Petrophysical taxa of diamond deposit of Komsomolskaya kimberlite pipe (Yakutsk diamondiferous province)

Petromagnetic and paleomagnetic studies of oriented samples from the main petrophysical taxa of the Komsomolskaya pipe diamond deposit (kimberlites, different-phase basites and terrigenous carbonate formations) were carried out in order to build a petrophysical model and solve various geological and geophysical problems on its basis: analysis of the behavior of the observed gravimagnetic field for diamond prospecting areas of geotypes 4 and 5, paleomagnetic dating of magmatic events, geodynamic reconstructions, etc. The features of the structural relationship of the petrophysical taxa of the deposit influenced the distribution of their physical properties which, as a result, affected the nature of the observed gravitational and magnetic fields. It is shown that when using vector parameters of petrophysical taxa in the "method of subtracting" potential fields from interference objects (basites of the Tunguska syneclise) it is possible to obtain a "pipe type" anomaly from the prospecting object (kimberlite pipe). In addition, based on the petrophysical model, the existence of gravimagnetic anomalies genetically related to the structures of the diatremic association - anomalies of the structural type, which should be taken into account in the process of interpreting geophysical survey data within the Yakutia diamondiferous province, was proved. Titanomagnetites have been identified as magnetization carrier minerals in dolerites, while kimberlites have a more diverse spectrum – magnetites, titanomagnetites, ilmenites and chrome spinelides. In the course of step-by-step demagnetization and subsequent component analysis of the vectors of natural residual magnetization, virtual geomagnetic poles were obtained characterizing the direction of the Earth's magnetic field at the time of introduction of kimberlites and basites. This makes it possible to establish not only the temporal sequence of tectono-magmatic events that formed the Komsomolskaya diamond deposit but also to clarify their scenario for the Yakutsk diamondiferous province as a whole. The paleomagnetic data on kimberlites of the Komsomolskaya pipe are in good agreement with the paleomagnetic data obtained on the basalts of the Upper Devonian D3ap Appai Formation basalts (Frasnian, 385–375 Ma) and the pre-ore dike of dolerites of the Vilyuiko-Markhi intrusive complex of the Mir mine (373.5 Ma) which may indicate its relatively early age and, possibly, a deeper level of erosion section. Paleomagnetic reconstructions have shown that the epochs of kimberlite and trap formation correspond to the current position of hot spots which can be used as a basis for predicting new kimberlite fields on the Siberian platform.