Misterios y rarezas del final del precámbrico: un enfoque paleomagnético

Desde hace dos décadas, en el Laboratorio de Paleomagnetismo Daniel A. Valencio del IGEBA venimos desarrollando estudios multidisciplinarios sistemáticos en rocas sedimentarias y volcánicas ediacaranas del cratón del Río de la Plata. Los estudios incluyen principalmente investigaciones paleomagnéticas con el fin de reconstruir la evolución paleogeográfica del cratón en el Ediacarano y aportar a conocer la cinemática de la formación del Gondwana. Recientemente estamos también avanzando en el conocimiento de las reversiones de polaridad del paleocampo magnético en el Ediacarano tardío. Dataciones geocronológicas precisas, estudios isotópicos sistemáticos y recientes hallazgos fósiles espectaculares, sumados a la información paleomagnética, están aumentando significativamente nuestro conocimiento de un período hasta hace dos décadas casi desconocido. Estos avances incluyen una reconstrucción esquemática de la evolución paleogeográfica del cratón del Río de la Plata entre aproximadamente 600 y 550 Ma, durante el cual el mismo habría migrado desde bajas a altas latitudes. Con esta información y la de otros cratones de Gondwana Occidental están surgiendo restricciones a las edades de anexión con Congo-São Francisco y África Occidental. También permiten especular con mayor sustento observacional sobre la posible existencia (o no) de un gran océano llamado Clymene en etapas finales de formación del Gondwana. El probable registro de la excursión Shuram en sedimentos calcáreos del cratón es una posibilidad concreta a medida que avanzan los estudios quimioestratigráficos. Si bien aún de modo incipiente, los primeros resultados magnetoestratigráficos que estamos obteniendo sugieren la aparente presencia de rápidas reversiones de polaridad. Esta sucesión de nuevos resultados marca límites a ciertos modelos o propuestas no actualistas mientras que es compatible con otros, abriendo un importante número de nuevos interrogantes. En este trabajo se presenta un breve resumen del conocimiento actual a nivel global de muchas de estas controversias, así como del avance de las investigaciones en nuestro país.For two decades, in the Daniel A. Valencio Paleomagnetism Laboratory of the IGEBA we have been developing systematic multidisciplinary studies in sedimentary and volcanic Ediacaran rocks of the Río de la Plata craton. The studies include mainly paleomagnetic investigations in order to reconstruct the paleogeographic evolution of the Ediacaran craton and to contribute to understand the kinematics of the formation of Gondwana. Recently we are also advancing in the knowledge of the polarity reversions of the magnetic paleofield in the late Ediacaran. Accurate geochronological dating, systematic isotopic studies and recent spectacular fossil finds, in addition to paleomagnetic information, are significantly increasing our knowledge of a period that until two decades ago was almost unknown. These advances include a schematic reconstruction of the paleogeographic evolution of the La Plata River craton between approximately 600 and 550 Ma, during which time it would have migrated from low to high latitudes. With this information and that of other West Gondwana cratons, constraints on the ages of annexation with Congo-São Francisco and West Africa are emerging. They also allow speculation with more observational support on the possible existence (or not) of a big ocean called Clymene in late stages of Gondwana formation. The probable record of the Shuram excursion in calcareous sediments of the craton is a concrete possibility as chemostratigraphic studies progress. Although still incipient, the first magnetostratigraphic results we are obtaining suggest the apparent presence of rapid polarity reversions. This succession of new results marks limits to certain models or non-current proposals while it is compatible with others, opening an important number of new questions. In this paper we present a brief summary of the current global knowledge of many of these controversies, as well as the progress of research in our country.Asociación Argentina de Geofísicos y Geodesta

Fábrica Magnética y Microestructuras a través de los Andes de Tierra del Fuego, Argentina

