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Littérature scientifique sur le sujet « Hydrothermal and continental sources »

Auteur : Grafiati

Publié le 16 novembre 2024

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Articles de revues sur le sujet "Hydrothermal and continental sources"

Li, Weiqiang, Brian L. Beard et Clark M. Johnson. « Biologically recycled continental iron is a major component in banded iron formations ». Proceedings of the National Academy of Sciences 112, n^o 27 (24 juin 2015) : 8193–98. http://dx.doi.org/10.1073/pnas.1505515112.

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Banded iron formations (BIFs) record a time of extensive Fe deposition in the Precambrian oceans, but the sources and pathways for metals in BIFs remain controversial. Here, we present Fe- and Nd-isotope data that indicate two sources of Fe for the large BIF units deposited 2.5 billion y ago. High-εNd and -δ56Fe signatures in some BIF samples record a hydrothermal component, but correlated decreases in εNd- and δ56Fe values reflect contributions from a continental component. The continental Fe source is best explained by Fe mobilization on the continental margin by microbial dissimilatory iron reduction (DIR) and confirms for the first time, to our knowledge, a microbially driven Fe shuttle for the largest BIFs on Earth. Detailed sampling at various scales shows that the proportions of hydrothermal and continental Fe sources were invariant over periods of 100–103 y, indicating that there was no seasonal control, although Fe sources varied on longer timescales of 105–106 y, suggesting a control by marine basin circulation. These results show that Fe sources and pathways for BIFs reflect the interplay between abiologic (hydrothermal) and biologic processes, where the latter reflects DIR that operated on a basin-wide scale in the Archean.

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Yuan, Jingying, Haigang Cao, Yuping Guo et Xuegang Chen. « Source and Evolution of Subduction–Related Hot Springs Discharged in Tengchong Geothermal Field, Southwest China : Constrained by Stable H, O, and Mg Isotopes ». Minerals 12, n^o 12 (23 novembre 2022) : 1490. http://dx.doi.org/10.3390/min12121490.

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The hydrothermal system plays a crucial role in material and energy cycling between the lithosphere and hydrosphere. In general, seafloor hydrothermal systems are one of important Mg sinks, but the situation may not be the same as it is in terrestrial hydrothermal systems. In addition, the behavior of Mg isotopes during hydrothermal circulation is still unclear. Thus, in this study, we determined the Mg isotopic compositions of the hydrothermal fluids discharged in the Tengchong region to understand better the fate of Mg in the continental hydrothermal system. The δ2H and δ18O values of the Tengchong hydrothermal fluids indicate that the recharge water sources are primary from meteoric water and influenced by the evaporation process. In contrast, the subduction–related volcanic water input is limited, except in for the Rehai area. The Mg in most of the samples is contributed by percolated meteoric water. The measured δ26Mg values range from –0.969 to 0.173‰, which are enriched in light Mg compared to the volcanic rocks of Tengchong. Combined with the precipitation dissolution of carbonate, we calculated the δ26Mg value for the endmember fluid before precipitation, which shows that the process of carbonate precipitation changes the Mg isotope of the fluid, substantially. The Shiqiang (SQ) vent is unique among all of the samples, characterized by an extremely a high δ26Mg value and Mg concentration, and it is estimated that it could have been mixed with an upper crustal material. This also reveals the diversity of the hydrothermal fluid material sources in the subduction zone.

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Coltat, Rémi, Philippe Boulvais, Yannick Branquet, Antonin Richard, Alexandre Tarantola et Gianreto Manatschal. « Moho carbonation at an ocean-continent transition ». Geology 50, n^o 3 (3 décembre 2021) : 278–83. http://dx.doi.org/10.1130/g49363.1.

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Abstract Carbonation of mantle rocks during mantle exhumation is reported in present-day oceanic settings, both at mid-ocean ridges and ocean-continent transitions (OCTs). However, the hydrothermal conditions of carbonation (i.e., fluid sources, thermal regimes) during mantle exhumation remain poorly constrained. We focus on an exceptionally well-preserved fossil OCT where mantle rocks have been exhumed and carbonated along a detachment fault from underneath the continent to the seafloor along a tectonic Moho. Stable isotope (oxygen and carbon) analyses on calcite indicate that carbonation resulted from the mixing between serpentinization-derived fluids at ~175°C and seawater. Strontium isotope compositions suggest interactions between seawater and the continental crust prior to carbonation. This shows that carbonation along the tectonic Moho occurs below the continental crust and prior to mantle exhumation at the seafloor during continental breakup.

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Zinchuk, N. N. « CRUSTS OF WEATHERING AS BASIC SUPPLIERS OF TERRIGENOUS MATERIAL DURING FORMATION OF ANCIENT DIAMONDIFEROUS PLACERS ». Proceedings of higher educational establishments. Geology and Exploration, n^o 2 (30 avril 2018) : 24–32. http://dx.doi.org/10.32454/0016-7762-2018-2-24-32.

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On the example of Mesozoic deposits of one of the main diamondiferous regions of the Siberian platform, basic suppliers of terrigenous material into the ancient diamondiferous placers under formation and their occurrences have been characterized. Special attention has been paid to characteristics of local sources of allothigenous material removal to sedimentation basins of the said period, the main of which were Middle-Late Triassic crusts of weathering on terrigenous-carbonate rocks, formations of trappean origin (dolerites, tuffs, tufogene thick layers) and kimberlites. Comparatively short transfer of weathering products and their accumulation mainly in freshwater continental basins determined weak hydrothermal effect of environment on allothigenous minerals. The received specific features of the mineral composition of various rocks' crusts of weathering have been recommended for application during paleogeographical reconstructions in diamondiferous regions, to determine source areas of terrigenous material, in particular. The stated recommendations have been implemented when assessing material from local sources of drift (including diamondiferous material as well) to continental (Irelyakh and Ukugut suites) and coastal (Pliensbachian and Toarcian stages) deposits of MaloBOtuobinsky region, where primary and placer diamond deposits are successfully mined.

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Chiaradia, Massimo, Lluís Fontboté et Agustín Paladines. « Metal Sources in Mineral Deposits and Crustal Rocks of Ecuador (1° N–4° S) : A Lead Isotope Synthesis ». Economic Geology 99, n^o 6 (1 septembre 2004) : 1085–106. http://dx.doi.org/10.2113/econgeo.99.6.1085.

