Academic literature on the topic 'Datation au carbonate U-Pb'
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Journal articles on the topic "Datation au carbonate U-Pb"
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Jahn, Bor-ming, and Henri Cuvellier. "PbPb and UPb geochronology of carbonate rocks: an assessment." Chemical Geology 115, no. 1-2 (July 1994): 125–51. http://dx.doi.org/10.1016/0009-2541(94)90149-x.
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Cocherie, Alain, Jean Chantraine, C. Mark Fanning, Marie-Pierre Dabard, Florentin Paris, Alain Le Hérissé, and Emmanuel Égal. "Datation U/Pb : âge Briovérien de la série d'Erquy (Massif armoricain, France)." Comptes Rendus de l'Académie des Sciences - Series IIA - Earth and Planetary Science 333, no. 8 (October 2001): 427–34. http://dx.doi.org/10.1016/s1251-8050(01)01669-x.
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Tartèse, Romain, and Ian C. Lyon. "In situ U–Pb dating of 4 billion-year-old carbonates in the martian meteorite Allan Hills 84001." Geochronology 4, no. 2 (December 6, 2022): 683–90. http://dx.doi.org/10.5194/gchron-4-683-2022.
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Abstract. In situ carbonate U–Pb dating studies have proliferated dramatically in recent years. Almost all these studies have targeted relatively young terrestrial calcite up to Carboniferous in age. To assess the robustness of the carbonate U–Pb chronometer in deep time, we carried out in situ U–Pb analyses in magnesite–ankerite–calcite carbonates in the martian meteorite Allan Hills (ALH) 84001. Carbonates in ALH 84001 formed at ca. 3.94 Ga, and there is little evidence that much happened to this rock since then, making it an ideal sample to test the robustness of the U–Pb system in old carbonates. We obtained a concordant date of 3941 ± 49/110 Ma (n=14, MSWD = 2.0), which is identical to the step-leaching Rb/Sr date determined previously. These results thus confirm that old carbonates are amenable to U–Pb dating in samples that have had a relatively simple history post-carbonate formation.
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Gorokhov, I. M., I. M. Vasil'eva, A. B. Kuznetsov, N. G. Rizvanova, and G. V. Konstantinova. "A Stepwise Dissolution Method Applied to Isotopic Chemostratigraphic and Geochronological Studies of Riphean Carbonate Rocks of the Baykit Uplift." Геохимия 68, no. 7 (July 1, 2023): 669–86. http://dx.doi.org/10.31857/s0016752523070038.
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The potential of the stepwise dissolution analytical procedure to obtain chemostratigraphic and geochronological information is demonstrated by a case study of Riphean carbonate rocks of the Kamovskaya Group of the Baykit Uplift (Eastern Siberia). The procedures suggested for studying Rb–Sr and U–Pb systems in carbonate rocks included (1) selection of samples with the lowest 87Sr/86Sr ratio on the basis of preliminary Rb–Sr analysis of the collection using the routine procedure of bulk leaching in 0.1N CH3COOH; (2) detailed study of the Rb–Sr system in selected samples using two-step dissolution in 0.2N CH3COOH and derivation of L(Rb–Sr)1 and L(Rb–Sr)2 fractions; (3) analysis of Pb isotope composition of the selected samples to derive the preliminary value of their age; (4) detailed study of U–Pb system of carbonate rocks using the stepwise dissolution in 0.5N HBr, resulting in six dissolved fractions L(U–Pb)1–L(U–Pb)6 for each of the selected samples; and (5) a final calculation of the Pb–Pb age of the studied rocks, based on the results from the obtained fractions, with the exclusion from the calculation of the initial fractions of this dissolution containing epigenetically altered carbonate material. The values of the primary 87Sr/86Sr ratio in L(Rb–Sr)2 fractions of carbonate rocks of the Kamovskaya Group are as follows: limestone of the Madrinskaya Formation, 0.70490; dolomites of the Yurubchenskaya Formation, 0.70495–0.70503; and dolomites of the Kuyumbinskaya and Vingoldinskaya formations, 0.70580 and 0.70521, respectively. These values characterizing the least altered carbonate material correspond to 87Sr/86Sr ratios in the Early Archean and can be used for chemostratigraphic calculations. Taking into account the Rb–Sr data, the U–Pb age of the Yurubchenskaya Formation carbonate rocks dissolved in six steps was calculated, starting from L(U–Pb)3. The slope of the resulting isochron in the coordinates 206Pb/204Pb–207Pb/204Pb corresponds to 1501 ± 23 Ma, which supports the conclusion that the carbonate rocks of the lower part of the Kamovskaya Group of the Baykit Uplift were formed in the Early Riphean.
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Stifeeva, M. V., N. V. Vladykin, A. B. Kotov, E. B. Salnikova, I. A. Sotnikova, E. V. Adamskaya, V. P. Kovach, Y. V. Plotkina, E. V. Tolmacheva, and N. V. Alymova. "AGE OF THE FORMATION OF EARLY PRECAMBRIAN CARBONATITES IN THE SOUTH-EASTERN PART OF THE CHARO-OLEKMINSKY GEOBLOCK, ALDAN SHIELD." Доклады Российской академии наук. Науки о Земле 508, no. 1 (January 1, 2023): 32–36. http://dx.doi.org/10.31857/s2686739722601880.
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Presents the results of U–Pb geochronological (ID–TIMS) studies of garnet and U–Th–Pb (LA–ICP–MS) “screening” geochronological studies of zircon from pyroxene-carbonate rocks of the Ukduska massif. The U–Pb age of garnets (1881 ± 8 million years) and age of zircon rim (1865 ± 16 million years) indicate the early Proterozoic age of these rocks. The results of geochronological studies allow to identify a new stage of carbonate magmatism within the southeastern part of the Charo-Olekminsky geoblock.
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Cocherie, Alain, Catherine Guerrot, C. Mark Fanning, and Albert Genter. "Datation U–Pb des deux faciès du granite de Soultz (Fossé rhénan, France)." Comptes Rendus Geoscience 336, no. 9 (July 2004): 775–87. http://dx.doi.org/10.1016/j.crte.2004.01.009.
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Winter, Bryce L., and Clark M. Johnson. "UPb dating of a carbonate subaerial exposure event." Earth and Planetary Science Letters 131, no. 3-4 (April 1995): 177–87. http://dx.doi.org/10.1016/0012-821x(95)00026-9.
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Beranoaguirre, Aratz, Iuliana Vasiliev, and Axel Gerdes. "In situ LA-ICPMS U–Pb dating of sulfates: applicability of carbonate reference materials as matrix-matched standards." Geochronology 4, no. 2 (September 6, 2022): 601–16. http://dx.doi.org/10.5194/gchron-4-601-2022.
