Datos históricos relevantes de la División Geología del Museo de La Plata : desde Rodolfo Hauthal hasta Alfredo J. Cuerda

Fil: Cingolani, Carlos Alberto. División Geología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

La dinámica de la tierra

Fil: Cingolani, Carlos Alberto. División Geología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Ramos, Víctor Alberto. Instituto de Estudios Andino (IDEAN). UB

Pre-Carboniferous Tectonic Evolution of the San Rafael Block, Mendoza Province

The pre-Carboniferous evolution of the San Rafael Block is described in different stages. The first one is referred to the Mesoproterozoic basement derived from a complex plutonic and volcanic protolith of Cerro La Ventana Formation. The signature of this basement indicates a common origin with the present eastern part of Laurentia. The carbonate platform of Cuyania terrane has been drifted away during Early Cambrian to Early Ordovician times. The Ordovician silico-carbonate sequences of the San Rafael Block are unconformably deposited over the basement near the present eastern slope of the Cuyania terrane. Detrital zircon ages show a provenance derived from Mesoproterozoic source. The El Nihuil dolerites with a tholeiitic ocean floor signature considered the southern end of the Famatinian ophiolites were interpreted as a Late Ordovician–Early Silurian extensional event. The collision of Cuyania produced a new west polarity subduction and a magmatic arc, represented by the Devonian Rodeo de la Bordalesa tonalite and the granitoids of the “Agua Escondida Mining District”. The Late Silurian–Early Devonian sequences of La Horqueta and Río Seco de los Castaños formations were deformed during the collision and accretion of the Chilenia terrane against the proto-Andean margin, and recorded an east vergent cleavage developed on the previous deformed rocks. This collision produced the strong angular unconformity between the La Horqueta/Río Seco de los Castaños Formations and the El Imperial Formation (Upper Paleozoic). The new subduction with east polarity characterized the beginning of the Gondwanian cycle. The new magmatic arc was interrupted by the intense Lower Permian deformation of the San Rafael tectonic phase.Centro de Investigaciones GeológicasUniversidad de Buenos Aire

Field guide on the ordovician of the Sierra Pintada, San Rafael Block, Mendoza

First day: Departure from San Juan City by bus, at 8 AM. Arrival at San Rafael City (about 370 km towards the South) in Mendoza Province at lunch time. During the trip by the plain road we can see the Eastern Precordillera and Frontal Cordillera sides and the Cuyo oil basin. This region is also famous for its vineyards and with a nice production of several wines. After accommodation at the hotel we will depart to Cerro Bola region (about 25 km towards the East of San Rafael City). The stop will be at Baños Cerro Bola (ancient spring baths) to see the more complete section of the siliciclastic sequence know as Pavón Formation. Graptolites from the Lower Caradoc age are common in black shales of this section. We can observe the sedimentary characteristics and structural style of the sequence. At about 7 PM we will return to the hotel at San Rafael City for dinner and sleeping. Second day: Departure from San Rafael City at 8.30 AM (with luggage) and we will go to the South-East side of the San Rafael Block known Ponón Trehue locality (about 70 km). The first stop will be at Ponón Trehue creek, where we can see the Precambrian basement (grenvillian crust) and the contact with Ordovician units from Tremadoc and Arenig carbonate rocks and Llanvirn-Llandeilo to Lower Caradoc clastic-carbonate sediments. The biostratigraphy of these Ordovician outcrops has been based on Conodont assemblages. The sedimentological and stratigraphical studies suggest that these units are megablocks, blocks and megaconglomerates and could be allochtonous deposits associated with an extensional regime well described in the Precordillera Terrane. After a field lunch we will go to the second stop at the Tortuga section, where the outcrops of the Ponón Trehue Formation represent the Pygodus serra Zone, Eoplacognathus robustus subzone and Eoplacognathus linstroemi subzone, and Pygodus anserinus Zone, Sagittodontina kielcensissubzone. We will observe the sedimentological characteristics of the sequences. At 5 PM we will return to Mendoza City. Arrival to Mendoza City at about 8 PM, location at the hotel and dinner. The field trip is finished.Centro de Investigaciones Geológica

