Geochronology

obligatory courses

Basic knowledge in mineralogy and petrology; passive knowledge of English at B2 level.

So called absolute age determination are crucial in geology. It concerns first of all crystalline rocks, where time scale is not preserved like in sedimentary rocks (i.e. fossils) . The subject presents various methods of age determination using both in situ measurements of isotopes ratios (i.e. U,Th-Pb dating on zircons) as well as combined mineral and whole rocks data (isochrones methods). The role of isotopes as tracers in mineralogical sciences are also outlined.

The subject presents modern techniques applied to the age determination based on measurements of isotope ratios in rocks and minerals. The course starts with presentation of some basic information on an atom composition. Radioactive decay and ways of dacay ( are presented. As a valuable method which is applied with the use of equipment present at the Faculty of Geology a chemical dating of monazite is described. Various methods of mass spectrometry applied to isotope ratio measurements are described – SIMS, TIMS and ICP-MS-LA (including a visit to geochronology and isotope geochemistry lab in the ING PAN in Cracow). Classic method of zircon dating based on U/Th-Pb decay is presented in details (including a visit to the ion microprobe -SHRIMP lab at the PIG-PIB). Examples of application of the method are analysed with the use of Isoplote program using various Concordia diagrams. A group of methods based on isochron geochronology are also presented. Applications of Rb-Sr, K-Ar, Re-Os, Sm-Nd, Lu-Hf methods are described. Ar-Ar as a new developed on a basis of the K-Ar method is also presented (also in practise in the ING PAN lab in Cracow).

Some examples of specific methods –thermochronology - fission tracks and (U+Th)/He, C14 method. Important role of isotopes as good tracers of important geological processes is also underlined. Presented theory is connected with practical exercises in different laboratories including optical microscopy lab, scanning microscopy and electron microprobe labs at the Faculty of Geology. Students have possibility to learn these techniques and apply to geochronology.

On completing the course, the student:

- has knowledge in

- choosing if dating in a given rock is possible and choose the best method to do it

- critical assessment of the obtained age results

- has skills in

- conducting the whole path of investigations to obtain the age of the analysed phases androcks, starting from documentation through SEM investigations, mass spectrometry methods analyses and the age calculations

- operating the scanning electron microscope (in a basic range) co-operation with the operator of the electron microprobe

Obtaining a course credit requires active participation in meetings. The course is credited based on the preparation of a presentation of a chosen, unconventional method of isotope dating and solution of some tasks given during the exercises.

A short written examination from theoretical part containing several open questions (5-8).

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