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Abstract Ecuador consists of terranes having both continental (Chaucha, Tahuin, Loja terranes) and oceanic (Macuchi, Alao, Salado terranes) affinity, which were accreted to the Amazon craton from Late Jurassic to Eocene. Four main magmatic arcs were formed by the subduction of the Farallon/Nazca plate since the Jurassic: a Jurassic continental arc on the western margin of the Amazon craton, a Jurassic island arc (Alao terrane), an early Tertiary island arc (Macuchi terrane), and a middle-late Tertiary continental arc encompassing the terranes of Macuchi, Chaucha, Tahuin, Loja, and Alao after complete assembly of the Ecuadorian crust. Mineral deposits formed during these magmatic arc activities include porphyry-Cu and gold skarn deposits in association with the Jurassic continental arc, polymetallic volcanic-hosted massive sulfide deposits (VHMS) in association with the Jurassic island arc of Alao, Au-Cu-Zn VHMS deposits in association with the early Tertiary island arc of Macuchi, and porphyry-Cu and precious-metal epithermal deposits in association with the middle-late Tertiary continental-arc magmatism on the newly assembled crust of Ecuador (Macuchi, Chaucha, Tahuin, Loja, and Alao terranes). In this study, we have compiled 148 new and 125 previously published lead isotope analyses on Paleozoic to Miocene metamorphic, intrusive, volcanic, and volcanosedimentary rocks, as well as on Jurassic to Miocene magmatic-related ore deposits of Ecuador. Lead isotope compositions of the magmatic rocks of the four main arc events derive from mixing of various sources including mantle, variably enriched by pelagic sediments and/or by a high 238U/204Pb component, and heterogeneous continental crust rocks. Lead isotope compositions of the Ecuadorian ore deposits display a broad range of values (206Pb/204Pb = 18.3–19.3, 207Pb/204Pb = 15.54–15.74, 208Pb/204Pb = 38.2–39.2), which is as large as the range previously reported for all magmatic-related ore deposits of the Central Andean provinces I and II combined. Ore deposits formed before complete assembly of the Ecuadorian crust through complete accretion of the several terranes (i.e., pre-Eocene) have lead isotope compositions overlapping those of the associated magmatic rocks, suggesting a largely magmatic origin for their lead. In contrast, post-assembly ore deposits (i.e., post-Eocene) have lead isotope compositions that only partly overlap those of the coeval magmatic rocks of the continental arc. In fact, several ore deposits have lead isotope compositions shifted toward those of the basement rocks that host them, suggesting that lead derives from a mixture of magmatic lead and basement-rock lead leached by hydrothermal fluids. Most Ecuadorian ores have high 207Pb/204Pb values (>15.55), suggesting a dominant continental crust or pelagic sediment origin of the lead. However, we caution against concluding that chalcophile metals (for example, Cu and Au) also have a continental crust origin. Ore deposits of the different terranes of Ecuador, irrespective of their age, plot in distinct isotopic fields, which are internally homogeneous. This suggests that lithologic factors had an important control on the lead isotope compositions. Ultimately, lead isotope compositions of the ore deposits of Ecuador mirror the isotopic compositions of the rocks of the host terranes and are consistent with the multiterrane nature of the Ecuadorian crust.

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Ansari, Arif H., Veeru Kant Singh, Pankaj Kumar, Mukund Sharma, Anupam Sharma, Satyakam Patnaik, Gurumurthy P. Gundiga, Ishwar Chandra Rahi, Mohammad Arif Ansari et AL Ramanathan. « Hydrogeochemistry, Geothermometry, and Sourcing of High Dissolved Boron, Tungsten, and Chlorine Concentrations in the Trans-Himalayan Hotsprings of Ladakh, India ». Hydrology 10, n^o 6 (24 mai 2023) : 118. http://dx.doi.org/10.3390/hydrology10060118.

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Boron (B) and Tungsten (W) are often found enriched in high-temperature geothermal waters associated with the development of subduction-related mafic to felsic arc magma. However, knowledge about the sourcing and transportation of these elements from such hydrothermal systems is sparse and ambiguous. Being the only active continental collision site in the world, the Trans-Himalaya offers a unique chance to study how continental collision sources the high boron and tungsten concentrations in geothermal fluids. This study investigated the distribution of trace elements, major cations, and anions in three physicochemically distinct hotspring sites in the Ladakh region. The results were integrated with the existing geochemical and isotopic data to address the research problem more effectively. This study exhibits that the extreme concentrations of boron, sodium, chlorine, potassium, and tungsten in the hotspring waters were primarily governed by magmatic fluid inputs. In addition, this study recorded the highest-ever chlorine and boron concentrations for the Trans-Himalayan hotspring waters. The highest-ever boron and chlorine concentrations in the hotspring waters probably represented an increase in magmatic activity in the deeper source zone.

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Chugaev, A. V. « Orogenic Gold Deposits of Northern Transbaikalia, Russia : Geology, Age, Sources, and Genesis ». Geochemistry International 62, n^o 9 (septembre 2024) : 909–78. http://dx.doi.org/10.1134/s0016702924700484.

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Abstract The paper presents newly obtained and summarizes preexisting data of long-term geochronological and isotope studies of orogenic mesothermal gold deposits in the world’s largest Lena metallogenic province and reviews interpretations of their genesis. Geochronologic data indicate that the gold mineralization was formed during three ore-forming Paleozoic events. The early Late Ordovician–Early Silurian (450–430 Ma) event produced the abundant veinlet—disseminated gold–sulfide mineralization in Neoproterozoic carbonaceous terrigenous–carbonate rocks of the Baikal–Patom foldbelt (BPB). The mineralization was formed simultaneously with regional metamorphic processes. The rejuvenation of hydrothermal activity in the BPB resulted in gold-bearing quartz veins, which was produced in the Middle Carboniferous (340–330 Ma) in relation to postcollisional granitoid magmatism. The latest ore-forming event occurred in the Early Permian (290–280 Ma) and affected exclusively in Precambrian structures of the Baikal-Muya foldbelt (BMB). It was synchronous with the development of intraplate alkaline and subalkaline magmatism in the region. Newly obtained and preexisting isotopic-geochemical (87Sr/86Sr, 143Nd/144Nd, Pb–Pb, and δ34S) data indicate that the mesothermal ore-forming systems of northern Transbaikalia were heterogeneous in their isotopic characteristics, which distinguishes them from the ore–magmatic (intrusion-related type) systems. Comparison of the Sr, Nd, and Pb isotopic composition of the ores and rocks, including magmatic rocks coeval with the gold mineralization, indicates that the Precambrian continental crust was the dominant source of mineral-forming components for the hydrothermal systems of the gold deposits. The contribution of the magmatic source to the genesis of the orogenic gold mineralization was limited and is identifiable only for the Early Permian ore-forming systems of the BMB, for which the input of metals from alkaline mafic melts was suggested.

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Wang, Zhigao, Wenyan Cai, Shunda Li et Xuli Ma. « Magma Sources and Tectonic Settings of Concealed Intrusive Rocks in the Jinchang Ore District, Yanbian–Dongning Region, Northeast China : Zircon U–Pb Geochronological, Geochemical, and Hf Isotopic Evidence ». Minerals 12, n^o 6 (1 juin 2022) : 708. http://dx.doi.org/10.3390/min12060708.

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The Jinchang deposit is a large Au deposit in the Yanbian–Dongning region, in Northeast China, and is the product of magmatic–hydrothermal activities related to Early Cretaceous concealed igneous intrusions. However, these Early Cretaceous ore-causative igneous intrusions and the ore-hosting rocks in the Jinchang ore district have rarely been studied, with their magma sources and tectonic settings being ambiguous. Here, we integrate new geochemical, zircon U–Pb and Hf isotopic data from the concealed ore-hosting monzogranite and the ore-causative granodiorite to constrain their magma sources and tectonic settings. Zircon U–Pb dating indicates that the two monzogranites from the drill holes JIZKN01 and J18ZK0303 have similar crystallization ages of 202.0 ± 1.6 and 200.9 ± 1.2 Ma, respectively, whereas the granodiorite from the drill hole JXI-1ZK1001 was formed in the Early Cretaceous period (107.0 ± 3.0 Ma). They are all enriched in large-ion lithophile elements (e.g., Rb, Th, and K) and light rare-earth elements, depleted in high field strength elements (e.g., Nb, Ta, and Ti) and heavy rare-earth elements, and yield similar positive εHf(t) values of +4.4 to +11.5, with their two-stage model ages ranging from 799 to 389 Ma. These results indicate that the concealed Early Jurassic ore-hosting monzogranite was derived from the partial melting of the Neoproterozoic–Paleozoic continental crust in a continental arc setting related to the Paleo-Pacific subduction. The ore-causative granodiorite originated from the partial melting of both the mantle wedge and the overlying continental crust, most likely caused by the dehydration and metasomatism of the subducted Paleo-Pacific slab involved in the rollback in the Early Cretaceous period.

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Ma, Guoxiong, Xiaobo Zhao, Chunji Xue et Renke Wang. « Neoproterozoic Aksu Diabase Dyke, Chinese South Tianshan : Magma Sources and Implications for Regional Gold Metallogeny ». Minerals 13, n^o 3 (25 février 2023) : 326. http://dx.doi.org/10.3390/min13030326.

