Geochronology Applied to Paleontology
Objectives
Gather knowledge about the potential application of geochronology in palaeontological studies. To learn about sampling techniques and the processing of geological materials for geochronological studies. Develop descriptive studies of heavy mineral concentrates used in geochronology. Have contact with the procedures for isotopic analysis of minerals using laser-coupled mass spectrometers. Develop the ability to interpret geochronological data with C14 in organic matter (coal, wood, peat, seeds, pollen, bones, limestone shells, eggshells, leather, hair, fabrics, paper, ceramics, cave paintings, resins, etc), which can be used in palaeontology to date samples up to around 50,000 years old and also in archaeology can offer clues to determine the age of an artefact (objects, inscriptions and historical documents). Analysing geochronological data on vertebrate bone fragments.
General characterization
Code
10938
Credits
6.0
Responsible teacher
Paulo Alexandre Rodrigues Roque Legoinha
Hours
Weekly - Available soon
Total - 51
Teaching language
Português
Prerequisites
No requirements.
Bibliography
Albardeiro, L., Pereira, M.F., Gama, C., Chichorro, M., Hofmann, M., Linnemann, U., (2014). Provenance study of Pliocene–Pleistocene sands based on ancient detrital zircons (Alvalade Basin, SW Iberian Atlantic coast). SEDIMENTARY GEOLOGY, 307, 47–58.
Allegre, C.J. (Ed.), 2008. Isotope Geology. Cambridge University Press.
Gehrels, G. (2011). Detrital Zircon U-Pb Geochronology: Current Methods and New Opportunities. Tectonics of Sedimentary Basins, John Wiley & Sons, Ltd: 45-62.
Pereira, M. F., Albardeiro, L., C., Gama, C., Chichorro, M., Hofmann, M., Linnemann, U., (2016). Provenance of Holocene beach sand in the Western Iberian margin: the use of the Kolmogorov–Smirnov test for the deciphering of sediment recycling in a modern coastal system. SEDIMENTOLOGY, 63, 1149–1167
Wagner, G. 1999. Age Determination of Young Rocks and Artifacts: Physical and Chemical Clocks in Quaternary Geology and Archaeology (Natural Science in Archaeology). Springer-Verlag.
Teaching method
Fieldwork for observation of stratigraphic sequence; Discussion of sedimentary environments, magmatism and tectonic conditions and global history and evolution of Earth.
Laboratory work in order to contact directly with the partition and grinding of rocks, separation by magnetic susceptibility / density, with the methods of preparing thin sections and mounts of minerals in resin. Binocular microscope observation of mineral for dating.
Support material will be given in digital format about the basic equipment for studies of mineralogy, petrography and geochronology (CL, LA-ICP-MS and SHRIMP);
Resolution of exercises on observation and interpretation of data by the method of radiocarbon geochronology in organic matter, U-Pb and K-Ar age data on detrital minerals in sedimentary rocks. Bibliographic research.
Evaluation method
The evaluation will include: 70% of a written report (theme to choose from a list suggested by the evaluator) and 30% of performance in school activities, exercises and participation
Subject matter
Characterization of the method of radiocarbon (C14), of the radiometric method using zircon U-Pb isotopic system, and of the K-Ar isotopic system with amphibole and mica. Methods of concentration, separation and selection of samples and minerals (sampling, grinding, separation by magnetic susceptibility and density by optical observation). Data processing and error estimate, preparation of Tera-Wasserburg diagrams and concordias using software that is suitable for organizing and presenting results. Practical examples of studied zircon, amphiboles and micas geochronology applied to the calibration of the ages of fossiliferous or non-fossiliferous sedimentary sequences, with crucial importance: in the interpretation of stratigraphic columns and analysis of sedimentary provenance and characterization of sources, in establishing maximum age of deposition and developing models of palaeogeographic reconstruction of regional and global scale.