TY - JOUR

T1 - Genetic conditions and a model for the origin of corundum-bearing metasomatic rocks in marbles

AU - Koltsov, A. B.

AU - Dufour, M. S.

AU - Zolotarev, A. A.

PY - 2002

Y1 - 2002

N2 - Ruby deposits in marble are known in the Urals, Pamirs, Kashmir, and in Afghanistan, with all of them characterized by similar geologic settings and rock compositions. Ruby crystals are spatially restricted to relatively thin silicate-rich layers in calcic marbles. The deposits have zoning with the transition from the host marbles to their Mg-bearing varieties, up to dolomite, and then to marbles with disseminated ruby and to polymineralic rocks with biotite, scapolite, pargasite, muscovite, albite, anorthite, pyrite, tourmaline, rutile, and aparite. The corundum-bearing metasomatic rocks (CMR) in the Central Pamirs were determined to have developed at T = 600-650°C, P = 4.5-6 kbar, and X co2 = 0.15-0.45, and CMR in other areas are characterized by similar genetic conditions. Their differences were caused by variations in the alkalinity, X Mg, and the K/Na ratio of the fluid. These parameters can be utilized to distinguish the following CMR facies: anorthite, muscovite, chlorite, pargasite, scapolite, biotite, and margarite. The numerical simulation of fluid-rock interaction indicates that the leading process producing CMR is desilication of marble that contained minor amounts of terrigenous material or thin intercalations of terrigenous rocks. The main distinctive features of the structure and mineralogy of CMR were predetermined by the development of metasomatic zoning in calc-silicate rocks and their variable proportions of carbonate and silicate constituents.

AB - Ruby deposits in marble are known in the Urals, Pamirs, Kashmir, and in Afghanistan, with all of them characterized by similar geologic settings and rock compositions. Ruby crystals are spatially restricted to relatively thin silicate-rich layers in calcic marbles. The deposits have zoning with the transition from the host marbles to their Mg-bearing varieties, up to dolomite, and then to marbles with disseminated ruby and to polymineralic rocks with biotite, scapolite, pargasite, muscovite, albite, anorthite, pyrite, tourmaline, rutile, and aparite. The corundum-bearing metasomatic rocks (CMR) in the Central Pamirs were determined to have developed at T = 600-650°C, P = 4.5-6 kbar, and X co2 = 0.15-0.45, and CMR in other areas are characterized by similar genetic conditions. Their differences were caused by variations in the alkalinity, X Mg, and the K/Na ratio of the fluid. These parameters can be utilized to distinguish the following CMR facies: anorthite, muscovite, chlorite, pargasite, scapolite, biotite, and margarite. The numerical simulation of fluid-rock interaction indicates that the leading process producing CMR is desilication of marble that contained minor amounts of terrigenous material or thin intercalations of terrigenous rocks. The main distinctive features of the structure and mineralogy of CMR were predetermined by the development of metasomatic zoning in calc-silicate rocks and their variable proportions of carbonate and silicate constituents.

UR - http://www.scopus.com/inward/record.url?scp=9244254206&partnerID=8YFLogxK

M3 - Article

AN - SCOPUS:9244254206

VL - 40

SP - S113-S124

JO - Geochemistry International

JF - Geochemistry International

SN - 0016-7029

IS - SUPPL. 1

ER -