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Tianshan is one of the world’s largest gold provinces; however, the relationship between gold mineralization and metasomatized subcontinental lithospheric mantle (SCLM) remains poorly understood. To improve our understanding, we present new bulk-rock geochemistry and platinum group element (PGE) concentrations of the SCLM-sourced Aksu Neoproterozoic diabase dykes in Chinese South Tianshan. These data, combined with in situ laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of hydrothermal pyrite grains in the diabase dykes, are used to discuss the SCLM source characteristics in the region and their potential links to formation of gold deposits. The diabase dykes exhibit high Th/Yb (0.47–0.62) and low Nb/U (13.4–16.3) ratios, indicating that magma evolution involves subduction-related fluid metasomatism and limited contamination of the continental crust. This is consistent with little variation in whole-rock Pd/Zr, Cu/Zr, and Ni/MgO ratios, suggesting that no sulfide segregation was caused by crustal contamination and magma mixing. In addition, the diabase dykes show low PGE and Au contents, with high Cu/Pd (>105) and low Cu/Zr (<0.5) ratios, indicating that magmas were derived from low-degree partial melting of the SCLM under S-saturated conditions. Such source characteristics indicate residual sulfides and chalcophile elements (e.g., PGEs, Au, and Cu) were concentrated at the SCLM reservoir in South Tianshan. Hydrothermal pyrite in the studied dykes has similar Au/Ag ratios and trace element distribution patterns to gold-bearing pyrite of lode gold deposits in Chinese South Tianshan, indicating that metasomatized SCLM may have contributed ore metals during the formation of these gold deposits. Adding to the available data, our study highlights that the SCLM may be a potential metal source reservoir, and it may have contributed to formation of the lode gold deposits in Chinese South Tianshan.

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Peverelli, Veronica, Alfons Berger, Martin Wille, Thomas Pettke, Benita Putlitz, Andreas Mulch, Edwin Gnos et Marco Herwegh. « Multifaceted orogenic fluid dynamics unraveled by hydrothermal epidote ». European Journal of Mineralogy 36, n^o 5 (24 septembre 2024) : 879–98. http://dx.doi.org/10.5194/ejm-36-879-2024.

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Abstract. Characterizing fluid circulation in orogens is key to understanding orogenic processes because fluid–rock interaction modifies the physical properties of rocks, hence their response to deformation and, for example, their suitability for radioactive waste storage. Fluid circulation can be dated by applying geochronological methods to fluid-precipitated minerals. Fluid sources and associated pathways can be traced using isotope data measured in the same or in other cogenetic minerals. We applied this concept to the Aar Massif (central Swiss Alps), which was part of the former European passive continental margin that was deformed and exhumed during the (Cenozoic) Alpine orogeny. Newly collected epidote from veins and from one cleft at several localities in meta-granitoids in the Aar Massif yielded U–Pb ages ranging from 27.7 ± 3.4 to 12.4 ± 1.9 Ma, which complement previously published geochronological data revealing Permian (278 ± 29, 251 ± 50, and 275 ± 18 Ma) and Miocene (19.2 ± 4.3 and 16.9 ± 3.7 Ma) epidote veins. We used Pb–Sr–O–H isotope geochemistry of epidote to evaluate fluid sources and pathways during Permian rifting and the Miocene compressional phases of Alpine orogeny. Strontium isotope data of Permian epidote are consistent with previous work suggesting meteoric water infiltration along syn-rift faults and through syn-rift sediments. A more-complex structural framework existed in the Miocene, when a sedimentary lid covered the Aar Massif. Strontium, O, and H isotope data of Miocene epidote-forming fluids indicate (1) meteoric water, mixing with (2) fluids derived from sedimentary units being compacted during orogenesis and/or (3) metamorphic water. All three fluid endmembers may have been circulating and mixing in the Aar Massif during Miocene deformation. Strontium isotope data further indicate that Miocene fluids contributed to imprinting a highly radiogenic Sr isotope composition onto Alpine shear zones or that the fluids inherited a highly radiogenic Sr isotope component by dissolving the Rb-rich, high 87Sr / 86Sr biotite therein. Both possibilities can coexist, and they imply that external fluids could modify the chemical composition of the post-Variscan granitoids hosting the studied epidote veins by fluid–rock interaction processes during deformation. Lead, Sr, and H isotopic differences among Miocene samples further suggest complexity of large-scale fluid circulation. Our work supports the fact that the reconstruction of multifaceted and multi-stage fluid circulation in highly deformed rocks benefits from extracting geochronological and isotope data from the same mineral.

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Thèses sur le sujet "Hydrothermal and continental sources"

Aquila, Quentin. « Explorer la géochimie des océans archéens avec les Formations de fer rubanées (BIF) : apport des compositions isotopiques Hf-Nd-Pb ». Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2024. http://www.theses.fr/2024UCFA0054.

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Les Formations de fer Rubanées (BIF) sont des archives sédimentaires uniques pour étudier les océans primitifs de l'Archéen. Cependant, l'environnement de formation et les mécanismes en jeu dans la formation de ces sédiments chimiques riches en fer et en silicium sont peu contraints. Les BIF ont été très peu étudiés pour leurs compositions isotopiques en Nd-Hf alors qu'elles pourraient permettre d'apporter de nouvelles contraintes sur les sources hydrothermales et continentales alimentant les anciens océans. Pour mieux contraindre l'environnement de formation des BIF, j'ai combiné des aspects de terrains et une étude pétro-géochimique sur une succession sédimentaire de la ceinture de Barberton (3,25 Ga, Afrique du Sud). Le modèle de dépôt des BIF de Barberton implique un milieu de dépôt profond, au bas d'une pente et distal du continent. Cet environnement est perturbé ponctuellement par des dépôts gravitaires terrigènes (mafiques) caractéristiques d'un système sédimentaire d'éventail sous-marin profond. J'ai évalué si la signature géochimique de l'eau de mer (REE+Y, faibles HFSE) permettait d'indiquer la préservation des compositions isotopiques Hf-Nd-Pb primaires sur un BIF de la ceinture de Isua (3,7 Ga, Groenland). Le BIF de Isua montre des perturbations post-dépôts des compositions isotopiques Hf-Nd attribués à la présence d'apatites secondaires. Il a cependant préservé un âge 207Pb-206Pb de 3810 ± 7 Ma hérité de zircons détritiques. Le spectre REE+Y typique de l'eau de mer ne garantit donc ni la préservation des compositions isotopiques Hf-Nd primaires de l'eau de mer, ni de l'absence de toute contamination terrigène. Enfin, j'ai exploré l'origine et la source du Nd et de l'Hf dans les BIF à l'échelle des bandes sur des échantillons provenant de la ceinture de Témagami (2,7 Ga, Canada). Les compositions isotopiques initiales en Nd-Hf des bandes de BIF de Témagami riches en Si montrent un découplage des deux systèmes isotopiques. A l'inverse, celles des bandes riches en Fe demeurent couplées en Nd-Hf. Les bandes riches en Si enregistrent une composition isotopique en Hf radiogénique provenant des eaux d'altérations des continents felsiques. A l'inverse, l'Hf et le Nd des bandes riches en Fe pourrait provenir principalement de l'hydrothermalisme sous-marin
The Banded Iron Formations (BIF) are unique sedimentary archives for studying the primitive oceans of the Archean. However, the environment of formation and the mechanisms involved in the formation of these iron- and silicon-rich chemical sediments are poorly constrained. The BIFs have been little studied for their Nd-Hf isotopic compositions, although they could provide new constraints on the hydrothermal and continental sources feeding the ancient oceans. To better constrain the BIFs environment of formation, I combined field observations with a petro-geochemical study on a sedimentary succession from the Barberton belt (3.25 Ga, South Africa). The deposition model of the Barberton BIFs involves a deep depositional environment, at the base of a slope and distal from the continent. This environment is occasionally disturbed by gravity-driven terrigenous deposits (mafic) characteristics of a deep-sea fan system. I evaluated whether the seawater geochemical signature (REE+Y, low HFSE) indicated the preservation of the primary Hf-Nd-Pb isotopic compositions in a BIF from the Isua belt (3.7 Ga, Greenland). The Isua BIF shows post-depositional disturbances in the Hf-Nd isotopic compositions attributed to the presence of secondary apatites. However, it preserved a 207Pb-206Pb age of 3810 ± 7 Ma inherited from detrital zircons. Therefore, the REE+Y spectrum typical of seawater does not guarantee the preservation of the primary Hf-Nd isotopic compositions of seawater, nor the absence of any terrigenous contamination. Finally, I explored the origin and source of Nd and Hf in the BIFs at the scale of the bands on samples from the Témagami belt (2.7 Ga, Canada). The initial Nd-Hf isotopic compositions of the Si-rich bands of the Témagami BIFs show a decoupling of the two isotopic systems. Conversely, those of the Fe-rich bands remain coupled in Nd-Hf. The Si-rich bands record a radiogenic Hf isotopic composition originating from the weathering waters of felsic continents. Conversely, the Hf and Nd in the Fe-rich bands could mainly originate from submarine hydrothermalism

