Etude minéralogique et pétrographique du massif du Chenaillet entre briançon et Cesana-Torinese ( Italie)

Mechanisms of sill and dyke intrusion require an understanding of fracture growth,stress distributions and intensities, dilation,intrusion rates, hydraulic pressure,host-rock effects,en echelon fracture arrays,and flow direction. The methods of previous studies have been applied to natural sill and dyke examples of the Karoo Igneous Province in northern Natal . An en echelon array of Jurassic dolerite sills occurs within Permian Ecca sediments along the Mhlatuze River, west of Empangeni. Dolerite emplacement occurred as two intrusive phases. The first phase resulted in thick, . coarse-grained dolerite sills. The second phase produced relatively thinner, fme-grained sills. The intrusion of fmegrained dolerite into older sills is demonstrated by abrupt variations in the whole-rock and mineral geochemistry profiles across the sills. Syn-crystallisation effects such as crystal settling and fractionation, and post-crystallisation hydrothermal activity is also manifested in the mineralogical and geochemical changes across the sills. The fine grained doleriteis associated with xenolithic dolerite which represents a contaminated magma propagation front of the fine-grained dolerite. The higher viscosity of the xenolithic dolerite hindered propagation, and was thus overtaken and engulfedby the mainmagmapulse. Consistent sinistral off setting of sill segments is interpreted to be the result of a fingered sill periphery intruding an en echelon fracture array. Dilation of individual segments, or fingers, occurred simultaneously. Subsequent interaction of near-tip stresses induced inwardly propagating curvature of adjacent segmentsin the array.Resultant linkage has produced a stepped-sill geometry; sill propagation and flow directions were orthogonal to the plane of linkage. The flow direction is confirmed by shape preferred-orientations of acicular mineral grains within the chilled margins of the sills, indicating the direction of flow to be perpendicular to the plane of the en echelon array, and parallel to strike directions of offset surfaces that link adjacent sill segments. Multiple dyke intrusion is examinedat an outcrop of the Rooi Rand Dyke Swarm, along the Pongola River. Individual intrusive episodes are identifiable on the basis of chill-zone relationships. The pattern along the Pongola River suggests that younger intrusive episodes frequently intrude through the centres of older dykes. A three dimensional analysis of en echelon dyke let segments allows a re-construction of the dilation history,and provides an explanation for the development of blunt-ended intrusion segments. Mineral geochemistry anomalies around dyke tips suggests possible facilitation of incipient fracture via decreases in mineral strengths manifested by geochemical changes. A statistical digital analysis of micro-phenocryst orientations within chilled dyke margins is shown to provide a viable method to ascertain magma flow directions within dykes, and may thus be a useful tool for future investigations. / Thesis (M.Sc.)-University of Natal, 1994.

Mémoire (M.Sc.A)- Université du Québec à Chicoutimi, 1978. / "Mémoire présenté en vue de l'obtention de la maîtrise ès Sciences appliquées en géologie". CaQCU Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Sc.A)-- Université du Québec à Chicoutimi, 1980. / "Mémoire présenté en vue de l'obtention de la maîtrise ès Sciences appliquées en géologie". CaQCU Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Sc.A.)--Université du Québec à Chicoutimi, 1986. / "Mémoire présenté à Chicoutimi en vue de l'obtention d'une maîtrise en science appliquée (géologie)" CaQCU Bibliogr.: p. 129-134. Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Sc.T.)--Université du Québec à Chicoutimi, 1989. / Document électronique également accessible en format PDF. CaQCU

