A Pc Compatible Brazilian Software For Obtaining Thermal Histories Using Apatite Fission Track Analysis

In this work a software developed in the Instituto de Física Gleb Wataghin, IFGW, UNICAMP, Campinas, SP, Brazil for obtaining thermal histories using apatite fission track analysis is presented. This software works in Microsoft-Windows environment. It will be freely disposable in the web site of the Departamento de Raios Cósmicos, IFGW, UNICAMP. Thermal histories obtained through this software are compared with those deduced using Monte Trax the software compatible with Apple Macintosh developed by Gallagher. © 2001 Elsevier Science Ltd. All rights reserved.341-6149154Almeida, F.F.M., Carneiro, C.D.R., Origem e evolução da Serra do Mar (1998) Rev. Bras. Geociênc., 28 (2), pp. 135-150Amaral, G., Born, H., Hadler, N.J.C., Iunes, P.J., Kawashita, K., Machado D.L., Jr., Oliveira, E.P., Tello, S.C.A., Fission track analysis of apatites from São Francisco Craton and Mesozoic alcaline-carbonatite complexes from central and southeastern Brazil (1997) J. S. Am. Earth Sci., 10, pp. 285-294Bigazzi, G., Length of fission tracks an age of muscovite samples (1967) Earth Planet. Sci. Lett., 3, pp. 313-318Bigazzi, G., Guedes, S., Hadler, N.J.C., Iunes, P.J., Paulo, S.R., Tello, S.C.A., Application of neutron dosimetry by natural uranium and thorium thin films in fission track dating (2000) Proceedings of the Nineth International Conference on Fission Track Dating and Thermocronology, pp. 33-35. , Lorne, Australia, February 6-11. Book of (extended) Abstracts, Geological Society of Australia Abstracts Series No. 58Duddy, I.R., Green, P.F., Laslett, G.M., Thermal annealing of fission tracks in apatite 3. Variable temperature behaviour (1988) Chem. Geol. (Isot. Geosci. Sect.), 73, pp. 25-38Gallagher, K., Evolving temperatures histories from apatite fission-track data (1995) Earth Planet. Sci. Lett., 136, pp. 421-435Gleadow, A.J.W., Fission track dating methods: What are the real alternatives? (1981) Nucl. Tracks, 5, pp. 3-7Gleadow, A.J.W., Duddy, I.R., Lovering, J.F., Fission track analysis: A new tool for the evaluation of thermal histories and hydrocarbon potencial (1983) Aust. Pet. Explor. Assoc. J., 23, pp. 93-102Green, P.F., Duddy, I.R., Gleadow, A.J.W., Tingate, P.R., Laslett, G.M., Thermal annealing of fission tracks in apatite, 1. A qualitative description (1986) Chem. Geol. (Isot. Geosci. Sect.), 59, pp. 237-253Green, P.F., The relationship between track shortening and fission track age reduction in apatite: Combined influence of inherent instability, annealing anisotropy, length bias and system calibration (1988) Earth Planet. Sci. Lett., 89, pp. 335-352Guedes, S., Hackspacher, P., Hadler, N.J.C., Iunes, P.J., Paulo, S.R., Ribeiro, L.F.B., Tello, S.C.A., Recognition of Cretaceous, Paleocene and Plio-Pleistocene activities through AFTA, in Precambriam areas of the Southeast Brazil: Association with the South Atlantic Ocean opening (2000) Proceedings of the Nineth International Conference on Fission Track Dating and Thermochronology, pp. 139-141. , Lorne, Australia, February 6-11. Book of (extended) Abstracts, Geological Society of Australia Abstracts Series No. 58Guedes, S., Hackspacher, P., Hadler, N.J.C., Iunes, P.J., Paulo, S.R., Ribeiro, L.F.B., Tello, S.C.A., (2000) Recognition of Cretaceous, Paleocene and Neogeno Activities, through AFTA, in Precambrian areas of the Southeast Brazil: association with the South Atlantic Ocean Opening, Tectonophysics, , submitted for publicationHadler, N.J.C., Iunes, P.J., Paulo, S.R., Tello, S.C.A., Obtainment of thermal histories for sets of geologically compatible localities by using apatite fission track analysis (1995) Rev. Bras. Fisica Aplicada Instrum., 10, pp. 1-10Hegarty, K.A., Weissel, J.K., Mutter, J.C., Subsidence history of Austria Southern margin: On basis models (1988) Am. Assoc. Pet. Geol. Bull., 72, pp. 615-633Iunes, P.J., (1999) Aplicação da Dosimetria de Neutrons através de Filmes Finos de Urânio Natural e Tório na Datação pelo Método dos Traços de Fissão, , Ph.D. Thesis, IFGW, UNICAMP, BrasilKantsler, A.J., Smith, G.C., Cook, A.C., Lateral and vertical rank variation: Implications for hydrocarbon exploration (1978) APEA J., 18 (1), pp. 143-156Laslett, G.M., Green, P.F., Duddy, I.R., Gleadow, A.J.W., Thermal annealing of fission tracks in apatite 2. A quantitative analysis (1987) Chem. Geol. (Isot. Geosci. Sect.), 65, pp. 1-13Lutz, T.M., Omar, G., An inverse method of modeling thermal histories from apatite fission-track data (1991) Earth Planet. Sci. Lett., 104, pp. 181-195Pereira, M.J., Feijó, F.J., Bacia de Santos (1994) Bol. Geociênc. Petrobrás, Brazil, 8 (1), pp. 219-234Storzer, D., Wagner, G.A., Correction of thermally lowered fission track ages of tektites (1969) Earth Planet. Sci. Lett., 5, pp. 463-468Tello, S.C.A., (1998) Estudo do Annealing de Traços de Fissão em Apatitas. Tanto em Seções Basais Como em Seções Sem Orientação Preferencial, a Partir do Comprimento e da Densidade de Traços de Fissão, , Ph.D. Thesis, IFGW, UNICAMP, BrasilWagner, G.A., Fission track dating of apatites (1968) Earth Planet. Sci. Lett., 5, pp. 463-46

