The article considers the peculiarities of the material (chemical and mineral composition) and their influence on the nuclear-physical characteristics (effective atomic number, atomic mass, photoelectric absorption index and macroscopic capture section of thermal neutrons) of the solid phase of rocks on the example of the volcanogenic-sedimentary sequence of the northeastern framing of the Krasnoleninsky arch in East Siberian region. The nuclear physical characteristics of the rocks of the studied object vary over a wide range. As the effective atomic number and atomic mass increase, the photoelectric absorption index and macroscopic capture section of thermal neutrons increase. The authors revealed positive correlations of the photoelectric absorption index and the macroscopic section of thermal neutron capture of the solid phase of rocks with the content of iron, magnesium, potassium, titanium oxides, as well as with the content of minerals – potassium feldspars, chlorite, and siderite. Negative correlations were revealed with the content of silicon, sodium oxides, also with the content of minerals – quartz and albite. It has been shown that the effective atomic number increases from acidic volcanites to medium, basic, ultramafic differences. Transformed by secondary processes volcanites are characterized by increased values of nuclear-physical characteristics, due to higher concentration of clay, carbonate minerals and secondary potassium feldspar. The need to take into account the influence of the material composition of the solid phase of rocks when interpreting neutron logging by thermal logs is shown. The prospects of using pulsed neutron and litho-density logs in the sections of volcanogenic deposits are shown in order to find intervals promising for testing.
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