Apatite fission track thermochronology studies are applied to unravel the tectonic history of the... more Apatite fission track thermochronology studies are applied to unravel the tectonic history of the onshore southernmost Brazilian margin. Analyzed samples are collected in the Sul-rio-grandense Shield to address the Phanerozoic morphotectonic evolution of the margin, which included the intracratonic Paraná Basin and Mesocenozoic rocks. The Sul-rio-grandense southern shield, southern Brazil, is a major geotectonic feature of southernmost Brazil that includes Paleoproterozoic basement areas and Neoproterozoic fold belts linked to Brasiliano/Pan-African cycle. Crustal reworking and juvenile accretion events related to this cycle were positioned in the region between 900 and 500 Ma1 and were responsible for the assembly of southwestern Gondwana in southeastern South America. This shield is surrounded by the Paleozoic to Triassic sedimentary rocks of the Paraná Basin, which is in turn covered by the Cretaceous magmatic rocks of the Serra Geral Fm., so-called Paraná basalts. The shield is ...
For the last three decades Petrobras continuously developed aggressive exploration and production... more For the last three decades Petrobras continuously developed aggressive exploration and production activity in deep and ultra deep waters of the Brazilian marginal basins. As a result, giant oil fields were discovered (e.g. Marlim, Albacora and Roncador oil fields) leading to a very fast growth of the Brazilian proved reserves. The main daily production comes from Cretaceous and Tertiary deep-water sandstones in Campos Basin until recently interpreted as turbidite depositional systems. The search for the best geological model to optimize production systems has generated over time an impressive data base of 3D and 4D seismic surveys, well logs, cores and fluid samples. Extensive core analysis of these sands, integrated with seismic data, reveals their depositional complexity. The purpose of this paper is to show that bottom currents played a fundamental role in reworking and redistributing turbidite sands. Marginally-derived coarse-grained and thick-bedded turbidite sands were trapped...
The interpretation of 12,000 km of very deep (PSTM to 16 sec., PSDM to 25 km) 2D seismic sections... more The interpretation of 12,000 km of very deep (PSTM to 16 sec., PSDM to 25 km) 2D seismic sections, coupled with gravimetric and magnetometric modeling line-by-line, and the integration of the results with the regional data bank of Petrobras, all together viewed in terms of the recent tectonic models developed for the rupturing and separation of mega-plates, led to a regional (500,000 km2), first-time ever, 3D-view of the deep structure underlying the prolific sedimentary basins of Santos, Campos and Espírito Santo in southeastern Brazil. The three basins are situated onto a continental margin that narrows gradually, from south to north, from a very wide (Santos), through an intermediate (Campos), and then to a narrow (Espírito Santo) passive margin. The seismic sections shows very well the dual rheological behavior of the continental crust, consisting of a deeper and plastic lower crust (with numerous short and strong reflections that display sub-horizontal ductile flow) and a shall...
Asymmetrical accretion by sediment gravity flows as initiation mechanism for the formation of sub... more Asymmetrical accretion by sediment gravity flows as initiation mechanism for the formation of submarine channels Silva, D.B.1, Puhl, E.1, Maestri, R.D.1, Viana, A.R.2 1: Necod/IPH/UFRGS, 91501-970, Porto Alegre (Brazil); danibayer@bol.com.br 2: CENPES/Petrobras, 21941-915, Rio de Janeiro (Brazil); Submarine channels are intriguing geological features which are broadly studied due to their relevance to the transport of sediments from shallow to the deep ocean. Turbidity currents are reported as a relevant mechanism that uses these channels as conduits to deliver coarse-grained sediment to the basin. Their deposits, known as turbidites, have great potential as petroleum reservoirs. Therefore, understanding the initiation and development of submarine channels has a large economic importance. Due to the fact that direct observation of these processes is very challenging physical modeling has being used as an alternative research method. This work reports the results of a total of 8 expe...