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Lopez, Benjamin. « Architecture et distribution des systemes carbonatés se développant autour des sources hydrothermales : cas d’étude du basin de Denizli (Turquie), de la region de Rapolano (Italie) et de Mammoth Hot Springs (Wyoming, USA) ». Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4326.

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Les carbonates de sources hydrothermales (ou Geothermal Spring Carbonate, GSC) sont des systèmes carbonatés qui se développent autour de sources dont les eaux ont circulé en profondeur et sont remontées le long de failles perméables. Leur développement est contrôlé en tout premier lieu par la nature des eaux souterraines auxquelles ils sont liés. La formation de ces carbonates dépend d’interactions complexes entre les processus hydrologiques, tectoniques et structuraux se produisant avant l’émergence. Par la suite, la sédimentation est régie par de nombreux processus résultant des variations hydrologiques et chimiques de l’eau ainsi que par l’activité biologique. Du fait des interactions complexes entre ces facteurs, la sédimentation est sensible à de faible variations environnementales et il en résulte ainsi un grand nombre d’environnement de dépôts et de lithofacies.Le but de cette étude est d’améliorer les connaissances et les concepts fondamentaux propres au développement des carbonates de sources hydrothermales (GSC). Pour cela, elle s’appuie principalement sur l’examen des faciès que ce soit à petite échelle, comme l’observation des microstructures (microfabrics), ou à grande échelle, comme leur agencement en trois dimensions. De tels examens ont été effectués dans des sites hydrothermaux où ces carbonates se sont développés au cours du Quaternaire (région de Rapolano en Italie, bassin de Denizli en Turquie ou encore le Parc du Yellowstone dans le Wyoming, USA)
Geothermal spring carbonate (GSC) corresponds to a complex carbonate system formed around carbonate-rich springs fed by rising groundwaters along permeable fault zones. Their development is mainly controlled by the nature of springwaters emerging above water table. Therefore carbonate deposition is, in this setting, intimately related to complex interactions between hydrological, tectonic and structural processes occurring prior to water emergence. Moreover, carbonate sedimentation from springwater results from sedimentary processes controlled by complex interactions between hydrological, chemical characteristics and biological activity. Such processes are sensitive to slight environmental variations and thus lead to a large spectrum of lithofacies and ecosystems.The aim of this study is to improve knowledge and fundamental concepts regarding development of geothermal spring carbonates. For that purpose, lithofacies investigation, from microfabrics at micro-scale to 3-dimensional configuration at field-scale, is considered as an essential tool. Such investigations had been carried out in sites where Quaternary and actively forming GSCs were abundant (e.g. Rapolano region, Italy, Denizli Basin, Turkey and Yellowstone National Park, Wyoming, USA)

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Mercer, Celestine Nicole. « Mineralogical indicators of magmatic and hydrothermal processes in continental arc crust / ». Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2009. http://hdl.handle.net/1794/10250.

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Mercer, Celestine Nicole 1979. « Mineralogical indicators of magmatic and hydrothermal processes in continental arc crust ». Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10250.

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xviii, 177 p. : ill., maps. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
This dissertation explores several important consequences of H 2 O-rich fluids in magmatic and ore-forming systems within continental arc crust. North Sister, a stratovolcano in the Oregon High Cascades, provides a window into magma generation processes in the deep crust. Eruption of a remarkably limited basaltic andesite composition over the lifespan of this volcano may reflect last equilibration of mantle derived magma within a deep crustal hot zone. High pressure, water-undersaturated phase equilibrium experiments show that an anhydrous, augite-rich gabbro at ∼12 kbar (40 km depth) and ∼ 1175°C is the most probable lithology with which North Sister basaltic andesite with ∼3.5 wt% H 2 O last equilibrated within the deep crust before erupting. While magma often erupts at the planets surface as at North Sister, a greater volume never reaches the surface and solidifies within the upper crust. Exsolution of magmatic fluids is an inevitable consequence of crystallization of hydrous crustal magmas. The fate of these fluids is the focus of the remainder of this dissertation. Modeling of CO 2 and H 2 O variations during crystallization of granitic magma reveals that exsolution of a large mass of fluid occurs only after CO 2 is largely degassed, creating ideal conditions for hydrofracturing and formation of porphyry copper deposits. CO 2 and H 2 O solubility relations suggest that H 2 O-rich magma was required to produce the porphyry-Cu-Mo deposit at Butte, Montana, which may explain its distinctively deep generation. Electron microprobe analyses of Ti in quartz and Zr in rutile in samples from Butte yield porphyry magma temperatures (630-770°C) that overlap substantially with hydrothermal vein temperatures (<430-750°C). Veins display large temperature ranges (50-250°C) that signify variable degrees of cooling of hot magmatic fluids upon contact with cooler wall rock during vein growth. Modeling of Ti diffusion in quartz suggests that individual dikes and veins likely cooled over short timescales (10s-1000s years), indicating that porphyry systems may evolve by episodic magmatic fluid injections with discrete thermal spikes. Modeling of Ti diffusion in quartz combined with electron backscatter diffraction maps show that small hydrothermal quartz veins likely formed by epitaxial growth. This dissertation includes co-authored material both previously published and in preparation for submission.
Committee in charge: A. Dana Johnston, Chairperson, Geological Sciences; Mark Reed, Member, Geological Sciences; Paul Wallace, Member, Geological Sciences; Richard P. Taylor, Outside Member, Physics

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Le, Gal Virginie. « Traçage thermique et géochimique des systèmes hydrothermaux : exemple d'un domaine océanique jeune et d'une marge continentale ». Electronic Thesis or Diss., Paris 6, 2017. https://theses.hal.science/tel-01886790.

