FLUID AND SOLID INCLUSIONS IN MINERALS OF THE QUARTZ-CASSITERITE-WOLFRAMITE VEIN “LIDERNAYA”, MODOTO ORE DEPOSIT, MONGOLIA: EVIDENCE FOR DISCONTINOUS FLUID EVOLUTION
Abstract
The focus of this study is the fluid evolution in relation to greisen-vein mineralization in the largest Mongolian tin deposit, Modoto. This deposit includes a number of districts with rare-metal mineralizations (Dandar, 1990); the information presented here was obtained using samples from the vein “Lidernaya” in the western part of the Modoto deposit. This vein was selected because it is fairly representative for the primary Sn-W ores in that area, contains a relatively diverse primary mineralization and shows the cross-cutting relationships between quartz-wolframite veins and younger greisen veinlets with cassiterite, topaz, muscovite, and fluorite.
In this study, only primary fluid inclusions were analyzed using microthermometric techniques and Raman spectroscopy because they provide information about the mineralization processes. With the exception of quartz, all host minerals show numerous growth zones; thus, primary inclusions were easily recognizable. Trails of secondary fluid inclusions are abundant particularly in quartz and fluorite. These inclusions were not a subject of this study because it was not possible within a reasonable degree of certainty to relate them to a mineralization event.
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