STAGES OF LITHOGENESIS AND ROCK COMPRESSION BEHAVIOR.

Purpose. To get new information about rock compression behavior at different stages of lithogenesis. Methodology. For achievement of the indicated purpose we have collected the primary data about the change of properties and state of rocks in different districts of the Donetsk basin, Dnepr-Donetsk cavity. Physical and mechanical properties of sedimentary rocks on different stages of lithogenesis in the basins of Ukraine and Russia have been studied. We have analyzed the results of study of porosity, permeability, and types of cement in different conditions. The tests were executed by standard methods and approved devices. In addition to the empiric information we have studied the considerable volume of information about the results of previous researches published in media. Findings. We have found out that in the existent reference books and dictionaries some lithological concepts, terms and stages of lithogenesis disagree. The qualitative distinction of sedimentary and metamorphic rocks was made in the middle of 20th century; but quantitative criteria of distinction still remain undeveloped. The depth of the diagenesis stage makes dozens, hundreds and thousands meters. In some districts the loose deposits appear at a depth of 2-3 km. The basic types of cement of terrigenous rocks are represented by quartz (silica), carbonates, and oxides of iron. To determine the structural jumps of transition of one stage of lithification into another, it is necessary to test the as big interval of rocks as possible. We have suggested the formula (at qualitative level) of determination of stages (sub-stages) of lithogenesis based on the fact of structuring of matter in the case of achievement of critical power limit. It requires consideration of the mineralogical factor, the presence of carbonates in the cement of rocks, and control over description of drill sample, to reduce the errors of first kind. Originality and practical value. The scientific value of the results consists in determination of laws of change in the properties and state of the matter reaching the critical power values. The applied meaning is prognostication of intervals productive on hydrocarbons in sedimentary rocks being at different stages of lithogenesis. The presence of productive intervals at different modern depths is the important applied factor. The properties and state of rocks depend not on its modern depth but on its paleodepth and the region formation history. [ABSTRACT FROM AUTHOR]