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Abstract. Recent developments in analytical capabilities in the field of in situ laser ablation mass spectrometry (LA-ICPMS) have expanded the applications of U–Pb geochronometers in low-U minerals such as carbonates or garnets. The rapid evolution of the technique relies on well-characterized matrix-matched reference materials. In this article, we explore the suitability of using carbonate as an “almost-matrix-matched reference material” for in situ U–Pb dating of sulfates. For such purpose, we have used the astrochronologically dated gypsum and anhydrite samples deposited during the Messinian Salinity Crisis (5.97–5.33 Ma) and compared these dates with the U–Pb ages obtained by LA-ICPMS. Although the majority of the samples failed due to the elevated common Pb content and low 238U/204Pb ratios, five of the samples showed a higher dispersion on U/Pb ratios. The obtained dates in four of these samples are comparable with the expected ages, while another gave an unexpected younger age, each of them with 6 %–11 % of uncertainty. The pit depth of the spots showed that the sulfates ablate similar to carbonates, so the offset due to the crater geometry mismatch or downhole fractionation can be assumed to be negligible. To sum up, the bias between the U–Pb and expected cyclostratigraphic ages, if any, is included in the uncertainty, and thus the results obtained here suggest that carbonate reference material is currently the best option for standardization of in situ U–Pb sulfate analyses.
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Rasbury, E. Troy, Theodore M. Present, Paul Northrup, Ryan V. Tappero, Antonio Lanzirotti, Jennifer M. Cole, Kathleen M. Wooton, and Kevin Hatton. "Tools for uranium characterization in carbonate samples: case studies of natural U–Pb geochronology reference materials." Geochronology 3, no. 1 (February 16, 2021): 103–22. http://dx.doi.org/10.5194/gchron-3-103-2021.
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Abstract. Laser ablation U–Pb analyses of carbonate (LAcarb) samples has greatly expanded the potential for U–Pb dating to a variety of carbonate-producing settings. Carbonates that were previously considered impossible to date using isotope dilution methods may preserve radiogenic domains that can be dated using spatially resolved laser ablation geochronology techniques. Work is ongoing to identify reference materials and to consider best practices for LAcarb. In this study we apply standard and emerging characterization tool sets on three natural samples with the dual goal of enhancing the study of carbonates and establishing a new set of well-characterized natural reference materials for LAcarb studies. We start with the existing carbonate reference material WC-1 from the Permian Reef Complex of Texas, building on the published description to offer a deeper look at U and associated trace elements. We consider a tufa sample from the Miocene Barstow Formation of the Mojave Block, California, as a possible secondary calcite reference material due to its well-behaved U–Pb systematics. There are currently no natural dolomite standards. We present an unusual dolomite sample with very well-behaved U–Pb systematics from the Miocene of the Turkana Basin of Kenya as a possible dolomite reference material for LAcarb dating. In addition to using X-ray fluorescence (XRF) mapping and spectroscopy to better understand U in these natural samples, we have analyzed multiple aliquots of each of them for 87Sr/86Sr by thermal ionization mass spectrometry (TIMS). The Sr isotope compositions are analytically homogeneous within petrographically homogeneous regions of all three samples, and thus these materials could be used as Sr isotope standards as well. While not part of the current contribution, this combination could streamline simultaneous LA analyses of 87Sr/86Sr and U–Pb geochronology.
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Vetrova, N. I., E. V. Vetrov, and E. F. Letnikova. "СHEMOSTRATIGRAPHY OF THE CARBONATE DEPOSITS OF THE KINTEREP FORMATION IN NORTHWESTERN SALAIR: FIRST DATA." Geology and mineral resources of Siberia, no. 2 (June 2022): 10–23. http://dx.doi.org/10.20403/2078-0575-2022-2-10-23.
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The results of geochemical, isotope-geochemical (Sr, C, O) surveys of the Kinterep Formation carbonate deposits of Northwestern Salair and U-Pb dating (LA-ICP-MS) of zircons were given. Carbonate rocks represented by pure limestones are characterized by normal values of δ18OSMOW from 19.8 to 23.8 ‰ and δ13 CPDB from –0.7 to +0.9, the isotopic composition of Sr (87Sr/86Sr ratio) varies in a narrow range from 0.708486 to 0.708582.Using Sr and C isotope chemostratigraphy and U-Pb dating of zircons, age limits (525-510 Ma) were determined for the formation time of carbonate deposits of the Kinterep Formation. The first data of isotope chemostratigraphy in combination with the results of geochronological studies made it possible to compare the limestones of the Kinterep Formation of Northwestern Salair with carbonate sections of Siberia and Central Asia.
Dissertations / Theses on the topic "Datation au carbonate U-Pb"
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Montano, Damaris. "Carbonate U-Pb dating via LA-ICPMS : insights into chronostratigraphy in lacustrine settings." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS545.
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Les dépôts lacustres font l'objet d'études approfondies car ils sont propices à l’enregistrement des modifications de nombreux facteurs environnementaux (changement climatique, modification du couvert végétal…), et également car ils renferment des ressources en matière première de toute première importance. Cependant, les reconstructions chronostratigraphiques dans ces contextes sont généralement entravées par la rareté des données permettant d’établir l'âge des dépôts de manière continue. L'objectif principal de ce projet de thèse est d'examiner les avantages et les limites de la datation au carbonate U-Pb (LA-ICPMS) (méthode LAcarb) comme un nouvel outil chronostratigraphique pour les dépôts lacustres. Le deuxième objectif est d'étudier plus précisément le potentiel de datation de la méthode en analysant sa capacité à établir un âge avec résolution temporelle pertinente en fonction des différents types de carbonates et de minéralogies. Pour atteindre ces objectifs, plusieurs phases carbonatées (microbialites, ooides, oncoides) et ciments diagenétiques ont été collectés dans deux exemples lacustres fossiles ayant un âge absolu relativement bien établit: le Miocène du bassin du cratère Ries (SW Allemagne) et la formation Yacoraite (Crétacé-Paléogène) du bassin de Salta (NW de l'Argentine). Une étude sédimentologique et diagenétique s’appuyant sur des analyses pétrographiques et des isotopes stables de l’oxygène (O) de du carbone (C), a permis de sélectionner les phases carbonatées les plus précoces. Ce travail a été réalisé afin de maximiser les chances d’avoir préservé la composition géochimique originelle en U-Pb des fluides en présence lors du dépôt. Dans le bassin du cratère Ries, la méthode LAcarb a fourni des âges précis qui ont permis des corrélations chronostratigraphiques à une résolution temporelle de l’ordre de la séquence stratigraphique du 3e ordre (0,5 à 5 Ma). Dans le cadre de la formation Yacoraite, deux modèles d'âge ont été obtenus le long d'une coupe stratigraphique de référence. L'un est dérivé de la géochronologie des zircons extraits des dépôts de cendre volcaniques intercalés dans la formation Yacoraite (modèle d'âge maximum des dépôts; MDA). Le second est dérivé de la méthode LAcarb (modèle d'âge minimum des dépôts; MIDA). Les deux modèles se superposent remarquablement et permettent de décrire une même dynamique des taux de sédimentation avec une résolution temporelle d'environ 0,9 à 2% (2σ). L'âge des dépôts révisé pour la formation Yacoraite a ensuite été intégré dans un modèle chronostratigraphique combinant les données biostratigraphiques, hemiostratigraphiques et magnétostratigraphiques issues de la littérature. La localisation de la limite Crétacé-Paléogène (KPg) a bien été