Structural Heterogeneities of Lithium-Bearing Layered Silicates of Paleokarst Near Kimberlites and Their Prospecting Value (Middle Markha Diamond-Bearing Region, Western Yakutia)

Abstract

Clay minerals formed as a result of hydrothermal activity within kimberlite pipes are redeposited into the horizons of the Lower Jurassic diamondiferous sedimentary rocks of proximal provenance. The mineral composition of the Lower Jurassic Dyakhtar Formation, composed of paleodeluvial and paleokarst deposits, has been studied in the immediate proximity and at a distance from kimberlite pipes. Mixed-layer minerals with structural heterogeneities, in which an increased concentration (up to 0.1 wt %) of lithium is noted, are found in sections of erosion plumes of weathered varieties of kimberlite rocks. The thickness of sediments with such minerals decreases sharply at distances of more than 2 km from the sought kimberlite body. The identified features in the mineral composition of the sedimentary rocks overlying kimberlite pipes can be used as new prospecting signs of the diamond potential during geological exploration of primary sources of diamonds.