2013

Geochemistry of Radioactive Elements in the Rocks

of the Guli Massif, Polar Siberia

L. N. Kogarko

Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences,

ul. Kosygina 19, Moscow, 119991 Russia

e_mail: kogarko@geokhi.ru  

The study of radioactive element distribution in the rocks of the Guli Complex revealed an increase of uranium and thorium contents in the final products of magmatic differentiation. In the carbonatite complex, the radioactive elements are mainly accumulated in the early rocks—phoscorites, while their contents in the late phases, dolomitic carbonatites, decrease. The Th/U ratio increases from near_chondritic values in the weakly differentiated highly_magnesian primary magmas to the late rocks—phoscorites, calcitic carbonatites, and dolomitic carbonatites. The majority of radioactive elements are hosted in rare_metal accessory minerals: perovskite, pyrochlore, calzirtite, and apatite. Rock_forming minerals are characterized by extremely low contents of radioactive elements