confortée dans la formation Yacoraite. De plus, la révision des âges de la partie sommitale de la formation Yacoraite a également permis de valider la localisation des deux phases hyperthermiques du Paléocène-Éocène (Paleocene-Eocene Thermal Maximum: PETM, et l’optimum climatique de l’Eocène; EECO) dans les deux formations sus-jacentes. Une analyse statistique a ensuite été réalisée sur la base des âges de 80 phases carbonatées de la formation Yacoraite. Les microbialites ont fourni les plus faibles succès en potentiel de datation (41 % d'âges cohérents avec le modèle MDA) ainsi que les plus basses précisions concernant l'âge (2σ <10 %). A l’inverse, les ciments lacustres ont été couronnés des meilleurs potentiels de datation (64 % d'âges cohérents avec le modèle MDA) avec des âges de meilleure précision. De plus, les phases dominées par la calcite ont généralement fourni des âges plus précis que les phases dolomitiques. Les avancées concernant les potentialités et les limites associées à la méthode LAcarb ont ainsi permis de proposer au travers de cette thèse une méthode complète pour construire un modèle d'âge robuste des dépôts en milieu lacustre. Les perspectives de ces travaux sont multiples, avec par exemple [...]Lacustrine deposits are extensively investigated because they play a pivotal role as environmental recorders and host valuable economic resources. However, chronostratigraphic reconstructions in these settings are usually hampered by the scarcity of data required to establish the depositional age of the system. The prime objective of this PhD project was examining benefits and limitations of carbonate U-Pb (LA-ICPMS) dating (LAcarb) as new chronostratigraphic tool for lacustrine deposits. The second objective was to investigate the dating potential, in terms of dating success and time resolution, of various carbonate types and mineralogies with the aim to better organize future LAcarb based research. To achieve these goals, depositional (microbialites, ooids, oncoids) and early diagenetic carbonate phases of known absolute age were collected from two lacustrine settings: the Ries Crater basin (Miocene, SW Germany) and the Yacoraite formation (Fm.) from the Salta rift basin (Cretaceous-Paleogene, NW Argentina). A sedimentologic and diagenetic study based on petrography and Oxygen (O) and Carbon (C) stable isotope analysis allowed to select carbonate phases that most possibly preserved the pristine U-Pb geochemical composition and consequently inform on the timing of deposition. In the Ries Crater basin, LAcarb provided accurate ages that allowed chronostratigraphic correlations at a time resolution of the 3rd order stratigraphic sequence (0.5–5Ma). In the framework of the Yacoraite Fm., two depositional age depth model were obtained along a stratigraphic section. One derived from zircon (ash layer) geochronology (maximum depositional age depth model; MDA depth model) and the other from LAcarb (minimum depositional age depth model; MIDA depth model). The two models remarkably overlap and describe the same sedimentation rate dynamic with a time resolution between 0.9 and 2% (2σ). The revised depositional age of the Yacoraite Fm. was then integrated in a chronostratigraphic model merging biostratigraphic, chemostratigraphy and magnetostratigraphy data from literature. Accordingly, the KPg limit was interpreted to be located in the Yacoraite Fm. whereas the two Paleocene-Eocene hyperthermals (Paleocene-Eocene Thermal Maximum, PETM; early Eocene Climate Optimum, EECO) were identified in the two overlying formations. A statistical analysis was achieved based on the ages of 80 carbonate phases from the Yacoraite Fm. Microbialites provided the lowest dating success (41% ages consistent with the MDA depth model) and age precision (2σ < 10%) in contrast with lacustrine cements that yielded the highest dating success (64% ages consistent with MDA depth model) and age precision (2σ < 3%). Furthermore, calcitic phases usually provided more precise ages than dolomitic phases. The better comprehension of potentialities and limitations of LAcarb acquired in this PhD allowed to propose a workflow to build a robust depositional age depth model in lacustrine settings. Three possible perspective scenarios were introduced: 1) the study of the Ries Crater basin as analogue of paleolakes on Mars; 2) the use of LAcarb to select pristine carbonates for chronostratigraphic studies; and 3) basin scale chronostratigraphic correlations in the Yacoraite Fm
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Godeau, Nicolas. "Développement et application de la méthode Uranium-Plomb à la datation des carbonates diagénétiques dans les réservoirs pétroliers, et apport à la reconstruction temporelle de l'évolution des propriétés réservoir." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0149.
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L'apport de contraintes chronologiques absolues sur les différents évènements et processus qui ont modelé la Terre constitue un des défis majeurs dans de nombreux domaines des sciences de la terre et de l'environnement. C'est en particulier le cas pour les bassins sédimentaires qui jouent un rôle économique majeur en étant sources d'importantes ressources naturelles, en particulier en hydrocarbures. L'objectif de cette thèse est de développer la datation absolue des minéraux secondaires carbonatés par la méthode U-Pb. Ces minéraux, quasi ubiquistes dans les réservoirs, témoignent des processus diagénétiques, tectoniques et des circulations fluides qui ont affecté ces systèmes. Au cours de cette thèse, plusieurs développements méthodologiques ont été mis en œuvre avec pour objectifs de repousser les limites de la méthode U-Pb. Des techniques d’analyses innovantes, comme le couplage ablation laser/SF-ICP-MS ou la sonde ionique, ont été testées et ont permis d’accroître de plusieurs ordres de grandeur la résolution spatiale des analyses U-Pb. Ces méthodes, couplées à la méthode plus classique de dilution isotopique ont été appliquées avec succès dans différents contextes d’exploration pétrolière permettant notamment d’apporter des contraintes temporelles sur des éléments clés du système pétrolier, comme le timing de la création/préservation du réservoir ou encore de la migration des hydrocarbures. Les différents résultats obtenus ont permis de dresser une synthèse des contextes les plus favorables à l’application de la méthode U-Pb, et de donner ainsi une vision d’ensemble du potentiel de la datation U-Pb sur carbonates secondaires appliquée aux réservoirs pétroliersAbsolute chronological constraints on the different events and processes that have shaped the Earth constitute a major challenge in numerous realms in Earth and Environmental sciences. In particular this is the case for sedimentary basins that play a major economic role as being source of important hydrocarbon resources. The objective of this thesis is to develop absolute uranium-lead dating methodology on secondary carbonate minerals. This ubiquitous mineral phase in petroleum reservoirs testifies their complex geodynamic and diagenetic histories. In this study, several developments were implemented in order to circumvent the limits of U-Pb methodology. Innovative analysis techniques such as laser ablation coupled with SF-ICP-MS or ion probe were tested to increase the spatial resolution of the U-Pb analysis by several orders of magnitude. These methodologies coupled to the more traditional isotope dilution was successfully applied in different oil exploration context allowing to bring absolute constraints on key diagenetic events such as creation/preservation of reservoir properties or hydrocarbon migration. The results obtained during this study allowed to draw a synthetic model of the most favorable contexts for U-Pb method and gives an overview of the U-Pb dating potential to secondary carbonates applied to petroleum reservoirs
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CUVELLIER, HENRI. "Etude isotopique (rb-sr et u-pb) des carbonates proterozoiques du craton sino-coreen et du brioverien de bretagne centrale : implications sur la datation directe des sequences sedimentaires." Rennes 1, 1992. http://www.theses.fr/1992REN10089.
