T186 Structural and Tectonic Controls on Gold Mineralization from the Roots of Mountain Belts to Hot Springs

Tuesday, 21 October 2014
8:00 AM - 12:00 PM
302/303

STRUCTURAL FRAMEWORK OF THE STRATONI FAULT CORRIDOR, KASSANDRA MINING DISTRICT, NORTHERN GREECE

Paper number: T186-14
Program: Technical Sessions
Time: 11:10 AM – 11:25 AM

Authors

Abstract

The Kassandra Mining District encompasses 12 Moz of gold contained in porphyry and intrusion-related carbonate-hosted replacement-style orebodies. The Stratoni fault corridor is host to economically significant Au- and Ag-rich base metal massive sulfides at Madem Lakkos (>10MT historic production), Mavres Petres (1.14Mt at 181g/t Ag, 6.8% Pb and 11.3% Zn) and the Mn-rich Au deposit at Piavitsa.

The Stratoni fault broadly defines the transition between the hanging wall Vertiskos and the footwall Kerdyllia assemblages of the Serbo-Macedonian Massif. Outcrop and drill core observations suggests a gradational contact between carbonaceous biotite gneiss and amphibolite hanging wall rocks with quartzo-feldspathic biotite gneiss, granite gneiss and marble in the footwall. These rocks underwent ductile deformation with a later brittle tectonic overprint.

Consistent deformation patterns in each assemblage suggest that both witnessed the same tectonic deformation events. These include (i) penetrative shallow SW-dipping (S1) foliation defined by alignment of peak metamorphic minerals; (ii) inclined, tight to isoclinal (F2) folds and associated south-dipping axial planar (S2) cleavage with F2 axial planes favoring top-to-the north transport; (iii) subsequent low-strain, spaced and steeply dipping (S3) foliation which warps the previously developed fabrics and is likely associated with a second generation of km-scale, upright, open to closed (F3) folds.

The strongly mineralized WNW-trending Stratoni fault has an approximate strike-length of 12 km. The fault consists of a complex semi-brittle shear zone displaying cataclastic textures with development of an internal foliation and pressure solution fabrics which localized slip, often associated with younger phases of banded fault gouge, matrix-supported breccia. Textures along with kinematic indicators suggest deformation under post-ductile semi-brittle conditions that define top-to-the SSW normal relative movement, demonstrating NNE-SSW extension that postdates regional ductile deformation. Extension along the Stratoni fault controlled Au-rich massive sulfide replacement of marble within and adjacent to the fault and may have influenced the emplacement of porphyritic intrusions.