№ 2, 2006Download the article
Geological-geochemical factors of Talysh subalkaline ultrabasic intrusives formation
Institute of Geology and Geophysics of Azerbaijan National Academy of Sciences, AZ1143, Baku, H.Javid av., 119
There are the following conclusions defined on the base of complex petrological-geochemical, mineralogical research.
Subalkaline picrite magma repeatedly melted from metasomatized garnetspinel peridotite substratum is the initial melt of Hamarat-Aliabad, Alashar-Yelagach, Nudus-Kalasy, Velikend, Dylmadi intrusives. Subalkaline olivine-basalt magma first melted from this substratum. This magma is initial for Eocene trachybasalt-trachyandesibasalt-phonolitic formation of Talysh zone. In these cases substratum is considerably impoverished by light basalt elements (CaO, TiO2, Al2O3, SrO). Subalkaline picrite melt is a little concentrated by infusible elements and correspondingly melt density increases.
Due to permeability reduction of the Earth Crust on the one hand and increase of density of subalkaline picrite melt, on the other hand, provides difficulties for melt rise to the upper horizons of the Earth crust. In such geological-petrological conditions subalkaline picrite melt was localized, mainly in intrusive chamber and partially in intermediate focus.
On the base of above-said material analysis one can conclude the upper mantle substratum consisting of metasomatically transformed spinel-garnet peridotite melted twice. First this substratum melted up to 2,5-9 %, and content of melt appropriated to subalkaline divine-basalt magma. Second time was subjected up to 17 % of melt where subalkaline picrite melt was formed.