Submitted by Igor Matos (igoryure.rm@gmail.com) on 2017-01-31T15:33:52Z No. of bitstreams: 1 DISS_2015_Gil Barreto Trindade Netto.pdf: 5049678 bytes, checksum: fc6de3140f191e6636dbf827b66bc627 (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2017-01-31T15:48:13Z (GMT) No. of bitstreams: 1 DISS_2015_Gil Barreto Trindade Netto.pdf: 5049678 bytes, checksum: fc6de3140f191e6636dbf827b66bc627 (MD5) / Made available in DSpace on 2017-01-31T15:48:14Z (GMT). No. of bitstreams: 1 DISS_2015_Gil Barreto Trindade Netto.pdf: 5049678 bytes, checksum: fc6de3140f191e6636dbf827b66bc627 (MD5) Previous issue date: 2015-07-16 / Dois tipos de diques máficos ocorrem na porção centro-leste de Rondônia, a sudoeste do Craton Amazônico. Os enxames posicionam-se na interface entre duas províncias geocronológicas e terrenos tectônicos distintos (Província Rio Negro-Juruena e Sunsás-Aguapeí, individualizadas no Terreno Jamari e Terreno Nova Brasilândia, respectivamente), separados pelo gráben paleozoico de Pimenta Bueno. Eles são denominados diabásio I e diabásio II. Diabásio I orienta-se preferencialmente segundo WNW-ESE, subordinadamente segundo NW-SE, e cortam rochas Proterozóicas das Formações Migrantinópolis e Terra Boa, e da Suíte Intrusiva Serra da Providência. Diabásio II é mais abundante na região e orienta-se preferencialmente segundo N-S e NNE-SSW, e subordinadamente segundo WSW-ESE. Esse enxame intrude rochas Paleozoicas das Formações Pedra Redonda e Pimenta Bueno. As principais diferenças petrográficas consistem na presença de ortopiroxênio somente nas amostras do diabásio II, e em diferentes texturas, predominantemente equigranular no diabásio II, e frequentemente porfirítica e microporfirítica no diabásio I. Geoquimicamente, as rochas de ambos os tipos classificam-se como basaltos toleíticos. Diabásio I (mg# 0,35-0,71) é mais enriquecido em FeO, TiO2, K2O, P2O5 e elementos incompatíveis em comparação a diabásio II (mg# 0,40-0,60). A diferença em grau de enriquecimento de ambos os magmas e a nítida distinção entre razões de elementos incompatíveis indicam que diabásio I e diabásio II são provenientes de diferentes mantos progenitores. A grande similaridade entre as médias e intervalos das razões de elementos incompatíveis dos diabásios I, Rb/Sr (0,03-0,39), K/Nb (197,42 - 1273,92), La/Nb (0,73 - 3,55), P/Nb (42,54 - 272,13), Ce/Zr (0,21 - 0,41), Ce/Yb (11,12 - 21,22), La/Yb (4,91 – 9,56), Zr/Th (61,05 – 140,54), Nb/Hf (1,34 – 7,48), Ce/Ta (36,20 – 199,65), Ba/Sr (0,65 – 2,15), Zr/Ti (75,85 – 203,08), Zr/Y (3,70 – 6,17) e metagabros do Grupo Nova Brasilândia (1,10 Ga), Rb/Sr (0,05-0,26), K/Nb (340,35 - 1304,49), La/Nb (1,68 - 3,23), P/Nb (74,20 - 264,74), Ce/Zr (0,19 - 0,67), Ce/Yb (7,04 – 57,85), La/Yb (2,86 – 25,23), Zr/Th (19,91 – 162,34), Nb/Hf (1,05 – 10,52), Ce/Ta (66,74 – 134,23), Ba/Sr (0,71 – 3,21), Zr/Ti (109,74 – 261,71), Zr/Y (2,96 – 6,16) sugere que ambos os magmas originaram-se de fontes mantélicas semelhantes, devendo-se levar em conta para futuras pesquisas, a possibilidade da proximidade das respectivas idades de intrusão. As características geológicas do enxame de diabásio II sugere idade Mesozoica, uma vez que cortam unidades paleozóicas. Os dados geológicos e geoquímicos indicam ambiente intracratônico para ambos os enxames / Two types of mafic dykes occur in the central eastern portion of Rondônia State, In the SW Amazonian Craton. They are located at the interface between two geochronological provinces and distinct tectonic terrains (Rio Negro Juruena and Sunsas Aguapei Provinces, and