Quartz from different zones within five granitic pegmatites of the rare-element class from the Borborema Pegmatite Province in northeast Brazil were analysed for fourteen trace elements using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The concentrations of Li (6À150 ppm), B (1À9 ppm) and Ge (1À23 ppm) in quartz show a positive correlation with Al (30À770 ppm). The concentrations of these elements increase from the border zone to the quartz core of pegmatites of the spodumene or lepidolite subtypes. The Ge concentrations in the quartz core are the highest so far reported in igneous quartz. In the less evolved pegmatites of the beryl-columbite subtype, the Al, Li, B, and Ge concentrations in quartz from all zones remain at the same level as the border and wall zones. The Ti concentrations in quartz from the core of the more evolved pegmatites are below 3 ppm (with Al >250 ppm), contrasting with 7À25 ppm (with Al <280 ppm) in samples from the border and wall zones of the less evolved and more evolved pegmatites. The concentrations of Al, Li, B, Ge, and Ti in quartz are therefore confirmed as good indicators of the degree of magma fractionation and analyses of pegmatite quartz cores can be used for exploration purposes to distinguish pegmatites with high metallogenic potential. Atoms of Li and Al are incorporated into quartz such that Li/Al ranges between 0.75 and 1.0. This suggests a coupled substitution of the form Si 4+ $ (Li + + Al 3+ ). The other elements analysed either showed an erratic distribution (e.g. Be and P) or were below the respective limits of detection (Na, K, Rb, Ca, Sr, Mn, Fe) in most samples.

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The objective of this research is to evaluate the engineering students' perception regarding sustainability. For this, a survey was developed based on sustainability parameters from a detailed analysis of the Global Reporting Initiative (GRI) and the Brazilian Institute of Corporate Governance (IBGC). The parameters were initially divided into seven groups: Financial and Productivity Aspects (FPA); Concern with employees (CWE); Support for Local Communities (SLC); Ethical and corporate governance issues (ECI); Environmental aspects (ENA); Sustainable aspects in the operations network (SON); Customers, development of new products and services (CPS). The survey was conducted with engineering undergraduate students from two Brazilian universities. The data were analyzed through structural equation modeling technique, more precisely by means of the PLS-SEM algorithm. We obtained 162 answers, which enabled the validation of the model tested, and showed that the students, in general, do not consider support for local communities and concern with employees when they are analyzing sustainability. Additionally, the most important construct for them is the customers, development of new products and services. This is an exploratory study and we believe that these findings may contribute to expand the debate about the sustainability insertion in engineering courses, helping educators in their didactic activities. As future research, it is suggested the replication of this study in other higher education institutions.

Tourmalines of intermediate schorl-dravite composition occur in iron formation (including metachert and tourmalinites), metasediments, calc-silicate and metabasic/intermediate rocks of the Morro da Pedra Preta Formation, a volcanic-sedimentary sequence of the Serra do Itaberaba Group (northeast of São Paulo City, southeastern Brazil). The Morro da Pedra Preta Formation is crosscut by quartz veins that contain both intermediate schorl-dravite and an alkali-deficient, Cr-(V-)bearing tourmaline, in which the occupancy of the X-site is 0.51 Ca 0.33 Na 0.15 , characterizing it as intermediate to foitite and magnesiofoitite endmembers. Mg# values for this tourmaline are higher than those for intermediate schorl-dravite. Raman spectroscopy also confirms the presence of two groups of tourmalines. Stable isotope data indicate sediment waters as fluid sources, rather than fluids from magmatic/post-magmatic sources. Delta 18 O compositions for tourmalines, host metachert, and quartz veins are similar, showing that fluid equilibration occurred during crystallization of both quartz and tourmaline. Syngenetic, intermediate schorl-dravite tourmalines were formed under submarine, sedimentaryexhalative conditions; amphibolite-grade metamorphism did not strongly affect their compositions. Younger tourmalines of compositions intermediate to foitite and magnesiofoitite reflect the composition of the host rocks of quartz veins, due to fluid percolation along faults and fractures that caused leaching of Cr (and V) and the crystallization of these alkali-deficient, Cr-(V-)bearing tourmalines.