Field guide on the ordovician of the Sierra Pintada, San Rafael Block, Mendoza

First day: Departure from San Juan City by bus, at 8 AM. Arrival at San Rafael City (about 370 km towards the South) in Mendoza Province at lunch time. During the trip by the plain road we can see the Eastern Precordillera and Frontal Cordillera sides and the Cuyo oil basin. This region is also famous for its vineyards and with a nice production of several wines. After accommodation at the hotel we will depart to Cerro Bola region (about 25 km towards the East of San Rafael City). The stop will be at Baños Cerro Bola (ancient spring baths) to see the more complete section of the siliciclastic sequence know as Pavón Formation. Graptolites from the Lower Caradoc age are common in black shales of this section. We can observe the sedimentary characteristics and structural style of the sequence. At about 7 PM we will return to the hotel at San Rafael City for dinner and sleeping. Second day: Departure from San Rafael City at 8.30 AM (with luggage) and we will go to the South-East side of the San Rafael Block known Ponón Trehue locality (about 70 km). The first stop will be at Ponón Trehue creek, where we can see the Precambrian basement (grenvillian crust) and the contact with Ordovician units from Tremadoc and Arenig carbonate rocks and Llanvirn-Llandeilo to Lower Caradoc clastic-carbonate sediments. The biostratigraphy of these Ordovician outcrops has been based on Conodont assemblages. The sedimentological and stratigraphical studies suggest that these units are megablocks, blocks and megaconglomerates and could be allochtonous deposits associated with an extensional regime well described in the Precordillera Terrane. After a field lunch we will go to the second stop at the Tortuga section, where the outcrops of the Ponón Trehue Formation represent the Pygodus serra Zone, Eoplacognathus robustus subzone and Eoplacognathus linstroemi subzone, and Pygodus anserinus Zone, Sagittodontina kielcensissubzone. We will observe the sedimentological characteristics of the sequences. At 5 PM we will return to Mendoza City. Arrival to Mendoza City at about 8 PM, location at the hotel and dinner. The field trip is finished.Centro de Investigaciones Geológica

Field guide on the ordovician of the Sierra Pintada, San Rafael Block, Mendoza

First day: Departure from San Juan City by bus, at 8 AM. Arrival at San Rafael City (about 370 km towards the South) in Mendoza Province at lunch time. During the trip by the plain road we can see the Eastern Precordillera and Frontal Cordillera sides and the Cuyo oil basin. This region is also famous for its vineyards and with a nice production of several wines. After accommodation at the hotel we will depart to Cerro Bola region (about 25 km towards the East of San Rafael City). The stop will be at Baños Cerro Bola (ancient spring baths) to see the more complete section of the siliciclastic sequence know as Pavón Formation. Graptolites from the Lower Caradoc age are common in black shales of this section. We can observe the sedimentary characteristics and structural style of the sequence. At about 7 PM we will return to the hotel at San Rafael City for dinner and sleeping. Second day: Departure from San Rafael City at 8.30 AM (with luggage) and we will go to the South-East side of the San Rafael Block known Ponón Trehue locality (about 70 km). The first stop will be at Ponón Trehue creek, where we can see the Precambrian basement (grenvillian crust) and the contact with Ordovician units from Tremadoc and Arenig carbonate rocks and Llanvirn-Llandeilo to Lower Caradoc clastic-carbonate sediments. The biostratigraphy of these Ordovician outcrops has been based on Conodont assemblages. The sedimentological and stratigraphical studies suggest that these units are megablocks, blocks and megaconglomerates and could be allochtonous deposits associated with an extensional regime well described in the Precordillera Terrane. After a field lunch we will go to the second stop at the Tortuga section, where the outcrops of the Ponón Trehue Formation represent the Pygodus serra Zone, Eoplacognathus robustus subzone and Eoplacognathus linstroemi subzone, and Pygodus anserinus Zone, Sagittodontina kielcensissubzone. We will observe the sedimentological characteristics of the sequences. At 5 PM we will return to Mendoza City. Arrival to Mendoza City at about 8 PM, location at the hotel and dinner. The field trip is finished.Centro de Investigaciones Geológica

The history of geochronology in La Plata: Borrello´s Project

El Dr. Angel V. Borrello hacia fines de la década de 1950 y principios de 1960 planificó la creación del primer laboratorio de Geocronología Rb-Sr en el país, con su instalación en la sede del Departamento de Geología de la Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, La Plata (CIC). Este hecho pionero que señalo aquí como ‘Proyecto Borrello’, fue un ambicioso desafío que se animó a enfrentar en aquellas épocas, consciente de la potencialidad de la investigación geocronológica en Argentina. Aconsejado por el especialista Dr. John Reynolds (Berkeley, USA) y también por el Dr. Umberto Cordani (SP, Brasil) quien iniciaba su liderazgo sudamericano en la temática, Borrello se decidió a instalar un laboratorio que pudiera ser superador y complementario de la metodología K-Ar que ya estaba en funcionamiento en San Pablo, Brasil. Logró el apoyo de la CIC para la instalación de la parte correspondiente a la trituración y concentración de minerales y el laboratorio ‘limpio’ de geoquímica. Este debía contar con estándares isotópicos, columnas cromatográficas, todo lo correspondiente a la purificación de reactivos y por otro lado la instalación del equipo denominado espectrómetro de masas (NUCLIDE, USA). El fallecimiento prematuro del Dr. Angel Borrello en 1971, fue el factor fundamental para que el ambicioso proyecto quedara inconcluso y se retrasaran las investigaciones geocronológicas en el país.Dr. Angel V. Borrello in the late 1950s and early 1960s planned the first Rb-Sr geochronological laboratory in Argentina, at the Department of Geology of the Commission for Scientific Research at the Buenos Aires province in La Plata. This pioneering fact that I point out here as 'Borrello Project' was an ambitious challenge, aware of the potential of the geochronological research in Argentina. Advised by specialist Dr. John Reynolds (Berkeley, USA) and also by Dr. Umberto Cordani (SP, Brazil) who initiated its South American leadership in the field, Borrello was decided to install a laboratory that could be complementary to the K-Ar method that was already in operation in Sao Paulo, Brazil. He obtained the support of the CIC from Buenos Aires province for the laboratory of crushing and mineral concentration and for 'clean' geochemistry. This should have isotopic standards, chromatographic columns, all corresponding to the purification of reagents and the installation of mass spectrometer equipment for measuring samples (NUCLIDE, USA). Borrello was death in 1971 at the age of 53 and that was the main factor for the ambitious project remained unfinished and geochronological investigations were delayed in the country.Facultad de Ciencias Naturales y Muse

