Modelagem evolutiva do planalto Sul de Minas através de correlações entre análise morfométrica da rede de drenagem e termocronologia por traços de fissão em apatitas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Uso da termocronologia por traços de fissão em apatita no reconhecimento de áreas de recarga e análises isotópicas de 234U/238U em águas subterrâneas do aquífero Itararé no município de Americana (SP)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo do annealing de traços de fissão em epídoto

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Contribuição ao conhecimento de processos atuantes no rifteamento continental, por traços de fissão em zircões e apatitas, aplicados no rift continental do sudeste do Brasil, bacias de Taubaté, Resende, Volta Redonda e circunvizinhanças

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização dos ambientes deposicionais na bacia do Ribeirão Entupido, complexo alcalino do Passa Quatro, estado de São Paulo

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Exumação tectônica e evolução associada do relevo no arco de Ponta Grossa, sul-sudeste do Brasil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Termocronologia e história denudacional da Serra do Mar e implicações no controle deposicional da Bacia de Santos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evolução termocronológica por traços de fissão em apatita e zircão das Bacias da Transição Proterozóico-Fanerozóico de Camaquã (RS), Castro (PR), Eleutério (SP/MG), Jaibaras e Cococi (CE)

Pós-graduação em Geologia Regional - IGCE

Morfotectônica da região centro-leste do Estado de São Paulo e áreas adjacentes de Minas Gerais: termocronologia e paleotensões

Pós-graduação em Geologia Regional - IGCE

Long-term landscape evolution and post-rift reactivation in the southeastern Brazilian passive continental margin: Taubat, basin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evolução da tectônica rúptil no nordeste do Brasil baseada na termocronologia por traço de fissão em apatita

Results of apatite fission tracks from twelve samples collected across a Borborema Province transect, northeastern Brazil, revealed two major paleothermal events: a cooling event occurred between Albian and late Cenomanian (110 - 80 Ma) and a second cooling event starting on early Paleocene (66 Ma). Given the wide expression of the studied area (sampling trend along four brazilian states) a correlation between the distribution of fission track data and the current geological / geomorphological scenario was made possible, considering the area’s tectono - stratigraphic past and its thermochronologic evolution until now. The fact that the employed thermochronologic tool relates to a relatively shallow geothermometer, substancially information for understanding the behavior of basement brittle tectonic was achieved. These data were used to analyze faults origin and reactivation, associated with sedimentary basins evolution in the context of South America - Africa continental breakup.

Contribuição à análise de proveniência sedimentar pelo método Traços de Fissão em zircão e influências estruturais para a formação do Planalto Residual de Marília

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Post-breakup tectonics in southeast Brazil from thermochronological data and combined inverse-forward thermal history modeling

The continental margin of southeast Brazil is elevated. Onshore Tertiary basins and Late Cretaceous/Paleogene intrusions are good evidence for post breakup tectono-magmatic activity. To constrain the impact of post-rift reactivation on the geological history of the area, we carried out a new thermochronological study. Apatite fission track ages range from 60.7 +/- 1.9 Ma to 129.3 +/- 4.3 Ma, mean track lengths from 11.41 +/- 0.23 mu m to 14.31 +/- 0.24 mu m and a subset of the (U-Th)/He ages range from 45.1 +/- 1.5 to 122.4 +/- 2.5 Ma. Results of inverse thermal history modeling generally support the conclusions from an earlier study for a Late Cretaceous phase of cooling. Around the onshore Taubate Basin, for a limited number of samples, the first detectable period of cooling occurred during the Early Tertiary. The inferred thermal histories for many samples also imply subsequent reheating followed by Neogene cooling. Given the uncertainty of the inversion results, we did deterministic forward modeling to assess the range of possibilities of this Tertiary part of the thermal history. The evidence for reheating seems to be robust around the Taubate Basin, but elsewhere the data cannot discriminate between this and a less complex thermal history. However, forward modeling results and geological information support the conclusion that the whole area underwent cooling during the Neogene. The synchronicity of the cooling phases with Andean tectonics and those in NE Brazil leads us to assume a plate-wide compressional stress that reactivated inherited structures. The present-day topographic relief of the margin reflects a contribution from post-breakup reactivation and uplift.

Rapporti tra tettonica e clima durante l'esumazione nelle Alpi Centrali. Evidenze dalla termocronologia e dall'analisi strutturale lungo il traforo ferroviario del Sempione

