ПЕТРОФИЗИЧЕСКИЕ ОРЕОЛЫ СТРУКТУР ДИАТРЕМОВОЙ АССОЦИАЦИИ

Petro- and paleomagnetic studies of Early Paleozoic rocks of carbonate basement of a number of diamond deposits in the Yakutsk diamondiferous province were carried out to study changes in the values of petrophysical parameters in the zone of dynamic influence of a kimberlite pipe. It is shown that during the formation of kimberlite diatrems accompanied by pulsational, upward-shifting explosions, thermoelastic stress fields characterized by epigenetic changes and related petrophysical aureoles appear in the kimberlite-bearing medium. Naturally, some of these petrophysical aureoles are petromagnetic heterogeneities of burning and stress, within which kimberlite-bearing rocks have contrastingly changed their original magnetic characteristics under the action of thermodynamic processes. Generally, petromagnetic aureoles are reflected in the changing nature of anisotropy magnetic susceptibility: from sedimentary to dyke geotype. In addition, petromagnetic magnetic susceptibility aureoles are accompanied by the formation of metachronous natural residual magnetization vectors in kimberlite-bearing rocks. The size of petromagnetic aureoles (petromagnetic heterogeneities) may significantly exceed the size of the kimberlite pipe itself, which helps to identify and delineate the most promising areas. In addition, the magnetoseismic effect can create zones near kimberlite bodies that are difficult to penetrate for relatively viscous, protocrystal-rich basite magmas. This explains their wedging out along petrophysical barriers: splitting into low-power "tongues", formation of trap-free "windows" and "corridors", toroidal shafts with sharply increasing thickness in intrusions, etc. Having relatively elevated values of magnetic and density parameters, such magmatic formations will be reflected in the observed geophysical fields. Thus, it is reasonable to consider petromagnetic aureoles as one of the important petrophysical search criteria for the detection of indigenous kimberlite bodies.