New contraints on ages of glasses proposed as Reference Materials for Fission-Track Dating

New analyses have been performed in order to enhance the data-set on the independent ages of four glasses that have been proposed as reference materials for fission-track dating. The results are as follows. Moldavite - repeated 40Ar/39Ar age determinations on samples from deposits from Bohemia and Moravia yielded an average of 14.34 ± 0.08 Ma. This datum agrees with other recent determinations and is significantly younger than the 40Ar/39Ar age of 15.21 ± 0.15 Ma determined in the early 1980s. Macusanite (Peru) - four K-Ar ages ranging from 5.44 ± 0.06 to 5.72±0.12 Ma have been published previously. New 40Ar/39Ar ages gave an average of 5.12 ± 0.04 Ma. Plateau fission-track ages determined using the IRMM-540 certified glass and U and Th thin films for neutron fluence measurements agree better with these new 40Ar/39Ar ages than the previously published ages. Roccastrada glass (Italy) - a new 40Ar/39Ar age, 2.45 ± 0.04 Ma, is consistent with previous determinations. The Quiron obsidian (Argentina) is a recently discovered glass that has been proposed as an additional reference material for its high spontaneous track density (around 100 000 cm-2). Defects that might producem “spurious” tracks are virtually absent. An independent 40Ar/39Ar age of 8.77 ± 0.09 Mamwas determined and is recommended for this glass. We believe that these materials, which will be distributed upon request to fission-track groups, will be very useful for testing system calibrations and experimental procedures

