Integraltion of Chaco-Paraná and Paraná basins terrestrial gravity data using GOCE geopotential model: a Major Proterozoic to Cambrian suture revealed

The Chaco-Paraná basin (CPB) is located mostly in the north-eastern Argentina, covering an area of approximately 700,000 km2 in a lowland region (~100 m a.s.l.), known as Chacopampean plain. The average sediment thickness of the basin is 4,000 m, and along the Las Breñas fault zone the sediment thickness may reach more than 6,000 m. The Paraná basin (PB) is located in south Brazil, covering an area of over 1,000,000 km2 and its cumulative sediment and basalt thickness reaches up to 7,000 m. The topography over the PB is more irregular and has an average altitude of 700 m around its borders and of 300 m along the Paraná River. (...)CAPES - Mincyt Project 234/13CNPqSECIT

Did Patagonia collide with Gondwana in the Late Paleozoic? Some insights from a multidisciplinary study of magmatic units of the North Patagonian Massif

The origin of Patagonia and its relations with the South American crustal blocks to the north have been a matter of debate for decades. We report results from a multidisciplinary study centered on Paleozoic granitoids exposed in the northeastern corner of the North Patagonian Massif. Microstructural and magnetofabric studies reveal two suites of granitoids. Late Carboniferous (?) granitoids (Yaminué Complex, Tardugno Granodiorite, Cabeza de Vaca leucogranite) were emplaced and subsequently deformed in a major NNE-SSW compressive stress regime that also provoked top-to-the-SW thrust deformation in shallow crustal levels. Gravity and geobarometric studies show that the same major deformation event has been recorded at different crustal levels. The age and type of deformation of this event recorded across the northern boundary of Patagonia strongly supports a Late Carboniferous - Early Permian frontal collision between Patagonia and Gondwana. This major deformation event ceased by 281 Ma when the Navarrete Plutonic Complex, which shows mainly magmatic fabrics, was emplaced under a far-field WNW-ESE stress regime. Crustal continuity between the North Patagonian Massif and the Pampia and Arequipa- Antofalla terranes is suggested by similar Late Paleoproterozoic crustal model ages, comparable detrital zircon ages in Early Paleozoic successions, the apparent continuity of an Early Ordovician continental magmatic arc and paleomagnetic data. Reconciliation of this evidence with the Late Paleozoic frontal collision is obtained in a tectonic model that suggests that the North Patagonian Massif is a parautochthonous crustal block

New geophysical evidences of the presence of a buried caldera in Laguna Pozuelos, Northern Puna

In the southern border of Laguna de Pozuelos Basin, the Pan de Azúcar volcanic complex crops out. It consists of several dacitic volcanic dome centers of ~ 12 Ma. Previous interpretation of seismic lines and a detailed ground magnetic survey indicated the presence of buried intrusive bodies. The determination of the existence of buried bodies has two major implications: 1) these volcanic complexes are closely associated with ore deposits (as part of the Bolivian tin ore polymetallic belt); and 2) the existence of a large ancient caldera (~12 Ma) beneath the central and southern part of the Laguna de Pozuelos Basin, covered by the infilling sediments was previously suggested. The volcanic complexes would represent the final stages of such a calderic magmatic system. In order to confirm the existence of other buried intrusives and/or a buried caldera system, detailed ground magnetic and gravity surveys were carried out. The magnetic map is dominated by positive and negative anomalies in the southern sector of the basin, associated with the dacitic domes. The residual Bouguer anomaly presents a semicircular pattern, having only positive values. We applied the curvature technique to analyse the magnetic and gravity signals and used Euler deconvolution to estimate the depth to the sources. Our results would support the hypothesis of a large caldera buried beneath the Laguna de Pozuelos Basin. The identification of such a large Middle Miocene caldera would bring new insight into the magmatic evolution of the northern Puna.Fil:Prezzi, C.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Poisson relation applied to the Navarrete Plutonic Complex, northeast North-Patagonian Massif, Argentina

Se realizó un estudio gravimétrico y magnetométrico en los afloramientos graníticos del Complejo Plutónico Navarrete, ubicado al noreste del Macizo Norpatagónico. Se analizó el grado de correlación entre ambos campos potenciales utilizando la relación de Poisson. Para ello, 1) se preparó un mapa de gradiente vertical de gravedad, que se comparó con el mapa de anomalías magnéticas reducidas al polo, 2) se calculó la relación magnetización - densidad encontrándose un notorio cambio de polaridad entre ambos campos potenciales. Cálculos complementarios como las soluciones de la señal analítica, en una sección transversal al Complejo Plutónico Navarrete, muestran la existencia de una falla geológica central que lo divide en dos bloques. La geometría inferida a partir de un modelo gravimétrico, y los cambios de polaridad en ambos lados del Complejo Plutónico Navarrete, indican diferencias de composición mineralógica y génesis, entre el Complejo Plutónico Navarrete Oriental y el Occidental. doi: https://doi.org/10.22201/igeof.00167169p.2010.49.4.13

Did Patagonia collide with Gondwana in the Late Paleozoic? Some insights from a multidisciplinary study of magmatic units of the North Patagonian Massif

The origin of Patagonia and its relations with the South American crustal blocks to the north have been a matter of debate for decades. We report results from a multidisciplinary study centered on Paleozoic granitoids exposed in the northeastern corner of the North Patagonian Massif. Microstructural and magnetofabric studies reveal two suites of granitoids. Late Carboniferous (?) granitoids (Yaminué Complex, Tardugno Granodiorite, Cabeza de Vaca leucogranite) were emplaced and subsequently deformed in a major NNE-SSW compressive stress regime that also provoked top-to-the-SW thrust deformation in shallow crustal levels. Gravity and geobarometric studies show that the same major deformation event has been recorded at different crustal levels. The age and type of deformation of this event recorded across the northern boundary of Patagonia strongly supports a Late Carboniferous - Early Permian frontal collision between Patagonia and Gondwana. This major deformation event ceased by 281 Ma when the Navarrete Plutonic Complex, which shows mainly magmatic fabrics, was emplaced under a far-field WNW-ESE stress regime. Crustal continuity between the North Patagonian Massif and the Pampia and Arequipa- Antofalla terranes is suggested by similar Late Paleoproterozoic crustal model ages, comparable detrital zircon ages in Early Paleozoic successions, the apparent continuity of an Early Ordovician continental magmatic arc and paleomagnetic data. Reconciliation of this evidence with the Late Paleozoic frontal collision is obtained in a tectonic model that suggests that the North Patagonian Massif is a parautochthonous crustal block