The Pontide metallotect is the major producing area in Turkey for base metals and has significant Au producing potential. Two major developments are currently at the feasibility stage and face opposition because of their potential environmental impact. Little information exists to substantiate past impacts.
This study describes reconnaissance water sampling and observations of the impact of some of the major current and disused operations. These are volcanic-hosted massive sulphide (VMS) deposits at Murgul, Kutlular, Lahanos and Çayeli. Smaller vein mines at Gümüşki Tepe and Midi Maden were also sampled. The VMS deposits have had considerable impact. At Kutlular and Lahanos acid mine drainage (AMD) is strongly developed and metals are transported into drainages. In contrast, this situation has been avoided at Murgul because tailings have been released into the local river and subsequently into the major Çoruh River resulting in Cu, Zn and Fe contamination that is transported across the border into Georgia and discharged into the Black Sea. Both As and Cd are potential contaminants at Murgul although their areal distribution requires further investigation. Remediation at the three VMS deposits is minimal. In contrast, the relatively modern mine at Çayeli has little impact, partly because tailings are disposed of at depth in the reducing Black Sea.
Limited sampling at the vein mines suggests that AMD is not a major problem. Stream sediment sampling shows that As may, however, be released during ore treatment at Midi Maden. Visual examination at the vein mines shows that surface erosion is a major problem, probably due to the high altitude and thin soils. Surface conditions at the Au prospect at Mastra suggest that AMD and metal release should not be a major problem. However, the use of cyanide presents a more significant public relations issue. Examination of porphyry prospects shows that natural AMD is developed in places. Any development is unlikely as grades are sub-economic.
Regional determination of potential AMD was made using the sulphide content of deposit type established in the local studies and related to measured water pH. The wide variation in rainfall was taken into account with areas of high rainfall on the Black Sea predicted as having high potential for AMD formation. Potential surface degradation was predicted using height information from a digital elevation model and deposit type.
- © 2004 AAG/The Geological Society of London