Tithonian–Berriasian calcisphere (calcareous dinoflagellate cysts) zones in the Neuquén Basin, Argentina: correlation between Southern Andes and Tethyan regions

Kietzmann, Diego Alejandro; Iglesia Llanos, Maria Paula ; Iovino, Franco
2 023
Newsletters On Stratigraphy, Volume 56 Number 2 (2023), p. 157 - 1850
This work presents a regional biostratigraphic study on the calcisphere (calcareous dinoflagellate cysts) zones of the Tithonian–Berriasian in the Neuquén Basin, Western Argentina. This stratigraphic interval is mostly represented by a thick rhythmic succession of marlstone and limestone, with an abundant fossil content and a remarkable stratigraphic continuity along several hundred meters, known as Vaca Muerta Formation. This formation was originated in distal hemipelagic setting of a carbonate ramp and is one of the most important unconventional hydrocarbon reservoirs in the world. The detailed study of six stratigraphic sections, allowed the elaboration of a reliable biostratigraphic scheme and its correlation with Andean ammonites, calpionellids, and polarity zones. Calcareous dinoflagellate cysts within the Vaca Muerta Formation are moderately preserved. Despite that, twenty-nine species and nine biozones have been identified: Committosphaera pulla, Parastomiosphaera malmica, Colomisphaera tenuis, Colomisphaera fortis, Stomiosphaerina proxima, Stomiosphaera wanneri, Colomisphaera vogleri and Colomisphaera conferta. These results allow to contribute to an increasingly solid chronostratigraphic framework in the Neuquén Basin.
https://www.schweizerbart.de/papers/nos/detail/56/101752/TithonianBerriasian_ca…

Premio - Dra. Tomezzoli

La Dra. Renata Tomezzoli ha sido distinguida con el Premio Asociación Geológica Argentina 2025 correspondiente a la disciplina Geofísica.

 

foto tomezzoli

 

Nos alegra mucho comunicarles que nuestra compañera, la Dra. Renata Tomezzoli, Investigadora Principal del CONICET ha sido distinguida con el Premio Asociación Geológica Argentina 2025 correspondiente a la disciplina Geofísica, otorgado en reconocimiento a su gran trayectoria y a sus muy destacadas contribuciones científicas al desarrollo del Paleomagnetismo.

 

premio tomezzoli

 

¡El IGeBA felicita a Renata Tomezzoli por este merecido premio!

The Gondwanide deformation along the southwestern border of the Río de la Plata Craton: Geochemical and geochronological constraints on ductile shear zones from the Ventania System basement, Argentina

Carlos A. Ballivián Justiniano, Sebastián Oriolo, Miguel A.S. Basei, Mabel E. Lanfranchini, Rodolfo O. Christiansen, Norberto J. Uriz, Sebastián E. Vázquez Lucero, Daniela A. Del Bono, Marnie A. Forster, Ricardo O. Etcheverry, Colombo C.G. Tassinari, Marcos A. Comerio, Claudia B. Prezzi
2 023
Journal of South American Earth Sciences Volume 124, April 2023
This work deals with the study of Gondwanide ductile shear zones developed in Neoproterozoic–middle Cambrian basement rocks of the Ventania System and possibly related to the reactivation of the Sierra de la Ventana Shear Zone. This reactivation was caused by the northeastward migration of the Gondwanide deformation from the North Patagonian Massif. The crustal shortening related to the Gondwanide Orogeny gave rise to thrusting of the Ventania System basement over Paleoproterozoic rocks of the Río de la Plata Craton. This work focuses on the study of muscovite ± quartz phyllonites of the Ventania System basement and quartz ± muscovite veins crosscutting basement and Paleozoic cover rocks of the system. Structural and magnetic surveys were performed in order to characterize the Gondwanide structures of the basement, while petrographic, X-ray diffraction, geochemical, and geochronological studies were carried out in order to investigate the nature, P-T conditions, element mobility, and age of these shear zone-related rocks. In the Sauce Chico Inlier, mylonitized basement rocks crop out along the western edge of the system, near the basement–Paleozoic cover interface, where the main structures are top-to-NNE reverse ductile shear zones with related phyllonites. Ductile shearing under greenschist-grade conditions (125–340 MPa and 300–400 °C) promoted major and trace element mobility. Phyllonites are the result of extreme hydrolysis of feldspars from the acidic igneous rocks of the basement, producing muscovite and releasing aqueous SiO2 later redeposited as quartz veins. These phyllonites developed in connection with reactivated contacts between basement units and also the basement–Paleozoic cover interface. New Rb–Sr quartz-muscovite and Ar/Ar muscovite ages for phyllonites and a quartz vein indicate a protracted tectono-metamorphic history mainly restricted to the Cisuralian (ca. 287 Ma), comprising regional folding and metamorphism, shear zone activity, vein-type mineralization, and syntectonic deposition of the Tunas Formation. Subsequent reactivations during the Lopingian (ca. 256 Ma) and probably in Late Triassic times (ca. 227 Ma) resulted from localized shearing along mylonitic belts.
Pub-Oriolo-The Gondwanide deformation along
https://www.sciencedirect.com/science/article/pii/S089598112300086X