Jamari Terrain and Nova Brasilandia Terrain, respectively) and are separated by the Pimento Bueno Paleozoic graben. They are named diabase I and diabase II. Diabase I trends predominantly WNW-ESE, and subordinately NW-SE, and crosscut Proterozoic rocks from Migrantopolis and Terra Boa Formations and from the Intrusive Suite of Serra da Providência. Diabase II is more widespread in the region and trends mainly N-S and NNE-SSW, and subordinately WSW-ESE. This swarm crosscuts both Proterozoic (Migrantinópolis and Terra Boa Formations), and Paleozoic rocks (Pedra Redonda and Pimenta Bueno Formations). The main petrographic differences refers to the presence of orthopyroxene only in the diabase II samples, and different textures, predominately equigranular in diabase II, and frequently porphyritic and microporphyritic in diabase I. Geochemically both types are classified as tholeiitic basalts. Diabase I (mg# 0.35-0.71) is more enriched in FeO, TiO2, K2O, P2O5 and in incompatible elements in comparison with diabase II (mg# 0.40-0.60). The difference between enrichment degree of both melts and the clear distinction between incompatible element ratios indicate that diabase I and diabase II originate from different progenitor mantles. The great similarity between the means and ranges of incompatible element ratios of diabase I dykes, Rb/Sr (0.03-0.39), K/Nb (197.42 – 1273.92), La/Nb (0.73 – 3.55), P/Nb (42.54 – 272.13), Ce/Zr (0.21 – 0.41), Ce/Yb (11.12 – 21.22), La/Yb (4.91 – 9.56), Zr/Th (61.05 – 140.54), Nb/Hf (1.34 – 7.48), Ce/Ta (36.20 – 199.65), Ba/Sr (0.65 – 2.15), Zr/Ti (75.85 – 203.08), Zr/Y (3.70 – 6.17) and metagabbros from the Nova Brasilândia Group (1.10 Ga), Rb/Sr (0.05-0.26), K/Nb (340.35 – 1304.49), La/Nb (1.68 – 3.23), P/Nb (74.20 – 264.74), Ce/Zr (0.19 – 0.67), Ce/Yb (7.04 – 57.85), La/Yb (2.86 – 25.23), Zr/Th (19.91 – 162.34), Nb/Hf (1.05 – 10.52), Ce/Ta (66.74 – 134.23), Ba/Sr (0.71 – 3.21), Zr/Ti (109.74 – 261.71), Zr/Y (2.96 – 6.16) suggest that both melts originate from similar sources, and forthcoming researches should take into account the possibility of similar intrusion ages. The geological setting of the diabase II swarm suggests that these intrusions could be Mesozoic, since intrude in Paleozoic units. Geologic and geochemical data indicate an intracontinental setting for both swarms

Este trabalho apresenta a caracterização geoquímica e isotópica (Sr-Nd-Pb) das rochas subalcalinas diferenciadas dos diques do Enxame da Serra do Mar (ESM), localizado na costa dos estados de São Paulo e Rio de Janeiro, sendo constituído principalmente por diques básicos com altos teores de TiO2 (>3%). Os diques intermediários e ácidos, encontrados apenas na Ilha de São Sebastião e costa adjacente, foram submetidos à análise de elementos traços por ativação com nêutrons (AAN), que possibilitou a determinação de elementos terras raras (La, Ce, Nd, Sm, Eu, Tb, Yb e Lu) e outros traços incompatíveis (U, Th, Hf, Ta, Ba e Rb), além de Co e Sc. As amostras foram também analisadas por espectrometria de massa com plasma indutivamente acoplado (ICP-MS), que permitiu efetuar uma comparação entre os resultados obtidos pelos dois métodos. Foram ainda determinadas as razões isotópicas de Sr, Nd e Pb em cinco amostras representativas. Os dados obtidos por AAN indicam precisão de até 14% (maioria abaixo de 10%) e exatidão de até 4%. A comparação estatística dos dados de AAN com ICP-MS mostrou que as técnicas fornecem resultados estatisticamente concordantes para a grande maioria dos elementos analisados. Os diques diferenciados são quimicamente representados por lati-andesitos (LTA), dacitos (DAC) e riodacitos (RC). Dentre os LTA observa-se um conjunto de 4 amostras (Grupo 1) com características