Barium minerals – baritе and chlorinedominant ferrokinoshitalite bafe2+3[cl2/al2si2o10] in plagioperidotites Yoko-Dovyren intrusion (Northern Baikal region) – products of epigenetic low grad metamorphism

Abstract

In the plagioperidotite of the ultamafite-mafic Yoko-Dovyren intrusion captured by low-grad metamorphism (NGM) under conditions of the prenite-pumpelliite facies (PPF), mobilization of Ba, Cl and Sr is observed The content of barium in plagioperidotite ranges from 36 to 313 (an average of 130 g / t); strontium from 25 to 169 (an average of 86 g / t); Ba / Sr value varies from 0.5 to 4 (on average 1.5). Barium minerals phlogopite and plagioclase; chlorine chloroferrisadanagite from inclusions in alumochromite, late-magmatic phlogopite, potassium chlorate ferropargassite and chlorapatite in the margins of sulphide nests. During the NGM processes, these minerals were replaced by chlorites, tremolite, diopside, which included very little Ba and Cl. In the areas of barium minerals development, plagioperidotites contain 348518 g/t of barium and 46 g/t of strontium, which indicates the redistribution of Ba and the removal of Sr. Metamorphogenic barium minerals non-strontium barite and Ba-Fe-Cl mica chloro-dominant ferrokinochitalit. They coexist with the minerals of the rodingite association hydrogarnet, tremolite, diopside, chlorite, antigorite, magnetite, hydroxylapatite. Ferrokosnoshitalit replaces phlogopite, plagioclase, sulfides, contains up to 21 wt. % BaO, 31% FeO, 11% Cl and has a iron index of f = 75.890.5. The composition of the most chlorine-rich individual responds (Ba0.83K0.16)0.99(Fe2+2.63Mg0.28Fe3+0.04Al0.02Cr0.01Mn0.01)3[(Cl1.86OH0.12S0.02)2/Al1.86Si2.14O10]. Since Yoko-Dovyrenskiy ferrokynosalital is chlordominant, this is a new mineral species.