Reference materials for Fission-Track Datig od natural glasses

The mutual understanding between geochronologists and users might be improved if the latter are enabled to estimate the accuracy of a given dating methodology. One of the grounds of accurate dating system calibrations is the availability of age standards. Only standards allow comparing data produced by different laboratories and/or with different dating methods. During last years much effort has been made to make available a set of reference materials for fission-track (FT) dating of glasses, representing the various experimental conditions one can meet. New analyses have been performed to improve the reference age data-set of these proposed reference glasses. Moldavite - Repeated 40Ar/39Ar age determinations on samples from Bohemian and Moravian deposits yielded a weighted average of 14.34 ± 0.08 Ma. This datum is significantly lower than the 40Ar/39Ar plateau age of 15.21 ± 0.15 Ma, which was considered for a long time the reference aae for this glass. FT age determinations using the recent IRMM - 540 standards glass and U and Th thin films for neutron fluence measurements yielded mean apparent ages of 14.03 ± 0.15 and 13.38 ± 0.66 Ma and mean plateau-corrected ages of 14.38 ± 0.16 and 13.98 ± 0.58 Ma, respectively. These plateau ages better agree with the new 40Ar/39Ar ages than with the previous one cited above. Macusanite (obsidian from the Macusani volcanic field, SE Peru) - New 40Ar/MAr ages have an average of 5.12 ± 0.02 Ma, significantly lower than the previously available K-Ar age (average 5.53 ± 0.06 Ma). Apparent and plateau ages of Macusanites using the same neutron dosimetres as for Moldavite have averages of 4.15 ± 0.09, 3.52 ± 0.07 Ma and 5.20 ±0.11 and 4.64 ± 0.17 Ma, respectively. Also for Macusanite these plateau ages better agree with the new 40Ar/39Ar ages than with previous ages. Roccastrada (population of glass shards separated from the Roccastrada rhyolite, Tuscany, Italy) - a new 40Ar/xAr age - 2.51 ± 0.02 Ma (average of 2 measures) - well consistent with the previous determination on sanidine (2.48 ± 0.05 Ma, recalculated with a new value for the FCT bt standard, is also available for this glass. Quiron (obsidian from the El Quevar volcanic complex, Salta Province, Argentina) - Quiron is a recently discovered phenocryst poor glass which has been prop6sed as an additional reference material for its high spontaneous track density. 40Ar/39Ar ages of 8.75 ± 0.09 (step-heating analysis) and 8.77 ± 0.09 Ma (laser total fusion analysis) were determined. Quiron glass yielded FT apparent and plateau ages of 7.27 ± 0.29 and 8.99 ± 0.31 Ma, respectively. All 40Ar/39Ar ages are given ±20 whereas FT ages are given ± 1. We believe that these glasses we distribute upon request may turn very useful for testing FT system calibrations and experimental procedures. It should be a good practice for analists to inform users on the performance of their system calibration on reference materials

Cognitive impairment and carotid atherosclerosis in a general Italian midlife and old population

The authors describe the design and the general, ultrasonographic, neuropsychological methodology of an observational epidemiological population survey, named REMEMBER (Registry Evaluation Memory in Buttrio e Remanzacco) conducted in the northeast of Italy in a randomized stratified sample of 1,026 subjects (554 F and 472 M) aged 55-98 years. The study was planned as cross-sectional and longitudinal survey of cognitive impairment, cardiovascular risk factors, carotid atherosclerosis in a midlife and older Italian population sample. The objectives of the first phase are to assess the prevalence of the different types of dementia, the cognitive impairment non-dementia, the cardiovascular risk factors, the carotid intima-media thickness and arterial distensibility, and of depression. The conclusions of this study will make it possible to organize preventive and interventional strategies for these epidemic conditions

U And Th Thin Film Neutron Dosimetry For Fission-track Dating: Application To The Age Standard Moldavite

