We present the first detailed geological map of the tectonic units documented in the easternmost branch of the Intra-Pontide suture (IPS) zone in the Tosya-Kastamonu area (Northern Turkey). The Main Map is at 1:50,000 scale and covers an area of about 350 km2. It derived from 1:25,000 scale classic field mapping and represents a detailed overview of the complexities documented in the IPS zone, a tectonic nappe stack originating from the closure of the Intra-Pontide Oceanic basin and the subsequent collision between the Istanbul-Zonguldak terrane and the Sakarya composite terrane. The map shows the orientations of superposed foliations, fold axes and mineral lineations on the basis of geometric cross-cutting relationships documented within the five tectonic units of the IPS zone and provides information on its present-day architecture resulting from activity of the North Anatolian Fault.
In northern Turkey, the Intra-Pontide suture zone represents one of the first-order tectonic structures located between the Istanbul–Zonguldak and the Sakarya continental terranes. It consists of an E–W-trending assemblage of deformed and variably metamorphosed tectonic units, including sedimentary rocks and ophiolites derived from a Neo-Tethyan oceanic basin, known as the Intra-Pontide oceanic basin. One of these units is represented by the Daday Unit that consists of a block-in-matrix assemblage derived from supra-subduction oceanic crust and related deep-sea sedimentary cover of Middle Jurassic age. This setting was acquired during Late Jurassic time by tectonic underplating at a depth of 35–42 km associated with blueschist-facies metamorphism (D1 phase). The following D2, D3 and D4 phases produced the exhumation of the Daday Unit up to shallower structural levels in a time span running from the Albian to late Paleocene. The high geothermal gradient detected during the D2 phase indicates that the Daday Unit was exhumed during a continent–arc collisional setting. The tectonic structures of the Intra-Pontide suture zone, resulting from the previously described tectonic history, are unconformably sealed by the upper Paleocene – Eocene deposits. This tectonic setting was intensely reworked by the activity of the North Anatolian Fault Zone, producing the present-day geometrical relationships of the Intra-Pontide suture zone of the Central Pontides.
Popularizing endogenic geological processes that act deep on the Earth during geologic time producing orogenic belts requires a great effort. Consequently, geosites dealing with structural geology are surveyed with a lower frequency. Geological structures, however, may strongly control and model the territory and/or trigger the exogenous processes responsible for a specific landform/landscape. We describe here three geosites in the Apuan Alps UNESCO Global Geopark (Tuscany, Italy) to highlight their geoheritage values. We used the classical methods applied in structural geology to conceive and design three new interpretative panels of structural geosites using simple language and graphic schemes that facilitate the understanding of geological structures. The three selected structures were produced by different deformation regimes and at different structural depths. The first geosite is the boundary between the metamorphic and non-metamorphic rocks and represents the boundary of the Apuan Alps tectonic window. The second geosite is the spectacular Mt. Forato natural arch and the third represents a beautiful example of folds. Each panel is characterized by QR codes that allow the reader to access a short geological glossary, the Apuan Alps Geopark website, and a short evaluation survey on the quality of the interpretative panel.