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Humans are part of nature, so natural landscapes can contain human impacts. The limit of this natural anthropomorphic influence, where landscape stops being natural, is not defined clearly, but major infrastructure, urbanization etc. are clearly non-natural elements. When a natural feature becomes important for humans, such as the iconic Puy de Dôme volcano in central France, it tends to attract human modification. The Puy de Dôme was a Druidic and Roman sacred site, with added temples and paths. Yet, outside these, the majority of the mountain remained in a natural state, evolving by erosion, slope movement, and accumulating debris on its lower flanks. The natural state can still be seen in the detailed morphometry of its flanks. Since the turn of the 20th century, increased human activity has further modified the site, with the construction of a spiral cog railway track, and infrastructure: restaurants, observatories, military and communication buildings, including the iconic spike - that inhabitants are so attached to. Despite this increased activity, the essential natural values of the mountain have been mostly maintained, although the spiral railway track has cut / modified the natural drainage to some extent. With UNESCO World Heritage inscription in 2018, visitation is on the increase, and with more visitors, further pressure has been seen. Occasional debris flows and landslides have also become newsworthy events, impacting the railway operation. New slope stability plans have been drawn up for the cog railway and the footpaths, which have included large scale bolting of outcrops, wire meshing and rock removal. These have been implemented only very partially due to opposition from ecology and geoheritage actors. To provide a clear picture of the natural state of the Puy de Dôme and to guide natural protection and risk management, a full geomorphological and morphometric analysis is needed. This abstract gives the first results of this work, presenting the geomorphology and morphometry, including a geomorphon and shape analysis, and 3-D Virtual Reality LiDAR topography. The resulting information allows us to determine the state of 'naturality' of the Puy de Dôme and establish the natural system and determine its anthropogenic influences. The volcano, since its eruption 11,000 years ago, has been slowly evolving under different climatic regimes, that have contributed to its present shape. Ongoing processes, which include natural-compatible pastoral and forest activity continue to shape the dome.Despite the human presence, the volcano is large enough to presently maintain its natural evolution in the long term and adapt to changing climatic conditions. However, there are many sites of concern, where installations have the potential to alter this, and to generate enhanced risk to the geological nature and to visitors. With our analysis, we can propose management strategies that can minimize impact, can be monitored, and which can protect the geoheritage and the fragile ecology, while allowing continued access to the site. Human access needs to respect and to be adapted to the natural conditions.

The A-type Huaco granite pluton of the Velasco range (Sierras Pampeanas of northwest Argentina) is formed by three coeval granitic facies and contains subordinate coeval-to-late facies, as well as enclaves, dikes and stocks that show different temporal relations, textures and compositions. The dominant facies (Regional Porphyritic Granite; RPG) is a porphyritic two-mica monzo- to syenogranite, with abundant microcline megacrysts up to 12 cm in size. It was emplaced in a dominant extensional setting and has a mainly crustal source but with participation of a mantle-derived component. The RPG transitions towards two coeval and co-genetic granite facies, at its margins (Border Granite; BG) and around Be-pegmatites (Adjacent Porphyritic Granite; APG). These two facies have a finer-grained texture and smaller and less abundant megacrysts. They are also monzo- to syenogranites, but a slight decrease in the biotite/muscovite ratio is observed from the BG to the RPG to the APG. Trace element modeling suggests that the RPG, BG and APG differentiated from the same magma source by fractional crystallization. Temporally older mafic (ME) and felsic (FE) enclaves are common in the pluton. The ME can be considered partially assimilated remnants of a mafic component in the genesis of the RPG, whereas the FE seem to be remnants of premature aplites. Other subordinate rocks intrude the RPG and are, hence, temporally younger: felsic dikes (FD), dioritic dikes (DD) and equiganular granites (EqG) are clearly posterior, whereas coeval-to-late Be-pegmatites (BeP) and orbicular granites (OG) formed during the final stages of crystallization of the pluton. The BeP, OG and FD indicate the presence of abundant water and volatiles. The EqG form small stocks that intrude the RPG and were possibly originated from purely crustal sources. The DD probably correspond to a younger unrelated episode of mafic magmatism. RESUMEN El Plutón Huaco, ubicado en la sierra de Velasco (en Sierras Pampeanas del noroeste de Argentina), es de afinidad granítica A y está conformado por tres facies graníticas y contiene varias rocas ígneas subordinadas, las que muestran diferentes relaciones temporales, texturas y composiciones. La facies granítica dominante (Granito Porfírico Regional; RPG) es un monzo-sienogranito de dos micas, de textura porfírica con abundantes megacristales de microclino que pueden alcanzar hasta 12 cm de longitud. Ha sido emplazado en un marco tectónico dominantemente extensional y habría tenido una fuente de origen cortical pero también con participación de componentes mantélicos. En los bordes del Plutón Huaco y envolviendo a pegmatitas de berilo contenidas en el mismo (BeP), se reconocen las facies cogenéticas BG y APG respectivamente, las cuales tienen contacto transicional con el RPG. Estas dos facies tienen textura de grano más fino y megacristales de menor tamaño y menos abundante que la unidad principal RPG. También son de composición monzo-sienogranítica y se observa un decrecimiento de la relación biotita/muscovita en el sentido BG-RPG-APG. Estas tres facies graníticas cogenéticas habrían sido formadas por procesos de cristalización fraccionada a partir de un mismo magma de acuerdo al modelado geoquímico utilizando elementos traza. Además, el plutón contiene enclaves máficos (ME) y félsicos (FE) los cuales se formaron temporalmente con anterioridad a la facies granítica dominante. Los ME pueden ser considerados como remanentes asimilados de un componente máfico durante la génesis del RPG, mientras que los FE podrían corresponder a remanentes de aplitas prematuras. Otras rocas subordinadas intruyen al RPG y por lo tanto son consideradas temporalmente posteriores: diques félsicos (FD), diques dioríticos (DD) y granitos de texturas equigranulares (EqG) son claramente posteriores, mientras que las BeP y un granito orbicular (OG) se formaron durante los estadios finales de cristalización del plutón. Las BeP, OG y FD indican la presencia de abundante agua y volátiles. Los EqG forman pequeños stocks que intruyen al RPG y se habrían formado a partir de una fuente puramente cortical. Los DD probablemente correspondan a un episodio independiente más joven de magmatismo máfico.