An anisotropy of magnetic susceptibility (AMS) transect was carried out across the Fuegian Andes, in Argentina, withthe aim of studying its tectonic evolution. Two-hundred and forty oriented samples were collected from 27 sites distributed between the Paso Garibaldi to the north and the Canal Beagle to the south. The study was restricted to the Upper Jurassic Lemaire Formation, with a single site located in the Lower Cretaceous Yahgán Formation. Stu-died rocks comprised basaltic, andesitic, volcaniclastic and sedimentary rocks affected by low-grade metamorphism. AMS measurements were complemented with thin section analyses of representative samples in order to characterize the microstructures and metamorphic assemblages. In general, the magnetic fabric shows dominantoblate shapes and a large variation in the anisotropy degree from 1.04 up to 2. The anomalously high values were observed to be associa-ted to growth of secondary pyrrhotite, which was identified by rock magnetic tests. Magnetic foliation was generally consistent with slaty cleaveage as observed in the field, confirming the tectonic origin of the magnetic fabric. Three geographic domains were distinguished in the study región on the basis of the pattern of the AMS axes distribution. In the northern domain, from Paso Garibaldi to Valle Carbajal, the orientation of the máximum susceptibility axis (κ1), or magnetic lineation, is N-S to NE-SW with modérate plunge towards the S-SW and coincides with previous determination of mineral lineations associated with the Andean deformation and very low grade metamorphism. The magnetic fabric pattern can be correlated with the main deformational phase responsible for the development of slaty cleavage (main Andean deformational phase) and the tectonic transport due to progression of the Fuegian fold and thrust belt in the Late Cretaceous. A different character is shown along the Valle Carbajal domain, where subvertical E-W magnetic foliation planes and roughly E-W to ESE-WNW subhorizontal magnetic lineations are more difficult to correlate with the main folding phase and suggest its relation to an E-W, possibly localized, strike-slip regime during the main deformational and metamorphic phase. The magnetic fabrics in the third domain, cióse to the Canal Beagle, displays a more heterogeneous character with both E-W and N-S striking foliations; in this case a population of subhorizontal E-W magnetic lineation (κ1) suggests the existence of a significant component of strike-slip deformation. Se presentan los resultados de una transecta de Anisotropía de Susceptibilidad Magnética (ASM) realizada en los Andes Fueguinos, Argentina. Se midieron 240 muestras orientadas provenientes de 27 sitios de muestreo distribuidos entre Paso Garibaldi, al norte y el Canal Beagle al sur. El muestreo se focalizó esencialmente en la Formación Lemaire del Jurásico Superior, con un único sitio en la Formación Yahgán del Cretácico inferior. Las litologías estudiadas incluyen basaltos, andesitas y rocas volcanoclásticas y sedimentarias afectadas por metamorfismo de bajo grado. Las mediciones de fábrica magnética se complementaron con el estudio microscópico de muestras representativas con el propósito de caracterizar las microestructuras y las asociaciones metamórficas. La fábrica magnética está dominada por formas obladas y presenta una gran variación en el grado de anisotropía (1,04-2). Los mayores valores de anisotropía están asociados a la presencia de pirrotina secundaria, identificada por medio de ensayos magnéticos. La foliación magnética muestra muy buena correspondencia con el clivaje medido en campo, confirmando el origen tectónico de la fábrica magnética. Los modelos de distribución de los ejes de ASM permitieron distinguir tres dominios geográficos. El dominio septentrional, entre Paso Garibaldi y Valle Carbajal, presenta lineaciones magnéticas (κ1) de orientación N-S aNE-SW con buzamiento moderado hacia el S-SW, coincidente con determinaciones previas de lineaciones minerales asociadas con la deformación andina. Este diseño de fábrica magnética se vincula a la fase de deformación principal responsable del desarrollo del clivaje pizarreño y de la faja plegada y corrida Fueguina en el Cretácico Tardío. Un segundo dominio corresponde al Valle Carbajal, caracterizado por foliaciones magnéticas E-W, subverticales y lineaciones magnéticas E-W (a ESE-WNW) subhorizontales que se interpretan como vinculados a regímenes localizados de transcurrencia. La fábrica magnética en el tercer dominio, en la zona del Canal Beagle, presenta un carácter más heterogéneo con foliaciones de orientación tanto E-W como N-S; la presencia de una población de lineaciones magnéticas subhorizontales de rumbo E-W sugiere la existencia de un componente de rumbo significativo