geoquímicas semelhantes às rochas basálticas Pitanga da Província Magmática do Paraná (PMP), embora apresentem razões isotópicas iniciais de Sr e Pb mais radiogênicas. Os demais LTA (Grupo 2) apresentam enriquecimento significativo de elementos fortemente incompatíveis. Entre as rochas mais diferenciadas dos LTA (Grupo 2) e aquelas dos DAC e RC há lacunas composicionais, sugerindo que a evolução não ocorreu por cristalização fracionada. À semelhança da gênese das rochas vulcânicas ácidas do tipo Chapecó-Ourinhos da PMP, é possível que os diques DAC e RC tenham sido originados por refusão de material de composição basáltica aprisionado na descontinuidade crosta-manto. As razões isotópicas dos diques do ESM sugerem que a gênese desse material basáltico envolveu fusão de manto litosférico subcontinental metassomatizado, conforme proposto para os diques mesozoicos do Espinhaço Meridional (Craton do São Francisco), que possuem composições isotópicas similares. Os magmas diferenciados gerados nesse processo podem ter sofrido contaminação crustal, conforme indicado também pelas composições isotópicas de Sr, Nd e Pb, requerendo, no entanto, um contaminante com características muito específicas. / The geochemical and isotopic (Sr-Nd-Pb) characterization of the subalkaline differentiated dykes from the Serra do Mar Swarm (ESM) is presented. These rocks are located at the coast of São Paulo and Rio de Janeiro states and are mainly composed by basic dikes with high contents of TiO2 (> 3%). Intermediate and acid dykes, which are found only in the São Sebastião Island and adjacent coast area were investigated by using neutron activation analysis (AAN), allowing determination of the concentrations of rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) and other compatible (Co and Sc) and incompatible trace elements (U, Th, Hf, Ta, Ba and Rb). The samples were also analyzed by mass spectrometry with inductively coupled plasma (ICP-MS), permitting the comparison between the results obtained by the two methods. The isotope compositions of Sr, Nd and Pb were also determined in five representative samples. The data obtained by AAN indicate precision of up to 14% (most below 10%) and accuracy of up to 4%. The statistical comparison of AAN and ICP-MS data showed that the techniques provide statistically identical results for the vast majority of the analyzed elements. The differentiated dykes are chemically represented by lati-andesites (LTA), dacites (DAC) and riodacites (RC). Four LTA samples (Group 1) have geochemical similarities with Pitanga basaltic flows from Paraná Magmatic Province (PMP), although presenting Sr and Pb initial ratios slightly more radiogenic. The remaining LTA (Group 2) rocks are enriched in highly incompatible trace elements. The compositional gap between the most evolved LTA (Group 2) and the DAC and RC suggests that the evolution of this rocks is not compatible with fractional crystallization processes. Likewise the genesis of Chapecó-Ourinhos acid volcanic rocks from PMP, it is possible that the DAC and RC have been generated by melting of basalt material, which was trapped in crust-mantle discontinuity. The isotope ratios of the ESM dykes suggest that this basaltic material was generated by melting of a metasomatized subcontinental lithospheric mantle source, due to ancient subduction processes, as proposed for the Mesozoic dykes from the Espinhaço Meridional (São Francisco Craton), whose isotope ratios are very similar. The differentiated magmas generated in this process would be affected by crustal contamination during their ascension, as also indicated by the Sr, Nd and Pb isotope compositions, requiring however, very specific characteristics for the contaminant.