La Puna es una región volcánica activa que forma parte de la Zona VolcánicaCentral de los Andes. Contiene tres tipos principales de volcanes: (1) Estratovolcanes: edificios generados por la acumulación de productos volcánicos durante un período de tiempo prolongado. Presentan variada morfología desde conos simples a macizos complejos. Sus productos, mayormente de composición andesítica y dacítica, consisten en coladas de lava, domos de lava y en menor medida depósitos piroclásticos. (2) Calderas de colapso: depresiones generadaspor grandes erupciones asociadas al vaciamiento de cámaras magmáticas. Producenextensos depósitos de flujos piroclásticos (ignimbritas) de composiciones mayormente dacíticas y riolíticas. (3) Conos de escoria y coladas de lava asociadas: producidos por volcanismo monogenético, de corta duración y escaso volumen; de composiciones mayormente andesitas basálticas. El volcanismo en la Puna tiene registros a partir de ~26 Ma, cobrando intensidad desde los ~15 Ma hasta el presente. Entre los ~15-8 Ma se construyeron numerosos estratovolcanes y calderas, principalmente a lo largo de lineamientos transversales NO-SE y en el borde oriental de la Puna. Entre los ~8-3 Ma el arco volcánico principal se estableció en su posición actual sobre el borde occidental de la Puna, con el desarrollo de estratovolcanes, mientras que calderas y centros máficos se generaron en el retroarco. La construcción de estratovolcanes sobre el arco principal continuó durante el Cuaternario y persiste en la actualidad.En el interior de la Puna la actividad cuaternaria se limitó a la Puna austral, con el desarrollo de centros máficos y tres calderas. Fil: Grosse, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación Miguel Lillo. Dirección de Geología. Instituto de Minerología y Petrografia; Argentina Fil: Guzman, Silvina Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina. Consejo Superior de Investigaciones Científicas; España

Este trabajo fue presentado en el XX Congreso Geológico Argentino, realizado en Tucumán en el año 2017, cuyo título y eje temático fue ¨Ciencias de la Tierra y los recursos naturales del NOA¨. En el Repositorio del SEGEMAR se suben únicamente los trabajos realizados por profesionales de nuestra institución, más cabe la aclaración que los mismos están compilados en un relatorio más amplio, del cual, conjuntamente con el presente trabajo, se adjunta el índice temático y las primeras páginas. La referencia bibliográfica del este relatorio es la siguiente: Muruaga, Claudia Marcela Ciencias de la tierra y recursos naturales del NOA : relatorio del XX Congreso Geológico Argentino / Claudia Marcela Muruaga ; Pablo Grosse. - 1a ed. - San Miguel de Tucumán : Claudia Marcela Muruaga, 2017. Libro digital, PDF Fil: Guzmán, Silvina. Instituto de Bio y Geociencias del NOA (IBIGEO), UNSa, CONICET y Instituto de Ciencias de la Tierra Jaume Almera, ICTJA-CSIC; Argentina. Fil: Grosse, Pablo. CONICET y Fundación Miguel Lillo; Argentina. Fil: Martí, Joan. Instituto de Ciencias de la Tierra Jaume Almera, ICTJA-CSIC; [España]. Fil: Petrinovic, Iván A. CICTERRA (CONICET-UNC); Argentina. Fil: Seggiaro, Raúl. Instituto de Bio y Geociencias del NOA (IBIGEO), UNSa, CONICET y SEGEMAR; Argentina. Las calderas de colapso han extruido más de 13.000 km3 de magma en el segmento 21-28° S de la Zona Volcánica Central de los Andes desde los ~17 Ma hasta los ~5.000 años AP. A partir de los 10 Ma hubo un profuso magmatismo relacionado a calderas que se concentró predominantemente al norte de 25° S y a partir de los 6 Ma hasta los 2 Ma fue importante a lo largo y ancho del plateau Altiplano-Puna. En territorio argentino, se conocen al menos 10 calderas de colapso elípticas a circulares. De estas calderas, ocho han emitido un volumen individual de magma de > 50 km3 hasta 1.400 km3, tienen el eje mayor de > 10 km, edades de entre ~17 a ~2 Ma y son predominantemente dacíticas a riodacíticas. Son dos las calderas que emitieron individualmente volúmenes < 21 km3, no superan 13 km de diámetro en su eje mayor, son < 1 Ma, son de composición riolítica a riodacítica y se encuentran al sur de 26° 30’ S. La mayoría de las calderas andinas han colapsado en etapas tempranas de la erupción, generando columnas eruptivas densas y de baja altura que formaron fl ujos piroclásticos casi rasantes; son escasos los ejemplos de calderas que estuvieron precedidas por erupciones plinianas.

