Türkiye Jeoloji Bülteni

Significant Geosites in Bursa Province (NW Türkiye)

Abstract: Geological heritage elements, consisting of geomorphological structures, minerals, rocks, and fossils, areused in uncovering the Earth`s past, identifying and mitigating natural hazards, and investigating global issues suchas adaptation to climate change. The protection and promotion of these structures, called geosites, is supported by UNESCO and other international institutions. Bursa, one of Türkiye`s major centers of culture, winter sports, and tourism, together with its surrounding area, contains numerous geological and geomorphological features of significant geoheritage value and geotourism potential. Bursa`s geological framework was shaped by the İzmir-Ankara suture zone, which formed as a resultof the subduction of the Tethys Ocean between the Sakarya Zone of the Pontides and the Tavşanlı Zone of the Anatolide-Tauride Block. Uludağ, often mistakenly regarded as volcanic, instead represents a classic metamorphic core complex (the Uludağ Massif), composed predominantly of gneiss, amphibolite, and marble. The principal geosites identified in Bursa Province include the Paşalar Mammal Fossil Bed, notable for its unique Middle Miocene fauna; the Kocasu Delta and the Karacabey Longozu (flooded forest), recognized as an important bird area; Lakes İznik and Uluabat, distinguished by their exceptional limnological and tectonic histories; andthe type locality of the mineral bursaite. Additional sites of mineralogical significance comprise the distinctive purple jadeite formations and the Uludağ scheelite deposit. The province also hosts numerous geomorphological features, including canyons (Sadağı, Fevziye, Sansarak, Tacir, and Yarhisar), waterfalls (notably Suuçtu Waterfall), and caves (Ayvaini, Oylat, Koca, Ayıini, and Gavurini). High-altitude areas of Uludağ display well developed periglacial features, glacial lakes, and tor structures formed in granite. Coal-bearing Mioceneunits are also wide spread within the Harmancık, Keles, Orhaneli, Mustafakemalpaşa, and İnegöl basins.This study draws on the outcomes of the Geological Heritage of Bursa Workshop held in 2023 and seeks to promote the protection and sustainable use of areas characterized by a rich and diverse geological heritage.