Composition and parageneses evaluation of picroilmenites found in sedimentary complexes to forecast their primary sources

Abstract

Heavy concentrate and mineralogical analysis of the composition and typomorphic peculiarities of picroilmenites and their parageneses found in the sedimentary complexes of the Olenyok region of western Yakutia has been carried out to forecast their primary sources. The form, survival rate and quantity of picroilmenite grains have been studied in the stream sediment sample. Their chemical composition has been determined and diagrams of TiO₂-MgO and Cr₂O₃-MgO content have been made. Within the boundaries of the region the dispersion halo of kimberlite indicator mineral (KIM) in the modern sediments is characterized by the highest survival rate in comparison with the neighboring territories that along with their superior size distribution and hurricane contents, clearly indicates the immediate vicinity of primary sources. Ulakhan-Yurege field,that has been forecast includes the basins of the Ulakhan-Yurege, Ulakhan-Talahtah and Tustakh rivers and is characterized by local KIM halo with a high survival rate in Lower Cretaceous and modern sediments (picroilmenite grain of class I and II up to 40%).