scholarly journals Petrology of Gameleira potassic lamprophyres, São Francisco Craton

2012 ◽  
Vol 84 (2) ◽  
pp. 377-398 ◽  
Author(s):  
Jorge Plá Cid ◽  
Cristiani S. Campos ◽  
Lauro V.S. Nardi ◽  
Luana Florisbal
Keyword(s):  
High Growth ◽  
Alkali Feldspar ◽  
High Growth Rate ◽  
Alkaline Magmatism ◽  
Mantle Heterogeneities ◽  
Microgranular Enclaves ◽  
Mafic Microgranular Enclaves ◽  
Liquid Chemical ◽  
Reverse Zoning ◽  
Basic Rocks

Gameleira lamprophyres are dykes and mafic microgranular enclaves associated with the shoshonitic Gameleira monzonite. This association belongs to the Paleoproterozoic alkaline magmatism from Serrinha nucleus, northeast Brazil. The liquidus paragenesis is diopside, pargasite, apatite and mica. Reverse zoning was identified in the groundmass alkali feldspar and was related to the undercooling of lamprophyric magma during the emplacement, with high growth rate of pargasite/edenite inducing disequilibrium between feldspars and liquid. Chemical data indicate that the lamprophyres are basic rocks (SiO2 < 48 wt%), with alkaline character (Na2O + K2O > 3 wt%) and potassic signature (K2O/Na2O ≈ 2). High contents of MgO and Cr are consistent with a signature of a primary liquid, and such concentrations, as well as Al, K, P, Ba, Ni- and light rare earth elements, are consistent with an olivine-free metasomatic mantle source enriched in amphibole, clinopyroxene and apatite. By contrast, the ultrapotassic lamprophyres from Morro do Afonso, contemporaneous alkaline ultrapotassic magmatism in Serrinha nucleus, were probably produced by melting of a clinopyroxene-phlogopite-apatite enriched-source. The identification of different mineral paragenesis in the source of potassic and ultrapotassic lamprophyres from Serrinha nucleus can contribute to the understanding of the mantle heterogeneities and tectonic evolution of this region.

scholarly journals Geoquímica das Rochas Máficas Toleíticas da Suíte Pós-Colisional Paulo Lopes, Neoproterozóico do Sul do Brasil

2005 ◽  
Vol 32 (2) ◽  
pp. 69 ◽  
Author(s):  
LUANA MOREIRA FLORISBAL ◽  
LAURO NARDI ◽  
MARIA DE FÁTIMA BITENCOURT ◽  
LEANDRO MENEZES BETIOLLO
Keyword(s):  
Coarse Grained ◽  
Main Body ◽  
Chronological Order ◽  
Orientation Field ◽  
Rapid Crystallization ◽  
Magmatic Rocks ◽  
Microgranular Enclaves ◽  
Mafic Microgranular Enclaves ◽  
Basic Rocks

The Paulo Lopes Suite (SPL), composed of the Paulo Lopes Granite (GPL), Garopaba Granitoids (GG) and Silveira Gabbro (GS), is an association of contemporaneous acid and basic rocks, comprising monzo and syenogranites associated to basic dikes, with abundant mafic microgranular enclaves, interpreted as co-mingling products. The contacts between the granitoids and the basic rocks are evidences of coeval and interactive magmas. The Silveira Gabbro occurs in the study area as a main body and several narrow dikes of NNE orientation. Field relations define a chronological order of magmatic events, where the GPL is the first magmatic pulse and, while steel partially crystallized, was intruded by mingled magmas, represented by the GG and the GS. The basic components are medium-grained, equigranular rocks, with subophitic and ophitic textures. The centre of the main body contains medium- to coarse-grained, equigranular rocks, where agglomerates of early-formed clinopyroxene and plagioclase crystals are found. In the chilled margins, they are microporphyritc rocks of aphanitic groundmass, indicative of rapid crystallization. The Silveira Gabbro rocks are composed of labradorite-andesine, orthopyroxene, augite, pigeonite, olivine (occasionally serpentinized), Fe-hornblende and magnesian hornblende, red biotite, magnetite, ilmenite, apatite, and baddeleyite. The composition is tholeiitic, similar to the high-Ti-P basalts of the Serra Geral Formation. Their high contents of K, Rb, Sr and Ba, as well as negative anomalies of Nb and Ta in multielemental diagrams are similar to the ones observed in magmatic rocks from mature arcs or post-collisional environments. The Neoproterozoic basic rocks may be discriminated from the ones belonging to the Cretaceous Serra Geral Formation by their higher contents of alcalis, Cs, U, Th, and by their fractionated REEpatterns, expressed in the La/LuN ratio. The associated granitoids are structural and compositionally compatible with the ones found in post collisional settings, which indicates that the SPL magmatism developed in such environment.

scholarly journals Textural Relations of Lamprophyric Mafic Microgranular Enclaves and Petrological Implications for the Genesis of Potassic Syenitic Magmas: the example of Piquiri Syenite, southern Brazil

2002 ◽  
Vol 29 (2) ◽  
pp. 21 ◽  
Author(s):  
JORGE PLÁ CID ◽  
LAURO VALENTIM STOLL NARDI ◽  
PERE ENRIQUE GISBERT
Keyword(s):  
Alkali Feldspar ◽  
Textural Features ◽  
Southern Brazil ◽  
Mineral Phase ◽  
Mineral Phases ◽  
Microgranular Enclaves ◽  
Mafic Microgranular Enclaves ◽  
Textural Relationship ◽  
Important Evidence ◽  
Liquidus Temperatures

