1,721,015 research outputs found
Morpho-sedimentary features of the south-western Scotia Sea
Get PDFFil: Rovira, Ignacio. 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: Tassone, Alejandro Alberto. 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: Esteban, Federico Damián. 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
Gateways and climate: The Drake Passage opening
Get PDFThe Oligocene opening of the Drake Passage between the southern tip of South America and the Antarctic Peninsula, and the subsequent evolution of the Scotia plate, have definitively separated Antarctica from the other continental masses, and have created conditions for the development of the Antarctic Circumpolar Current. This annular water flow has had a profound influence on the global climate system because it has allowed the free transfer of water masses between the Pacific and Atlantic Oceans at mid to high southerly latitudes. The comparative seismic analysis of the passive margins of the western sector of the Scotia plate, represented by the Tierra del Fuego continental margin to the north, and by the Terror Rise to the south, has shown significant morphological and structural similarities between these two margins, supporting the interpretation that they were conjugate before the Drake Passage opened. Moreover, the identification of the oldest magnetic anomalies present at the base of the two margin pairs, corresponding to about 32 million years ago, has allowed the reconstruction, through time, of the relative positions of the two continental margins, and to constrain the events that occurred immediately after the break-up and opening of the Drake Passage. These timings correlate with events seen in the oxygen isotope record from benthic foraminera, and support the view that the Drake Passage opening was the trigger for abrupt Eocene-Oligocene climate deterioration and the growth of extensive ice sheets on the Antarctic continent.Fil: Lodolo, Emanuele. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Tassone, Alejandro Alberto. 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
Morphostructure of the western sector of the North Scotia Ridge
Get PDFThe North Scotia Ridge (NSR) is the submerged morpho-structural expression of the Scotia plate northern edge. It is constituted by the Tierra del Fuego continental margin, isla de Los Estados, Burdwood (BB), Davis and Aurora banks, and the Georgias islands shelf (Parker et al., 1996; Barker, 2001; Giner-Robles et al., 2003; Pandey et al., 2010). About 40 Ma these blocks were grouped forming a continental link between Tierra del Fuego and Antarctica. Afterwards, with the development of the Scotia plate, the blocks drifted towards the east to their actual position (Barker, 2001; Pandey et al., 2010). Several authors have established that the actual movement of the South America - Scotia plate boundary is left-lateral (Forsyth, 1975; Pelayo and Wiens, 1989; Giner-Robles et al., 2003; Thomas et al., 2003; Smalley et al., 2007). In the Tierra del Fuego region, the plate boundary is represented by a mostly transtensional fault system known as Magallanes-Fagnano (Lodolo et al., 2002, 2003, 2006, Tassone et al., 2008; Menichetti et al., 2008). Towards east, the boundary is located in the Malvinas trough, at the north of the BB and it would be transpressive (Cunningham et al., 1998; Giner-Robles et al., 2003; Bry et al., 2004). The change of the tectonic regime (transtensional to the W to transpressional to the E) would occur at 63.5 ºW (Lodolo et al., 2003; Yagupsky et al., 2003). As part of a study of the evolution of the SW Atlantic continental margin, we analyze and describe the morpho-structure of the western sector of the North Scotia Ridge.Fil: Esteban, Federico Damián. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tassone, Alejandro Alberto. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lodolo, E.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Menichetti, M.. Università di Urbino; Itali
I laghi: testimoni del clima del passato
Get PDFDai depositi lacustri della Tierra del Fuego e della Patagonia meridionale si possono ricostruire le variazioni climatiche e gli ambienti del passato. Recenti campagne geofisiche e geologiche rivelano come la coltre di ghiaccio che un tempo copriva buona parte di questo settore meridionale dell’America del Sud, abbia subito una serie di avanzamenti e ritiri a partire dall’Ultimo Massimo Glaciale. Queste dinamiche sono ricostruibili sia attraverso le geometrie delle sequenze sedimentarie, sia attraverso le geometrie delle sequenze sedimentarie, sia attraverso approfondite analisi geochimiche e mineralogiche condotte su carote prelevate dal fondo dei laghi.Fil: Lodolo, Emanuele. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Baradello, L.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Caffau, M.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Grossi, M.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Lippai, Horacio Francisco. 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: Tassone, Alejandro Alberto. 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: Menichetti, Marco. Università di Urbino; Itali
Structural characterization of the Magallanes-Fagnano transform fault, Tierra del Fuego, South America