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L'application recente des methodes u-pb et pb-pb a la datation directe des carbonates offre un nouvel outil pour etablir la chronologie absolue des sequences sedimentaires. Cependant, les ages obtenus jusqu'a present ne permettaient pas de distinguer entre la periode de depot et les recristallisations diagenetiques du sediment. Au cours de ce travail, nous avons demontre que les ages radiometriques u-pb et pb-pb des dolomies et des calcaires du proterozoique moyen et superieur du craton sino-coreen sont plus anciens que le depot des formations; pour expliquer ces resultats, le modele de diffusion du radon est utilise. La migration de 222rn, preferentiellement a 219rn de periode tres courte, provoque un deficit de 206pb radiogenique. En consequence, les ages pb-pb et u-pb sont vieillis. Cette caracteristique a ete retrouvee dans les calcaires cambriens de st. Jean de la riviere (cotentin, france), mais pas dans les carbonates brioveriens (proterozoique superieur?) de bretagne centrale, ni dans les calcaires archeens du craton sud-africain (jahn et al, 1990). Comme dans toutes les methodes geochronologiques, la reussite d'une datation sur carbonate repose sur l'etat de fermeture du systeme u-pb. Toutefois, cette nouvelle technique a considerablement etendu le potentiel de datation directe des sequences sedimentaires qui reste un probleme majeur en sciences de la terre
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Rongemaille, Emmanuelle. "Application des terres rares et de la datation U/Th à l'étude des carbonates authigènes de suintements froids : exemple du delta profond du Niger." Brest, 2011. http://www.theses.fr/2011BRES2074.
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Les zones de suintements froids sont le siège d’expulsions actives de fluides enrichis en méthane auxquels sont associées d’abondantes précipitations de carbonates authigènes. Dans le but de mieux contraindre l'origine et la composition de ces sorties de fluides, cette thèse présente les résultats 7Sr/86Srd'études minéralogique, isotopiques (d13c, d18O et 87Sr/86Sr) et géochimiques (terres rares, U/Th) réalisées sur des carbonates authigènes provenant de différentes sorties de fluides (volcan de boue, diapir, pockmark) du delta profond du Niger. Les valeurs de d18O des carbonates authigènes indiquent que certains ont précipité en équilibre isotopique avec l'eau de fond actuelle alors que d'autres présentent des valeurs qui sont très éloignées de l'équilibre isotopique avec l'eau de fond. Les valeurs de d13C suggèrent diverses contributions de fluides caractérisés par des signatures de d13C distinctes. La composition isotopique du Strontium révèle aussi diverses contributions de fluides. Les spectres de terres rares ressemblent aux spectres obtenus à partir des sédiments marins de sub-surface anoxiques pour l'aragoite. Les calcites magnésiennes et dolomites montrent une gamme de spectres importante au niveau des terres rares lourdes. La composition des terres rares dans les carbonates est contrôlée par : le fluide et l'alcalinité. Les résultats expérimentaux montrent qu'il n'y a pas de fractionnement pendant la précipitation de l'aragonite et de la calcite, mais que le magnésium et la température jouent un rôle dans l'incorporation des terres rares. Les données U/Th montrent que le pockmark est actif depuis au moins 8000 ans et qu'il y a eu un enfoncement de la SMICold seeps are common features which correspond to localized sites for methane-rich fluid release. Fluid expulsions are generally associated with abundant precipitation of authigenic carbonates. In order to better constrain fluid origin and composition, this PhD presents the results of mineralogical, isotopic (d13C, d18O and 87Sr/86Sr) and geochemistry (REE) studies on authigenic carbonates from various fluid-venting features (mud volcano, diapir, and cold seep) of the Niger Delta. The d18O values of authigenic carbonates indicate that some precipitated in isotopic equilibrium with present day bottom water conditions, while others have values that are very far from the equilibrium with present day bottom water conditions. The d13C values suggest different contributions of fluids characteriez by distinct d13C signatures. The isotopic composition of strontium also reveals diverse contribution of fluids. Aragonite concretions exhibited very similar shale-normalized REE patterns that closely resembled those of anoxic pore-water in sub-surface marin sediments. The magnesian and dolomite concretions displayed a wide range of HREE patterns. Our results showed that the REE composition of carbonates controlled by the fluid composition and by changes of alkalinity. Experimental results show that there is no fractionation during the precipitation of aragonite and calcite, but as magnesium and temperature play a role in the incorporation of rare earths. Data U/Th show that pockmark is active since at least 8000 years and ther has been a recent sinking of the SMI
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Huang, Yi-Ming. "U-Th-Pb fractionation in selected carbonate and silicate systems." Thesis, Open University, 1995. http://oro.open.ac.uk/57547/.
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V-Th-Pb fractionation trends, and the associated variations in Pb-isotopes, provide important constraints on the nature, and age, of a wide range of geological processes. This thesis presents three detailed case studies from a carbonatite intrusive complex, lower crustal granulite xenoliths, and young volcanic rocks which represent a range of processes that fractionate V, Th and Pb. New major, trace element and Sr, Nd and Pb isotope results are presented for carbonatites and pyroxenites from the 130 Ma old Jacupiranga complex in southern Brazil. The data preclude simple models in which the Sr-Nd and Sr-Pb isotope arrays are the result of crustal contamination processes, or liquid immiscibility between the carbonatites and magmas similar to those from which the pyroxenites crystallised. The initial Sr, Nd and Pb isotope ratios in the Jacupiranga complex are similar to those in the Parana high-Ti basalts and to the oceanic basalts of the Walvis Ridge and Tristan da Cunha, and were apparently inherited from the mantle source regions associated with incipient magmatism of the Tristan da Cunha hotspot and the opening of the South Atlantic. Most carbonatites have high V/Pb and low Rb/Sr ratios and infiltration and/ or metasomatism by such melts is one process that may be responsible for the negative correlation of U/Pb and Rb/Sr inferred for the source of certain oceanic basalts such as Tristan da Cunha. Correlations between trace and major elements in mostly mafic granulite xenoliths from southern Africa probably result from magmatic processes such as fractional crystallisation and crystal accumulation. From Pb and Nd isotope systematics it can be inferred that the northern Lesotho xenoliths are Proterozoic in age, whereas Cape province xenoliths appear to have been fonned in the Archaean and to have had their Nd isotopes reset in the Proterozoic. Most Pb isotope ratios from the granulites xenoliths are unradiogenic relative to the Geochron, which indicates relatively low V /Pb ratios in the later parts of their histories. The correlation between Pb isotope ratios and K2O/A12O3 in the granulites from Markt is considered to reflect magmatic control of the V /Pb fractionation. The Archaean, and some of the younger mantle derived rocks on the Kaapvaal craton, plot on similar Pb isotope trends. It is argued that segments of the crust and uppennost mantle beneath southern Africa stabilised together in the Archaean, and that both were remobilised in subsequent magmatic and orogenic events. Volcanic rocks in the Northland-Auckland peninsula, New Zealand, range from silica-undersaturated basanites to tholeiites and andesites. Although all the volcanic fields are in intraplate settings, two types of mantle source enrichment can be recognised. One is subduction-related and characterised by high Sr and low Nd isotope ratios and negative Nb anomalies. The other type has geochemical features characteristic of intraplate enriched mantle sources with Sr and Nd isotope ratios and Nb/Ba, Ba/La, similar to HIMV OIB, which has been attributed to the deep recycling of oceanic crust. The differences in Pb isotopes between the two mantle sources, i.e. higher /lB/4 and 7/4, but lower 206Pb/204Pb in the subduction-related material than in the inferred HIMU source, indicate that V/Pb in shallow recycled crustal material tend to be lower than in the deeper recycled material. These case studies confirm that (i) metasomatism by small degree melts can have significant effects on mantle trace element characteristics, (ii) the lower crust is a relatively low 11 environment and crystal accumulation may be an important mechanism in the fractionation of Th and U from Pb, cUld (iii) incorporation of recycled crustal material at different levels can result in different V-Th-Pb fractionation and so, with time, different Pb isotope ratios.