Jurassic cooling ages in Paleozoic to early Mesozoic granitoids of northeastern Patagonia : 40Ar/39Ar, 40K–40Ar mica and U–Pb zircon evidence

University of Buenos Aires (PICTUBACYT X183), CONICET and ANPCYT (PICT20131162) financial support is acknowledged.U–Pb SHRIMP zircon crystallization ages and Ar–Ar and K–Ar mica cooling ages for basement rocks of the Yaminué and Nahuel Niyeu areas in northeastern Patagonia are presented. Granitoids that cover the time span from Ordovician to Early Triassic constitute the main outcrops of the western sector of the Yaminué block. The southern Yaminué Metaigneous Complex comprises highly deformed Ordovician and Permian granitoids crosscut by undeformed leucogranite dikes (U–Pb SHRIMP zircon age of 254 ± 2 Ma). Mica separates from highly deformed granitoids from the southern sector yielded an Ar–Ar muscovite age of 182 ± 3 Ma and a K–Ar biotite age of 186 ± 2 Ma. Moderately to highly deformed Permian to Early Triassic granitoids made up the northern Yaminué Complex. The Late Permian to Early Triassic (U–Pb SHRIMP zircon age of 252 ± 6 Ma) Cabeza de Vaca Granite of the Yaminué block yielded Jurassic mica K–Ar cooling ages (198 ± 2, 191 ± 1, and 190 ± 2 Ma). At the boundary between the Yaminué and Nahuel Niyeu blocks, K–Ar muscovite ages of 188 ± 3 and 193 ± 5 Ma were calculated for the Flores Granite, whereas the Early Permian Navarrete granodiorite, located in the Nahuel Niyeu block, yielded a K–Ar biotite age of 274 ± 4 Ma. The Jurassic thermal history is not regionally uniform. In the supracrustal exposures of the Nahuel Niyeu block, the Early Permian granitoids of its western sector as well as other Permian plutons and Ordovician leucogranites located further east show no evidence of cooling age reset since mica ages suggest cooling in the wake of crystallization of these intrusive rocks. In contrast, deeper crustal levels are inferred for Permian–Early Triassic granitoids in the Yaminué block since cooling ages for these rocks are of Jurassic age (198–182 Ma). Jurassic resetting is contemporaneous with the massive Lower Jurassic Flores Granite, and the Marifil and Chon Aike volcanic provinces. This intraplate deformational pulse that affected northeastern Patagonia during the Early Jurassic (Sinemurian–Pliensbachian) was responsible for the partial (re)exhumation of the mid-crustal Paleozoic basement along reactivated discrete NE–SW to ENE–WSW lineaments and the resetting of isotopic systems. These new thermochronological data indicate that Early Permian magmatic rocks of the Nahuel Niyeu block were below 300 °C for ca. 20 Ma prior to the onset of the main magmatic episode of the Late Permian to Triassic igneous and metaigneous rocks of the Yaminué block.PostprintPeer reviewe

Vertical-axis rotations and deformation along the active strike-slip El Tigre Fault (Precordillera of San Juan, Argentina) assessed through palaeomagnetism and anisotropy of magnetic susceptibility

Palaeomagnetic data from poorly consolidated to non-consolidated late Cenozoic sediments along the central segment of the active El Tigre Fault (Central-Western Precordillera of the San Juan Province, Argentina) demonstrate broad cumulative deformation up to ~450 m from the fault trace and reveal clockwise and anticlockwise vertical-axis rotations of variable magnitude. This deformation has affected in different amounts Miocene to late Pleistocene samples and indicates a complex kinematic pattern. Several inherited linear structures in the shear zone that are oblique to the El Tigre Fault may have acted as block boundary faults. Displacement along these faults may have resulted in a complex pattern of rotations. The maximum magnitude of rotation is a function of the age of the sediments sampled, with largest values corresponding to middle Miocene–lower Pliocene deposits and minimum values obtained from late Pleistocene deposits. The kinematic study is complemented by low-field anisotropy of magnetic susceptibility data to show that the local strain regime suggests a N–S stretching direction, subparallel to the strike of the main fault