Devonian to Early Carboniferous Retreating—Advancing Subduction Switch in the Northwestern Patagonia Accretionary Orogen: U-Pb and Lu-Hf Isotopic Insights

Paulo Marcos, Emiliano M. Renda, Pablo D. González, Sebastián Oriolo, Nicolás Scivetti, Leonardo Benedini, Mauro Geraldes, Daniel Gregori, María Belén Yoya, Marcos Bahía
2 023
Tectonics, Volume42, Issue11 November 2023
In this contribution, we present new early middle Devonian igneous and metaigneous units with a major juvenile magmatic source input in the North Patagonian Massif, which were discovered through U-Pb and Lu-Hf zircon analyses. Afterward, we assessed their tectonic implications for northwestern Patagonia and then for southern South America, combining our results with available database information consisting of igneous crystallization ages and isotopic data of the Devonian to early Carboniferous magmatic units, tectonic-metamorphic analyses, and thermochronologic record. This study allows for distinguishing retreating and advancing subduction switching in northwestern Patagonia (38°30′ to 44°S) and a contrasting coetaneous evolution for basement outcrops exposed further north (27°30′ and 37°30′S). The early middle Devonian (400–380 Ma) northwestern Patagonian magmatism is characterized by widespread magmatism and positive εHf–εNd linked to forearc and backarc magmatism that evolved within a retreating subduction stage. A tectonic switching toward advancing orogeny stage began in the late Devonian, evidenced by a lull in magmatic activity with a negative εHf–εNd trend, possibly contemporaneous with the first tectonic-metamorphic event in western Patagonia. An early Carboniferous magmatic gap, followed by the subsequent development of the main foliation in the basement during the Carboniferous-Permian period, denotes the acme of this contractional stage. In contrast, the Devonian period in the northern segment is characterized by mostly negative εHf–εNd values, reverse shear zone activity in the foreland, and an inboard magmatism migration, evidencing a compressive tectonic setting that changed to an extensional configuration in the early Carboniferous with widespread arc magmatism development.
Pub-Oriolo-Devonian to Early Carboniferous
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022TC007533

Análisis sedimentológico de la Formación Los Molles (Bajociano superior - Bathoniano inferior) en el arroyo Carreri, Neuquén

Grado: Tesis de Licenciatura

Alumno: Tomás Lopez Cajaraville 

Año: 2019

Directora:  Dr. Diego A. Kietzmann 

Resumen

En el presente Trabajo Final de Licenciatura se realizó un análisis de las características sedimentológicas de los afloramientos de la Formación Los Molles ubicados en la margen oriental del arroyo Carreri en la cuenca Neuquina, con el fin de comprender la evolución del sistema sedimentario y su vinculación con las sedimentitas deltaicas de la Formación Lajas. Para ello se levantó un perfil sedimentológico de 370 metros donde se reconocieron un total de 6 asociaciones de facies que fueron interpretadas como facies de abanico submarino y frente deltaico en base a sus características sedimentológicas y estratigráficas. Asimismo, a partir del material paleontológico hallado en la unidad se pudo acotar la edad de la sucesión al lapso Bajociano superior – Batoniano inferior. De manera complementaria, se realizó un estudio de anisotropía de susceptibilidad magnética en los primeros 100 m del perfil para conocer la petrofábrica de las rocas en las facies más distales del sistema. Esto permitió reconocer una clara dirección de progradación del sistema en sentido NE lo cual es coincidente con lo observado en estructuras sedimentarias de esta misma unidad en otras partes de la cuenca.  Se realizó un registro de la radiación gamma natural emitida por el afloramiento en dos facies características del sistema, las cuales mostraron ser consistentes con lo esperado para estas facies y a su vez pudieron ser contrastadas con depósitos de la misma unidad observados en el subsuelo del depocentro Barda Colorada Este. Finalmente, se analizaron cortes delgados para conocer la fábrica microscópica de cada facies como así también se realizó un análisis mediante microscopia electrónica de barrido (SEM) para conocer tanto la distribución como la forma del sistema poral asociado a la matriz y el cemento en estas rocas.