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Triantafyllou, Antoine. "Évolution géodynamique d’un arc insulaire néoprotérozoïque de l’Anti -Atlas marocain : caractérisation des processus de croissance intra-océanique et d’accrétion." Thesis, Nantes, 2016. http://www.theses.fr/2016NANT4031/document.
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Les reliques néoprotérozoïques d’un système d’arc intra-océanique affleurent dans l’Anti-Atlas au Sud du Maroc, dans les fenêtres du Sirwa et de Bou Azzer. Les deux zones présentent des ensembles fortement tectonisés représentés au Nord par une séquence ophiolitique d’arrière-arc charriée sur des complexes d’arc accrétés au Sud. Ces complexes d’arc (complexes de Tachakoucht, Tazigzaout et Bougmane) sont composés de gneiss granodioritiques et d’amphibolites dont les protolithes, datés entre 750 et 730 Ma, montrent des signatures typiques d’arcs océaniques. Ces derniers ont été enfouis, déformés et métamorphisés sous des conditions de MP-MT (700°C – 8 kbar) à Tachakoucht et de HP-MT à Bougmane (750°C – 10 kbar) avant que des magmas basiques hydratés (hornblendites, gabbros à hornblende) d’affinités d’arcs océaniques ne les intrudent successivement à ~700 et ~650 Ma. Ces épisodes magmatiques ont bouleversé le régime thermique de l’arc entrainant la granulitisation et la fusion partielle des roches encaissantes à plusieurs niveaux crustaux de l’arc et générant des magmas granodioritiques à granitiques recoupant la section crustale du paléo-arc et de l’ophiolite sus-jacente. Cette étude de terrain, pétrologique, géochimique et géochronologique a mis en évidence trois épisodes de magmatisme océanique d’arc sur une période de plus de 120 Ma (de 760 à 640 Ma). La croissance de ce paleo-arc fut contrôlée par les phases successives d’alimentation magmatique mais aussi par des processus tectoniques d’épaississement en domaine intra-océanique et ce, avant l’obduction de l’arc sur le Craton Ouest africain autour de 630-600 MaRelics of an intra-oceanic arc system are exposed in the Anti-Atlas in southern Morocco, in the Sirwa and Bou Azzer windows. Both of these areas form a highly tectonized patchwork made of a back-arc ophiolitic sequence to the north thrusted onto accreted arc complexes to the south. These arc complexes (Tachakoucht, Tazigzaout and Bougmane complexes) are made of granodioritic gneisses and amphibolites with typical oceanic arc signature and for which igneous ages range from 750 to 730 Ma. These magmas were buried, deformed and metamorphosed under MP-MT conditions in Tachakoucht (700°C - 8kbar) and HP-MT in Bougmane (750°C - 10 kbar) prior to several magmatic events dated at 700 and 650 Ma and the intrusion of hydrous basic magmas (hornblende gabbros, hornblendites) with oceanic arc signatures. This episodic magmatism strongly perturbed the thermal regime of the arc leading to the granulitization of the host rocks at different levels of the arc crust and to the genesis of intermediate to felsic magmas (granodioritic to granitic). These ones have been segregated through the crustal section intruding both stacked paleo-arc and ophiolitic remnants. This field, petrological, geochemical and geochronological study established that oceanic arc magmatism in the Anti-Atlas occurred in three flare-ups on a 120 Ma long time span (760 to 640 Ma). The growth of the arc was controlled and driven both by successive magmatic inputs and intra-oceanic tectonic thickening processes while final collision of the intraoceanic system with the West African Carton occurred later, around 630-600 Ma
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Martin, Laure. "Signification des âges U-Pb sur zircon dans l'histoire métamorphique de Naxos et Ikaria (Cyclades, Grèce)." Nancy 1, 2004. http://www.theses.fr/2004NAN10231.
Full textAbstract:
La compréhension de l'évolution des chaînes de montagnes nécessite la reconstruction des chemins pression-température-temps suivis par les roches métamorphiques. La datation U-Pb est souvent utilisée pour dater des événements métamorphiques, mais le lien entre les conditions du métamorphisme et l'âge fourni par les datations U-Pb sur zircon n'est pas direct. Les isotopes de l'oxygène sont proposés dans cette étude pour mettre en relation la croissance du zircon avec celle du grenat dans les roches métamorphiques du domaine égéen. L'étude de quatre échantillons de l'île de Naxos a montré que cette relation est possible si (i) l'équilibre isotopique de l'oxygène est atteint entre le grenat et le zircon au moment de leur formation et (ii) le grenat et le zircon sont restés clos pour l'oxygène et le plomb après leur formation. Cette méthode a permis de dater le début de l'exhumation des roches métamorphiques de Naxos entre 40 et 60 Ma, et le début du chemin rétrograde entre 13 et 19 Ma. A Ikaria et à Naxos, la croissance préférentielle du zircon entre 40 et 60 Ma localisée dans des roches provenant de zones riches en schistes indique que la pression et les circulations de fluides sont les paramètres qui ont favorisé la formation des zircons pendant le métamorphismeThe knowledge of pressure - temperature - time paths in metamorphic rocks is necessary to the understanding of orogenic belts evolution. U-Pb method is commonly used for dating metamorphic events, but the link between metamorphic conditions and ages obtained on zircon is not straightforward. Oxygen isotopes are proposed in this study for likening zircon to garnet growth in metamorphic rocks of the Aegean domain. The study of four samples from Naxos island showed that this correlation is possible if (i) isotopic equilibrium of oxygen is reached between garnet and zircon during their formation and (ii) garnet and zircon remained in closed system for oxygen and lead after their formation. This method permitted to date the beginning of the exhumation of metamorphic rocks from Naxos between 40 and 60 Ma, and the beginning of the retrograde path between 13 and 19 Ma. The preferential formation of zircon between 40 and 60 Ma in rocks localised in schist rich zones indicate that pressure and fluid circulation are the parameters that triggered zircon formation during the metamorphism
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Turrillot, Paul. "Fusion crustale et évolution tardi-orogénique du Domaine Sud Armoricain." Phd thesis, Université d'Orléans, 2010. http://tel.archives-ouvertes.fr/tel-00561098.