Neutron dosimetry based on U and Th thin films was used for fission-track dating of the age standard Moldavite, the central European tektite, from the Middle Miocene deposit of Jankov (southern Bohemia, Czech Republic). Our fission-track age (13.98±0.58Ma) agrees with a recent 40Ar/39Ar age, 14.34±0.04Ma, based on several determinations on Moldavites from different sediments, including the Jankov deposit. This result indicates that the U and Th thin film neutron dosimetry represents a reliable alternative for an absolute approach in fission-track dating. © 2005 Elsevier Ltd. All rights reserved.396665668Balestrieri, M.L., Bigazzi, G., Bouška, V., Labrin, E., Hadler Neto, J.C., Kitada, N., Osorio Araya, A.M., Zúñiga, A., Potential glass age standards for fission-track dating: An overview (1998) Advances in Fission-Track Geochronology, pp. 287-304. , P. Van den haute F. De Corte Kluwer Academic Publishers DordrechtBigazzi, G., Guedes, S., Hadler Neto, J.C., Iunes, P.J., Oddone, M., Osorio Araya, A.M., Paulo, S.R., Zúñiga, A., Potentialities and practical limitations of an absolute neutron dosimetry using thin films of uranium and thorium applied to the fission track method (1999) Radiat. Meas., 31, pp. 651-656Bouška, V., (1994) Moldavites. The Czech tektites, , Stylizace PragueGleadow, A.J.W., Fission track dating methods: What are the real alternatives? (1981) Nucl. Tracks, 5, pp. 3-14Guedes, S., Hadler Neto, J.C., Iunes, P.J., Zúñiga, A., Tello, S.C.A., Paulo, S.R., The use of the U(n,f) reaction dosimetry in the determination of the λf value through fission-track techniques (2003) Nucl. Instrum. Methods Phys. Res. A, 496, pp. 215-221Holden, N.E., Hoffman, D.C., Spontaneous fission half-lives for ground-state nuclides (2000) Pure Appl. Chem., 72, pp. 1525-1562Hurford, A.J., Standardization of fission track dating calibration: Recommendation by the Fission-Track Working Group of the IUGS subcommission on Geochronology (1990) Chem. Geology (Isot. Geosci. Section), 80, pp. 171-178Hurford, A.J., Zeta: The ultimate solution or just an interim measure? (1998) Advances in Fission-Track Geochronology, pp. 19-32. , P. Van den haute F. De Corte Kluwer Academic Publishers DordrechtHurford, A.J., Green, P.F., The Zeta age calibration of fission track dating (1983) Chem. Geol. (Isot. Geosci. Section), 1, pp. 285-317Iunes, P.J., Hadler Neto, J.C., Bigazzi, G., Tello, S.C.A., Guedes, S., Paulo, S.R., Durango apatite fission-track dating using length-based age corrections and neutron fluence measurements by natural thorium thin films and natural U-doped glasses calibrated through natural uranium thin films (2002) Chem. Geol., 187, pp. 201-211Lange, J.-M., Bollinger, H., Horn, P., Jessberger, E.K., Schaaf, P., Storzer, D., Moldavites from Lusatia (Germany) III: Sr isotope, 40Ar/ 39Ar, and fission track studies (1995) 26th Lunar and Planetary Science Conference, pp. 823-824Laurenzi, M.A., Bigazzi, G., Balestrieri, M.L., Bouška, V., 40Ar/39Ar laser probe dating of the Central European tektite-producing impact event (2003) Meteor. Planet. Sci., 38, pp. 887-894McDowell, F.W., Keizer, R.P., Timing of mid-tertiary volcanism in the Sierra Madre occidental between Durango city and Mazatlan, Mex (1977) Geol. Soc. Am. Bull., 88, pp. 1479-1487Schwarz, W.H., Lippolt, H.J., Coeval 40Ar/39Ar ages of moldavites from the Bohemian and Lusatian strewn fields (2002) Meteor. Planet. Sci., 37, pp. 1757-1763Spadavecchia, A., Hahn, B., Die Rotationskammer und einigen Anwendungen (1967) Helv. Phys. Acta, 40, pp. 1063-1069Staudacher, T., Jessberger, E.K., Dominik, B., Kirsten, T., Schaeffer, O.A., 40Ar/39Ar ages of rocks and glasses from the Nördlinger Ries crater and the temperature history of impact breccias (1982) J. Geophys., 51, pp. 1-11Storzer, D., Poupeau, G., Ages-plateaux de minéraux et verres par la méthode des traçes de fission (1973) Comp. Rend. Acad. Sci. Paris, 276 (500), pp. 137-139Storzer, D., Jessberger, E.K., Kunz, J., Lange, J.-M., Synopsis von spaltspuren- und kalium-argon-datierungen an ries-impaktgläsern und Moldaviten (1995) Exkurs. F. U. Veröfftl. GGW, 195, pp. 79-8

The Th/U ratio in minerals by a fission-track technique: application to some reference samples in order to estimate the influence of Th in fission-track dating.

In this work, a recent technique for the determination of the Th/U ratio in minerals and glasses was applied to relevant samples used as reference in fission-track (FT) dating. This technique, developed for estimating the influence of tracks due to the induced fission of thorium in the irradiation with neutron used in the FT dating routine, proved to be adequate for this purpose. One of the age standard used for FT dating, the Durango apatite, yielded a very high Th/U ratio (around 30). Only in case of such a high Th/U ratios did the technique used in this work yield a Th/U value with acceptable precision. For the other studied samples—glasses Macusanite, Moldavite and JAS-G1—which have Th/U ratios < 5, the experimental error of the Th/U measurement is very high. However, in these cases the contribution of the Th fission to the population of induced tracks is also negligible. For its large Th/U ratio the Durango apatite may introduce systematic errors in FT dating, unless irradiation facilities with high thermalization are used

Late- to post-orogenic exhumation of the Central Pyrenees revealed through combined thermochronological data and modelling

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