Get PDFStructural analyses in the area of Fagnano and Deseado lakes show different deformational events that took place in the southernmost South America. The compressional structures represent at least two deformational episodes associated with the Upper Cretaceous Andean Orogeny. A series of NE-vergent thrust faults, product of this compression, show that these faults have accommodate some sinistral motion during Upper Cretaceous times. The NE orientation of reverse faults in the Monte Hope area may indicate the later rotation of these faults by the left-lateral strike-slip motion of the Magallanes-Fagnano fault. The secondary faults of the Deseado and Magallanes-Fagnano fault zones fit quiet well with the Riedel shear model, and some of the normal faults cut the Quaternary sediments, indicating a recent activity. These faults may be the evidence of a significant extensional component of the transcurrent system.Fil: Palotti, Priscila Fiorella. Università di Urbino; ItaliaFil: Menichetti, Marco. Università di Urbino; ItaliaFil: Cerredo, Maria Elena. 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: Tassone, Alejandro Alberto. 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
Una nuova datazione U-Pb sugli zirconi della Formazione Lemaire delle Ande Fuegiane, Terra del Fuego, Argentina
Get PDFUna nuova datazione U-Pb sugli zirconi che provengono da un campione riolitico dall’area delle terme di Rio Valdez permette integrare temporaneamente le rocce vulcaniche delle Andes Fueginos con la evoluzione del bacino di Rocas Verdes. Le età concordanti ottenute delle 11 zirconi analizzati danno un range compreso tra 155-170 Ma, posizionando la roccia nel Giurassico Medio a Superiore. Il resto dei risultati, discordanti, sono stati tracciati su un grafico di concordia, in cui la intercetta inferiore indica un età di cristallizzazione di 163.9 ± 3.6 Ma. In un contesto regionale, questa età conferma l’ipotesi di apertura da SE a NW del bacino marginale di Rocas Verdes, e potrebbe rappresentare un magmatismo precedente alla generazione di crosta quasi-oceanica. Inoltre, non e stata riconosciuta una relazione con la migrazione a SW del magmatismo acido Giurassico.Fil: Palotti, Priscila Fiorella. Università di Urbino Carlo Bó. Dipartimento di Scienze della Terra, della Vita e dell'Ambiente; ItaliaFil: Menichetti, Marco. Università di Urbino Carlo Bó. Dipartimento di Scienze della Terra, della Vita e dell'Ambiente; ItaliaFil: Cerredo, Maria Elena. 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: Tassone, Alejandro Alberto. 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
Western Scotia Sea margins: Improved constraints on the opening of the Drake Passage
Get PDFWe present a revised tectonic interpretation (from ∼28 Ma to 3.2 Ma) of the western sector of the Scotia Sea, incorporating new multichannel seismic reflection profiles and magnetic anomaly identifications for the continental margin off the Tierra del Fuego Island, and available complementary data for the conjugate margin of the northwestern flank of the South Scotia Ridge. Seismic profiles show a remarkable diversity of the pair of conjugate passive margins of the western Scotia Sea in both their morphology and structural framework. The Tierra del Fuego continental margin can be related to a classic rifted passive margin, while the southwestern margin of the Scotia Sea is characterized by steep slopes mostly generated by subvertical faults that abruptly separate the continental crust of the South Scotia Ridge from the oceanic crust of the western Scotia Sea. This structural difference was caused by intense strike-slip tectonism, mostly concentrated along the modern South Scotia Ridge since the early development of the western Scotia Sea. We find evidence for a previously unrecognized magnetic anomaly 10 (∼28 Ma) at the foot of the Tierra del Fuego continental margin; the same anomaly is present at the conjugate northern flank of the South Scotia Ridge. The timing of events leading to the earliest development of the western Scotia Sea, which determined the opening of the Drake Passage is important because this gateway opening had a profound effect on global circulation and climate. The thickness and the distribution of the sedimentary cover overall in the abyssal plain off the two western Scotia Sea margins is different. This is due to the different regimes of the bottom-current flows which affected the western Scotia Sea, both in the past and in the present time.Fil: Lodolo, Emanuele. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Donda, Federica. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Tassone, Alejandro Alberto. 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
Middle Mesozoic to Present Geological Evolution of the Central-Northern Sector of the Falkland/Malvinas Plateau as Inferred From Seismic Data
