Date

2018-04-13

Author

Çam, Mehmet
Kuşcu, İlkay
Kaymakcı, Nuretdin

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Karadere low sulfıdation type epithermal gold deposit is located within NE-SW trending dextral deformationcorridor in southern part of Biga Peninsula, nortwest Turkey. This corridor is 80 km long and 10 km wide, andgold deposit is hosted by the volcanic rocks emplaced into the pull-apart basin within the corridor. This workinvolves structural mapping of veins and faults as to identify the geometrical and spatial relationships betweenthem; slip data collection to find main pressure-tension axes and stress directions; oriented sample collection alongpredetermined traverses; and petrographical analyses to identify characteristics of hydrothermal phases, quartzmineral textures and dynamic recrystallization textures. The paleostress findings based on analyses of structuraldata collected from NE-SW trending show that the principle stress directions are NW-SE (03◦/127◦) forσ1(contraction) and NE-SW (06◦/217) forσ3 (extension) and they are approximately horizontal, alsoσ2 indicatesan approximately vertical orientation .The relative orientation of the principle stress directions with respect tothe NE-SW deformation zone suggests that the faults were formed in a dextral strike-slip tectonic regime. Thestrike directions of fault sets measured within the deformation zone shows that they occur in mostly two dominanttrends as N0◦-30◦W and nearly E-W. Based on the geometric relations between the principle stress directionsand predominant directions for different fault sets, the N70◦E-N80◦W (nearly E-W) trending faults resemble to R(synthetic); N0◦-30◦W (NNW-SSE) dominant faults resemble to R’(antithetic) shears with respect to Riedel ShearModel. This work reveals that the faults are integral component of a pull-apart basin formed by dextral strike-slipfault; and the mineralized veins are conformable to N0◦-30◦W and N70◦E-N80◦W striking dextral faults withnormal-slip component.The petrographic and textural studies resulted in identification of two hydrothermal phases for the silicifi-cation; early and late silicification phases. The petrographic studies also enabled the recognition of bladed textureswithin the main mineralized veins. Microstructural analyses of the veins formed during early silicification phaseyielded a predominant trend of E-W whereas those formed during late silicification phase yielded predominantdirections both in E-W and N10◦-20◦W. The spatial correlations between fault and vein geometries with respectto Riedel Shear Model showed that the early silicification phase is conformable to the R-shear formed duringearly stage of strike-slip faulting and late silicification phase is conformable both with the R and R’-shearsformed during the later stages of deformation. Also, the existence of bladed textures indicate periodic crack-sealand boiling events, while existence of dynamic recrystallization textures indicate syn-tectonic silicification andmineralization.

Subject Keywords

Dynamic recrystallization textures, Pithermal, Low sulfidation, Paleostress, Principal stresses, Quartz Vein, Quartz textures, Structural control

URI

https://meetingorganizer.copernicus.org/EGU2018/EGU2018-8057-1.pdf
https://hdl.handle.net/11511/71932

Collections

Department of Geological Engineering, Conference / Seminar