TIMS
Thermal Ionization Mass Spectrometry

A Finigan Mat 262 thermal ionization mass spectrometer (TIMS) was installed in the Department of Geoscience in 1994. The instrument is equipped with five collectors, 23cm radius, 90° magnetic sector mass analyzer, and a 13-sample magazine ion source. Due to the large dispersion and high ion transmission, it is possible to make precise isotope analyses of elements ranging from lithium to the transuranium series. Currently, Sr, Nd, and Pb isotope ratios of rocks, minerals, fossils and other geological samples can be measured routinely in our department. Nanogram size samples can be measured. TIMS is also useful for determining concentrations of trace elements in samples by isotope dilution methods.

Based on Rb-Sr, Sm-Nd and U-Pb methods, we can determine solidification and cooling ages of igneous rocks, and metamorphic ages of rocks and minerals. Consideration of initial isotope ratios of these elements is now essential in modern petrological studies of magma sources and magmatic processes. Such isotope data are also valuable for inferring provenance of sedimentary rocks, and Sr isotope ratios of fossils can be used for inferring paleoenvironment and paleogeography. Thus, TIMS is useful not only in conventional petrological, geochronological and sedimentological studies, but also has application in paleontological and paleoenvironmental research.