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Résumé Les processus hydrothermaux affectent l'ensemble des domaines océaniques et contrôlent efficacement leur régime thermique. Cependant, les études de flux de chaleur à l'échelle globale conduisent à des interprétations parfois en contradiction avec les études locales. Il est donc essentiel de comparer les effets de l'hydrothermalisme dans différents contextes régionaux. Dans cette optique, nous avons étudié le rôle de l'hydrothermalisme sur le régime thermique d'un domaine océanique jeune (en Atlantique) et d'une marge continentale jeune (Sud Baléares). Pour cela, nous avons quantifié les transferts et pertes de chaleur et de matière en utilisant des traceurs thermiques (mesures du flux de chaleur) et des traceurs chimiques (analyse des fluides interstitiels). Le domaine océanique jeune se situe dans l'océan Atlantique sur le premier segment au sud de la faille transformante Oceanographer. Les faibles valeurs du flux de chaleur indiquent que les circulations hydrothermales, induites par les nombreux affleurements, extraient d'importantes quantités de chaleur de la croûte. La composition de l'eau interstitielle est similaire à l'eau de mer, indiquant un temps de résidence faible de l'eau dans le socle. Nous avons identifié que la rugosité du plancher océanique est un des paramètres majeurs qui contrôlent l'efficacité de ces circulations de fluides. Ce relief à petite échelle a été comparé à d'autres régions où l'efficacité des processus hydrothermaux avait préalablement été discutée. Nous en avons déduis une relation empirique qui relie la fraction du flux de chaleur à ce relief. Sur la marge Sud des Baléares, les processus hydrothermaux semblent plus restreints car leur impact thermique est plus local. Sur la pente continentale, des contrastes importants du flux de chaleur ont été mis en évidence. Ils suggèrent des circulations hydrothermales controlées par la présence de nombreux monts volcaniques. Cependant, la chimie des fluides reste proche de celle de l’eau de mer et ne permet pas de confirmer ces observations. En revanche, les processus hydrothermaux sont limités dans le bassin par les épais dépôts de sédiments. La chimie des fluides indique la présence de saumures résiduelles et leur simple diffusion vers la surface. Les valeurs du flux de chaleur sont perturbées par les contrastes de conductivité thermique induits par la présence de diapirs de sel ou du socle. Dans les deux zones d’étude, les circulations de fluides sont liées à la présence de structures basaltiques fracturées dont la perméabilité est supérieure de plusieurs ordres de grandeur à celle des sédiments alentours. La rugosité initiale du plancher océanique et le taux de sédimentation contrôlent la tranche d’âge durant laquelle la croûte reste connectée à l’océan. En revanche, les circulations sont rapidement inhibées sur les marges par les apports importants de sédiments venant du continent proche. Cette conclusion est contrebalancée par d’autres événements pouvant survenir sur les marges telles que le volcanisme ou la tectonique active
Hydrothermal processes affect all oceanic domains therby controlling their thermal regime. At global scale, heat flow studies may lead to different interpretations than local studies. Comparing hydrothermal effects in different local contexts is essential to overcome this scale- issues. To do so, we studied the hydrothermal impact on the thermal regimes of a young oceanic domain (Atlantic Ocean) and a young margin (South Balearic). We quantified heat and matter transfers and heat losses with heat flow measurements and pore water chemical analyses. The young oceanic domain is situated on the first segment south of Oceanographer transform fault in the Atlantic Ocean. The low heat flow values indicate that hydrothermal circulations, conveyed by numerous outcrops, extract a lot of crustal heat. The composition of water in pores is similar to that of seawater. This points to a short residence time of water in the basement. We identified that the ruggedness of the seabed is one of the key parameters that control the fluid circulation efficiency. This small scale relief was compared to others regions where hydrothermal processes have already been debated. We deduced an empirical relation which links the fraction of the conductive heat flow to this relief. On the Southern Balearic margin, hydrothermal processes appear to be more limited because of their more local thermal impact. On the continental slope, great heat flow contrasts are highlighted. They suggest that hydrothermal circulation is controlled by numerous volcanic mounts. On one hand, pore fluid chemistry remains close to seawater composition and does not allow confirming these observations. On the other hand, hydrothermal processes in the basin are limited by thick sediment deposits and pore fluid chemistry indicates residual brines and their diffusion towards the surface. Heat flow values along the Southern Balearic margins are perturbed by thermal conductivity contrasts induced by salt diapirs or basement topography. In both study areas, fluid circulations are linked to fractured basaltic structures with a much larger permeability than the surrounding sediments. The seabed’s initial ruggedness and the sedimentation rate control the age range during which the crust is connected to ocean. Nevertheless, fluid circulations cease quickly due to important sediment flows from the nearby continent. This conclusion is partially offset by other events that may occur on the margins such as volcanism or active tectonic

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Cook, James Matthew. « Mid-fifteenth-century English mass cycles in continental sources ». Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/30778/.

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Fifteenth-century English music had a profound impact on mainland Europe, with several important innovations (e.g. the cyclic cantus firmus Mass) credited as English in origin. However, the turbulent history of the Church in England has left few English sources for this deeply influential repertory. The developing narrative surrounding apparently English technical innovations has therefore often focussed on the recognition of English works in continental manuscripts, with these efforts most recently crystallised in Curtis and Wathey's 'Fifteenth-Century English Liturgical Music: A List of the Surviving Repertory'. The focus of discussion until now has generally been on a dichotomy between English and continental origin. However, as more details emerge of the opportunities for cultural cross-fertilisation, it becomes increasingly clear that this may be a false dichotomy. This thesis re-evaluates the complex issues of provenance and diffusion affecting the mid-fifteenth-century cyclic Mass. By breaking down the polarization between English and continental origins, it offers a new understanding of the provenance and subsequent use of many Mass cycles. Contact between England and the continent was frequent, multifarious and quite possibly reciprocal and, despite strong national trends, there exists a body of work that can best be understood in relation to international cultural exchange. This thesis helps to clarify the provenance of a number of Mass cycles, but also suggests that, for Masses such as the anonymous Thomas cesus and Du cuer je souspier, Le Rouge's So ys emprentid, and even perhaps Bedyngham's Sine nomine, cultural exchange is key to our understanding. This thesis also offers a more detailed overview of the chronology of fifteenth-century English Mass cycles and defines their various structural norms, as well as those Masses which depart from these.

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Le, Gal Virginie. « Traçage thermique et géochimique des systèmes hydrothermaux : exemple d'un domaine océanique jeune et d'une marge continentale ». Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066530/document.

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Tizzard, Louise Helen. « The Contribution to atmospheric methane from sub-seabed sources in the UK continental shelf ». Thesis, University of Newcastle upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445613.

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Qu, Zihan. « Chemical properties of continental aerosol transported over the Southern Ocean : Patagonian and Namibian sources ». Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066002/document.

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Patagonie et la Namibie sont deux sources importantes d'aérosol minéral qui alimente la section Atlantique Sud de l'océan Austral avec les micronutriments.L'objet de ma thèse est d'étudier 1) la concentration atmosphérique et la variation temporel de la poussière en Patagonie, 2) l'hétérogénéité spatiale de composition élémentaire de poussière en Patagonie et en Namibie, et 3) la solubilité élémentaire de poussière en Patagonie et en Namibie. Ces trois aspects sont les principaux enjeux pour modéliser les inventaires des émissions de micronutriments biodisponibles à partir de sources de poussière.La concentration en poussière mesurée en Patagonie montre une variation saisonnière avec un niveau plus bas en hiver. Les données météorologiques suggèrent que cette variation saisonnière est associée à la variation de l'humidité du sol dans les zones source plutôt qu'à la vitesse du vent. Des échantillons d'aérosol minéral ont été générés à partir des sols de Patagonie et de Namibie. La composition élémentaire des poussières diffère de celles des sols parents, en particulier en Namibie en raison de l'effet de dilution par le quartz dans les sols. Des compositions élémentaires varient spatialement aux échelles continentale et régionale en Patagonie et Namibie. Les variations de Ca et Mg sont les principales raisons conduisant à l'hétérogénéité spatiale de la composition élémentaire des poussières. Les solubilités élémentaires des aérosols minéraux de Patagonie et de Namibie augmentent avec l'acidité de la solution altérante. Les poussières riches en calcium présentent une solubilité plus élevée pour les éléments les plus solubles (Ca, etc.) en raison de la présence de carbonate. Le suivi de la concentration en poussières obtenu en Patagonie peut aider à mieux en quantifier les émissions dans la région subantarctique et ainsi à mieux contraindre les modèles. La base de données que nous avons obtenue sur les poussières et leur solubilité contribue également à l'évaluation des émissions d'éléments solubles dans la région Australe
Mineral dust is considered to be an important supplier of micronutrient for the Southern Ocean where the primary production is limited by insufficient supply of micronutrients. Patagonia (South America) and Namibia (Southern Africa) are two main dust sources for the South Atlantic section of the Southern Ocean. Emission inventories of bioavailable micronutrients from these two regions regulate the final biological impact on marine ecosystem in the South Atlantic Ocean. This thesis is mainly focused on the investigation of 1) the atmospheric dust concentration and its temporal pattern in Patagonia, 2) the spatial heterogeneity of dust elemental composition in Patagonia and Namibia, and 3) the pH dependence of elemental solubility in Patagonian and Namibian dust. These three aspects are the key issues to model the emission inventories of bioavailable micronutrients from dust sources. Dust concentration measurements were conducted in Patagonia-Atlantic Coast and revealed a seasonal pattern of dust concentration with lower dust level in winter than the other three seasons. Meteorological records suggest that this seasonal pattern is associated with the variation of soil moisture in source areas rather than the recurrently high wind speed. Dust samples were generated from Patagonian and Namibian soils to investigate the elemental composition and the elemental solubility of source dust. Dust elemental composition differs to different degrees from their parents soils, particularly in Namibia due to the dilution effect of quartz in soil. Spatial variability of dust elemental composition was observed at both continental scale and regional scale in Patagonia and Namibia. Variations in Ca and Mg content are the main reasons for the spatial heterogeneity of dust elemental composition. Elemental solubility of Patagonian and Namibian dust increased with acidity of leaching solution. More soluble elements namely Ca, K, Mg, Mn, Sr and Ba showed much higher solubility in calcium-rich dust due to the presence of carbonate. The dust concentration record obtained in Patagonia may help to better quantify the dust emission in subantarctic region and to constrain dust models. Database of dust elemental composition and elemental solubility in Patagonia and Namibia also contributes to the evaluation of emission inventories of soluble elements from dust sources to the Southern Ocean

