SOME HYDROGEOCHEMICAL CHANGES IN GEOTHERMAL SYSTEMS WITH ACTIVE TECTONIC ORIGIN: A CASE STUDY IN MUĞLA PROVINCE

Abstract

The study area is located within the borders of Muğla province in SW Anatolia. Approximately NW-SE trending Karaova-Milas and Muğla-Yatağan Fault Zone and Ula-Ören Fault Zone which has approximately E-W trending along the south of Gökova Gulf are the most active faults of region as in shown active faults on the Turkey Active Fault Map. In addition to these faults, it is known that there are many active tectonic elements in the area. However, during the instrumental period (1900-2019) in the study area and its surroundings, approximately 450 earthquakes with magnitudes greater than M=4.0 occurred and the activity still continues. In addition, there were one Mw=7.7 in 1926, one Mw=6.4 in 1933, two Mw=6.0 in 1941, one Mw=6.3 in 1961 and Mw=6.6 magnitude earthquakes happened on 21 July 2017. Many geothermal areas in the area which is very rich in terms of geothermal systems and the surrounding region -Yatağan (Bozüyük), Bodrum (Karaada), Datça (Ilıca, Gölbaşı), Köyceğiz (Sultaniye), Dalyan (Delibey Girmesi, Rızaçavuş Girmesi, Gelgirme), Sarıgerme (Çürükardı) and Fethiye (Gebeler). Most of these geothermal areas are also located on active fault zones. A three-year monitoring study (on-site measurement and water sampling) was carried out from the hot water resources (Savran-Milas, Bozüyük-Yatağan, Sultaniye-Köyceğiz and Kapukargın-Dalaman) determined in these geothermal areas. The relationship between geothermal resources and active faults in the study area was revealed and it was tried to be associated with this high earthquake activity. In the study area, two earthquakes with Mw = 5.0 on 22 November 2017 and Mw = 5.3 on 25 November 2017 occurred around Muğla. Considering the chemical analysis results of the waters taken during the sampling periods of October 2017 and December 2017, it was observed that some values were affected by these earthquakes.