Get PDFThe sequence stratigraphy is a methodology that, by means of the recognition of depositional sequences in stratigraphic architecture, reconstructs tectonic phases and relationships between tectonic, sedimentation and eustasy. A seismo-stratigraphic study of the northern sector of the Falkland Plateau (FMP) is derived from integrated analysis of two unpublished seismic reflection profiles combined with published seismic profiles, bathymetric and well data. Data analysis allowed the identification of an acoustic basement, four seismic sequences (A to D) and their bounding unconformities (r1, r2, r3 and r4), aged from middle Jurassic to Present. The precambric acoustic basement, bounded by r1 unconformity, overlain by the Middle-Late Jurassic syn-rift continental deposits of sequence A, which is bounded at the top by the r2 unconformity, testify a tectonic behaviour of uplift around the Jurassic/Cretaceous boundary. The overlying sequences B and C represent the post-rift phase. From the late Cretaceous up to Cretaceous/Paleogene boundary, a widespread erosion in the northern part of the FMP is suggested by the r4 unconformity cutting the underlying sequences C and B. The erosion is probably due to a southward tilting linked to underthrusting of the southern sector of the FMP. The lower and constant thickness of sequence D suggests, during the Cenozoic, a slow rate of subsidence, probably linked to the contemporaneous stop of the subduction of the FMP under the Scotia Plate.Fil: Petruccione, E.. Consiglio Nazionale delle Ricerche; Italia. Istituto per l'Ambiente Marino Costiero; ItaliaFil: Tassone, Alejandro Alberto. 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. 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: Nardi, G.. Università degli Studi di Napoli Federico II; ItaliaFil: Lodolo, Emanuele. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Iorio M.. Consiglio Nazionale delle Ricerche; Italia. Istituto per l'Ambiente Marino Costiero; Itali
Holocene seismic stratigraphy of the southern arms of Lago Argentino
No full textLago Argentino hosts various calving glaciers, including the famous Perito Moreno. Although the onland Holocene glacier dynamics is rather well constrained, the paleoenvironments developed in association with a retreating ice front remain largely unknown. A detailed analysis of high-resolution seismic reflection profiles acquired in the southern arms of Lago Argentino has allowed the identification of several unconformities within the lacustrine sedimentary infill. Four seismostratigraphic sequences have been identified in Brazo Rico and three in Brazo Sur. These sequences are separated by three erosive unconformities in Brazo Rico and two in Brazo Sur, and reflect the sedimentation of a pre-Holocene deep basin in a proglacial lake. The older unconformities are associated with instability events within the basin which triggered several mass movements, possibly related to enhanced seismic activity. The younger erosive unconformities were correlated with the “Pearson 1a/Frias 1 advance”, the major glacier advance in the Holocene of the Lago Argentino Basin. This research highlights the importance of studying the glaciolacustrine sediments, representing decisive records of the glacial history and palaeoclimate, which could help unveiling the factors controlling glacier dynamics in the basin and reconstructing the deglacial landscape of the area.Fil: Lozano, Jorge Gabriel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentina. 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: Bran, Donaldo Mauricio. 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 Ciencias Geológicas; ArgentinaFil: Lodolo, Emanuele. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; ItaliaFil: Tassone, Alejandro Alberto. 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 Ciencias Geológicas; ArgentinaFil: Vilas, Juan Francisco A.. 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 Ciencias Geológicas; Argentin
The submerged footprint of Perito Moreno glacier
Get PDFPerito Moreno is the most famous calving glacier of the South Patagonia Icefield, the largest temperate glacier system of the Southern Hemisphere. Unlike most of the glaciers in the region that have strongly retreated in recent decades, the position of Perito Moreno glacier front remained relatively unchanged in the last century. However, earliest photographic documents show that, at the end of the nineteenth century, the front was ca. 800 m behind the current position. There is no reliable information about the positions of the Perito Moreno front in earlier times. Here we show evidence of two subaqueous moraine systems both in the Canal de Los Témpanos and in the Brazo Rico, the two arms of Lago Argentino along which Perito Moreno glacier has flowed over time. These moraines, identified for the first time in the Canal de Los Témpanos from bathymetric and high-resolution seismic profiles, mark the position of the largest glacier advance, tentatively correlated with the moraines of the “Herminita advance” identified and dated onland. We interpret these bedforms as the evidence of the most pronounced advance of Perito Moreno glacier during the mid-Holocene cooling event that characterized this sector of the Southern Hemisphere. This study highlights the importance of subaqueous glacial bedforms, representing decisive records of the glacial history and palaeoclimate, which could help unveiling the origin of the different behavior of glaciers like Perito Moreno that in a warming climate are relatively stable.Fil: Lodolo, Emanuele. Istituto Nazionale di Oceanografa e di Geofsica Sperimentale ; ItaliaFil: Donda, Federica. Istituto Nazionale di Oceanografa e di Geofsica Sperimentale ; ItaliaFil: Lozano, Jorge Gabriel. 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: Baradello, Luca. Istituto Nazionale di Oceanografa e di Geofsica Sperimentale ; ItaliaFil: Romeo, Roberto. Istituto Nazionale di Oceanografa e di Geofsica Sperimentale; ItaliaFil: Bran, Donaldo Mauricio. 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: Tassone, Alejandro Alberto. 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
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