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Qu, Zihan. « Chemical properties of continental aerosol transported over the Southern Ocean : Patagonian and Namibian sources ». Electronic Thesis or Diss., Paris 6, 2016. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2016PA066002.pdf.

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Livres sur le sujet "Hydrothermal and continental sources"

Lucien, Laubier, Centre national de la recherche scientifique (France), Institut français de recherche pour l'exploitation de la mer. et Colloque "les sources hydrothermales de la ride du Pacifique oriental, biologie et écologie" (1985 : Institut océanographique, Paris), dir. Biologie et écologie des sources hydrothermales = : Biology and ecology of the hydrothermal vents : Institut océanographique - Paris, 4-7 novembre 1985. Montrouge, France : Gauthier-Villars, 1988.

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Saco, Alfredo. Difusión continental del aprismo. Lima, Perú : Okura Editores, 1985.

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Andrew, Wachtel, dir. Petrushka : Sources and contexts. Evanston, Ill : Northwestern University Press, 1998.

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Umberto, Leanza, Sico Luigi, Ciciriello Maria Clelia, II Università degli studi di Roma. et Università di Napoli, dir. Mediterranean continental shelf : Delimitations and regimes : international and legal sources. Dobbs Ferry, N.Y : Oceana Publications, 1988.

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Christie's. Genre : Victorian and 19th century continental pictures from various sources. London : Christie's, 1998.

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World Clean Energy Conference (1991 Geneva, Switzerland). Cleaner energy for sustainable development : Proceedings of the World Clean Energy Conference, World Energy Coalition for the global energy charter : Geneva International Conference Centre, 4-7 November 1991. Zürich : Cercle mondial du consensus = World Circle of the Consensus, 1991.

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International, Workshop on Water Dynamics (5th 2007 Sendai-shi Miyagi-ken Japan). Water dynamics : 5th International Workshop on Water Dynamics, Sendai, Japan, 25-27 September 2007. Melville, N.Y : American Institute of Physics, 2008.

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Platonov, Andreĭ Platonovich. The foundation pit. Evanston, Ill : Northwestern University Press, 1994.

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United States. Congress. House. Committee on Natural Resources. Subcommittee on Energy and Mineral Resources., dir. Renewable energy opportunities and issues on the outer continental shelf : Joint oversight hearing before the Subcommittee on Fisheries, Wildlife, and Oceans, joint with the Subcommittee on Energy and Mineral Resources of the Committee on Natural Resources, U.S. House of Representatives, One Hundred Tenth Congress, first session, Tuesday, April 24, 2007. Washington : U.S. G.P.O., 2007.

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Platonov, Andreĭ Platonovich. Kotlovan : Tekst, materialy tvorcheskoĭ istorii. Sankt-Peterburg : Nauka, 2000.

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Chapitres de livres sur le sujet "Hydrothermal and continental sources"

Pirajno, Franco. « Hydrothermal Mineral Deposits of Continental Rift Environments ». Dans Hydrothermal Mineral Deposits, 507–77. Berlin, Heidelberg : Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-75671-9_14.

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Nieva, David, Rosa María Barragán et Víctor Arellano. « Geochemistry of Hydrothermal Systems ». Dans Power Stations Using Locally Available Energy Sources, 61–78. New York, NY : Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7510-5_306.

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Sim, Stuart. « A Brief Pre-history of Super-Scepticism : Sources and Influences ». Dans Contemporary Continental Philosophy, 19–29. London : Routledge, 2021. http://dx.doi.org/10.4324/9781315200293-3.

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Eidel, J. J., et C. Meyer. « Scientific Drilling to Study the Roots and Margins of Hydrothermal Mineral Systems ». Dans Exploration of the Deep Continental Crust, 123–29. Berlin, Heidelberg : Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-45601-5_10.

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Nielson, Dennis L., et Jeffrey B. Hulen. « Observations in an Active Hydrothermal System Through Deep Drilling : Valles Caldera, New Mexico ». Dans Exploration of the Deep Continental Crust, 308–22. Berlin, Heidelberg : Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-45601-5_21.

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Schreiber, Ulrich C., et Christian Mayer. « The New Model : Hydrothermal Systems in the Early Continental Crust ». Dans The First Cell, 89–113. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45381-7_7.

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Schreiber, Ulrich C., et Christian Mayer. « A Hypothetical Approach : Hydrothermal Systems in the Early Continental Crust ». Dans The First Cell, 115–60. Cham : Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45381-7_8.

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Fournier, Robert O. « Continental Scientific Drilling to Investigate Brine Evolution and Fluid Circulation in Active Hydrothermal Systems ». Dans Exploration of the Deep Continental Crust, 98–122. Berlin, Heidelberg : Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-45601-5_9.

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Huo, Zhibao. « Highly Selective Hydrothermal Production of Cyclohexanol from Biomass-Derived Cyclohexanone Over Cu Powder ». Dans Diverse Hydrogen Sources for Biomass-derivatives Conversion, 133–46. Singapore : Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1673-3_8.

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Storey, Michael, John J. Mahoney et Andrew D. Saunders. « Cretaceous Basalts in Madagascar and the Transition Between Plume and Continental Lithosphere Mantle Sources ». Dans Large Igneous Provinces : Continental, Oceanic, and Planetary Flood Volcanism, 95–122. Washington, D. C. : American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm100p0095.

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Actes de conférences sur le sujet "Hydrothermal and continental sources"

Kelechi, F. M., et O. I. Owoka. « The Future Perspective : Geothermal Energy in Nigeria – An Option to be Explored ». Dans SPE Nigeria Annual International Conference and Exhibition. SPE, 2023. http://dx.doi.org/10.2118/217204-ms.