Este trabalho apresenta a caracterização geoquímica e isotópica (Sr-Nd-Pb) das rochas subalcalinas diferenciadas dos diques do Enxame da Serra do Mar (ESM), localizado na costa dos estados de São Paulo e Rio de Janeiro, sendo constituído principalmente por diques básicos com altos teores de TiO2 (>3%). Os diques intermediários e ácidos, encontrados apenas na Ilha de São Sebastião e costa adjacente, foram submetidos à análise de elementos traços por ativação com nêutrons (AAN), que possibilitou a determinação de elementos terras raras (La, Ce, Nd, Sm, Eu, Tb, Yb e Lu) e outros traços incompatíveis (U, Th, Hf, Ta, Ba e Rb), além de Co e Sc. As amostras foram também analisadas por espectrometria de massa com plasma indutivamente acoplado (ICP-MS), que permitiu efetuar uma comparação entre os resultados obtidos pelos dois métodos. Foram ainda determinadas as razões isotópicas de Sr, Nd e Pb em cinco amostras representativas. Os dados obtidos por AAN indicam precisão de até 14% (maioria abaixo de 10%) e exatidão de até 4%. A comparação estatística dos dados de AAN com ICP-MS mostrou que as técnicas fornecem resultados estatisticamente concordantes para a grande maioria dos elementos analisados. Os diques diferenciados são quimicamente representados por lati-andesitos (LTA), dacitos (DAC) e riodacitos (RC). Dentre os LTA observa-se um conjunto de 4 amostras (Grupo 1) com características geoquímicas semelhantes às rochas basálticas Pitanga da Província Magmática do Paraná (PMP), embora apresentem razões isotópicas iniciais de Sr e Pb mais radiogênicas. Os demais LTA (Grupo 2) apresentam enriquecimento significativo de elementos fortemente incompatíveis. Entre as rochas mais diferenciadas dos LTA (Grupo 2) e aquelas dos DAC e RC há lacunas composicionais, sugerindo que a evolução não ocorreu por cristalização fracionada. À semelhança da gênese das rochas vulcânicas ácidas do tipo Chapecó-Ourinhos da PMP, é possível que os diques DAC e RC tenham sido originados por refusão de material de composição basáltica aprisionado na descontinuidade crosta-manto. As razões isotópicas dos diques do ESM sugerem que a gênese desse material basáltico envolveu fusão de manto litosférico subcontinental metassomatizado, conforme proposto para os diques mesozoicos do Espinhaço Meridional (Craton do São Francisco), que possuem composições isotópicas similares. Os magmas diferenciados gerados nesse processo podem ter sofrido contaminação crustal, conforme indicado também pelas composições isotópicas de Sr, Nd e Pb, requerendo, no entanto, um contaminante com características muito específicas. / The geochemical and isotopic (Sr-Nd-Pb) characterization of the subalkaline differentiated dykes from the Serra do Mar Swarm (ESM) is presented. These rocks are located at the coast of São Paulo and Rio de Janeiro states and are mainly composed by basic dikes with high contents of TiO2 (> 3%). Intermediate and acid dykes, which are found only in the São Sebastião Island and adjacent coast area were investigated by using neutron activation analysis (AAN), allowing determination of the concentrations of rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) and other compatible (Co and Sc) and incompatible trace elements (U, Th, Hf, Ta, Ba and Rb). The samples were also analyzed by mass spectrometry with inductively coupled plasma (ICP-MS), permitting the comparison between the results obtained by the two methods. The isotope compositions of Sr, Nd and Pb were also determined in five representative samples. The data obtained by AAN indicate precision of up to 14% (most below 10%) and accuracy of up to 4%. The statistical comparison of AAN and ICP-MS data showed that the techniques provide statistically identical results for the vast majority of the analyzed elements. The differentiated dykes are chemically represented by lati-andesites (LTA), dacites (DAC) and riodacites (RC). Four LTA samples (Group 1) have geochemical similarities with Pitanga basaltic flows from Paraná Magmatic Province (PMP), although presenting Sr and Pb initial ratios slightly more radiogenic. The remaining LTA (Group 2) rocks are enriched in highly incompatible trace elements. The compositional gap between the most evolved LTA (Group 2) and the DAC and RC suggests that the evolution of this rocks is not compatible with fractional crystallization processes. Likewise the genesis of Chapecó-Ourinhos acid volcanic rocks from PMP, it is possible that the DAC and RC have been generated by melting of basalt material, which was trapped in crust-mantle discontinuity. The isotope ratios of the ESM dykes suggest that this basaltic material was generated by melting of a metasomatized subcontinental lithospheric mantle source, due to ancient subduction processes, as proposed for the Mesozoic dykes from the Espinhaço Meridional (São Francisco Craton), whose isotope ratios are very similar. The differentiated magmas generated in this process would be affected by crustal contamination during their ascension, as also indicated by the Sr, Nd and Pb isotope compositions, requiring however, very specific characteristics for the contaminant.