Studies of Quaternary deformation zones through geomorphic and geophysical evidence

At the northern sector of the Precordillera Sur (31° 50′-32° 40′ SL/68° 45′-69° 20′ WL), Central Andes of Argentina, NW-trending sinistral transpressive shear zones at different scales, product of the Late Cenozoic Andean deformation, are recognized. The most significant of them is the 120. km long Barreal-Las Peñas Belt and within it, a small-scale (7. km long) Quaternary sinistral transpressive shear zone, called Los Avestruces, has been detected from geomorphological and geophysical analysis (32° SL/69° 21 WL). Geophysical techniques were applied to better characterize the shallow structure and kinematics of some representative structures in this shear zone. In particular, the use of tomography of electrical resistivity methods allowed characterizing the subsurface geometry of some areas of interest, enabling the recognition of Quaternary layers against their original slope, the geometry of the reverse fault which uplifted the Pleistocene deposits of one of the highs, the geometry of a likely previous extensional fault reactivated and inverted during the Quaternary as well as the presence of a reverse blind fault, which has uplifted the Quaternary deposits of the Los Avestruces bog.The location of the above mentioned shear zones coincides with the northern branch of the NW-trending extensional Triassic Cuyana basin. Thus, their presence appears to be related to Andean reactivation of older (Triassic), mainly NW-trending, structures. In the northern area of the Precordillera Sur, as well as in other places of the world here discussed, these kinds of paleotectonic oblique features play a major role in defining the geometry and kinematics of Late Cenozoic deformation.Fil: Terrizzano, Carla Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Laboratorio de Neotectónica; ArgentinaFil: Fazzito, Sabrina Yesica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; ArgentinaFil: Cortes, Jose Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Laboratorio de Neotectónica; ArgentinaFil: Rapalini, Augusto Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; Argentin

Neotectonic transpressive zones in the Precordillera Sur, Central Andes of Argentina: a structural and geophysical investigation

On the flat-slab segment of the Central Andes of Argentina, the southern portion (31°30' - 33° SL) of the Precordillera is characterized by a singular Late Cenozoic tectonic style related to the tectonic inversion of paleotectonic anisotropics. Different scale, neotectonic NW trending deformation zones are described at this area. All these belts show me same structural style, defined by an en échelon array of morphotectonic features which indicate a left-lateral component of displacement under a transpressive regime. Oblique paleotectonic features seem to play a major role in the geometry and kinematics of Late Cenozoic deformation of the northern Precordillera Sur. In agreement with geological data, a tomography of electrical resistivity survey across one of these zones suggests a Quaternary reverse reactivation of a NW trending extensional paleotectonic fault.Fil: Terrizzano, Carla Marina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Laboratorio de Neotectónica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cortes, Jose Maria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Laboratorio de Neotectónica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fazzito, Sabrina Yesica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rapalini, Augusto Ernesto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Episodic remagnetizations related to tectonic events and their consequences for the South America polar wander path

