Spinel group minerals, found within various rock types, exhibit distinct categorizations based on their host rocks. According to Barnes and Roeder (2001), these minerals can be classified into eight primary groups, each further subdivided into variable numbers of subgroups that can be related to a particular tectonic setting. This classification is based on the cations corresponding to the end-members of the spinel prism and is traditionally analyzed in this prismatic space or using projections of it. In this prismatic representation, several categories tend to overlap, making it impossible to determine which is the tectonic environment in that scenario. An alternative to solve this problem is to generate representations of these groups considering more attributes, making the most of the many values measured during the geochemical analysis. In this paper, we present SpinelVA, a visual exploration tool that integrates Machine Learning techniques and allows the identification of groups using the cations considered by Barnes and Roeder and some additional ones obtained from chemical analysis. SpinelVA allows us to know the tectonic environment of unknown samples by categorizing them according to the Barnes and Roeder classification. Additionally, SpinelVA integrates a collection of visual analysis techniques alongside the already used spinel prism projections and provides a set of interactions that assist geologists in the exploration process. Users can perform a complete data analysis by combining the proposed techniques and associated interactions.

The continental lower crust constitutes a key zone for understanding the mantle-crust magmatic and mechanical transfers, but its study is hampered by the paucity of lower crust samples. Here, we characterise the petrological, geochemical and petrophysical processes structuring the lower crust of the North Patagonian Massif (NPM; Argentina) using a suite of representative mafic granulite and websterite xenoliths. These xenoliths were entrained by alkaline lavas from five volcanic centres that erupted between the Oligocene and Pleistocene. Electron microprobe and Laser Ablation Inductively Coupled Plasma Mass Spectrometer (LA-ICPMS) were used to obtain in situ geochemical data on the minerals, while microstructural data were obtained by Electron BackScatter Diffraction (EBSD). Both granulites and websterites display a granoblastic texture and sometimes a weak inherited magmatic layering. Mafic granulite xenoliths show a plagioclase + clinopyroxene +/- orthopyroxene assemblage commonly associated with spinel or titanomagnetite. Websterite xenoliths show an association of clinopyroxene + orthopyroxene + spinel, along with accessory plagioclase. Mafic granulites and websterites have SiO2 contents ranging from 44 to 53 wt %, while their Mg# varies from 53 to 79. Clinopyroxenes are characterised by weak convex upward chondrite-normalised Rare Earth Elements - REE patterns (Light-REE << Mid-REE > Heavy-REE) which are similar to clinopyroxene phenocrysts and megacrysts from intra-plate basalts. Calculated liquid in equilibrium with clinopyroxene have similar REE patterns to those found in Cenozoic basalts from the NPM, suggesting that the xenolith suite represents evidence for underplating processes, possibly related to one of the magmatic events that have occurred in the NPM since the Permo-Trias. Mafic granulites and websterites show a weak mineral shape preferred orientation and an associated weak Crystal Preferred Orientation (CPO) related to the magmatic layering. Recorded plastic deformation is associated with the activation of both (100)[001] and (001)[100] slip systems in clinopyroxene, (100)[001] in orthopyroxene and (010)[001] in plagioclase. However, the activation of slip systems is generally not correlated with CPO in granulites, suggesting that the lower crust underwent subsolidus equilibration and weak plastic deformation in an inactive tectonic context, thereby preserving an inherited magmatic layering. Two-pyroxene (Fe-Mg) thermometer and pseudosection calculations define P-T conditions of the main paragenesis at 760 degrees C to 1120 degrees C and 7.2 to 10.3 kbar, which allows to define the Cenozoic geotherm of the NPM crust at 30 degrees C/km and to reconsider the petrologic Moho depth at ca. 40 km.

In the geological context, the analysis of multidimensional data is a very common task and requires visualization techniques for exploration. General Line Coordinates (GLC) is a technique especially intended for lossless representation among the various techniques available for the visualization of multidimensional data. In this study, the application of GLC for pattern analysis and identification in mineral datasets is investigated. Furthermore, we develop a web-based tool to explore the possibility of employing GLC to leverage these approaches to derive visual discovery rules for pattern recognition.

