Trace Element Distribution in Perovskite & Pyrochlore of Kaiser-stuhl Sovite Carbonatites

摘要

Pyrochlore and perovskite are considered as REE-rich accessory phases in manycarbonatitecomplexes, which with their presence can effect the distribution of Trace elementsespecialy REEs. Bythis study, pyrochlores of Orberg's sovite and perovskite of Badberg's sovite fromKaiserstuhlcarbonatitic complex have been analysed for REE, U-TH-Pb as well as other traceelements (Ba, Sr, Nb, Hf,...) with the help of "LA-ICP MS Element 2" at the University of Frankfurt. Fordoing this, aftermeasuring the samples (concentrates in resin) with laser, the main phase of eachmineral wasanalysed via EPMA (Superprobe JXA-8900) in order to find the most suitable element fornormalizingthe data.Although perovskite and pyrochlore have a different concentration of traceelements, they haveshown a parallel distribution of REEs i.e.: an increasing enrichment in REEs fromLu to La, with theexception of higher concentration of Ce than La. A very high concentration of Nb andSr and lowconcentration of Hf were also one of their in common properties.The next step for collectingmore data on the REEs distribution trend in pyrochlore and perovskite, isby analysing suitable crystalsin thick section of their host rock (SOvite). In order to approach this,BSE and SEI photos were takenand main elements concentrations were analysed. An other furtheraim of this study is the in-situmeasurements of the Hf-Nd ratio isotopes with the help of LA-ICP MSwhich can result in precisemeasurments. In-situ analysis allows the isotopic data to beinterpreted within a microstructural contextand the acquisition of multiple datasets (e.g. trace REEPb,PGE-Os, Pb-Hf, Pb-Os) on single grains orparts of grains (N.J. Pearson, W.L. Griffin, S.Y.O'Reilly, 2008).