Volcanic cone fields are generally made up of tens to hundreds of monogenetic cones, sometimes related to larger polygenetic edifices, which can exhibit a wide range of morphologies and degrees of preservation. The Virunga Volcanic Province (VVP) developed itself in a transfer zone which separates two rift segments (i.e. Edward and Kivu rift) within the western branch of the East-African Rift. As the result of volcanic activity related to this tectonic regime of continental extension, the VVP hosts eight large polygenetic volcanoes, surrounded by over 500 monogenetic cones and eruptive fissures, scattered over the vast VVP lava flow fields. Some cones lack any obvious geo-structural link to a specific Virunga volcano. Using recent high-resolution satellite images (SPOT, Pléiades) and a newly created 5-m-resolution digital elevation model (TanDEM-X), we have mapped and classified all monogenetic cones and eruptive fissures of the VVP. We analysed the orientation of all mapped eruptive fissures and, using the MORVOLC program, we calculated a set of morphometric parameters to highlight systematic spatial variations in size or morphometric ratios of the cones. Based upon morphological indicators, we classified the satellite cones into 4 categories: 1. Simple cones with one closed-rim crater; 2. Breached cones with one open-rim crater; 3. Complex cones with two or more interconnected craters and overlapping cones; 4. Other edifices without a distinguishable crater or cone shape (e.g. spatter mounds and levees along eruptive fissures). The results show that cones are distributed in clusters and along alignments, in some cases parallel with the regional tectonic orientations. Contrasts in the volumes of cones positioned on the rift shoulders compared to those located on the rift valley floor can possibly be attributed to contrasts in continental crust thickness. Furthermore, higher average cone slopes in the East-VVP (Bufumbira zone) and central-VVP cone clusters suggest a morphologically younger age, which contradicts the previous assumption that the overall VVP volcanic activity shifted over time from E to W. This study thus demonstrates the usefulness of relatively rapid cone morphometry quantification on digital elevation models in volcanic areas where future volcanic hazards are poorly understood.

Volcanoes display very diverse morphologies as a result of a complex interplay of several constructive and destructive processes. Here the role played by the spatial distribution of eruption centre and by an underlying strike-slip fault in controlling the long term growth of volcanoes is investigated with analogue models. Volcano growth was simulated by depositing loads of granular material (sand-kaolin mixtures) from a point source. An individual load deposited at a fixed location produces a simple symmetrical cone with flank slopes at the angle of repose of the granular material (~33º) that can be considered as the building-block for the experiments. Two sets of experiments were undertaken: (1) the location of deposition of the granular material (i.e. the volcano growth location) was shifted with time following specific probability density functions simulating shifts or migrations in vent location; (2) the location of deposition was kept fixed, but the deposition rate (i.e. the volcano growth rate) was varied coupled with the movement of a basal plate attached to a step-motor simulating a strike-slip displacement under the growing cone (and hence deformation of the cone). During the progression of the experiments, the models were photographed at regular time intervals using four digital cameras positioned at slightly different angles over the models. The photographs were used to generate synthetic digital elevation models (DEMs) with 0.2 mm spatial resolution of each step of the models by applying the MICMAC digital stereo-photogrammetry software. Morphometric data were extracted from the DEMs by applying two IDL-language algorithms: NETVOLC, used to automatically calculate the volcano edifice basal outline, and MORVOLC, used to extract a set of morphometric parameters that characterize the volcano edifice in terms of size, plan shape, profile shape and slopes. Analysis of the DEM-derived morphometric parameters allows to quantitatively characterize the growth evolution of the volcano models in terms of vent distribution and growth rate-deformation rate ratios.