tesis lic-dir Kietzmann

Relationships between Payenia volcanism and deep-seated structural controls: Insights from geophysical methods at Nevado volcanic field, Mendoza, Argentina

M. Soledad Morales Volosín, Claudia Prezzi, Corina Risso
2 022
Journal of South American Earth Sciences Volume 116, June 2022
The Nevado Volcanic Field (NVF), in southern Mendoza foothills, is part of the Payenia Volcanic Province, a large Quaternary retro-arc volcanic area composed principally of basaltic lava flows and monogenetic volcanoes. Monogenetic volcanism location, distribution and evolution are extremely sensitive to previous rheological discontinuities or faults affecting their basement. With the aim of exploring the subsurface configuration and contributing to a better understanding of this volcanism, we analysed and interpreted aeromagnetic and gravity datasets in addition to structural and volcanic alignments information. Our results show that location of volcanism would have been mainly controlled by NW-SE trending structures. These structures would extend at least to middle crust levels. On the other hand, a secondary control might be related to crustal domains with different densities, which could have affected magma propagation to the surface, hence, controlling the spatio-temporal distribution of volcanoes. The complex interplay between these factors would be responsible for the distribution of volcanic centres. Finally, we discuss the implications of these controls concerning the tectonic stress regime contemporaneous with volcanic activity.
Pub-Prezzi-Relationships between Payenia volcanism
https://www.sciencedirect.com/science/article/pii/S0895981122000700

Statistical analysis of the connection between geomagnetic field reversal, a supernova, and climate change during the Plio–Pleistocene transition

Maria Julia Orgeira, Victor Manuel Velasco Herrera, Luiggina Cappellotto & Rosa Hilda Compagnucci
2 022
International Journal of Earth Sciences, Volume 111, pages 1357–1372, (2022)
A significant change in the Earth’s climate occurred during the Pliocene–Pleistocene transition. Different external and internal forcings were interrelated in such a way that they promoted the cooling of the climate and environmental changes. We analyzed these changes using a mathematical and statistical approach based on a new algorithm combining Artificial Intelligence and the new multiple cross-wavelet analysis. Although the geomagnetic field (GF) paleointensity showed oscillations over time and not a uniform decay, the results of the Radial Basis Function Artificial Neural Networks showed a long periodicity oscillation with a downward trend practically throughout the Plio–Pleistocene transition. A weakened GF could have allowed an increase in the flux of galactic cosmic rays (GCR) penetrating the Earth’s atmosphere. This led us to hypothesize that, during the Plio–Pleistocene transition, the increase in GCR could have induced a gradual increase in clouds and, therefore, the albedo intensified, causing a progressive decrease in the Earth's surface temperature, as recorded in different paleoclimatic reconstructions of the Plio–Pleistocene. In addition to the known variations in orbital parameters, the GF behavior (the Gauss–Matuyama reversal) and a feasible influence of a coetaneous near supernova event (at less than 100 pc), could have reinforced the climatic forcings towards glacial conditions during the Plio–Pleistocene transition (~ 2.5 Ma).
Pub-Orgeira-Statistical analysis of the
https://link.springer.com/article/10.1007/s00531-022-02184-3

Hydrocarbon distribution along the Soapaga thrust (Eastern Cordillera, Colombia) based on new strategic geochemistry samples

Eduardo A. Rossello & Rolando Di Primio
2 022
Acta Geochimica, Volume 41, pages 335–350, (2022)
The Colombian Eastern Cordillera constitutes a region with potential for finding hydrocarbon reserves that are still under-explored, despite the existence of oil and tar sand production. The intense tectonic deformation affects the petroleum systems and increases exploration challenges due to the different generation, maturation, and entrapment conditions that they produce. Diverse geochemical analysis conducted on strategic samples determines that these are likely generated by the same anoxic marine source rock type. Two source rock samples we investigated are characterized by very different biomarker signals as compared to the tar sands and oil samples. Both samples are dominated by hopanes as compared to tri- and tetracyclic terpanes, with very low (Tibasosa Formation) to no (Chipaque Formation) extended tricyclic terpanes. The Soapaga Thrust, along which the analyzed samples are located, has exercised first-rate regional structural control of the distribution of hydrocarbons in the studied area. The uplift of their Mesozoic hanging wall produces intense erosion with sediment transport towards the eastern footwall forming the present infill of the Arcabuco basin. The kitchen areas were connected with the shallower entrapment sectors where excellent reservoir levels such as the Picacho Formation before the Soapaga Thrust movement. The high degree of biodegradation observed in the Picacho Fm. tar sands support early charge before the Soapaga thrust movement, and severe biodegradation following the thrust movement when hydrocarbon supply from the kitchen was interrupted. This work aims to contribute to a better understanding of the geochemical characteristics of the petroleum systems due to the action of the Soapaga Thrust.
https://link.springer.com/article/10.1007/s11631-021-00498-8