El Fierro intrusive body is one of the bodies that compose the La Jovita-Las Aguilas mafic-ultramafic belt, located in the Sierra Grande de San Luis, Argentina. The units of this belt carry a base metal sulfide (BMS) mineralization and platinum group minerals (PGM). The macroscopic description of mafic and ultramafic rocks, as is usually done by the mining exploration companies, leads to an imprecise modal classification of the rocks. In this study, we develop a random forest-based prediction model, which uses geochemical parameters to classify mafic and ultramafic rocks intercepted by drill cores. This model showed an accuracy of between 86% and 94%, and an f1_score of 96%. Random forest classification is a widely adopted Machine Learning approach to construct predictive models across various research domains. However, as models become more complex, their interpretation can be considerably difficult. To interpret the model results, we use both global and local perspectives, incorporating the SHAP (SHapley Additive exPlanations) method. The SHAP technique allows us to analyze individual samples using force plots, and provides a measure of the importance of each geochemical input attribute in the model output. As a result of analyzing the contribution of each input feature to the model, the three variables with the highest contributions were identified in the following order: Al2O3, MgO, and Sr.

The Meseta de Coli Toro is a mafic volcanic plateau located in the Rio Negro province, north of Patagonia, Argentina. It belongs to the Somun Cura Massif geological province and its origin remains uncertain. The previous information concerning the volcanic rocks of Meseta de Coli Toro is limited to field outcrop and petrographic descriptions and one bulk rock geochemical analysis. Based on that information, the lavas were included in the Basalto Meseta Coli Toro unit. This contribution presents new petrographic and geochemical information from three different areas of the plateau: northeastern, central, and western, contributing to the knowledge of the origin and evolution of this volcanic plateau. Most of the studied lava flows classify as alkali basalts with OIB signature. Regarding their petrological features and geochemical signature the lava flows were linked to the Oligocene-Middle Miocene volcanism of the Meseta de Somuncur ' a in northern Patagonia, specifically to the Vulcanitas Corona Chico unit. Based on a published isotope analysis (87Sr/86Sr = 0.70439 and 143Nd/144Nd = 0.51275) and the petrological modelling proposed by other authors for the Vulcanitas Corona Chico unit, the lava flows of Basalto Meseta Coli Toro unit derived from 1 to 8% of partial melting of a spinelbearing pyroxenite source, with an isotopic composition equivalent to 96% of DM and 4% of EM1.

The Meseta de Somuncur acute accent a is the largest intraplate mafic volcanic field of north Patagonia, Argentina, whose origin is the subject of an ongoing debate and remains uncertain. This contribution presents petrographic, geochemical, and isotopic characteristics of trachybasalts and subordinated basaltic trachyandesites lava flows and basanite volcanic rocks located in the northwestern part of the Meseta de Somuncur acute accent a. The trachybasalts and subordinated basaltic trachyandesites lava flows have OIB signature and based on their isotopic composition (0.70406-0.70422 of 87Sr/86Sr and 0.512787-0.512817 of 143Nd/144Nd) and the petrological modelling, they derived from 1 to 5% of partial melting of a spinel-bearing pyroxenitic source, with an isotopic composition equivalent to 97% of DM and 3% of EM1. The basanites comprise a volcanic cone and lava flows of short extension located at the top of the volcanic stratigraphy of the meseta. They carry peridotite xenoliths and are slightly enriched compared with OIB standards. According to their isotopic composition (0.70407 of 87Sr/86Sr and 0.512772 of 143Nd/144Nd) and the petrological modelling, they derived from 0.1 to 1% of partial melting of a garnet-bearing peridotite, with an isotopic composition equivalent to 97% of DM and 3% of EM1, which was affected by metasomatism prior to its melting. Although both studied lithologies show mobile element ratios that suggest slab influence, that is more evident in the trachybasalts than in the basanites. These two groups of rocks were attributed to the early Miocene Vulcanitas Corona Chico unit. However, the new information presented in this contribution shows that the trachybasalts and subordinated basaltic trachyandesite lavas have geological characteristics equivalent to the Vulcanitas Corona Chico unit, while the basanites show differences with this unit. Therefore, we recommend to exclude the basanites from this group and assign them to a different volcanic unit, probably younger than the Vulcanitas Corona Chico unit. This new information and the geochemical data previously published for the basic volcanic units cropping out in the northwestern area of the meseta show an increase in the alkalinity with time, resulting in lower degrees of partial melting in the youngest lavas. In addition, geochemical and isotopic data suggest that the lavas from different volcanic units have distinct mantle sources. Although the volcanic rocks from Meseta de Somuncur acute accent a have some geochemical characteristics that could be explained by the presence of rising mantle plume(s), the model that so far best explains the geochemistry and isotopic composition of the volcanic rocks in this region is one that invoke the presence of a stagnant slab below Patagonia.

