by Annie Ewing Rassios
The Limogardi area comprises a complex deformed thrust sequence, including two thrust sheets of pillow lavas and oceanic chert of the Othris ophiolite. The higher ophiolitic sheet is chiefly composed of hydrothermally altered lavas and gossan, with scattered copper occurrences, metalliferous jasper horizons, silicified lavas and occasional “mosaic” sulfide deposits. A drilling program within the mineralized lavas encountered several small massive sulfide deposits in at least two distinct horizons, and several volcanic breccia units representing a hydrothermal “vent.”
While the ore bodies are not of present economic size, the geology as exposed and revealed through the drilling program indicates that the mineralized lavas of the immediate area represent an ore environment characterized by numerous, probably small-scale, hydrothermal events, over-lapping spatially and stratigraphically. Most probably, these reflect the ore environment of a fossil ridgecrest: there is good potential for formation of a sizable “Cyprus-type” ore body in this environment. Unfortunately, the ore bodies themselves accommodate thrusting, so that locally, the deposits are preferentially destroyed by the major faults. Thus, while the lavas represent a high-potential ore environment, tectonism severely reduces the potential for preservation of an economic deposit.
The thickness of the host lavas in the drilled area is insufficient for location of new ore bodies. Mapping in the Limogardi region reveals several area in which tectonism may have left large ore bodies preserved. A jasper-metalliferous sediment horizon continuous over one k crops out in the Northern Area. Metalliferous pillow breccia extends from the Northern to Eastern areas (~two km2), partially covered by thin capping limestone. Both types of mineralization are parallel to and associeated with apparent listric fault systems. Targeting new geophysical and drilling exploration programs along these systems might result in location of additional ores, sufficient to bring the district into production.The Limogardi Area has been under study as an ore environment since 1982. This report covers the completion of mapping of the region, including three detailed maps of high-potential areas. A drilling program in one of these areas (1985 – 1987) located several small massive sulfide ore bodies in nine boreholes completed before the project was terminated. I have re-done figures and maps included in this version to be more easily interpreted. Large maps (1:1000 and 1:5000 scale) can be made available by contacting me.
No clear-cut minable deposits have been found: exploitation would require the location of several additional ore bodies in the area to meet present economic criteria. In addition to the ores located in the drilling program, this report suggests sites where “blind” deposits might be located at shallow depth.
The ore and tectonic environments of Limogardi are representative of lava-hosted copper deposits of the Othris region. The primary controls for ore deposition seem to be a series of exposed and inferred listric faults, with parallel mineralization, dating from an ocean ridge system. During obduction and later compression tectonism, the lavas and ores were severely deformed, with the ores themselves preferentially sheared. The ore-destructive nature of the thrust terrane is well demonstrated at Limogardi. These environments are expected to be repeated throughout Othris. Future investigation of copper occurrences should be based on recognition of these important controls.
Acknowledgements are made to the following scientists for discussion and advice, sometimes taken: Dr Joe Cann, Dr Andreas Panayiotou, Elias Grivas, Dr Spiros Dabitzias, and Dr Stavros Kalogeropoulos. Personal communication with Eldridge Moores, particularly with regards to then un-published research from Cyprus ore terrane greatly aided interpretation of the ore environment. Maria Vonisakou helped to map the East Limogardi Area. George Vrahatis explored the old mine tunnels, saving me a lot of very nasty work. Figures and maps were drafted by A. Tsioulakis, C. Panayiotou, and K. Dougalis.
See full text in the attached file.
