The studied area is situated in southwestern Birjand (South
Khorasan). Lithologic units which are studied contains part of the late
Cretaceous coloured melange, Cretaceous and Paleogen flysh sediments,
Neogen congolmerate and Tertiary volcanic rocks. The listwaenite of this
area often appears along fault zone, boundary of units, bedding planes and
schistiosity as yellow and brownish vein. The effect of CO2 bearing
hydrotermal solutions on mentioned units, in suitable physico - chemical and
termodynamic conditions, caused Listwaenitization reactions. Field and
microscopic' studies revealed that alteration process comprises pre-sta~e
reactions (specially serpentine and talc forming reactions in ultrabasic rocks)
and main reactions of listwaenitization which in primary mineral paragenesis
is changed to silisic - carbonate assemblages listwaenite). Abundance and
type of minerals is depended on composition of primary rock, PH, Eh, T,
PCOl and PH)o' Microscopic studies and XRD analysis show presence of
magnesite, breunerite, dolomite, calcite, smithsonite, quartz, clinochlore,
talc, muscovite, chromite, pyrite and magnetite. Also SEM analysis and
polyshed section studies represents Fe, Ni, Fe-Ni-Co sulphur that must be
considered as pathfinder minerals for prospecting of Au, Ag, Hg, ....