El bajo de El Cain es una depresion topografica ubicada en la provincia de Rio Negro, en el ambito de la Meseta de Somuncura, donde afloran numerosos diques, cuellos y conos volcanicos asi como cuerpos subvolcanicos, de composicion basica a intermedia. Estos cuerpos volcanicos y subvolcanicos corresponden a la Formacion Cerro Cortado, aunque en este sector carecen de estudios estratigraficos, petrograficos y geoquimicos de detalle. Se estudiaron tres cerros: Verdin, Herradura y El Morro en el sector del bajo de El Cain, cuyas relaciones estratigraficas con las demas unidades del area no son visibles en el campo. Estos, presentan morfologias de diques y conos volcanicos, y clasifican geoquimicamente como traquibasaltos y traquiandesitas basalticas con caracteristicas de intraplaca. Estas rocas son levemente evolucionadas respecto a otros basaltos de la Formacion Cerro Cortado y unidades equivalentes, y presentan caracteristicas geoquimicas comparables con las rocas del evento volcanico post-plateau cercanas al area de estudio. A pesar de que no se ha podido, hasta el momento, establecer una fuente de origen comun para estas rocas, se realizo un modelo petrogenetico de fusion parcial y se obtuvieron resultados consistentes con 1-5 % de fusion parcial de una peridotita moderadamente enriquecida y rica en granate.

El bajo de El Cain, donde afloran numerosos diques, cuellos y conos volcanicos asi como cuerpos subvolcanicos de composicion basica a intermedia, es una depresion topografica ubicada en la provincia de Rio Negro, en el ambito de la Meseta de Somuncura. Se estudiaron tres cerros: Verdin, Herradura y El Morro en el sector del bajo de El Cain correspondientes a la Formacion Cerro Cortado, del Eoceno, cuyas relaciones estratigraficas con las demas unidades del area no son visibles. Los afloramientos tienen morfologias de diques y conos volcanicos, y clasifican geoquimicamente como traquibasaltos y traquiandesitas basalticas con caracteristicas de intraplaca. Las rocas son levemente mas evolucionadas respecto a otros basaltos de la Formacion Cerro Cortado y unidades equivalentes, y presentan caracteristicas geoquimicas comparables con las unidades volcanicas miocenas cercanas al area de estudio. Se postula un posible origen comun para las rocas del bajo de El Cain mediante un modelo petrogenetico de fusion parcial, a partir del cual se obtuvieron resultados consistentes con 1-5% de fusion parcial de una peridotita moderadamente enriquecida y rica en granate.

Fil: Asiain, Lucia Montserrat. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Bahia Blanca. Instituto Geologico del Sur. Universidad Nacional del Sur. Departamento de Geologia. Instituto Geologico del Sur; Argentina. Universidad Nacional del Sur. Departamento de Geologia; Argentina

The spinel group minerals provide useful information regarding the geological environment in which the host rocks were formed, constituting excellent petrogenetic indicators, and guides in the search for mineral deposits of economic interest. In this article, we present the Spinel Web, a web application to visualize the chemical composition of spinel group minerals. Spinel Web integrates most of the diagrams commonly used for analyzing the chemical characteristics of the spinel group minerals. It incorporates parallel coordinates and a 3D representation of the spinel prisms. It also provides coordinated views and appropriate interactions for users to interact with their datasets. Spinel Web also supports semi-automatic categorization of the geological environment of formation through a standard Web browser.

