Akhtylsky analcimites complex of the North-Sosvinskaya structural-formational zone (Northern Urals)

Object of the study. The article describes the first identified and mapped Akhtyl basanite-analcimite complex, established within the southern part of the Severo-Sosvinskaya structural-formational zone of the Tagil trough (sources of the Malaya Sosva River, Khanty-Mansiysk Autonomous Okrug). Objective of the work – Study of the geology, mineralogical and petrochemical composition and mineralization of unique, rarely encountered basanite-analcimite magmatites that appeared in the Permian-Triassic stage of development of the Ural North. Methodology and research methods. The work is based on the results of our own research with the generalization and reinterpretation of the results of studying the core of well no. 4 of the Akhtyl profile, including the work on the problem of “Study of plume magmatism and minerageny of intraplate geodynamic settings of the Ural North” (G- 18), contract no. 35-07/TPI/3 (59-202-07) and the “Priority 2030” program, which are supplemented by the study of the morphology, internal structure, chemical composition of volcanics in the Central Laboratory of the Federal State Budgetary Educational Institution of Higher Education “Ural State Mining University” and the Central Laboratory “Geoanalyst” of the Ural Branch of the Russian Academy of Sciences (Ekaterinburg). The article presents the results of studies on a VEGA LMS electron microscope from TESCAN with an Xplore 30 energy-dispersive attachment from Oxford Instruments, as well as an XRD 7000 X-ray diffractometer (Shimadzu), etc. Results. For the first time, relatively rare rocks (analcimites) in the Akhtyl basanite-analcimite complex were diagnosed and studied using modern research methods, their mineralogical, petrographic and petrochemical composition was determined, geological and isotopic data on the age of the complex rocks and the geodynamic setting of their formation were obtained. Analcimite is a volcanogenic rock of the extrusive facies consisting of analcime phenocrysts with inclusions of olivine, pyroxene and lepidocrocite, immersed in an orthoclase-analcimite base with inclusions of garnet, apatite, titanite and a rash of ore mineral. It is shown that the chemical composition of most analcimite minerals is characterized by a high aluminum content, indicating nonequilibrium conditions of its formation.