The role of clinopyroxenes in the process of formation of subalkaline olivine-basaltic magma of the Talysh zone (Azerbaijan)

Based on the study of the compositions, relationships of coexisting minerals, as well as the minal components of clinopyroxenes of trachybasalt-trachyandesibasalt-phono- lite formation of the Talysh zone, it was established that they characterize different stages of crystallization of subalkali In addition, the role of clinopyroxenes in the process of formation of subalkaline olivine-basaltic magma of the Talysh zone was determined. The characteristics of the Eocene volcanism of trachyba- salt-trachyandesite-basalt-phonolite formation of the Talysh zone were studied. Using new analytical data of author’s materials, the composition of rocks and minerals of the trachybasalt-trachyandesite-basalt-phonolite formation of the Talysh zone were analyzed. Analyses of rocks and parts of clinopyroxenes were carried out in the chemical laboratory “Uralgeology” of the Ministry of Geology of the Russian Federation (Ekaterinburg). The composition of clinopyroxenes and the melt inclusions they contain were determined by microprobe analysis (Camebax-micro) in the corresponding laboratories of the United Institute of Mineralogy of the Russian Academy of Sciences (Novosibirsk). It was determined that in the complex, under the conditions of the Astara uplift, the rise of subalkaline olivine-basaltic melt into the upper horizons of the earth’s crust was solidified and the early accumulative cumulates of rock minerals in intermediate sources had time to completely dissolve. In the Gosmolyan-Pilachai trough, with the mobility of its transverse mag- ma-supplying faults, such a melt did not have time to crystallize and fractionate. As a result, the transition between petrographic types of rocks in this case is gradual and accumulative inclusions of rocks, minerals were preserved in the melt. The first case is noted by crystallized melt microinclusions, represented by biotite, potassium feldspar, residual glass, the composition belonging to trachydacite and trachyrhyolite, their homogeneous temperature genesis fluctuates between 900-1000oC. In the second case, crystallites of leucite, phlogopite, olivine, etc. were found and molten microinclusions in composition are close to the main alkaline varieties of rocks of the complex under consideration.