NEW DATA ON STRATIGRAPHY AND LITHOFACIES REGIONING OF CAMBRIAN AND LOWER ORDOVICIAN DEPOSITS IN THE SOUTH TUNGUSKA OIL-BEARING AND GAS-BEARING REGION

On the basis of the data on oil-and gas-prospecting drilling, the type s of Cambrian and Lower Ordovician sections in the South Tunguska oil- and gas-bearing region (OGBR) are considered. The original and specifi c composition and structure of the deposits penetrated by boreholes Sv etlaya-1 and Svetlaya-2 in the west of the OGBR as well as their compa rison with the deposits from the adjacent regions indicate that the Le tnyaya Formation in this region has wider range of stratigraphic units , and a new lithofacies zone - Svetlaya - can be distinguished here. T his permits the region of searching for reef hydrocarbon traps to be e xtended, with the junction of the Tynepa and Svetlaya lithofacies zone s included into it.