Name：Thermal Ionization Mass Spectrometer (TIMS)
Type： Triton Plus
Manufacturer：Thermo Fisher Scientific Co.,Ltd
Purchasing time: April 2013
Measuring Sr、Nd 、Ca and Cr isotopes of bulk rocks and minerals
Rb-Sr and Sm-Nd systematics have been widely used in geochronology and isotopic tracing. Geological reservoirs possess Sr, Nd isotopic ratios different among each other due to their different Rb/Sr and Sm/Nd ratios and long-term radiogenic accumulation. The Sr and Nd isotopic ratios do not change significantly during short-term geological processes, e.g., partial melting, fractional crystallization, and etc, and thus can be used as an important tracer for material sources of rocks. As for geochronology, for some rocks lack of zircons and other suitable minerals for U-Pb dating, Rb-Sr and Sm-Nd systematics can provide precise rock-formation ages, such as the crystallization or metamorphic age. Furthermore, due to different closure temperatures of Rb-Sr, Sm-Nd and U-Pb systems, multiple geochrons are used to reveal the P-T-t paths of metamorphic processes in some studies of metamorphic rocks.
Ca isotope has been one of the most focused metallic isotopes in the new century. Since Ca is one of the main elements in carbonates(calcite, dolomite, aragonite etc.), most of the Ca isotope research have been concentrated on the area about carbonates, including Ca isotope evolution of paleoocean, oceanic anoxic events and mass extinction in the past. Also, there are a few research focusing on the isotopic features during magmatic evolution, but more work needs do be done.
Cr isotopes also gain much attention during the first decade of the 21st century. Due to the variations of the valence of Cr, Cr isotope can used to tracing the redox state of paleoenvironmentin bio-geochemistry. Among one of the heavy metals, Cr is harmful to the environment, animals and humankind. The reduction of Cr(VI) can effectively reduce the harm to the environment, and this process will be accompanied by significant Cr isotopic fractionation. Therefore, Cr isotopes can be used to trace the pollution situation, such as the source and migration process of Cr pollutant in environmental geochemistry. Another significantly applied area of Cr isotope is cosmochemistry. Due to short-lived radionuclide 53Mn, 53Mn-53Cr systematics of bulk samples from a differentiated planetesimal can yield important constraints on its time of differentiation and valuable information on large scale processes within early solar system bodies. 53Mn-53Cr system has been becoming one of the most powerful method to analyze the evolution of solar system in the first few million years.