Abstract-Petrographic and geochemical data obtained on the Araguainha impact crater (Goi as/Mato Grosso States, Brazil) indicate the existence of several molten products that originated during impact-induced congruent melting of an alkali-granite exposed in the inner part of the central uplift of the structure. Although previous studies have described these melts to some extent, there is no detailed discussion on the petrographic and geochemical variability in the granite and its impactogenic derivatives, and therefore, little is known about the geochemical behavior and mobility of trace elements during its fusion in the central part of the Araguainha crater. This paper demonstrates that the preserved granitoid exposed in the core of the structure is a magnesium-rich granite, similar to postcollisional, A-type granites, also found in terrains outside the Araguainha crater, in the Bras ılia orogenic belt. The molten products are texturally distinct and different from the original rock, but have very similar geochemical composition, making it difficult to separate these lithotypes based on concentrations of major and minor elements. This also applies for trace and rare earth elements (REE), thus indicating a high degree of homogenization during impact-induced congruent melting under high pressure and postshock temperature conditions. Petrographic observations, along with geochemical data, indicate that melting occurs selectively, where some of the elements are transported with the melt. Simultaneously, there is an effective dissolution of the rock (granite), which leads to entrainment of the most resistant solid phases (intact or partially molten minerals) into the melt. Minerals more resistant to melting, such as quartz and oxides, contribute substantially to a chemical balance between the preserved granite and the fusion products generated during the meteoritic impact.

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Terra Nova, 23, 225–231, 2011 Abstract Biotite is an abundant hydrous silicate in the Earth’s crust and plays a critical role in the formation of felsic magmas via incongruent melting. Although biotite incongruent melting reactions have been described for various contact and regional metamorphic environments, the effects of impact‐induced melting of biotite remain poorly understood. Our observations from the 40‐km‐wide Araguainha impact structure indicate that biotite can undergo incongruent melting during impact processes, producing aluminous melts that can accumulate as pockets or fracture networks in crystalline target rocks. We observed that as much as 9% of the crystalline target at Araguainha is a crystallization product after biotite breakdown. Given the relatively low shock pressures recorded in the Araguainha central uplift (20–25 GPa), our results imply that impacts in the size of Araguainha or larger are capable of generating substantial volumes of incongruent aluminous melts in crystalline crust underlying large (>40 km diameter) impact structures.

Intergrowths of orthorhombic and tetragonal Nb-Ta-Ti-(Sn) oxides were at first recognized by conventional X-ray diffraction and electron-microprobe analyses in six pegmatite occurrences of the Borborema Pegmatitic Province in northeastern Brazil. In three of these cases, electron-diffraction patterns (HRTEM) on chips 0.15 mm thick obtained by focused ion-beam (FIB) sampling were necessary to confirm the preliminary identification of titanian ixiolite. Electron-microprobe analyses reveal very variable bulk-compositions and extents of compositional gaps between the coexisting tetragonal and orthorhombic phases in the Nb,Ta -Ti,Sn -Fe,Mn triangular plot. This behavior is difficult to explain as a result of a simple solvus along a pseudobinary section between rutile and tapiolite -columbite -ixiolite -wodginite. In two of six cases, the data obtained plot exactly within the compositional gaps observed between these phases in other pegmatitic provinces. This apparent violation of the gap is due to abnormally high Ti-contents in ixiolite and high levels of Ta + Nb (up to 55 wt.% Nb + Ta oxides) observed in the tetragonal phase. Therefore, in the cases studied, the observed trends and gaps seem to be the result of disequilibrium (or incomplete equilibrium) between the coexisting phases, despite the exsolution-like, cuneiform to vermicular intergrowths observed in three of the occurrences studied. Compositional growth-zoning observed in the other cases agrees with the hypothesis of disequilibrium. In five of the six cases, a partition of Ta and Fe in favor of the tetragonal phase and of Nb and Mn in the coexisting orthorhombic phase is observed; it agrees with the behavior of similar intergrowths elsewhere. The sixth case is noteworthy because of the higher Ta:Nb ratio in the ixiolite in comparison with the coexisting niobian rutile. This enrichment of Nb and Fe from core to rim represents an anomalous pattern of fractionation behavior. tHE caNadiaN miNEraLogiSt SommairE Nous avons d'abord documenté la présence d'oxydes orthorhombique et tétragonal de Nb-Ta-Ti-(Sn) par approche conventionnelle avec diffraction X et analyses par microsonde électronique dans six exemples de pegmatite granitiques de la province pegmatitique de Borborema, dans le nord-est du Brésil. Dans trois des cas, nous avons de plus eu recours à la diffraction d'électrons en microscopie électronique par transmission; nous avons analysé des pellicules d'une épaisseur de 0.15 mm, obtenues par échantillonage avec un faisceau d'ions focalisé (FIB) afin de confirmer notre identification préliminaire de l'ixiolite titanifère. Les analyses à la microsonde électronique révèlent des compositions globales et des étendues des lacunes de miscibilité très variables entre les phases tétragonale et orthorhombique coexistantes dans un diagramme triangulaire Nb,Ta -Ti,Sn -Fe,Mn. Ce comportement est très difficile à expliquer en termes d'un simple solvus dans une section pseudobinaire entre rutile et tapiolite -columbite -ixiolite -wodginite. Dans deux des six cas, les p...