The Iberian margin is a well-studied region and presently the best tectonic setting for understan... more The Iberian margin is a well-studied region and presently the best tectonic setting for understanding the dynamic process of margin's formation and evolution. The world largest available dataset enabled to properly constrain the crustal structure and opened new paradigms for passive margins studies. Nevertheless, there are numerous remaining questions, as for example what is the spatial extent of continental inheritance along the margin and what is the role of fluids (serpentinization/magmatism) during margin's formation/deformation? The observation of a hyper-extended crustal domain, now also identified in other margins reveals the highly diverse nature of the crust along rifted margins. What are its physical properties and how do they change laterally? The aim of this study is to explore the physical signature of the serpentinized crust, which composes this hyper-extended domain, to identify the limits of the system and discuss its nature and importance. To investigate the...
The climate influences how sediments is carried out on marine environment, acting in sediment typ... more The climate influences how sediments is carried out on marine environment, acting in sediment type and amount, rainfall (increasing the flow) and sea level changes. To simulate these factors in laboratory a physical model was used to evaluate the gravity flows in a marine environment. At total three different climate scenarios were performed: interglacial humid, glacial semi-arid and glacial arid. A 3D basin tank (7.00 m x 4.66 m) with a shelf-slope-basin configuration was used, and the injected flow was composed of a mixture of coal (scaled down as silt/sand) and kaolin (scaled down as clay fraction). At first, a previous series of runs with constant parameters (no climate scenarios) were performed in order to build a sedimentary substrate for the main long run. As a result, a river-dominated delta with a deep incised valley in a 2 m long shelf was generated. The main series were 53 min long and lowered 16.8 cm the water level. During interglacial humid scenario (23 min long, flow ...
Uma exsudação de petróleo de grandes proporções foi identificada em águas ultra profundas da Baci... more Uma exsudação de petróleo de grandes proporções foi identificada em águas ultra profundas da Bacia do Espírito Santo, na costa leste brasileira. A descoberta foi feita durante a missão de pesquisas Iatá-Piuna, realizada através de cooperação técnica entre os governos do Brasil e do Japão, tendo como principal objetivo investigar ecossistemas marinhos de grandes profundidades no Oceano Atlântico Sul, associados ao escape de fluidos. Para tal investigação foi utilizado o navio de pesquisas R/V Yokosuka e o submersível tripulado HOV Shinkai 6500, capaz de realizar mergulhos tripulados em lâminas d’água de até 6500 metros. Durante a segunda pernada da missão (Leg 2), realizada entre os dias 10 e 24/05/2013, foi descoberta uma mega-exsudação de petróleo em lâmina d’água de 2728 m, ao longo de uma escarpa com 200 m de desnível no leito marinho, localizada a cerca de trinta quilômetros a oeste do limite crustal continente-oceano (COB) e a cerca de 170 km da cidade de Vitória. Nessa escarpa...
The study of hyperpycnal flows (a type of sediment gravity flow) is extremely important in the pe... more The study of hyperpycnal flows (a type of sediment gravity flow) is extremely important in the petroleum industry, since deposits generated by such flows become potential hydrocarbon reservoirs. In order to understand these sedimentary processes in marine environment, laboratory experiments (physical modeling) with controlled input parameters are being performed more accurately to reproduce this natural complex phenomenon. Using this power tool, this work aims to compare the behavior of a hyperpycnal flow in two different situations, i.e., confined and unconfined flow in a subaqueous channel. We sought to establish the hydrodynamic differences and their implications in the transport and deposition of sediments during a short instant of time from a tridimensional physical experiment of long duration. Through the analysis of images was possible to establish correlations of velocity, acceleration and geometry between the two flow situations. The results show that the hyperpycnal flow g...
