Distribution de l'or de type orogénique le long de grands couloirs de déformation archéens : modélisation numérique sur l'exemple de la ceinture de l'Abitibi

Cette thèse visait à mieux définir les méthodes de ciblage et apporter des éléments de réponse sur la genèse des gisements d'or de type orogénique en périphérie des grands couloirs de déformation archéens par le biais d'approches numériques novatrices. Cette thèse est présentée sous forme de trois articles. Le premier article traite de la distribution mathématique des gisements aurifères de type orogénique le long des grands couloirs de déformation. Une approche permettant de d'établir que la localisation des gisements se situant le long de structure de premier ordre n'est pas indépendante de la localisation de ses voisins a été développée. Cette approche permet de donner des éléments de réponse sur la formation de ces gisements et de générer des probabilités de découvertes à l'échelle régionale. La deuxième partie de cette présente une méthode l'évaluation du potentiel minéral sous couverture sédimentaire en 3D. Les teneurs aurifères compilées dans le secteur ont permis d'évaluer et de quantifier les relations spatiales existantes entre certaines entités géologiques et les emplacements minéralisés afin de cibler les endroits à haut potentiel. Enfin, les travaux présentés dans le dernier chapitre visent à délimiter les zones possédant une perméabilité structurale accrue lors de l'épisode de déformation contemporain à la mise en place de gisements aurifères de type orogénique. Une modélisation géomécanique 3D qui tient compte des propriétés physiques des roches a été effectuée sur un segment de faille choisi en utilisant un code d'élément fini. La déformation s'effectue en attribuant sur chaque discontinuité structurale des vecteurs ou des champs de déplacement en fonction des observations de terrain.\ud _____________________________________________________________________________

Orogenic type gold distribution along major archean fault zones : numerical modelling in the Abitibi Belt

Cette thèse visait à mieux définir les méthodes de ciblage et apporter des éléments de réponse sur la genèse des gisements d’or de type orogénique en périphérie des grands couloirs de déformation archéens. Cette thèse est présentée sous forme de trois articles. Le premier article traite de la distribution mathématique des gisements aurifères de type orogénique le long des grands couloirs de déformation. Une approche permettant de d’établir que la localisation des gisements se situant le long de structure de premier ordre n’est pas indépendante de la localisation de ses voisins a été développée. Cette approche permet de donner des éléments de réponse sur la formation de ces gisements et de générer des probabilités de découvertes à l’échelle régionale. La deuxième partie de cette présente une méthode l’évaluation du potentiel minéral sous couverture sédimentaire en 3D. Les teneurs aurifères compilées dans le secteur ont permis d’évaluer et de quantifier les relations spatiales existantes entre certaines entités géologiques et les emplacements minéralisés afin de cibler les endroits à haut potentiel. Enfin, les travaux présentés dans le dernier chapitre visent à délimiter les zones possédant une perméabilité structurale accrue lors de l’épisode de déformation contemporain à la mise en place de gisements aurifères de type orogénique. Une modélisation géomécanique 3D qui tient compte des propriétés physiques des roches a été effectuée sur un segment de faille choisi en utilisant un code d’élément fini. La déformation s’effectue en attribuant sur chaque discontinuité structurale des vecteurs ou des champs de déplacement en fonction des observations de terrainThis thesis had the objective to define targeting methods adapted to orogenic gold deposits hosted in greenstone belts and to better understand the formation mechanism of these deposits. The work accomplished is presented in three distinct articles. The first article aimed to determine if a mathematical relation can characterize the spatial distribution of orogenic gold deposits along a crustal scale fault zone within or if the localization of a deposit is independent of the position of each other. A uniform law was fitted between the frequency and the curvilinear inter-distance between successive orogenic gold occurrences along the CLLF for distances ranging from 315 to 5600 m. This approach gave insights on the formation mechanism and allowed the generation of a probability map for undiscovered deposits at a regional scale. The second chapter of this thesis focuses on a sector of the Cadillac Larder Lake Fault that was considered as having a high potential for discovery using the methodology presented in the last chapter. Compiled assays allowed the evaluation of the spatial association of certain geological features with orogenic gold mineralizations to allow targeting high potential areas. Finally, the work presented in the last chapter aimed at identifying dilatant zones during the deformation that is contemporaneous to the orogenic gold deposit formation. A 3D geomechanical modelling which takes rock properties into account was performed on a chosen segment of a fault zone using a finite element code. The deformation was induced using displacement vectors or fields interpreted from field dat