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L'évolution tardive du Domaine Sud Armoricain (segment de la chaîne Varisque Ouest Européenne), se traduit par un effondrement gravitaire de la croûte préalablement épaissie dans un contexte tectonique extensif. Cette extension s'accompagne, dans tout le domaine, d'une fusion partielle de la croûte moyenne à inférieure et de l'exhumation des roches métamorphiques issues de niveaux crustaux profonds. L'approche pluridisciplinaire conduite dans cette étude permet de proposer un calendrier précis de la fusion crustale et d'étudier les mécanismes de la déformation responsable de l'exhumation de la croûte moyenne à inférieure. Une des démarches adoptées associe l'identification structurale et cinématique précise des témoins de l'étirement et leur datation multiméthodes (U-Th/Pb sur monazite, et A/Ar sur micas). Dans la partie occidentale du Domaine Sud Armoricain, cette approche permet ainsi de documenter un continuum de déformation extensive durant plus de 20 Ma, qui accompagne en partie l'exhumation des roches de haut grade qui elle, se développe entre 325 Ma et 300 Ma. L'étude géophysique, combinant ASM et gravimétrie, permet en outre de caractériser la structure interne et la géométrie en profondeur du complexe granitique de Carnac, dont la mise en place apparaît être le témoin du stade le plus précoce de ce continuum. La fusion partielle des migmatites et la mise en place des plutons granitiques, interprétées à la fois comme le moteur et la conséquence de l'étirement et de l'exhumation, est estimée entre 335 Ma et 320 Ma. Cette anatexie généralisée apparaît synchrone à l'échelle de tout le domaine, ce qui permet un regard nouveau sur les stades tardi-orogéniques du Domaine Sud Armoricain. L'étude de la déformation extensive et de l'exhumation dans les portions occidentale et orientale, met en évidence des contrastes de style tectonique, suggérant une exhumation plus importante des parties orientales du Domaine Sud Armoricain.
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Didier, Amélie. "Comportement géochimique du chronomètre U-Th-Pb dans la monazite : approche par analyses in-situ au LA-ICP-MS." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2013. http://tel.archives-ouvertes.fr/tel-00966588.
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La richesse en Th et en U de la monazite en fait un excellent géochronomètre pour dater les roches magmatiques et métamorphiques de la croûte terrestre. Peu sensible à la diffusion du Pb dans sa structure cristalline, elle peut enregistrer des évènements géologiques de haute température sans risque de remise à zéro de son géochronomètre. Réservoir principal des actinides et des lanthanides, elle participe à de nombreuses réactions minéralogiques, faisant aussi d'elle un très bon traceur pétrogénétique. Coupler sa chimie à son isotopie permet donc d'interpréter précisément la nature des processus géologiques dont elle enregistre l'âge. L'étude de trois objets géologiques distincts a permis de montrer que la monazite est très sensible aux interactions avec les fluides. Ils vont induire sa dissolution partielle ou totale, suivie de la recristallisation de nouveaux grains. De multiples paramètres vont influencer son comportement face au fluide. Ainsi, à basse température (350°C - 450°C) dans un microgranite, un fluide riche en fluor et carbonates va favoriser la dissolution-précipitation de la monazite, alors qu'un fluide riche en éléments alcalins n'aura aucun effet sur elle. Par contre, à plus haute température (> 600°C) dans des roches métapélitiques, ce même fluide va induire sa dissolution-précipitation. En fonction de la mobilité du Pb, du Th et de l'U, le mécanisme de dissolution-précipitation peut avoir différents impacts sur le géochronomètre : ainsi, l'âge des grains recristallisés peut soit correspondre à l'âge du grain initial, soit dater l'interaction avec le fluide, soit n'avoir aucune signification géologique. Les systèmes isotopiques U-Pb et Th-Pb peuvent également être affectés par l'incorporation de Pb commun dans la monazite lors de sa cristallisation (jusqu'à plusieurs centaines de ppm), ce qui va artificiellement vieillir les âges enregistrés. L'ensemble de ces observations montre que l'âge enregistré par la monazite s'interprète au cas par cas. Dans l'avenir, l'optimisation de l'utilisation de la monazite comme géochronomètre doit passer par (1) une amélioration des techniques d'analyses (augmentation de la résolution spatiale pour résoudre des problèmes géologiques à l'échelle nanométrique, standardisation avec des monazites homogènes) et (2) un couplage de différents types d'analyses (chimie, datation, isotopes de l'oxygène). Ceci devrait permettre d'interpréter aux mieux les âges qu'elle enregistre.
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Alexandrov, Pavel. "Géochronologie U/Pb et ⁴⁰ Ar/ ³⁹ Ar de deux segments de la chaîne varisque : le haut limousin et les pyrénées orientales." Vandoeuvre-les-Nancy, INPL, 2000. http://www.theses.fr/2000INPL062N.
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Différents corps métamorphiques et magmatiques dans leLlimousin et dans les Pyrénées orientales ont été datés par la méthode u/pb à la microsonde ionique et 4 0ar/ 3 9ar sur monograin. Les résultats permettent d'avancer de nouvelles idées sur l'évolution orogénique de ces segments de la chaîne varisque. 1. Pyrénées orientales. L'orthogneiss de canigou-caranca a été daté par la méthode u/pb à la microsonde ionique sur zircons selectionnes. Les âges 2 0 6pb/ 2 3 8u des trois echantillons analyses varient entre 460 et 500 ma. Cet âge invalide le modèle classique de disposition en socle et couverture des séries métamorphiques. 2. Limousin. Le protolithe de la leptynite de vergonzac qui fait partie de l'unité supérieure des gneiss, a été daté à 525 6 ma (u/pb sur zircons a la microsonde ionique). Cet âge est compatible avec les âges des autres unités métamorphiques du Limousin. La mise en place du leucogranite péralumineux de blond a été datée à 319 7 ma (u/pb sur zircons a la microsonde ionique). Les âges 4 0ar/ 3 9ar sur muscovites de cette intrusion varient entre 311 et 306 ma. Ils sont interprétés non pas comme des âges de refroidissement, mais comme caractérisant une activite magmatique et hydrothermale importante. Les granitoides sous couverture du seuil du Poitou ont donné des âges 4 0ar/ 3 9ar sur biotites et amphiboles entre 350 et 345 ma. Une modélisation numérique a permis de les interpréter en termes de refroidissement et d'exhumation. Les minéralisations a w et sn de moulin-barret et de puy-les-vignes ont fourni des âges de 324 ma, ce qui implique l'existance d'un épisode de minéralisations au namurien. Une synthèse de tous les résultats permet de proposer une exhumation et une extension tardi-orogenique précoce, respectivement vers 340 ma et 320 ma. 3. Méthodologie. Quelques réflexions sur la calibration des analyses u/pb à la microsonde ionique sont proposées. La forme des spectres d'âge 4 0ar/ 3 9ar, leur signification en termes d'âge et l'interprétation des âges 4 0ar/ 3 9ar sont abordées.