En esta contribucion se documentan las caracteristicas petrograficas y geoquimicas de coladas lavicas expuestas en el sector noroestede la Meseta de Somuncura, correspondientes a la unidad Vulcanitas Corona Chico y a la facies basica del Complejo VolcanicoBarril Niyeu (Superunidad Quinelaf), ambas adjudicadas por varios autores al evento volcanico post-plateau. Las coladas lavicasestudiadas poseen predominantemente textura afirica seriada a microporfirica con microfenocristales de olivino y plagioclasa, enuna pasta integrada por plagioclasa, olivino, clinopiroxeno, minerales opacos y apatito. Quimicamente estas rocas se clasifican comotraquibasaltos y traquiandesitas basalticas de la suite alcalina sodica, con senal geoquimica similar a OIB y con anomalia relativapositiva de Ba. Sobre la base de trabajos de relevamiento de campo, estudios petrograficos y los primeros datos geoquimicos deroca total para la unidad Vulcanitas Corona Chico presentados en esta contribucion, se propone ampliar la caracterizacion de estaunidad informal, incorporando coladas de lava ampliamente distribuidas en el sector noroccidental de la meseta. Asimismo, se planteahomogeneizar y simplificar la nomenclatura de las unidades volcanicas referidas al evento post-plateau en el sector noroccidental dela meseta. De este modo, teniendo en cuenta que el evento post-plateau presenta variaciones composicionales, se recomienda hacerreferencia a las unidades volcanicas utilizando nombres formacionales o de complejos volcanicos segun corresponda, limitando eluso de los terminos plateau y post-plateau unicamente para indicar la temporalidad de tales eventos volcanicos.

Gathering data on the field is a crucial task in many disciplines. Moreover, in the Geosciences the GPS positioning is relevant to the data acquisition as well as to the planning of the fieldwork. Nowadays, mobile devices are widespread, constituting an accessible platform consisting of single devices coupled with different sensors for data acquisition, such as GPS, compass, magnetometer, etc. Emerging technologies such as Augmented Reality (AR) enable the use of these devices as a software platform to complement the perception of our surrounding environment. Despite the fact that there are several AR applications focused on different aspects of Geosciences, a comprehensive fieldwork oriented system, which can be easily adapted to the community needs, is still missing. Based on a multidisciplinary work between professionals from Geosciences and Computer Sciences, we designed and developed a framework based AR system named ARGeo. The proposed system constitutes a complementing tool for the geologist's fieldwork carefully designed to be used in remote sites, using only the mobile device hardware and without the need of an internet connection for data acquisition.ARGeo complements the fieldwork observation and the precise recording of geological data needed, e.g., for the interpretation of folded structures. It allows the user to register geo-tagged information such as points of interests (i.e. references on the field or the fold itself) using natural interactions. In addition, it provides two novel features: an interactive dipping plane measurement from distant points of view and a back-in-time visualization of previous recorded positions, in order to help understanding the spatial relations among the recorded samples. Pilot studies were conducted with domain experts of geology and they agree on the potential of the system. Results point out that ARGeo naturally integrates mobile devices and AR to the geologists' fieldwork. Its possible extension with new features to the Geosciences as well as to other application fields is detailed.

Spinel-group minerals are excellent indicators of geological environments and are of invaluable help in the search for mineral deposits of economic interest. The geologists analyze them by means of Barnes and Roeder's contours. In this paper, we present a collection of novel, interactive methods, which assist geologists in the categorization of spinel-group minerals. We fully integrate Barnes and Roeder's contours using a polygonal representation. This makes it possible to efficiently superimpose user-provided point data over the contours, and to automatically rank the contours based on the number of enclosed points. We also allow the expert to create contours for the user-provided point data. Once user contours are created, they can be compared with Barnes and Roeder's contours. During the analysis, the user can drill-down by means of brushing. As we deal with specific data, we apply two novel brushing techniques, i.e., the percentile brush and the contour brush. The novel brushing mechanisms along with the interactive comparison speed-up the analysis significantly. We evaluate the newly introduced approach and the resulting novel workflow using real-word data from different locations in Argentina. According to the domain experts, the classification of spinel minerals needs several minutes now, while it took a few days with the current state of the art approach in the domain.