(U-Th)/He and fission-track analyses of apatite along deep-seated tunnels crossing high-relief mountain ranges offer the opportunity to investigate climate and tectonic forcing on the topographic evolution. In this study, the thermochronologic analysis of a large set of samples collected in the Simplon railway tunnel (western-central Alps; Italy and Switzerland) and along its surface trace, coupled with kinematic and structural analysis of major fault zones intersecting the tunnel, constrains the phenomena controlling the topographic and structural evolution, during the latest stage of exhumation of the Simplon Massif, and the timing in which they operated. The study area is located at the western margin of the Lepontine metamorphic dome where a complex nappe-stack pertaining to the Penninic and Ultrahelvetic domains experienced a fast exhumation from the latest Oligocene onward. The exhumation was mainly accommodated by a west-dipping low-angle detachment (the Simplon Fault Zone) which is located just 8 km to the west of the tunnel. However, along the section itself several faults related to two principal phases both with important dip-slip kinematics have been detected. Cooling rates derived from our thermocronological data vary from about 10 °C/Ma at about 10 Ma to about 35 °C/Ma in the last 5 Ma. Such increase in the cooling rate corresponds to the most important climatic change recorded in the northern hemisphere in the last 10 Ma, i.e. the shift to wetter conditions at the end of the Messinian salinity crisis and the inception of glacial cycles in the northern hemisphere. In addition, (U-Th)/He and fission-track age patterns lack of important correlation with the topography suggesting that the present-day relief morphology is the result of recent erosional dynamics. More in details, the (U-Th)/He tunnel ages show an impressive uniformity at 2 Ma, whereas cooling rates calculated at 1 Ma increase towards the two major valleys. This indicates a focusing of erosive processes in the valleys which led to the shaping of present-day topography. Structural analysis documents the presence of two phases of brittle deformation postdating the metamorphic phases in the area. The first one is directly related to the last phase of activity along the Simplon Fault Zone and is characterized by extension towards SO and vertical shortening. The young one is characterized by extension towards NO and horizontal shortening in a along the NE-SO direction. Structures related to the first phase of brittle deformation generate important variations in the older ages' dataset, until 3 Ma, suggesting that tectonics controlled rocks exhumation up to that age. Structures related to the second phase generate some variations also in the younger age dataset, highlighting the activity of faults bordering the massif and suggesting a continuous activity also after 2 Ma. However, most of (U-Th)/He tunnel ages, varying slightly around 2 Ma, document that the Simplon area has experienced primarily erosional exhumation in this time span. In conclusion, all our data suggest that in the central Italian Alps the climatic signal gradually overrode the tectonic effects after about 5 Ma, as a consequence of the climatic instability started at end of Messinian salinity crisis and improved by the onset of glaciations in the northern hemisphere.

Erosione e sollevamento nell'arco calabro-peloritano

The Calabrian-Peloritani arc represents key site to unravel evolution of surface processes on top of subducting lithosphere. During the Pleistocene, in fact the arc uplifted at rate of the order of about 1mm/yr, forming high-standing low-relief upland (figure 2). Our study is focused on the relationship between tectonic and land evolution in the Sila Massif, Messina strait and Peloritani Mts. Landforms reflect a competition between tectonic, climatic, and surficial processes. Many landscape evolution models that explore feedbacks between these competing processes, given steady forcing, predict a state of erosional equilibrium, where the rates of river incision and hillslope erosion balance rock uplift. It has been suggested that this may be the final constructive stage of orogenic systems. Assumptions of steady erosion and incision are used in the interpretation of exhumation and uplift rates from different geologic data, and in the formulation of fluvial incision and hillslope evolution models. In the Sila massif we carried out cosmogenic isotopes analysis on 24 samples of modern fluvial sediments to constrain long-term (~103 yr) erosion rate averaged on the catchment area. 35 longitudinal rivers profiles have been analyzed to study the tectonic signal on the landscape evolution. The rivers analyzed exhibit a wide variety of profile forms, diverging from equilibrium state form. Generally the river profiles show at least 2 and often 3 distinct concave-up knickpoint-bounded segments, characterized by different value of concavity and steepness indices. River profiles suggest three main stages of incision. The values of ks and θ in the lower segments evidence a decrease in river incision, due probably to increasing uplift rate. The cosmogenic erosion rates pointed out that old landscape upland is eroding slowly at ~0.1 mm/yr. In the contrary, the flanks of the massif is eroding faster with value from 0.4 to 0.5 mm/yr due to river incision and hillslope processes. Cosmogenic erosion rates mach linearly with steepness indices and with average hillslope gradient. In the Messina area the long term erosion rate from low-T thermochronometry are of the same order than millennium scale cosmogenic erosion rate (1-2 mm/yr). In this part of the chain the fast erosion is active since several million years, probably controlled by extensional tectonic regime. In the Peloritani Mts apatite fission-track and (U-Th)/He thermochronometry are applied to constraint the thermal history of the basement rock. Apatite fission-track ages range between 29.0±5.5 and 5.5±0.9 Ma while apatite (U-Th)/He ages vary from 19.4 to 1.0 Ma. Most of the AFT ages are younger than the overlying terrigenous sequence that in turn postdates the main orogenic phase. Through the coupling of the thermal modelling with the stratigraphic record, a Middle Miocene thermal event due to tectonic burial is unravel. This event affected a inner-intermediate portion of the Peloritani belt confined by young AFT data (<15 Ma) distribution. We interpret this thermal event as due to an out-of–sequence thrusting occurring in the inner portion of the belt. Young (U-Th)/He ages (c. 5 Ma) record a final exhumation stage with increasing rates of denudation since the Pliocene times due to postorogenic extensional tectonics and regional uplift. In the final chapter we change the spatial scale to insert digital topography analysis and field data within a geodynamic model that can explain surface evidence produced by subduction process.