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Abstract As the transition towards a green energy future intensifies, cleaner energy sources are expected to drive the decline in the demand for fossil fuels. This creates room for renewable energy sources such as geothermal. Geothermal energy is generated from the earth's crust which is transported through cracks and fractures in the host rocks and its natural fluids at temperatures above the ambient level. The rate of heat flow in the crust is estimated to be 59Mw/m2 [1.9*10-2 Btu/h/ft2]. In mature continental cratons, the geothermal gradient can be as low as 10 °C per kilometer. However, in active volcanic areas, it can exceed 100 °C per kilometer. A typical geothermal gradient of 25 °C km− 1 gives a conductive heat flux of 60 mWm− 2 for electricity generation. Considering the Nigerian basement complex, the estimated geothermal gradient of Borno and Sokoto States, both located in the Northern region are 1.1 to 5.9°C/100m with a heat flow of 8.9 to 117.8mW/m-2 and 0.9 to 7.6°C/100m with a geothermal heat flow of 52.11 to 130.28mWm-2 respectively. In addition, in eastern Nigeria, Anambra State, the estimated geothermal gradient is 2.5 to 4.9°C/100m with a heat flow of 64.4 to 97.3 mWm-2. Geothermal energy has the potential to improve Nigeria's current poor energy dynamic. Enhanced Geothermal System would exploit heat energy that is trapped in the subsurface host rock by creating an open system of connected fractures along which water can flow down the injection wells and get heated through contact with the rocks. This is then recovered to the surface in production wells to form a closed loop. The idea is an extrapolation that emulates a hydrothermal circulation system – which produces electricity that can be applied commercially.

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Scholz, Christopher A. « Advancing Models of Facies Variability and Lacustrine Source Rock Accumulation in Rifts : Implications for Exploration ». Dans SPE/AAPG Africa Energy and Technology Conference. SPE, 2016. http://dx.doi.org/10.2118/afrc-2577056-ms.

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ABSTRACT Important syn-rift hydrocarbon discoveries in the Tertiary East African Rift and in the South Atlantic subsalt basins have in recent years promoted renewed interest in the variability of source and reservoir rock facies in continental rifts. This talk considers several important new observations and developments in our understanding of the sedimentary evolution of lacustrine rift basins. Offshore subsalt basins in the South Atlantic demonstrate the importance of lacustrine carbonates, and especially microbialites, as reservoir facies in extensional systems. The role of rift-related magmatism is significant in these basins, both as drivers of hydrothermal systems around and within rift lakes, and as a source of solutes that facilitate carbonate accumulations. In the Tertiary East African Rift, substantial new hydrocarbon resources have been identified, including onshore siliciclastic reservoirs in remarkably young and shallow parts of the sedimentary section in the Albertine Graben. Rollover anticlines and fault-related folds serve as important structures for several new fields in the East African Rift, but larger structures affiliated with accommodation zones, in many instances located far offshore in the modern lakes, remain untested. Lacustrine source rocks that accumulated in stratified lake basins are the source of the oil and gas in these systems, however there is still much to be learned about their spatial and temporal variability. There is observed considerable variation in the character of organic matter on the floors of modern African lake basins, even adjacent ones. A number of factors likely govern the amount of total organic carbon preserved within the basins. These include 1) primary productivity; 2) degree of siliciclastic dilution, which is controlled in part by offshore slopes and the extent of onshore catchments, and 3) physical limnology, controlled by climate and basin-scale physiography, and the fetch-depth ratio of the lakes, which determines the likelihood of water column stratification. Scientific drilling in the African Rift lake basins is providing considerable information on the high temporal hydroclimate variability of the region, especially in the later Tertiary and Quaternary, which substantially controls basin lithofacies.

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Andrade-Barahona, Eva, et Alysia Cox. « Copper and iron uptake in continental hydrothermal systems ». Dans Goldschmidt2023. France : European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.13652.

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Zakharov, David, Dmitry Zozulya, Daniela Rubatto, Dylan Colon et Johanna Marin-Carbonne. « NEOARCHEAN CONTINENTAL EXPOSURE AND HYDROLOGICAL CYCLE RECORDED IN A 2.67 GA MAGMATIC-HYDROTHERMAL SYSTEM ». Dans GSA Connects 2021 in Portland, Oregon. Geological Society of America, 2021. http://dx.doi.org/10.1130/abs/2021am-365415.

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Rzonca, Bartlomiej, et Dirk Schulze-Makuch. « Investigation of hydrothermal sources in the Rio Grande rift region ». Dans 53rd Annual Fall Field Conference. New Mexico Geological Society, 2002. http://dx.doi.org/10.56577/ffc-53.319.

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Follmann, Jörg, Froukje van der Zwan, Sven Petersen et Matthias Frische. « Hydrothermal mineralization at continental breakup - geochemical insights from sulfide minerals from the South China Sea ». Dans Goldschmidt2022. France : European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.11378.

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Silaev, Valeriy Ivanovich, Irina Grigorievna Dobretsova, Anna Ivanovna Antoshkina, Vasily Nikolaevich Filippov, Boris Alexandrovich Makeev, Irina Vladimirovna Smoleva et Anton Fedorovich Khazov. « Hydrothermal sulfide mines in the Russian exploration area of the Middle Atlantic Ridge ». Dans Проблемы минералогии, петрографии и металлогении. Научные чтения памяти П. Н. Чирвинского. ПЕРМСКИЙ ГОСУДАРСТВЕННЫЙ НАЦИОНАЛЬНЫЙ ИССЛЕДОВАТЕЛЬСКИЙ УНИВЕРСИТЕТ, 2022. http://dx.doi.org/10.17072/chirvinsky.2022.226.

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The results of new studies of sulfide mineralization from the rift valley of the Mid-Atlantic Ridge are considered. The regularities of the chemical and mineral composition, the peculiarities of mineralogical zoning at the local and regional scales are analyzed. The genetic aspects of the isotopic composition of sulfur and carbon in the products of oceanic and continental volcanism are discussed.

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Mingyuan Zhu, Yibo Yang, Yemin Hu, Ying Li et Hongming Jin. « Preparation of MnO2 nanoflakes on Ti substrate by hydrothermal method ». Dans 8th International Vacuum Electron Sources Conference and Nanocarbon (2010 IVESC). IEEE, 2010. http://dx.doi.org/10.1109/ivesc.2010.5644157.

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Yun-Chieh Yeh, Di-Yan Wang et Chun-Wei Chen. « Work function evolution of graphene oxide by utilizing hydrothermal treatment ». Dans 8th International Vacuum Electron Sources Conference and Nanocarbon (2010 IVESC). IEEE, 2010. http://dx.doi.org/10.1109/ivesc.2010.5644196.

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Cao, Wenrong, et Cin-Ty A. Lee. « SCALING ANALYSIS AND NUMERICAL MODELING OF HYDROTHERMAL CIRCULATION IN COOLING AND EXHUMING HOT CONTINENTAL ARC CRUST ». Dans GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-302219.

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Rapports d'organisations sur le sujet "Hydrothermal and continental sources"

Davis, K. J., S. J. Richardson et N. L. Miles. A virtual tall tower network for understanding continental sources and sinks of CO2. Office of Scientific and Technical Information (OSTI), mars 2007. http://dx.doi.org/10.2172/900564.

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Leet, R. C. Investigation of hydrothermal boiling and steam quenching as possible sources of volcanic tremor and geothermal ground noise. Office of Scientific and Technical Information (OSTI), mai 1991. http://dx.doi.org/10.2172/5524334.

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Goff, F. Caldera processes and magma-hydrothermal systems continental scientific drilling program : thermal regimes, Valles caldera research, scientific and management plan. Sous la direction de D. L. Nielson. Office of Scientific and Technical Information (OSTI), mai 1986. http://dx.doi.org/10.2172/5467724.

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Petty, S., B. J. Livesay, W. P. Long et J. Geyer. Supply of geothermal power from hydrothermal sources : A study of the cost of power in 20 and 40 years. Office of Scientific and Technical Information (OSTI), novembre 1992. http://dx.doi.org/10.2172/6961102.

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Hulen, J. B., et D. L. Nielson. Hydrothermal brecciation in the Jemez Fault zone, Valles Caldera, New Mexico : Results from CSDP (Continental Scientific Drilling Program) corehole VC-1. Office of Scientific and Technical Information (OSTI), juin 1987. http://dx.doi.org/10.2172/6386155.