Orogenic type gold distribution along major archean fault zones (numerical modelling in the Abitibi Belt)

Cette thèse visait à mieux définir les méthodes de ciblage et apporter des éléments de réponse sur la genèse des gisements d or de type orogénique en périphérie des grands couloirs de déformation archéens. Cette thèse est présentée sous forme de trois articles. Le premier article traite de la distribution mathématique des gisements aurifères de type orogénique le long des grands couloirs de déformation. Une approche permettant de d établir que la localisation des gisements se situant le long de structure de premier ordre n est pas indépendante de la localisation de ses voisins a été développée. Cette approche permet de donner des éléments de réponse sur la formation de ces gisements et de générer des probabilités de découvertes à l échelle régionale. La deuxième partie de cette présente une méthode l évaluation du potentiel minéral sous couverture sédimentaire en 3D. Les teneurs aurifères compilées dans le secteur ont permis d évaluer et de quantifier les relations spatiales existantes entre certaines entités géologiques et les emplacements minéralisés afin de cibler les endroits à haut potentiel. Enfin, les travaux présentés dans le dernier chapitre visent à délimiter les zones possédant une perméabilité structurale accrue lors de l épisode de déformation contemporain à la mise en place de gisements aurifères de type orogénique. Une modélisation géomécanique 3D qui tient compte des propriétés physiques des roches a été effectuée sur un segment de faille choisi en utilisant un code d élément fini. La déformation s effectue en attribuant sur chaque discontinuité structurale des vecteurs ou des champs de déplacement en fonction des observations de terrainThis thesis had the objective to define targeting methods adapted to orogenic gold deposits hosted in greenstone belts and to better understand the formation mechanism of these deposits. The work accomplished is presented in three distinct articles. The first article aimed to determine if a mathematical relation can characterize the spatial distribution of orogenic gold deposits along a crustal scale fault zone within or if the localization of a deposit is independent of the position of each other. A uniform law was fitted between the frequency and the curvilinear inter-distance between successive orogenic gold occurrences along the CLLF for distances ranging from 315 to 5600 m. This approach gave insights on the formation mechanism and allowed the generation of a probability map for undiscovered deposits at a regional scale. The second chapter of this thesis focuses on a sector of the Cadillac Larder Lake Fault that was considered as having a high potential for discovery using the methodology presented in the last chapter. Compiled assays allowed the evaluation of the spatial association of certain geological features with orogenic gold mineralizations to allow targeting high potential areas. Finally, the work presented in the last chapter aimed at identifying dilatant zones during the deformation that is contemporaneous to the orogenic gold deposit formation. A 3D geomechanical modelling which takes rock properties into account was performed on a chosen segment of a fault zone using a finite element code. The deformation was induced using displacement vectors or fields interpreted from field dataNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

A comparative study of three-driven Mineral Potential Mapping techniques.

International audienceHigh prices of mineral resources and progresses in models of mineral deposits maintain a high activity in mining exploration. Many data integration techniques exist to assess the mining potential of a region, and it may be difficult for the practitioner to select the most appropriate. This paper compares two types of data-driven methods to estimate a probability map of mineralization occurrences from several sources of information: multivariate logistic regression, under the assumption that all indicators are independent, and weights of evidence, which assumes only conditional independence. A proposal to depart from conditional independence assumptions in Weights of Evidence is also presented, that allows a better management of data redundancy. All three methods are applied to gold potential mapping in a 3D geo-model of the Duparquet region located on the Porcupine Destor fault in the Abitibi subprovince, Canada

Circulating Tumor DNA as a Prognostic Determinant in Small Cell Lung Cancer Patients Receiving Atezolizumab