Books on the topic "Datation au carbonate U-Pb"
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Cuvellier, Henri. Etude isotopique (U-Pb et Rb-Sr) des carbonates properozoiques du craton sino-coreen et du brioverien de Bretagne Centrale: Implications sur la datation directe des séquences sédimentaires. 1992.
Find full textBook chapters on the topic "Datation au carbonate U-Pb"
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El-Ghali, Mohamed A. K., Osman Salad Hersi, Iftikhar Abbasi, Hezam Al-Awah, and Mohamed S. H. Moustafa. "U–Pb Age Dating for Carbonate Sequences: An Example from Late Neoproterozoic Kharus Formation, Al Jabal Al-Akhdar, Northern Oman." In Recent Research on Sedimentology, Stratigraphy, Paleontology, Tectonics, Geochemistry, Volcanology and Petroleum Geology, 79–82. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-43222-4_17.
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JACKSON, MICHAEL J., PETER N. SOUTHGATE, and ROD W. PAGE. "GAMMA-RAY LOGS AND U-Pb ZIRCON GEOCHRONOLOGY—ESSENTIAL TOOLS TO CONSTRAIN LITHOFACIES INTERPRETATION OF PALEOPROTEROZOIC DEPOSITIONAL SYSTEMS." In Carbonate Sedimentation and Diagenesis in the Evolving Precambrian World, 23–41. SEPM (Society for Sedimentary Geology), 2000. http://dx.doi.org/10.2110/pec.00.67.0023.
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Dumoulin, Julie A., Katherine J. Whidden, William A. Rouse, Richard O. Lease, Adam Boehlke, and Paul O’Sullivan. "Biosiliceous, organic-rich, and phosphatic facies of Triassic strata of northwest Alaska: Transect across a high-latitude, low-angle continental margin." In Understanding the Monterey Formation and Similar Biosiliceous Units across Space and Time. Geological Society of America, 2022. http://dx.doi.org/10.1130/2022.2556(11).
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ABSTRACT The Shublik Formation (Middle and Upper Triassic) is a mixed siliciclastic-carbonate-phosphatic unit in northern Alaska. It generated oil found in Prudhoe Bay and other accumulations and is a prospective self-sourced resource play on Alaska’s North Slope. Its distal, deeper-water equivalent—the Otuk Formation—consists largely of radiolarian chert, mudstone, and limestone and contains potential gas accumulations in the Brooks Range foothills to the south. New petrographic, fossil, geochemical, spectral gamma-ray, and zircon U-Pb data yield insights into facies changes in these units, which were deposited across a shallowly dipping shelf margin in a high-latitude setting. Samples come from four localities along a transect that extends ~410 km from present-day northeast (proximal) to southwest (distal) in northwest Alaska. Proximal Shublik facies (Brontosaurus 1 well) contain abundant siliciclastic detritus and local phosphate. Shublik-Otuk transitional facies occur in the probable onshore extension of the Hanna Trough (Surprise Creek); new zircon U-Pb data indicate an early Norian age for a bentonite bed in this section. Distal Otuk facies (Red Dog district, Cape Lisburne) are fine grained, biosiliceous, and organic rich. New detrital zircon U-Pb data from a distinctive sandstone member in the Otuk Formation at Cape Lisburne reinforce previous interpretations of a provenance to the present-day northwest and indicate a protracted history of Triassic magmatism for this source area. Triassic facies patterns in northwestern Alaska were shaped by sea-level change, climate, and regional tectonism. Organic-rich facies developed best at times (Ladinian–middle Norian) and/or in settings (distal shelf, Hanna Trough) with minimal dilution of organic matter by other detritus.
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Dong, Zhicheng, Chenhao Xu, Lin Wang, Shuxing Liu, and Lina Zhang. "Concentration, Speciation and Risk of Migration and Transformation of Soil Metals Around a Pb-Zn Mine." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220338.
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The migration and transformation of soil heavy metals around mines is a hot issue of global concern. In order to evaluate the potential risk of migration and transformation, investigation and surface soil sample collection were conducted around a Pb-Zn mine. Contents of fourteen metals in four different fields were analyzed. And speciation of As, Cd, Cr, Cu, Ni, Pb and Zn was detected by sequential extraction procedures. Then, characteristics of them are discussed. Moreover, the risk of migration and transformation was evaluated based on the risk index (RI), bioavailability index (BI), easier migration index (EMI), harder migration index (HMI). The results show that metal contents in Field 2, Field 3 and Field 4 are higher than the background values. And they are also higher than that in the cleaning and control field (Field 1), except for Co, Mo, Th, Tl and U. The results also indicate that the speciation contents of exchangeable and carbonate bounds in Field 3 and Field 2 are higher than that in Field 4. Furthermore, the RI and the HMI in Field 4 are higher than that in Field 2 and Field 3, with the values of 21.2, 18.8, 10.2 and 1.95, 1.72, 1.49. Nevertheless, the BI and the EMI in Field 3 are higher than that in Field 2 and Field 4, with the values of 1.22, 1.00, 0.85 and 1.823, 1.816, 1.765. This indicates that based on element migration, transformation and bioavailability, more attention should be paid to Field 3 and Field 2 than Field 4. Finally, the results also show that Zn, Cd and Pb should be concerned in order. All of these above not only aid to determine the priority order of soil heavy metals, but also provide a basis for the selection and decision making of remediation strategies.
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Miller, Elizabeth L., Mark E. Raftrey, and Jens-Erik Lund Snee. "Downhill from Austin and Ely to Las Vegas: U-Pb detrital zircon suites from the Eocene–Oligocene Titus Canyon Formation and associated strata, Death Valley, California." In Tectonic Evolution of the Sevier-Laramide Hinterland, Thrust Belt, and Foreland, and Postorogenic Slab Rollback (180–20 Ma). Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2555(14).