Disentangling the Medieval Climatic Anomaly in Patagonia and its impact on human societies

Ivana L Ozán, María E de Porras, Ramiro Barberena
2 022
The Holocene, Volume 32 Issue 8, August 2022
This paper revises paleoenvironmental data from Patagonia (southern South America) to discuss the occurrence, characteristics, and human impact of the Medieval Climatic Anomaly (MCA). The analysis of continuous paleoenvironmental archives with multidecadal-to-centennial resolution is based on a quality assessment regarding data interpretation, chronological control, and time range adequacy within the MCA lapse. After applying this three-stepped quality filters on the total dataset (N = 48), 18 cases can accurately be ascribed to the MCA. Except for two sites indicating wetter conditions, these records show dry and/or warm conditions between ca. 750 and 1350 CE (core period at ca. 800–1200 CE). Even though MCA records come mostly from forests and forest-steppe ecotones, all previous archeological hypotheses about the MCA effects on past hunter-gatherers were proposed for the steppes, particularly in southern sectors, thus requiring an assessment of the source of the signal, their synchronicity and causality between human-environmental processes. In the southern steppe, paleoenvironmental records partially overlapping with the MCA time window actually show a predominance of wet conditions between 47° and 50° S, whereas a generalized aridity is recorded in southern tip of the continental Patagonia between 51° and 52° S. Thus, a complex scenario of landscape fragmentation can be supported in the southern steppes during the MCA, produced not only by enhanced aridity in dry environments, but also because of the presence of wet and more resilient areas. This landscape heterogeneity must be considered to deepen the understanding of behavioral changes contemporaneous to the MCA. However, a scenario of demographic growth suggested around 1000 CE for the entire Patagonia could have promoted human changes similar to those expected for the MCA. Finally, no-archeological discussions linked to the MCA were developed for forest regions, despite their robust paleoenvironmental records, implying that changes in proxy data might not have necessarily involved important environmental changes.
Pub-Ozan-Disentangling the Medieval Climatic
https://journals.sagepub.com/doi/full/10.1177/09596836221095993

Recent advances on tectonics of the Andes and their foreland and southern North America, as part of special issues published in the Journal of South American Earth Sciences in the last three years (2019-20-21)

Folguera Telichevsky, Andres; Vega, F.; Costa, Carlos Horacio; Calmus, T.; Dávila, F.; Alasino, Pablo Horacio; Limarino, Carlos Oscar; Martinez, F.; Paredes, José Matildo; Oriolo, Sebastián; Agusto, Mariano Roberto; Contreras Reyes, E.; Palazzesi, Luis; Euillades, Pablo Andrés; Carretier, S.; Hauser, N.; Rapalini, Augusto Ernesto; Kietzmann, Diego Alejandro
2 022
Journal of South American Earth Sciences, Volume 118, October 2022
This Editorial is based on the recent advances presented in the Special Issues related to tectonics across South America, released in the last three years. Its objective is to display the intense work focused on different lines of research of the Andean and Pre-Andean tectonic field and also to summarize key aspects extracted from these volumes in one single document. These Special Issues describe recent advances related to supercontinent Gondwana formation and posterior peripheral accretions during the Early Paleozoic, the instalment of coetaneous arc along the paleo-Pacific trench, the development of Late Paleozoic basins in the retro-arc region, Early Mesozoic extension related to the break-up of Gondwana, Late Cretaceous-Cenozoic closure of main retroarc depocenters, conformation of the proto-Andes, the growth of their structure and temporal destabilization during the Cenozoic, exhumation degree, paleoenvironmental changes experienced during these processes, and their neotectonic and seismological behavior. In the following paragraphs we will describe their general content and main achievements reached in these volumes.
https://www.sciencedirect.com/science/article/pii/S0895981122002218?via%3Dihub=
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