In the period between September 2010 and December 2011, Christchurch was shaken by a series of strong earthquakes including the MW7.1 4 September 2010, Mw 6.2 22 February 2011, MW6.2 13 June 2011 and MW6.0 23 December 2011 earthquakes. These earthquakes produced very strong ground motions throughout the city and surrounding areas that resulted in soil liquefaction and lateral spreading causing substantial damage to buildings, infrastructure and the community. The stopbank network along the Kaiapoi and Avon River suffered extensive damage with repairs projected to take several years to complete. This presented an opportunity to undertake a case-study on a regional scale of the effects of liquefaction on a stopbank system. Ultimately, this information can be used to determine simple performance-based concepts that can be applied in practice to improve the resilience of river protection works. The research presented in this thesis draws from data collected following the 4th September 2010 and 22nd February 2011 earthquakes. The stopbank damage is categorised into seven key deformation modes that were interpreted from aerial photographs, consultant reports, damage photographs and site visits. Each deformation mode provides an assessment of the observed mechanism of failure behind liquefaction-induced stopbank damage and the factors that influence a particular style of deformation. The deformation modes have been used to create a severity classification for the whole stopbank system, being ‘no or low damage’ and ‘major or severe damage’, in order to discriminate the indicators and factors that contribute to ‘major to severe damage’ from the factors that contribute to all levels of damage a number of calculated, land damage, stopbank damage and geomorphological parameters were analysed and compared at 178 locations along the Kaiapoi and Avon River stopbank systems. A critical liquefiable layer was present at every location with relatively consistent geotechnical parameters (cone resistance (qc), soil behaviour type (Ic) and Factor of Safety (FoS)) across the study site. In 95% of the cases the critical layer occurred within two times the Height of the Free Face (HFF,). A statistical analysis of the geotechnical factors relating to the critical layer was undertaken in order to find correlations between specific deformation modes and geotechnical factors. It was found that each individual deformation mode involves a complex interplay of factors that are difficult to represent through correlative analysis. There was, however, sufficient data to derive the key factors that have affected the severity of deformation. It was concluded that stopbank damage is directly related to the presence of liquefaction in the ground materials beneath the stopbanks, but is not critical in determining the type or severity of damage, instead it is merely the triggering mechanism. Once liquefaction is triggered it is the gravity-induced deformation that causes the damage rather than the shaking duration. Lateral spreading and specifically the depositional setting was found to be the key aspect in determining the severity and type of deformation along the stopbank system. The presence or absence of abandoned or old river channels and point bar deposits was found to significantly influence the severity and type of deformation. A review of digital elevation models and old maps along the Kaiapoi River found that all of the ‘major to severe’ damage observed occurred within or directly adjacent to an abandoned river channel. Whilst a review of the geomorphology along the Avon River showed that every location within a point bar deposit suffered some form of damage, due to the depositional environment creating a deposit highly susceptible to liquefaction.