provides further evidence that the included cores of zircons in the Port Leyden nelsonite are inherited. This unusual occurrence may be possible considering that the mafic igneous rocks described above are part of the bimodal anorthosite-mangerite-charnockite-granite (AMCG) magmatic complex in the Adirondacks (McLelland et al, 1988). It is conceivable that during magma mixing, zircon from granite or charnockite may have become incorporated into coeval jotunite or oxide-apatite gabbronorite. Subsequently, the latter magma experienced either unmixing (Philpotts, 1967) or crystal settling (Dymek and Owens, 2001) to produce the Port Leyden nelsonite.
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Yu, Jingfeng, Diao Zhou, Bo Zhang, Haiping Meng, Tong Li, Li Wang, Yong Wang, et al. "Horizontal Well Drilling and Geosteering Optimization with Integrated Innovation Technologies: Case Studies from the World Largest Conglomerate Reservoir in West China." In International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21482-ms.
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Abstract MH oilfield is a fan delta deposited unconventional tight oil reservoir with complex lithology of volcanic rocks, metamorphic rocks, conglomerate, and claystone. The drilling efficiency was optimized by using the first-generation boundary mapping technology with Rotary Steering System (RSS) during the first batch drilling campaign (H2-2016∼H1-2017), which was mentioned in IADC/SPE-190998-MS. But with the development going further, more and more wells drilled into shale interbed causing low pay zone exposure, long drilling duration, and numerous drilling hazards. The overall drilling performance was not optimistic as before, the average Rate Of Penetration (ROP) decreased by 30.7% and the average footage per run decreased by 38.9% during horizontal section operation in some specific blocks of MH oilfield. By reviewing the detailed drilling and geology material of the first batch drilling, the challenges were defined. There is lateral irregular thin shale interbed existing in this conglomeratic reservoir which is rarely observed from the nearby wells in the first batch drilling zone. That unstable shale interbed with 0.5-2m thickness isolated the target into 2 to 3 components. The first-generation boundary mapping technology can only detect the nearest up or down boundary, with this limitation, it is difficult to reveal these laterally unstable shale interbed. It is crucial to precisely delineate the irregular thin interbed to develop this complex reservoir. Meanwhile, the bit selection which didn't catch up with the formation change is another issue that needs to be optimized timely. To solve the above challenges, the new generation boundary mapping while drilling technology was introduced to this project, it has 3 or more boundaries detecting ability at the same time, which can delineate the irregular thin interbed and optimize real-time Well Placement decision making. Meanwhile, the bit design and selection based on the timely geological data interpretation helped to improve drilling efficiency. This innovative integrated method deployed in phase II horizontal well drilling campaign proved to be an effective approach to optimize geosteering and drilling performance. The clear reservoir geometry delineation effectively helps avoid entering the irregular shale interbed in real-time, thus improve the pay zone exposure and trajectory smoothness. Till 2018, more than 50 wells were completed, the overall drilling performance of 2018 has been improved by 47.2% of footage per run and 42.2% of ROP compared with statistical results of H2-2017 of the M131 block and nearly back to the normal level. In this paper, the authors will demonstrate how this integrated approach helps optimize Well Placement, enhance drilling efficiency and save budget with some exemplary case studies. With this success, the authors believe this approach and techniques could effectively address the following horizontal well drilling campaign in this unconventional tight oil reservoir.
Reports on the topic "Metamorphic rocks New Caledonia"
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Changes in the nomenclature and stratigraphy of Proterozoic metamorphic rocks, Tusas Mountains, north-central New Mexico. US Geological Survey, 1985. http://dx.doi.org/10.3133/b1571.
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