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Showing 21 to 24 of 24 (0.026 seconds)Spelling suggestions: "subject:"granito.""
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Middle-Late Jurassic Cu-Pb-Zn-bearing and W-bearing granitoids and their skarn mineralization in the Nanling Range, South China : the Tongshanling and Weijia deposits / Les granitoïdes du jurassique moyen et les skarns à Cu-Pb-Zn et à W associées dans la région de Nanling (Chine du Sud) : les gisements de Tongshanling et de WeijiaHuang, Xu-Dong 28 October 2018 (has links)
Les granitoïdes associés aux skarn à Cu-Pb-Zn et au W, dérivent, respectivement, de la fusion partiellede roches mafiques à amphiboles dans la croute inférieure et de roches métas-édimentaires riches enmuscovite dans la croute moyenne-supérieure. Ces sources fertiles mobilisées pour la formation de cesplutons a permis la formation de gisements à Cu-Pb-Zn, et W au cours du Jurassique moyen. L’originedans la croûte moyenne de la granodiorite de Tongshanling, associée aux minéralisations à Cu-Pb-Zn, aété montrée par l’étude des enclaves microgranulaires dioritiques qui sont des restites remaniées issuesde la fusion partielle des amphibolites de la croûte inférieure. Le Cu et le Zn associées à ces plutons sontprobablement issus de la croûte inférieure et ces métaux ont probablement étés remobilisés au cours dela fusion partielle. Le Pb issue de la croute supérieur a été collecté lors de l’ascension du magma qui adonné la granodiorite. Lors de leur mise en place ces granitoïdes ont exprimé leur potentielminéralisateur. L’étude structural montre que la géométrie des corps minéralisés et en lien avec ladéformation induite par la mise en place des plutons. Les différentes expressions de la minéralisationdans le district à Cu-Mo-Pb-Zn-Ag de Tongshanling sont génétiquement lié à l’hydrothermalisme et à sonévolution lors du développement du skarn. Le granite de Weijia a cristallisé à partir d’un magma saturéen eau et riche en Fluor. Les facteurs qui ont contrôlé la formation de ce skarn magnésien riche en W,suppose l’existence d’une source enrichie en W dans les sources métasédimentaires et d’un magmariche en Fluor très différentia par cristallisation fractionnée. / The Middle-Late Jurassic Cu-Pb-Zn-bearing and W-bearing granitoids in the Nanling Range were mainlyderived from non-simultaneous partial melting of the mafic amphibolitic rocks in the lower crust and themuscovite-rich metasedimentary rocks in the upper-middle crust, respectively. The fertile sources in theNanling Range are beneficial to the formation of Cu-Pb-Zn and W deposits during Middle-Late Jurassic.The lower-crust origin of the Cu-Pb-Zn-bearing granodiorites is further demonstrated by the dioriticmicrogranular enclaves in the Tongshanling granodiorite which are reworked restite enclaves derivedfrom partial melting of the mafic amphibolitic source. The Cu and Zn associated with these intrusionswere most probably released from the mafic amphibolitic lower crust by partial melting, whereas, Pb wasextracted from the upper crust by ascending granodioritic magmas. The emplacement of these orebearinggranitoid magmas may have a structural connection with the subsequent polymetallicmineralization in some way. For instance, the exoskarn and sulfide-quartz veins in the Tongshanling Cu-Pb-Zn deposit are evidently controlled by magma emplacement-induced wall-rock deformation. Thedifferent mineralization types and ore deposits in the Tongshanling Cu-Mo-Pb-Zn-Ag ore district aregenetically linked together in the same skarn system as the productions of evolution and zonation. TheWeijia granite was crystallized from a F-rich and water-saturated magma. The key factors controlling theoccurrence of unusual magnesian skarn W mineralization during Late Jurassic in the Nanling Rangemainly include a W enriched metasedimentary source, a fluorine-rich magma, a strong crystalfractionation, and a fluorine-rich hydrosaline melt
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Magmatismo máfico associado ao granito Encruzilhada do Sul, RS: significado tectônico e importância para a geração do magmatismo graníticoJacobs, Maciel Gilmar January 2017 (has links)
A integração de mapeamento geológico com estudos petrográficos e geoquímicos permitiram caracterizar a evolução petrológica do Granito Encruzilhada do Sul. Este maciço ocorre na parte norte do Batólito Pelotas, porção leste do Cinturão Dom Feliciano. O Granito Encruzilhada do Sul apresenta relações de mistura química com a formação dos granitóides híbridos e física com rochas máficas representadas por dioritos e enclaves máficos. Os dados geoquímicos mostram a afinidade toleítica do magmatismo máfico e classifica as rochas graníticas como do tipo-A. A zonação petrográfica e composicional foi gerada a partir do resfriamento de uma única câmara magmática, caracterizada por monzogranitos porfiríticos ricos em enclaves máficos nos bordos leste e oeste, gradando para sieno a monzogranitos ricos em quartzo e com baixo teor de minerais máficos na porção central. Uma fácies de sienogranitos tardios ocorre na porção centro-norte e representa a cúpula parcialmente preservada do maciço. O posicionamento do granito foi controlado por uma fase cinemática extensional da Zona de Cisalhamento Dorsal de Canguçu, que permitiu a ascenção dos magmas até sua colocação em níveis superiores da crosta. Os dados obtidos sugerem que a geração da suíte ocorreu no período pós-colisional da orogênese Dom Feliciano, associada à fusão parcial de uma crosta granulítica desidratada, promovida pelo aumento do gradiente geotérmico associado aos magmas máficos. As condições de alta temperatura dos magmas permitiram em estágio precoce da cristalização, a mistura química entre pólos félsico e máfico. A evolução da cristalização, entretanto, modifica a viscosidade e densidade dos magmas e favorece o desenvolvimento de estruturas geradas pela mistura física. / The integration of