ABSTRACT The evolution of deep-water rifted margins is intimately linked with complex and poly-ph... more ABSTRACT The evolution of deep-water rifted margins is intimately linked with complex and poly-phase fault structures. These structures known as detachment faults are responsible for extreme crustal thinning and mantle exhumation. During the evolution of detachment faults fluid-rock interaction play an important role, changing the chemical and physical properties of rocks with major implications for the strain localization and structural evolution of the margin. The change in rock chemistry and rheology is best indicated by the breakdown of feldspars and olivine into clays and serpentine minerals, and the pervasive cementation and precipitation of quartz within the fault rocks and veins along detachment faults. Although the chemistry reaction is well known it is still unclear to what extent those reactions can lead to changes in the rheology of the lithosphere and how they can affect the thermal evolution of deep water, hyper-extended rifted margins. Another important question arise about the origin, timing, pathways and composition of these fluids. Are they mantle-derived fluids and/or of marine origin? In this work we present preliminary results from fossil rift-related detachment faults exposed in the Alps and Pyrenees and discuss the role of fluids during lithospheric thinning. We compare the results obtained from these fossil rifted margins with those from the present-day Iberia rifted continental margin.
ABSTRACT Oceanic accretion is thought to be the process of oceanic crust (and lithosphere) edific... more ABSTRACT Oceanic accretion is thought to be the process of oceanic crust (and lithosphere) edification through adiabatic melting of shallow convecting mantle at oceanic spreading ridges. It is usually considered as a post-breakup diagnostic process following continents rupturing. However, this is not always correct. The structure of volcanic passive margins (representing more than 50% of passive continental margins) outlines that the continental lithosphere is progressively changed into oceanic-type lithosphere during the stage of continental extension. This is clear at least, at crustal level. The continental crust is 'changed' from the earliest stages of extension into a typical -however thicker- oceanic crust with the typical oceanic magmatic layers (from top to bottom: lava flows/tuffs, sheeted dyke complexes, dominantly (sill-like) mafic intrusions in the lower crust). The Q-rich continental crust is highly extended and increases in volume (due to the magma) during the extensional process. At the continent-ocean transition there is, finally, no seismic difference between this highly transformed continental crust and the oceanic crust. Using a large range of data (including deep seismic reflection profiles), we discuss the mantle mechanisms that governs the process of mantle-assisted continental extension. We outline the large similarity between those mantle processes and those acting at purely-oceanic spreading axis and discuss the effects of the inherited continental lithosphere in the pattern of new mafic crust edification.
Apatite fission track thermochronology studies are applied to unravel the tectonic history of the... more Apatite fission track thermochronology studies are applied to unravel the tectonic history of the onshore southernmost Brazilian margin. Analyzed samples are collected in the Sul-rio-grandense Shield to address the Phanerozoic morphotectonic evolution of the margin, which included the intracratonic Paraná Basin and Mesocenozoic rocks. The Sul-rio-grandense southern shield, southern Brazil, is a major geotectonic feature of southernmost Brazil that includes Paleoproterozoic basement areas and Neoproterozoic fold belts linked to Brasiliano/Pan-African cycle. Crustal reworking and juvenile accretion events related to this cycle were positioned in the region between 900 and 500 Ma1 and were responsible for the assembly of southwestern Gondwana in southeastern South America. This shield is surrounded by the Paleozoic to Triassic sedimentary rocks of the Paraná Basin, which is in turn covered by the Cretaceous magmatic rocks of the Serra Geral Fm., so-called Paraná basalts. The shield is ...
For the last three decades Petrobras continuously developed aggressive exploration and production... more For the last three decades Petrobras continuously developed aggressive exploration and production activity in deep and ultra deep waters of the Brazilian marginal basins. As a result, giant oil fields were discovered (e.g. Marlim, Albacora and Roncador oil fields) leading to a very fast growth of the Brazilian proved reserves. The main daily production comes from Cretaceous and Tertiary deep-water sandstones in Campos Basin until recently interpreted as turbidite depositional systems. The search for the best geological model to optimize production systems has generated over time an impressive data base of 3D and 4D seismic surveys, well logs, cores and fluid samples. Extensive core analysis of these sands, integrated with seismic data, reveals their depositional complexity. The purpose of this paper is to show that bottom currents played a fundamental role in reworking and redistributing turbidite sands. Marginally-derived coarse-grained and thick-bedded turbidite sands were trapped...