Semblanza : Eduardo Jorge Llambías

Fil: Cingolani, Carlos Alberto. División Geología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

Primitive Vascular Plants and Microfossils from the Río Seco de los Castaños Formation, San Rafael Block, Mendoza Province, Argentina

In this contribution we describe fossil plant remains from Río Seco de los Castaños Formation, at San Rafael Block, Mendoza Province, Argentina. The fossil plants comprise non-forked and forked axes without or with delicate lateral expansions, which are assigned to Bowerophylloides cf. mendozaensis and Hostinella sp. We refer them to primitive land plants and discuss about their systematic affiliation. Furthermore, we mention the presence of a diverse acritarch assemblage present in the same lithostratigraphic unit. On the basis of the taxonomical information and stratigraphic correlation, we could infer that Río Seco de los Castaños Formation has an Early Devonian age. The taphonomical conditions of this fossil association would indicate that the plants were transported some distance from their presumed coastal and riverbank habitats. Finally, studying the amount and the percentage of kaolinite within charcoal levels, warm to cool temperate paleoclimatic conditions were deduced.Facultad de Ciencias Naturales y Muse

Relevant historical data of the Geology Division in the La Plata Museum: from Rodolfo Hauthal to Alfredo J. Cuerda

The history of the Geology Division of the La Plata Museum started with Francisco P Moreno who was the first to dedicate a showroom to Geology and Mineralogy, Later, he was the leader of several expeditions to Patagonia and in 1891 he was in charge to designate the German geologist Rodolfo (Rudolf) Hauthal as the first chief of the ‘Geological Section’, who spent 14 years working at the Museum. Hauthal provided important geological contributions on different areas of Argentina and also with Moreno was part of the Argentine-Chilean Limits Commission. The documentation left by Rodolfo Hauthal includes several papers; many of them published in the Revista del Museo de La Plata. The paleontological discoveries of Hauthal and co-authors in the caves of Ultima Esperanza had a special impact. After his return to Germany, he was replaced by another German geologist invited by Moreno: Walther Schiller. He worked in the Museum of La Plata for 40 years, interrupted only by the time he returned to Germany to participate in World War I. The performance of Schiller, who settled down in La Plata with his family, was a long lasting legacy for the Geology of the Museum. He died during an expedition to the Aconcagua in 1944. The Museum belonged to the Province of Buenos Aires until 1905, when it was incorporated as a part of the new National University of La Plata after the resignation of its Director E P. Moreno. In 1920 the Museum was reorganized into five different Departments: Anthropology, Geology and Mineralogy, Vertebrate Paleontology, Invertebrate Paleontology and Zoology. In 1923, a new re-organization was approved; Schiller occupied the Geology and Physical Geography and the Mineralogy and Petrography Departments. At this time Juan Keidel was incorporated in the geological staff of the Museum as a Visitor Professor. Then Angel V. Borrello, graduated from the Institute of Museum” became the new Chief of the Geological Division. He made relevant institutional contributions, recognized the importance of magmatism in geological evolution processes and founded the first laboratory of Rb-Sr geochronology in the Department of Geology from the Scientific Commission of the Buenos Aires province that also interacted constantly with the Geology Division of the Museum. The permanent public concern for the published and unpublished literature in the country, led him to make agreements with the Secretaria de Mineria de la Nación, in this way, more than 12,000 bibliography references were preserved in the Geology Division. In 1958 Alfredo J. Cuerda was incorporated as Associate Professor of Historical Geology. Later in 1971, he replaced A. V. Borrello after his death and served as a Chief of Geology Division until 1998. In the 1960 A, Cuerda began an activity that would become his true passion: the study of graptolites. Fe produced several syntheses af Ordovician Systems, Silurian-Devonian and many hiostratigraphical papers. Lt is important to note that several South American studied specimens are a valuable scientific heritage. In the late 1970s different geological research groups from Geology Division and athers working in the Museum discuss to create a new institution: a Geological Research Centre (CIG).Centro de Investigaciones Geológica