Ophicalcites from Tinos Island, Cyclades, Greece, better known as ‘green marble of Tinos’, comprise polygenetic serpentinitic breccias with calcitic matrix and numerous carbonate veins crosscutting the formation. They have undergone intense exploitation for building and decorative purposes since ancient times. Serpentinitic clasts of the ophicalcites are composed mainly of antigorite and they show characteristic mesh textures, while locally pseudomorphic and non-pseudomorphic textures are developed. The carbonate phase consists mostly of calcite, whereas dolomite replaces calcite locally, especially along zones of intense tectonic activity. Calcite, mostly as cement material, presents a strong granoblastic texture that bonds tightly the serpentinitic clasts. Chlorite is present in many samples and seems to be a quite common accessory mineral of the formation whereas talc, spinel, hematite and magnetite can also be found. Meter-sized bodies of chromitites with irregular shapes were also observed in the studied ophicalcites. They consist of aluminian chromite, partially replaced by magnetite, Crchlorite, calcite and base metal sulphides. Mineralogical, textural and field relationships data support the idea of a combined tectonichydrothermal origin of these ophicalcites, while sedimentary mechanisms have played a minor role to their formation.
MINERALOGY AND PETROGRAPHY OF THE NW TINOS ISLAND OPHICALCITES, CYCLADES, GREECE.
Mavrogonatos K
;
2014-01-01
Abstract
Ophicalcites from Tinos Island, Cyclades, Greece, better known as ‘green marble of Tinos’, comprise polygenetic serpentinitic breccias with calcitic matrix and numerous carbonate veins crosscutting the formation. They have undergone intense exploitation for building and decorative purposes since ancient times. Serpentinitic clasts of the ophicalcites are composed mainly of antigorite and they show characteristic mesh textures, while locally pseudomorphic and non-pseudomorphic textures are developed. The carbonate phase consists mostly of calcite, whereas dolomite replaces calcite locally, especially along zones of intense tectonic activity. Calcite, mostly as cement material, presents a strong granoblastic texture that bonds tightly the serpentinitic clasts. Chlorite is present in many samples and seems to be a quite common accessory mineral of the formation whereas talc, spinel, hematite and magnetite can also be found. Meter-sized bodies of chromitites with irregular shapes were also observed in the studied ophicalcites. They consist of aluminian chromite, partially replaced by magnetite, Crchlorite, calcite and base metal sulphides. Mineralogical, textural and field relationships data support the idea of a combined tectonichydrothermal origin of these ophicalcites, while sedimentary mechanisms have played a minor role to their formation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
