我国首次发现冰洲石－方解石巨晶、超巨晶群体及形成机制探讨

GIGANTICANDSUPERGIGANTICCRYSTAL CLUSTEROFICELANDSPAR- CALCITE,MECHANISMOFFORMATION

文章在阐明冰洲石－方解石巨晶、超巨晶群体的地质特征和矿物学特点的基础上，着重讨论了其巨型晶的形成条件和岩溶成矿机制问题。

Gigantic and supergigantic crystal clusters of iceland spar-calcite were discovered for thefirst time in 1990 in the Hejiawan iceland spar mineral land in southwest Guizhou. Singlecrystal weights mostly a few tons, even 10-20 tons, and the biggest reaches 25 tons. Theyare of perfect idiomorphism and found in clusters. Such gigantic single crystal occurrence oficeland spar-calcite appears to be of scarcity at home and abroad.Investigation shows thatthey are product of activity by shallow-seated and low-temperature thermal fluid,which indi-cates the possibility of their formation in upper part of the earth crust with moderate temper-ature and moderate pressure,and indicates the relation to some extent to karst process.The broad well-closed space where minerals occur,abundant pure material sources,sta-ble tectonic setting and special temperature for crystallization all condition theformation ofgigantic iceland spar-calcite crystals ,which belong to karst mineral deposit.The view of the occurrence of these gigantic crystal clusters has given a challenge to thetraditional concept that pegmatite metallogepic process is carried out by crystallization ofresidual magma rich in volatile constituents under the deep circumstance of high temperatureand high pressure.