The South American record of remagnetizations is linked to specific events of its tectonic history stretching back to Precambrian times. At the Ediacaran-Cambrian time interval (570-500 Ma), the final stages of the western Gondwana assemblage led to remagnetization of Neoproterozoic carbonates within the São Francisco-Congo Craton and at the border of the Amazon Craton, along the Araguaia-Paraguay-Pampean Belt. From the late Permian to early Triassic, the San Rafaelic orogeny and the emplacement of the Choiyoi magmatic province was responsible for widespread remagnetizations in Argentina and Uruguay. Cretaceous remagnetization has also been documented in Brazil and interpreted to result from magmatism and fault reactivations linked to the opening of the South Atlantic Ocean. We present a review of these widespread remagnetization events principally based on palaeomagnetic data and, when available, on rock magnetic and radiogenic isotope age data. This study gives an overview of the geographical distribution of the remagnetization events in South America, and provides important clues to better understand the geodynamic evolution of the South American plate at these times. In addition, magnetic mineralogy data for the different case studies presented here constrain the physical-chemical mechanisms that led to partial or total resetting of magnetic remanences in sedimentary rocks.Fil: Font, E.. Universidade de Lisboa. Faculdade de Ciências; BrasilFil: Rapalini, Augusto Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; ArgentinaFil: Tomezzoli, Renata Nela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología. Instituto de Geofísica "Daniel Valencio"; ArgentinaFil: Trindade, R. I. F.. Universidade do Sao Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas; BrasilFil: Tovher, E.. University of Western Australia; Australi

Characterization of Quaternary faults by electric resistivity tomography in the Andean Precordillera of Western Argentina

Structural and geomorphic surface observations are frequently insufficient for a proper geometric and kinematic characterization of Quaternary faults. In order to improve the geological knowledge of three Quaternary faults in the Precordillera of western Argentina (30°46′ S-32°24′ S, 69°07′ W-69°15′ W), a shallow 2D Electrical Resistivity Tomography (ERT) survey was performed along seven short cross-sections, perpendicular to the fault traces. The survey was carried out across the San Bartolo fault, the Los Avestruces high and the El Tigre fault in the Precordillera of western Argentina in the San Juan and Mendoza provinces. During the survey, different electrical arrangements were assessed, including different arrays (dipole-dipole and Wenner-Schlumberger), diverse electrode separations and different depth of investigation. Tomographic models showed low resistivity zones lying below the fault scarps, as well as significant resistivity contrasts across the inferred fault-zones in the subsurface. This information permitted better characterization of the geometry and kinematics of these fault zones. ERT results showed that the San Bartolo fault is extensional. In the Los Avestruces high a positive inversion of an extensional fault was recorded by the electrical images. In the resistivity sections of the El Tigre strike-slip fault, a near vertical fault plane associated with blind splays could be identified. Our results confirm that the resistivity method is a valuable tool to image fault planes and to characterize the general geometry of extensional, reverse and strike slip faults at depth.Fil: Fazzito, Sabrina Yesica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Rapalini, Augusto Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Cortes, Jose Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Terrizano, Carla. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin

The geometry of the active strike-slip El Tigre Fault, Precordillera of San Juan, Central–Western Argentina: integrating resistivity surveys with structural and geomorphological data

The geometry and related geomorphological features of the right-lateral strike-slip El Tigre Fault, one of the main morphostructural discontinuities in the Central– Western Precordillera of Argentina, were investigated. Achievements of this survey include: recognition of structural and geometrical discontinuities along the fault trace, identification and classification of landforms associated with local transpressional and transtensional sectors, observation of significant changes in the fault strike and detection of right and left bends of different wavelength. In the Central Segment of the El Tigre Fault, 2D electrical resistivity tomography surveys were carried out across the fault zone. The resistivity imaging permitted to infer the orientation of the main fault surface, the presence of blind fault branches along the fault zone, tectonic tilting of the Quaternary sedimentary cover, subsurface structure of pressure ridges and depth to the water table. Based on this information, it is possible to characterize the El Tigre Fault also as an important hydro-geological barrier. Our survey shows that the main fault surface changes along different segments from a high-angle to a subvertical setting whilst the vertical-slip component is either reverse or normal, depending on the local transpressive or transtensive regime induced by major bends along the trace. These local variations are expressed as sections of a few kilometres in length with relatively homogeneous behaviour and frequently separated by oblique or transversal structures.Fil: Fazzito, Sabrina Yesica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Cortes, Jose Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Rapalini, Augusto Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Terrizzano, Carla Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Basicas, Aplicadas y Ambientales de Buenos Aires; Argentin