The Neoproterozoic Piquiri Syenite exhibits a large amount of mafic microgranular enclaves (MME) with elliptical-shape and millimeter to centimeter-size dimensions. These enclaves were originated by co-mingling of minettetype lamprophyre and potassic syenite magmas, producing the typical textural features of quenched magmas. They show elongated crystals of diopside and Mg-biotite, and acicular apatite. Early crystallized phases are represented by the same minerals, which occur as phenocrysts (diopside + Mg-biotite) and euhedral smaller crystals (apatite). The textural relationship and the identification of mineral phases as K-clinopyroxene and pyrope in the MME, suggest that mingling started at mantle conditions, when lamprophyric and syenitic magmas were near crystal-free and close to liquidus temperatures. The absence of syenite xenocrysts and chilled-margins in MME, are consistent with the high temperature of co-mingling. Alkali feldspar laths that poikilitically enclose quenched phases, represent late-magmatic mineral phase. The Piquiri Syenite MME represent a quite rare example of co-mingling between lamprophyre and intermediate magmas, and represents important evidence for the genesis of potassic silica-saturated magmas at mantle conditions.

The Job Of Microfinance For The Advancement Of Self Help Groups In India

2019 ◽  
Vol 118 (8) ◽  
pp. 236-240
Author(s):  
Dr.R. Murugesan ◽  
M. Leelavathi ◽  
Dr. K. Ravindran
Keyword(s):  
High Growth ◽  
High Growth Rate ◽  
Entrepreneurial Skills ◽  
Self Help ◽  
The Poor ◽  
Total Food ◽  
Self Help Groups ◽  
Positive Step ◽  
Food Consumed

towards jumping from the category of developing economy to developed economy there is one big factor that stops and poses a hindrance in its path of advancement and that obstacle is termed as Poverty. The Indian economic policy focuses on a high growth rate along with a equal participation of the poor so that they avail the opportunities available in the market economy. And in order to ensure the participation of the poor it has become important for the country to create a platform where the poor can easily access the various financial products. Microfinance is one such strategy for inclusive growth. Microfinance can change the life of the poor though not completely but a reasonable change can be ensured. In different phases of life women play a crucial role despite the discrimination that is faced by them. But equality can be endowed to women by enhancing the entrepreneurial skills in them. This is possible through Self Help Groups (SHGs). In India women produce around 30% of the total food consumed but she gets only 10% of the property or wealth of the country. Development of women is inevitable for the development and growth of any economy. SHGs happen to be a positive step in this direction. Along with these mediums there should be a cheap and easy source of credit for them and Microfinance fulfills the requirement. This study aims to find the role of this strong medium of Microfinance in the advancement of SHGs in India

Exploring SiC Growth Limitation of Vapor-Liquid-Solid Mechanism when Using Two Different Carbon Precursors

2013 ◽  
Vol 740-742 ◽  
pp. 323-326
Author(s):  
Kassem Alassaad ◽  
François Cauwet ◽  
Davy Carole ◽  
Véronique Soulière ◽  
Gabriel Ferro
Keyword(s):  
Growth Rate ◽  
High Growth ◽  
High Growth Rate ◽  
Carbon Precursor ◽  
Growth Limitation ◽  
Vapor Liquid Solid ◽  
Partial Pressures ◽  
Vapor Liquid Solid Mechanism ◽  
Vls Growth ◽  
Vapor Liquid

Abstract. In this paper, conditions for obtaining high growth rate during epitaxial growth of SiC by vapor-liquid-solid mechanism are investigated. The alloys studied were Ge-Si, Al-Si and Al-Ge-Si with various compositions. Temperature was varied between 1100 and 1300°C and the carbon precursor was either propane or methane. The variation of layers thickness was studied at low and high precursor partial pressure. It was found that growth rates obtained with both methane and propane are rather similar at low precursor partial pressures. However, when using Ge based melts, the use of high propane flux leads to the formation of a SiC crust on top of the liquid, which limits the growth by VLS. But when methane is used, even at extremely high flux (up to 100 sccm), no crust could be detected on top of the liquid while the deposit thickness was still rather small (between 1.12 μm and 1.30 μm). When using Al-Si alloys, no crust was also observed under 100 sccm methane but the thickness was as high as 11.5 µm after 30 min growth. It is proposed that the upper limitation of VLS growth rate depends mainly on C solubility of the liquid phase.

scholarly journals Influence of Adding Encapsulated Phase Change Materials in Aerial Lime Based Mortars

2013 ◽  
Vol 687 ◽  
pp. 255-261 ◽  
Author(s):  
Sandra Cunha ◽  
José Barroso Aguiar ◽  
Victor Ferreira ◽  
António Tadeu
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Renewable Energy Sources ◽  
High Growth ◽  
High Energy ◽  
High Growth Rate ◽  
Aesthetic Appearance ◽  
Hardened State ◽  
High Energy Consumption

Increasingly in a society with a high growth rate and standards of comfort, the need to minimize the currently high energy consumption by taking advantage of renewable energy sources arises. The mortars with incorporation of phase change materials (PCM) have the ability to regulate the temperature inside buildings, contributing for an increase in the level of thermal comfort and reduction of the use of heating, ventilation and air conditioning (HVAC) equipment, using only the energy supplied by the sun. However, the incorporation of PCM in mortars modifies some of its characteristics. Therefore, the main objective of this study was the characterization of mortars doped with two different phase change materials. Specific properties of different PCM, such as particle size, shape and enthalpy were studied, as well as the properties of the fresh and hardened state of these mortars. Nine different compositions were developed which were initially doped with microcapsules of PCM A and subsequently doped with microcapsules of PCM B. It was possible to observe that the incorporation of phase change materials in mortars causes differences in properties such as compressive strength, flexural strength and shrinkage. After the study of the behaviour of these mortars with the incorporation of two different phase change materials, it was possible to select the composition with a better compromise between its aesthetic appearance, physical and mechanical characteristics.

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