International audienceBackground: The IFCT-1603 trial evaluated atezolizumab in small cell lung cancer (SCLC). The purpose of the present study was to determine whether circulating tumor DNA (ctDNA), prospectively collected at treatment initiation, was associated with the prognosis of SCLC, and whether it identified patients who benefited from atezolizumab.Methods: 68 patients were included in this study: 46 patients were treated with atezolizumab and 22 with conventional chemotherapy. Circulating DNA was extracted from plasma and NGS (Next Generation Sequencing) looked for mutations in the TP53, RB1, NOTCH1, NOTCH2, and NOTCH3 genes. ctDNA was detectable when at least one somatic mutation was identified, and its relative abundance was quantified by the variant allele fraction (VAF) of the most represented mutation.Results: We found that 49/68 patients (70.6%) had detectable baseline ctDNA. The most frequently identified mutations were TP53 (32/49; 65.3%) and RB1 (25/49; 51.0%). Patients with detectable ctDNA had a significantly lower disease control rate at week 6 compared with patients with no detectable ctDNA, regardless of the nature of the treatment. Detection of ctDNA was associated with a poor OS prognosis. The detection of ctDNA at a relative abundance greater than the median value was significantly associated with poor overall survival (OS) and progression free survival (PFS). Interestingly, the benefit in overall survival (OS) associated with low ctDNA was more pronounced in patients treated with atezolizumab than in patients receiving chemotherapy. Among patients whose relative ctDNA abundance was below the median, those treated with atezolizumab tended to have higher OS than those in the chemotherapy arm.Conclusion: ctDNA is strongly associated with the prognosis of SCLC patients treated with second-line immunotherapy. Its analysis seems justified for future SCLC clinical trials

A Randomized Non-Comparative Phase II Study of Anti-Programmed Cell Death-Ligand 1 Atezolizumab or Chemotherapy as Second-Line Therapy in Patients With Small Cell Lung Cancer: Results From the IFCT-1603 Trial

International audienceThis randomized phase II trial aimed at evaluating the engineered programmed cell death ligand 1 (PD-L1) antibody atezolizumab in SCLC progressing after first-line platinum-etoposide chemotherapy

Strategies to safely rule out pulmonary embolism in COVID-19 outpatients: a multicenter retrospective study

International audienceObjectives: The objective was to define a safe strategy to exclude pulmonary embolism (PE) in COVID-19 outpatients, without performing CT pulmonary angiogram (CTPA).Methods: COVID-19 outpatients from 15 university hospitals who underwent a CTPA were retrospectively evaluated. D-Dimers, variables of the revised Geneva and Wells scores, as well as laboratory findings and clinical characteristics related to COVID-19 pneumonia, were collected. CTPA reports were reviewed for the presence of PE and the extent of COVID-19 disease. PE rule-out strategies were based solely on D-Dimer tests using different thresholds, the revised Geneva and Wells scores, and a COVID-19 PE prediction model built on our dataset were compared. The area under the receiver operating characteristics curve (AUC), failure rate, and efficiency were calculated.Results: In total, 1369 patients were included of whom 124 were PE positive (9.1%). Failure rate and efficiency of D-Dimer > 500 µg/l were 0.9% (95%CI, 0.2–4.8%) and 10.1% (8.5–11.9%), respectively, increasing to 1.0% (0.2–5.3%) and 16.4% (14.4–18.7%), respectively, for an age-adjusted D-Dimer level. D-dimer > 1000 µg/l led to an unacceptable failure rate to 8.1% (4.4–14.5%). The best performances of the revised Geneva and Wells scores were obtained using the age-adjusted D-Dimer level. They had the same failure rate of 1.0% (0.2–5.3%) for efficiency of 16.8% (14.7–19.1%), and 16.9% (14.8–19.2%) respectively. The developed COVID-19 PE prediction model had an AUC of 0.609 (0.594–0.623) with an efficiency of 20.5% (18.4–22.8%) when its failure was set to 0.8%.Conclusions:The strategy to safely exclude PE in COVID-19 outpatients should not differ from that used in non-COVID-19 patients. The added value of the COVID-19 PE prediction model is minor

Forced subduction initiation recorded in the sole and crust of the Semail Ophiolite of Oman

Subduction zones are unique to Earth and fundamental in its evolution, yet we still know little about the causes and mechanisms of their initiation. Numerical models show that far-field forcing may cause subduction initiation at weak pre-existing structures, while inferences from modern subduction zones suggest initiation through spontaneous lithospheric gravitational collapse. For both endmembers, the timing of subduction inception corresponds with initial lower plate burial, whereas coeval or delayed extension in the upper plate are diagnostic of spontaneous or forced subduction initiation, respectively. In modern systems, the earliest extension-related upper plate rocks are found in forearcs, but lower plate rocks that recorded initial burial have been subducted and are inaccessible. Here, we investigate a fossil system, the archetypal Semail Ophiolite of Oman, which exposes both lower and upper plate relics of incipient subduction stages. We show with Lu–Hf and U–Pb geochronology of the lower and upper plate material that initial burial of the lower plate occurred before 104 million years ago, predating upper plate extension and the formation of Semail oceanic crust by at least 8 Myr. Such a time lag reveals far-field forced subduction initiation and provides unequivocal, direct evidence for a subduction initiation mechanism in the geological record