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Paradis, S., G. J. Simandl, N. Drage, R J D'Souza, D. J. Kontak et Z. Waller. Carbonate-hosted deposits (Mississippi Valley-type, magnesite, and REE-F-Ba) of the southeastern Canadian Cordillera : a review and isotopic data comparison. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/327995.

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The Mississippi Valley-type, magnesite, and REE-F-Ba deposits in the southeastern Canadian Cordillera are in the weakly deformed/metamorphosed Paleozoic carbonate platform of the Rocky Mountains. Most are hosted in dolostones of the middle Cambrian Cathedral, upper Cambrian Jubilee, and Upper Devonian Palliser formations and spatially associated with hydrothermal dolomite. They occur along structurally controlled facies transitions between the shallow-water carbonate platform and deeper water basin rocks of the Paleozoic continental margin. Their location and morphology reflect episodic rifting along the Paleozoic margin. The carbonate protolith was replaced by fine-grained 'replacive dolomite' followed by several stages of coarser saccharoidal, sparry, and saddle dolomites and sulfides replacing dolostone and filling open spaces. The 87Sr/86Sr, delta-18O, delta-13C, and fluid-inclusion data are consistent with high-temperature fluids interacting with host rocks and show influence of adjacent or underlying siliciclastic rocks. The large range of delta-34S values of sulfides suggests that thermochemical sulfate reduction of seawater sulfate was the main sulfur-reducing process, but bacterial sulfate reduction also occurred locally. Lead isotopes suggest a mixing trend involving highly radiogenic and non-radiogenic end members. These observations are consistent with hydrothermal fluids replacing protoliths, precipitating sulfides, and possibly REE-F-Ba mineralization.

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Vaughan, W. C., Frederick A. Bowles et Joshua W. Chatelain. Compilation of Data Sources Used to Construct Bottom-Sediment Province Maps for the United States East Coast Continental Shelf from Cape Kennedy to Cape Hatteras and for Various Indonesian Waters. Fort Belvoir, VA : Defense Technical Information Center, décembre 2004. http://dx.doi.org/10.21236/ada429967.

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Scanlan, E. J., M. Leybourne, D. Layton-Matthews, A. Voinot et N. van Wagoner. Alkaline magmatism in the Selwyn Basin, Yukon : relationship to SEDEX mineralization. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328994.

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Several sedimentary exhalative (SEDEX) deposits have alkaline magmatism that is temporally and spatially associated to mineralization. This report outlines interim data from a study of potential linkages between magmatism and SEDEX mineralization in the Selwyn Basin, Yukon. This region is an ideal study site due to the close spatial and temporal relationships between SEDEX deposits and magmatism, particularly in the MacMillan Pass, where volcanic rocks have been drilled with mineralization at the Boundary deposit. Alkaline volcanic samples were analysed from the Anvil District, MacMillan Pass, Keno-Mayo and the Misty Creek Embayment in the Selwyn Basin to characterise volcanism and examine the relationship to mineralization. Textural and field relationships indicate a volatile-rich explosive eruptive volcanic system in the MacMillan Pass region in comparison to the Anvil District, which is typically effusive in nature. High proportions of calcite and ankerite in comparison to other minerals are present in the MacMillan system. Cathodoluminescence imaging reveals zoning and carbonate that displays different luminescent colours within the same sample, likely indicating multiple generations of carbonate precipitation. Barium contents are enriched in volcanic rocks throughout the Selwyn Basin, which is predominately hosted by hyalophane with rare barite and barytocalcite. Thallium is positively correlated with Ba, Rb, Cs, Mo, As, Sb and the calcite-chlorite-pyrite index and is negatively correlated with Cu. Anvil District samples display a trend towards depleted mid-ocean ridge mantle on a plot of Ce/Tl versus Th/Rb. Hydrothermal alteration has likely led to the removal of Tl from volcanic rocks in the region. Ongoing research involves: i) the analysis of Sr, Nd, Pb and Tl isotopes of volcanic samples; ii) differentiating magmatic from hydrothermal carbonate using O, C and Sr isotopes; iii) examining sources of Ba in the Selwyn Basin; iv) and constraining age relationships through U-Th-Pb geochronology.

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Jefferson, C. W., S. Pehrsson, V. Tschirhart, T. Peterson, L. Chorlton, K. Bethune, J. C. White et al. Geology and metallogeny of the northeast Thelon Basin region, Nunavut, and comparison with the Athabasca Basin, Saskatchewan. Natural Resources Canada/CMSS/Information Management, 2024. http://dx.doi.org/10.4095/332499.

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Based on extensive remapping of the northeast Thelon Basin region in Nunavut, uranium exploration criteria are adapted from those of the Athabasca Basin in Saskatchewan, as basin-specific paradigms. The Athabasca Basin straddles the Rae and Hearne cratons and the Taltson magmatic zone, whereas the Thelon Basin rests entirely within the Rae Craton. In the Athabasca Basin, four unconformity-bounded siliciclastic sequences with different paleocurrents record a complex depositional history, whereas the Thelon Formation is a single, albeit cyclic siliciclastic unit with uni-modal paleocurrents. Beneath the Athabasca Basin, amphibolite-grade, conductive graphitic-pyritic-Paleoproterozoic units localize all major deposits. Conductor analogues below the Thelon Basin are barren, impermeable, black slate of anchizone to lower-greenschist-facies grade. Instead, the Thelon uranium deposit host rocks are Neoarchean pyritic greywacke and epiclastic rocks that range in metamorphic grade from lower- to upper-amphibolite facies. Similar mineralogical sources, saline brines, alteration (fluorapatite, aluminum-phosphate-sulphate minerals, chlorite, clays, and desilicification), and reactivated intersecting faults focused unconformity-type uranium mineralization in each basin. Previously published ages for pre-ore fluorapatite cements of the Athabasca and Thelon basins (1638 versus 1688 to 1667 Ma, respectively) reaffirm their independent diagenetic-hydrothermal histories.

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Kindt, Roeland, Ian K Dawson, Jens-Peter B Lillesø, Alice Muchugi, Fabio Pedercini et James M Roshetko. The one hundred tree species prioritized for planting in the tropics and subtropics as indicated by database mining. World Agroforestry, 2021. http://dx.doi.org/10.5716/wp21001.pdf.

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A systematic approach to tree planting and management globally is hindered by the limited synthesis of information sources on tree uses and species priorities. To help address this, the authors ‘mined’ information from 23 online global and regional databases to assemble a list of the most frequent tree species deemed useful for planting according to database mentions, with a focus on tropical regions. Using a simple vote count approach for ranking species, we obtained a shortlist of 100 trees mentioned in at least 10 of our data sources (the ‘top-100’ species). A longer list of 830 trees that were mentioned at least five times was also compiled. Our ‘top-100’ list indicated that the family Fabaceae (syn. Leguminosae) was most common. The information associated with our mined data sources indicated that the ‘top-100’ list consisted of a complementary group of species of differing uses. These included the following: for wood (mostly for timber) and fuel production, human nutrition, animal fodder supply, and environmental service provision (varied services). Of these uses, wood was most frequently specified, with fuel and food use also highly important. Many of the ‘top-100’ species were assigned multiple uses. The majority of the ‘top-100’ species had weediness characteristics according to ‘attribute’ invasiveness databases that were also reviewed, thereby demonstrating potential environmental concerns associated with tree planting that need to be balanced against environmental and livelihood benefits. Less than half of the ‘top-100’ species were included in the OECD Scheme for the Certification of Forest Reproductive Material, thus supporting a view that lack of germplasm access is a common concern for trees. A comparison of the ‘top-100’ species with regionally-defined tree inventories indicated their diverse continental origins, as would be anticipated from a global analysis. However, compared to baseline expectations, some geographic regions were better represented than others. Our analysis assists in priority-setting for research and serves as a guide to practical tree planting initiatives. We stress that this ‘top-100’ list does not necessarily represent tree priorities for the future, but provides a starting point for also addressing representation gaps. Indeed, our primary concern going forward is with the latter.

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