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ABSTRACT In a reconnaissance investigation aimed at interrogating the changing topography and paleogeography of the western United States prior to Basin and Range faulting, a preliminary study made use of U-Pb ages of detrital zircon suites from 16 samples from the Eocene–Oligocene Titus Canyon Formation, its overlying units, and correlatives near Death Valley. The Titus Canyon Formation unconformably overlies Neoproterozoic to Devonian strata in the Funeral and Grapevine Mountains of California and Nevada. Samples were collected from (1) the type area in Titus Canyon, (2) the headwaters of Monarch Canyon, and (3) unnamed Cenozoic strata exposed in a klippe of the Boundary Canyon fault in the central Funeral Mountains. Red beds and conglomerates at the base of the Titus Canyon Formation at locations 1 and 2, which contain previously reported 38–37 Ma fossils, yielded mostly Sierran batholith–age detrital zircons (defined by Triassic, Jurassic, and Cretaceous peaks). Overlying channelized fluvial sandstones, conglomerates, and minor lacustrine shale, marl, and limestone record an abrupt change in source region around 38–36 Ma or slightly later, from more local, Sierran arc–derived sediment to extraregional sources to the north. Clasts of red radiolarian-bearing chert, dark radiolarian chert, and quartzite indicate sources in the region of the Golconda and Roberts Mountains allochthons of northern Nevada. Sandstones intercalated with conglomerate contain increasing proportions of Cenozoic zircon sourced from south-migrating, caldera-forming eruptions at the latitude of Austin and Ely in Nevada with maximum depositional ages (MDAs) ranging from 36 to 24 Ma at the top of the Titus Canyon Formation. Carbonate clasts and ash-rich horizons become more prevalent in the overlying conglomeratic Panuga Formation (which contains a previously dated 15.7 Ma ash-flow tuff). The base of the higher, ash-dominated Wahguyhe Formation yielded a MDA of 14.4 Ma. The central Funeral Mountains section exposes a different sequence of units that, based on new data, are correlative to the Titus Canyon, Panuga, and Wahguyhe Formations at locations 1 and 2. An ash-flow tuff above its (unexposed) base provided a MDA of 34 Ma, and the youngest sample yielded a MDA of 12.7 Ma. The striking differences between age-correlative sections, together with map-based evidence for channelization, indicate that the Titus Canyon Formation and overlying units likely represent fluvial channel, floodplain, and lacustrine deposits as sediments mostly bypassed the region, moving south toward the Paleogene shoreline in the Mojave Desert. The profound changes in source regions and sedimentary facies documented in the Titus Canyon Formation took place during ignimbrite flareup magmatism and a proposed eastward shift of the continental divide from the axis of the Cretaceous arc to a new divide in central Nevada in response to thermal uplift and addition of magma to the crust. This uplift initiated south-flowing fluvial systems that supplied sediments to the Titus Canyon Formation and higher units.
Conference papers on the topic "Datation au carbonate U-Pb"
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Aguirre Palafox, Luis Erick, Isabel Montanez, Noah M. McLean, Andreas Möller, and Neil J. Tabor. "U-PB CARBONATE DATING OF EARLIEST DIAGENETIC CEMENTS WITHIN PALEOSOL CARBONATE NODULES: PRELIMINARY WORK AND FUTURE OPPORTUNITIES." In GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-380880.
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Guillong, Marcel, Nathan Looser, Lorenzo Tavazzani, Dawid Szymanowski, Maria Ovtcharova, Inigo Müller, Elias Samankassou, Perach Nuriel, and Oscar Tomé. "A new reference material candidate RA138 for U-Pb carbonate dating by LA-ICP-MS." In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.20119.
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Fukuyama, Mayuko, and Masatsugu Ogasawara. "Timing of the Oritate travertine formation by comparison between its carbonate U-Pb age and zircon U-Pb age of the overlain tuffaceous sandstone, Toyama Prefecture, Japan." In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.19053.
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Mangenot, X., M. Gasparrini, M. Bonifacie, A. Gerdes, M. Ader, and V. Rouchon. "Novel Thermo-Chronological Approaches of Carbonate Diagenesis Quantification (Δ47 and U/Pb): Case of the Paris Basin." In EAGE Workshop on Petroleum Geochemistry in Operations and Production. Netherlands: EAGE Publications BV, 2016. http://dx.doi.org/10.3997/2214-4609.201602335.
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Mottram, Catherine, and Dawn Kellett. "SYNCING FAULT ROCK CLOCKS; DIRECT COMPARISON OF U-PB CARBONATE AND K-AR ILLITE FAULT DATING METHODS." In GSA 2020 Connects Online. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020am-352267.
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Center, Marc, and Andreas Möller. "TIMING OF BRITTLE DEFORMATION IN THE CAÑON CITY EMBAYMENT, CO: LASER ABLATION U-PB DATING OF CARBONATE FRACTURES." In Joint 118th Annual Cordilleran/72nd Annual Rocky Mountain Section Meeting - 2022. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022cd-373735.
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Salih, Namam Muhammed, Howri Mansurbeg, Kamal Kolo, Axel Gerdes, and Alain Préat. "U-Pb Direct Dating of Multiple Diagenetic Events in the Upper Cretaceous Carbonate Reservoir of Bekhme Formation, Kurdistan-NE Iraq." In 2020 AAPG Middle East Region Geosciences Technology Workshop: Carbonate Reservoirs of the Middle East. Tulsa, OK, USA: American Association of Petroleum Geologists, 2020. http://dx.doi.org/10.1306/51671muhammed2020.
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Shen, Anjiang, Anping Hu, and Feng Liang. "Laser Ablation in situ U-Pb Dating in Constraining the Diagenetic History and Porosity Evolution of Ancient Marine Carbonate Reservoirs." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.2356.
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Chew, David, Kerstin Drost, and Vincent Monchal. "An image mapping approach to U-Pb LA-ICP-MS carbonate dating applied to far-field Pyrenean compression in Ireland." In Goldschmidt2023. France: European Association of Geochemistry, 2023. http://dx.doi.org/10.7185/gold2023.15392.
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Melcher, Frank, Victor Bertrandsson-Erlandsson, Veronika Gartner, Elisabeth Henjes-Kunst, Johann Raith, Gerd Rantitsch, Peter Onuk, Friedhelm Henjes-Kunst, Barbara Potocnik-Krajnc, and Ales Soster. "Carbonate-hosted “Alpine-type” Zn-Pb deposits in the Eastern and Southern Alps – trace element geochemistry and isotopic data of sulphides." In Irish-type Zn-Pb deposits around the world. Irish Association for Economic Geology, 2023. http://dx.doi.org/10.61153/niwu8065.
Full textAbstract:
More than 500 occurrences of carbonate-hosted Pb-Zn ores are documented in the Eastern and Southern Alps. They are invariably hosted by shallow lagoonal and reef carbonates of Middle and more frequently Upper Triassic (Anisian and Carnian) age and are collectively termed “Alpine-type” deposits. The local palaeogeography and synsedimentary structures influenced ore mineralization. Although they occur in a wide region, they share common features such as a simple mineralogical composition, complex ore textures, light sulphur isotopic compositions, Late Palaeozoic Pb model ages, and similar trace element compositions in sphalerite, galena and pyrite. Sphalerite records a low-temperature (60-140°C) precipitation. It is low in Fe, Mn, Co, Ag and In, but commonly contains elevated Cd, Ge, As, Tl and Pb. Galena is Ag-poor, although both sphalerite and galena tend to higher Ag concentrations towards the northern Districts. Minor Fe sulphides are low in Co and Ni but carry considerable As and Tl. Rb-Sr dating of sphalerite from the type locality Bleiberg reveals an age of ≈229 Ma for ores of the Raibl Group, and ages of ≈207 and ≈201 Ma for trace element-rich breccia ore in the western part of the Bleiberg deposit. The older age corresponds to U-Pb ages obtained on calcite associated with the Pb-Zn mineralization at the Gorno deposit (Southalpine). The younger age suggests fluid flow within the carbonate sequence in an extensional tectonic regime due to fracturing of the carbonate platform during initial rifting of the Penninic Ocean.
Reports on the topic "Datation au carbonate U-Pb"
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Scanlan, E. J., M. Leybourne, D. Layton-Matthews, A. Voinot, and 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.