Authors:	Litvinenko, Andrey K. Sorokina, Elena S. Häger, Tobias Kostitsyn, Yuri A. Botcharnikov, Roman E. Somsikova, Alina V. Ludwig, Thomas Romashova, Tatiana V. Hofmeister, Wolfgang
Title:	Petrogenesis of the Snezhnoe ruby deposit, Central Pamir
Online publication date:	10-Jul-2020
Year of first publication:	2020
Language:	english
Abstract:	The Snezhnoe ruby deposit is located in the Muzkol–Rangkul anticlinorium within the Cimmerian zone of the Central Pamir. On the local scale, the deposit occurs on discrete relict bedding planes of calcitic marbles belonging to the Sarydzhilgin suite. Four ruby-bearing mineral assemblages are present within the main parts of the deposit: (1) scapolite + phlogopite + muscovite + margarite; (2) plagioclase + muscovite + margarite; (3) muscovite + phlogopite + margarite; (4) calcite. The ruby + calcite association is the most economically important, whereas the association of plagioclase + scapolite + phlogopite + muscovite is typical for the ruby-free parts of the deposit. Mica group minerals with a distinctive green color due to enhanced Cr and V concentrations are the main prospecting indicators for the ruby mineralization. The oxygen isotopic composition of the rubies is +15.3‰, a common value for crustal metamorphic and sedimentary rocks. The ratios of indicative trace elements in the rubies are Ga/Mg < 8.2, Fe/Mg < 51.2, Cr/Ga > 6.9 and Fe/Ti < 31.6. These values are characteristic for metamorphic corundum. The bulk ruby-bearing rocks have an initial 87Sr/86Sr ratio of ~0.70791 and εNd of ~−9.6, also pointing to the crustal origin of the deposit in agreement with the geological data. Ancient Al-enriched sediments are suggested to be a possible protolith for the ruby-bearing rocks. The temperature of the metamorphic processes was estimated at 760 ± 30 °C using Zr-in-rutile geothermometry. Raman mapping of rutile inclusions trapped within the ruby crystal indicates that the minimum pressure of mineralization was about one kilobar. The age determined by the Rb–Sr thermal ionization mass spectrometry of phlogopite, plagioclase and bulk rock is 23 ± 1.6 Ma, corresponding to the timing of relaxation after peak metamorphism during the Alpine–Himalayan Orogeny
DDC:	550 Geowissenschaften 550 Earth sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-4933
Version:	Published version
Publication type:	Zeitschriftenaufsatz
License:	CC BY
Information on rights of use:	https://creativecommons.org/licenses/by/4.0/
Journal:	Minerals 10 5
Pages or article number:	Art. 478
Publisher:	MDPI
Publisher place:	Basel
Issue date:	2020
ISSN:	2075-163X
Publisher URL:	https://doi.org/10.3390/min10050478
Publisher DOI:	10.3390/min10050478
Appears in collections:	JGU-Publikationen