The interpretation of 12,000 km of very deep (PSTM to 16 sec., PSDM to 25 km) 2D seismic sections... more The interpretation of 12,000 km of very deep (PSTM to 16 sec., PSDM to 25 km) 2D seismic sections, coupled with gravimetric and magnetometric modeling line-by-line, and the integration of the results with the regional data bank of Petrobras, all together viewed in terms of the recent tectonic models developed for the rupturing and separation of mega-plates, led to a regional (500,000 km2), first-time ever, 3D-view of the deep structure underlying the prolific sedimentary basins of Santos, Campos and Espírito Santo in southeastern Brazil. The three basins are situated onto a continental margin that narrows gradually, from south to north, from a very wide (Santos), through an intermediate (Campos), and then to a narrow (Espírito Santo) passive margin. The seismic sections shows very well the dual rheological behavior of the continental crust, consisting of a deeper and plastic lower crust (with numerous short and strong reflections that display sub-horizontal ductile flow) and a shall...
Asymmetrical accretion by sediment gravity flows as initiation mechanism for the formation of sub... more Asymmetrical accretion by sediment gravity flows as initiation mechanism for the formation of submarine channels Silva, D.B.1, Puhl, E.1, Maestri, R.D.1, Viana, A.R.2 1: Necod/IPH/UFRGS, 91501-970, Porto Alegre (Brazil); danibayer@bol.com.br 2: CENPES/Petrobras, 21941-915, Rio de Janeiro (Brazil); Submarine channels are intriguing geological features which are broadly studied due to their relevance to the transport of sediments from shallow to the deep ocean. Turbidity currents are reported as a relevant mechanism that uses these channels as conduits to deliver coarse-grained sediment to the basin. Their deposits, known as turbidites, have great potential as petroleum reservoirs. Therefore, understanding the initiation and development of submarine channels has a large economic importance. Due to the fact that direct observation of these processes is very challenging physical modeling has being used as an alternative research method. This work reports the results of a total of 8 expe...
The Iberian margin is a well-studied region and presently the best tectonic setting for understan... more The Iberian margin is a well-studied region and presently the best tectonic setting for understanding the dynamic process of margin's formation and evolution. The world largest available dataset enabled to properly constrain the crustal structure and opened new paradigms for passive margins studies. Nevertheless, there are numerous remaining questions, as for example what is the spatial extent of continental inheritance along the margin and what is the role of fluids (serpentinization/magmatism) during margin's formation/deformation? The observation of a hyper-extended crustal domain, now also identified in other margins reveals the highly diverse nature of the crust along rifted margins. What are its physical properties and how do they change laterally? The aim of this study is to explore the physical signature of the serpentinized crust, which composes this hyper-extended domain, to identify the limits of the system and discuss its nature and importance. To investigate the...
The climate influences how sediments is carried out on marine environment, acting in sediment typ... more The climate influences how sediments is carried out on marine environment, acting in sediment type and amount, rainfall (increasing the flow) and sea level changes. To simulate these factors in laboratory a physical model was used to evaluate the gravity flows in a marine environment. At total three different climate scenarios were performed: interglacial humid, glacial semi-arid and glacial arid. A 3D basin tank (7.00 m x 4.66 m) with a shelf-slope-basin configuration was used, and the injected flow was composed of a mixture of coal (scaled down as silt/sand) and kaolin (scaled down as clay fraction). At first, a previous series of runs with constant parameters (no climate scenarios) were performed in order to build a sedimentary substrate for the main long run. As a result, a river-dominated delta with a deep incised valley in a 2 m long shelf was generated. The main series were 53 min long and lowered 16.8 cm the water level. During interglacial humid scenario (23 min long, flow ...