geological mapping, petrographic and geochemical studies allowed the characterization of the petrological evolution of the Encruzilhada do Sul Granite. This massif occurs in the northern part of the Pelotas Batholith, eastern portion of the Dom Feliciano Belt. The Encruzilhada do Sul Granite present chemical mixing relations with the formation of hybrid granitoids and physical mixing with mafic rocks represented by diorites and mafic microgranulares enclaves. Geochemical data indicate the tholeiitic composition of mafic magmatism and that granitic rocks are A-type. The petrographic and compositional pattern zonation generated from a single cooling magma chamber and defined by porphyritic monzo to granodiorite, rich in mafic enclaves, on the eastern and western border, transitioning to heterogranular syeno and monzogranites, rich in quartz and poor in mafic minerals in the central portion. An equigranular facies composed by syenogranites occurs in the northern central portion, representing the partially preserved top of the magma chamber. The emplacement of the granite was controlled by an extensional kinematic phase of the regional Dorsal do Canguçu Shear Zone, which allowed the rise of magmas up to superior levels of a crust. The data suggest that the generation of the suite took place in the post-collisional period of Dom Feliciano orogeny and was associated with partial melting of a granulite crust promoted by increased of the geothermal gradient by the mafic magmas from the mantle. The high temperature conditions of the magmas allowed the chemical mixing between felsic and mafic poles at an early stage of crystallization. The evolution of crystallization modified the viscosity and density of the magmas and favors the development of mingling structures.
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Magmatismo máfico associado ao granito Encruzilhada do Sul, RS: significado tectônico e importância para a geração do magmatismo graníticoJacobs, Maciel Gilmar January 2017 (has links)
A integração de mapeamento geológico com estudos petrográficos e geoquímicos permitiram caracterizar a evolução petrológica do Granito Encruzilhada do Sul. Este maciço ocorre na parte norte do Batólito Pelotas, porção leste do Cinturão Dom Feliciano. O Granito Encruzilhada do Sul apresenta relações de mistura química com a formação dos granitóides híbridos e física com rochas máficas representadas por dioritos e enclaves máficos. Os dados geoquímicos mostram a afinidade toleítica do magmatismo máfico e classifica as rochas graníticas como do tipo-A. A zonação petrográfica e composicional foi gerada a partir do resfriamento de uma única câmara magmática, caracterizada por monzogranitos porfiríticos ricos em enclaves máficos nos bordos leste e oeste, gradando para sieno a monzogranitos ricos em quartzo e com baixo teor de minerais máficos na porção central. Uma fácies de sienogranitos tardios ocorre na porção centro-norte e representa a cúpula parcialmente preservada do maciço. O posicionamento do granito foi controlado por uma fase cinemática extensional da Zona de Cisalhamento Dorsal de Canguçu, que permitiu a ascenção dos magmas até sua colocação em níveis superiores da crosta. Os dados obtidos sugerem que a geração da suíte ocorreu no período pós-colisional da orogênese Dom Feliciano, associada à fusão parcial de uma crosta granulítica desidratada, promovida pelo aumento do gradiente geotérmico associado aos magmas máficos. As condições de alta temperatura dos magmas permitiram em estágio precoce da cristalização, a mistura química entre pólos félsico e máfico. A evolução da cristalização, entretanto, modifica a viscosidade e densidade dos magmas e favorece o desenvolvimento de estruturas geradas pela mistura física. / The integration of geological mapping, petrographic and geochemical studies allowed the characterization of the petrological evolution of the Encruzilhada do Sul Granite. This massif occurs in the northern part of the Pelotas Batholith, eastern portion of the Dom Feliciano Belt. The Encruzilhada do Sul Granite present chemical mixing relations with the formation of hybrid granitoids and physical mixing with mafic rocks represented by diorites and mafic microgranulares enclaves. Geochemical data indicate the tholeiitic composition of mafic magmatism and that granitic rocks are A-type. The petrographic and compositional pattern zonation generated from a single cooling magma chamber and defined by porphyritic monzo to granodiorite, rich in mafic enclaves, on the eastern and western border, transitioning to heterogranular syeno and monzogranites, rich in quartz and poor in mafic minerals in the central portion. An equigranular facies composed by syenogranites occurs in the northern central portion, representing the partially preserved top of the magma chamber. The emplacement of the granite was controlled by an extensional kinematic phase of the regional Dorsal do Canguçu Shear Zone, which allowed the rise of magmas up to superior levels of a crust. The data suggest that the generation of the suite took place in the post-collisional period of Dom Feliciano orogeny and was associated with partial melting of a granulite crust promoted by increased of the geothermal gradient by the mafic magmas from the mantle. The high temperature conditions of the magmas allowed the chemical mixing between felsic and mafic poles at an early stage of crystallization. The evolution of crystallization modified the viscosity and density of the magmas and favors the development of mingling structures.
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Late Mesozoic to Cenozoic erosion and sediment dispersal in the Dinaride orogen: a sedimentary provenance approach / Spätmesozoische bis Känozoische Erosion und Sedimentschüttung im Dinarischen Orogen: Ansätze aus der ProvenanzanalyseMikes, Tamás 16 December 2008 (has links)
No description available.
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