The Virorco layered mafic-ultramafic intrusion is part of a belt that extends over 100 km from NE to SW in the Eastern Sierras Pampeanas of San Luis, Argentina, The rocks of this belt carry a Fe-Cu-Ni sulphide mineralization in veins and as disseminated and massive ore. Platinum group minerals are associated with the sulphides. The Virorco intrusion exhibits modal, textural and cryptic layering. New results allow the characterization of six layered units (Modal Layered Unit, Pyroxenitic Macro-Layered Unit, Gabbroic Unit, Banded Unit, Hornblende Norite Unit and Gabbronorite Unit) present in three sectors of the intrusion (Eastern, Central and Western). The units from the Western Sector (Banded Unit, Hornblende Norite Unit and Gabbronorite Unit) and the Modal Layered Unit from the Eastern Sector belong to the Marginal Border Series of the intrusion. Meanwhile, the Central sector units (Pyroxenitic Macro-Layered Unit and Gabbroic Unit) are from the Layered Series. The presence of crescumulate texture (Modal Layered Unit) and colloform banding (Banded Unit) are evidences of "in situ" crystallization due to supercooling of a MgO-rich hydrated mafic magma, where cooling proceeded from the walls towards the interior of the magma chamber. In previous studies the mafic-ultramafic rocks have been considered to be Cambrian to Ordovician. Here we present a Sm-Nd whole rock isochron which shows that the formation age of these intrusions is 1002 +/- 150 Ma and that the protolith age of the Pringles Metamorphic Complex metasedimentary rocks is 1289 +/- 97 Ma. Our study also indicates that the San Luis mafic-ultramafic layered intrusives most probably formed in a back-arc tectonic setting, from an enriched sub-continental mantle, influenced by a subducting slab and/or crust injection into the Pampia Terrane prior to its collision with the Rio de la Plata Craton. (C) 2017 Elsevier Ltd. All rights reserved.

En el sector noroccidental de la Meseta de Somuncura, afloran rocas volcanicas basicas con caracteristicas petro-mineralogicas y geoquimicas que permiten diferenciarlas en dos grupos: A) Rocas lavicas con fenocristales de ortopiroxeno que desarrollan bordes de reaccion con la pasta, ademas de fenocristales de plagioclasa y olivino subordinado, en una mesostasis de textura intersertal compuesta por plagioclasa, augita titanifera y olivino. Corresponden a andesitas basalticas transicionales entre alcalinas y subalcalinas, con tendencia geoquimica entre los patrones EMORB y OIB. Presentan anomalias relativas positivas en Ba y Sr. B) Rocas lavicas con fenocristales de plagioclasa y olivino subordinado, en una pasta de textura intersertal con plagioclasa, augita titanifera y olivino. Son traquibasaltos con caracteristicas geoquimicas similares al patron de OIB. Poseen anomalias relativas positiva en Ba y negativa en Zr. Teniendo en cuenta los aspectos antes mencionados y los estudios previos realizados en el area de la meseta, se propone la correspondencia de estos grupos con la Formacion Somuncura ( plateau ) y la Superunidad Quinelaf (post- plateau ), respectivamente. Por otra parte, en el area de estudio, se han reconocido depositos volcaniclasticos interdigitados entre las coladas basicas, en sectores donde no habian sido mencionados previamente. Tales depositos estan expuestos principalmente en los bajos topograficos, aunque no siempre aflora la base sobre la cual se apoyan. Las caracteristicas observadas en estos niveles volcaniclasticos resultan insuficientes, sin embargo, para asignarlos a una formacion previamente definida.

Luján Ganuza, Juan Manuel Trippel Nagel, Nicolás Gazcón, Silvia Castro, Ernesto Bjerg, Florencia Gargiulo, Gabriela Ferracutti, Krešimir Matković y Eduard Gröller 1 Lab. de Investigación y Desarrollo en Visualización y Computación Gráfica (VyGLab) Departamento de Ciencias e Ingeniería de la Computación, Universidad Nacional del Sur 2 INGEOSUR y Departamento de Geología, Universidad Nacional del Sur 3 Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) 4 VRVis Research Center, Vienna, Austria 5 Technische Universität Wien, Institut für Computergraphik und Algorithmen, Vienna, Austria

We explore if and how immersive analytics, in particular AR and Sketch-Like Visualization, can be used to support the geologists’ field workflow. Fieldwork involves careful observations and measurements in the field, the collection of rock and fossil samples and the recording of complementary information for further analysis. In the field, the workflow comprises in-situ hand drawing of sketches through careful observation of the area to be explored and the incorporation of all the data that the geologist collects in the field to these drawings. This implies that a constant association of 2D (sketch)-3D (real environment) information is being carried out at all times, taking into account a previously defined scale of work. Our main goal is to support the field workflow integrating the real environment with an automatically generated sketch to facilitate the geologists’ fieldwork. Our system is based on an interactive AR approach on mobile devices. We evaluated the introduced approach using a real-life case study. User feedback and observations from our interdisciplinary team indicate the utility of the approach for the current case study as well as some shortcomings and areas for future research.