Uma exsudação de petróleo de grandes proporções foi identificada em águas ultra profundas da Baci... more Uma exsudação de petróleo de grandes proporções foi identificada em águas ultra profundas da Bacia do Espírito Santo, na costa leste brasileira. A descoberta foi feita durante a missão de pesquisas Iatá-Piuna, realizada através de cooperação técnica entre os governos do Brasil e do Japão, tendo como principal objetivo investigar ecossistemas marinhos de grandes profundidades no Oceano Atlântico Sul, associados ao escape de fluidos. Para tal investigação foi utilizado o navio de pesquisas R/V Yokosuka e o submersível tripulado HOV Shinkai 6500, capaz de realizar mergulhos tripulados em lâminas d’água de até 6500 metros. Durante a segunda pernada da missão (Leg 2), realizada entre os dias 10 e 24/05/2013, foi descoberta uma mega-exsudação de petróleo em lâmina d’água de 2728 m, ao longo de uma escarpa com 200 m de desnível no leito marinho, localizada a cerca de trinta quilômetros a oeste do limite crustal continente-oceano (COB) e a cerca de 170 km da cidade de Vitória. Nessa escarpa...
The study of hyperpycnal flows (a type of sediment gravity flow) is extremely important in the pe... more The study of hyperpycnal flows (a type of sediment gravity flow) is extremely important in the petroleum industry, since deposits generated by such flows become potential hydrocarbon reservoirs. In order to understand these sedimentary processes in marine environment, laboratory experiments (physical modeling) with controlled input parameters are being performed more accurately to reproduce this natural complex phenomenon. Using this power tool, this work aims to compare the behavior of a hyperpycnal flow in two different situations, i.e., confined and unconfined flow in a subaqueous channel. We sought to establish the hydrodynamic differences and their implications in the transport and deposition of sediments during a short instant of time from a tridimensional physical experiment of long duration. Through the analysis of images was possible to establish correlations of velocity, acceleration and geometry between the two flow situations. The results show that the hyperpycnal flow g...
ABSTRACT The evolution of deep-water rifted margins is intimately linked with complex and poly-ph... more ABSTRACT The evolution of deep-water rifted margins is intimately linked with complex and poly-phase fault structures. These structures known as detachment faults are responsible for extreme crustal thinning and mantle exhumation. During the evolution of detachment faults fluid-rock interaction play an important role, changing the chemical and physical properties of rocks with major implications for the strain localization and structural evolution of the margin. The change in rock chemistry and rheology is best indicated by the breakdown of feldspars and olivine into clays and serpentine minerals, and the pervasive cementation and precipitation of quartz within the fault rocks and veins along detachment faults. Although the chemistry reaction is well known it is still unclear to what extent those reactions can lead to changes in the rheology of the lithosphere and how they can affect the thermal evolution of deep water, hyper-extended rifted margins. Another important question arise about the origin, timing, pathways and composition of these fluids. Are they mantle-derived fluids and/or of marine origin? In this work we present preliminary results from fossil rift-related detachment faults exposed in the Alps and Pyrenees and discuss the role of fluids during lithospheric thinning. We compare the results obtained from these fossil rifted margins with those from the present-day Iberia rifted continental margin.
ABSTRACT Oceanic accretion is thought to be the process of oceanic crust (and lithosphere) edific... more ABSTRACT Oceanic accretion is thought to be the process of oceanic crust (and lithosphere) edification through adiabatic melting of shallow convecting mantle at oceanic spreading ridges. It is usually considered as a post-breakup diagnostic process following continents rupturing. However, this is not always correct. The structure of volcanic passive margins (representing more than 50% of passive continental margins) outlines that the continental lithosphere is progressively changed into oceanic-type lithosphere during the stage of continental extension. This is clear at least, at crustal level. The continental crust is 'changed' from the earliest stages of extension into a typical -however thicker- oceanic crust with the typical oceanic magmatic layers (from top to bottom: lava flows/tuffs, sheeted dyke complexes, dominantly (sill-like) mafic intrusions in the lower crust). The Q-rich continental crust is highly extended and increases in volume (due to the magma) during the extensional process. At the continent-ocean transition there is, finally, no seismic difference between this highly transformed continental crust and the oceanic crust. Using a large range of data (including deep seismic reflection profiles), we discuss the mantle mechanisms that governs the process of mantle-assisted continental extension. We outline the large similarity between those mantle processes and those acting at purely-oceanic spreading axis and discuss the effects of the inherited continental lithosphere in the pattern of new mafic crust edification.
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