Composition and distribution of clay minerals in the Upper-Jurassic rocks of the Chim-Loptyuga oil shale deposit in the north-east of the Russian plate

The Upper-Jurassic Chim-Lоptyuga oil-shale deposit is situated in the North- East of the Russian plate. In the area the sediments of Oxfordian, Kimmeridgian and Volgian (Tithonian) stages of total thickness up to 40 m are identified. The rocks are mainly presented by caustobioliths, calcareous dark grey and greenish-grey clays, rare clay-marls and glauconitic-quartz sandstones. We determined the composition and distribution of clay minerals in all rock types. Our conclusions are based on the investigation of 155 samples from 10 wells.The phase composition of the clay fraction (