The Meme copper mine, in the Terre-Neuve Mountains of Haiti, is one of the largest hypogene metal mines in the Greater Antilles. Mineralization at the Meme deposit is localized at the contact between the 66 m.y.-old Terre-Neuve quartz monzonite and a large block of Upper Cretaceous limestone that was surrounded by the intrusion. Mineralization was preceded by extensive magmatic assimilation that formed zones of syenodiorite and granodiorite around the limestone. Following crystallization of magma adjacent to the limestone, both the igneous rock and limestone were replaced by skarn containing garnet, diopside, hedenbergite, epidote, wollastonite, idocrase, scapolite, tremolite, and calcite. Metallization followed skarn formation and included deposition of hematite, magnetite, pyrite, molybdenite, chalcopyrite, bornite, chalcocite, and digenite(?) in that paragenetic order.The thermal stability of wollastonite at the estimated P T and P (sub CO 2 ) of mineralization indicates that early skarn formation occurred between 480 and 640 degrees C. Textural evidence suggests that the minimum temperature of copper-iron sulfide formation exceeded 350 degrees C and latest ore formed above 250 degrees C. The upper limit of this temperature range can be verified by calculating the contact temperature between marble and just-crystallized igneous rock on the basis of conductive heat transfer using calculated values for the heat of crystallization of a hydrous magma. The change of fluid composition during mineralization can be illustrated by constructing fugacity diagrams for pertinent parts of the Cu-Fe-S-O system at the observed temperatures and plotting them on an axis that represents changing composition, temperature, and time. During mineralization, f (sub O 2 ) decreased from 10 (super -15) to 10 (super -35) atm and f (sub S 2 ) varied from 10 (super -4) or less to 10 (super -11) atm.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

First page PDF preview
You do not have access to this content, please speak to your institutional administrator if you feel you should have access.