Abstract In this field-trip guide we explore the tectonics of Samos and the Menderes Massif, two fascinating areas within the eastern Mediterranean section of the Tethyan orogen. We include detailed outcrop descriptions, maps, and diagrams to explore along-strike variations in the Hellenide-Anatolide orogen, including the architecture of the Early Tertiary Alpine nappe stack and its strong Miocene extensional overprint. The suggested itinerary is based on the 2010 Geological Society of America Field Forum “Significance of Along-Strike Variations for the 3-D Architecture of Oro-gens: The Hellenides and Anatolides in the Eastern Mediterranean.” We start the outcrop descriptions with Day 1 in Samos, where, untypically for the N-S–stretched Aegean region, Miocene extension is E–W. We describe a section in western Samos, where the Cycladic Blueschist Unit is in contact with the underlying External Hel-lenides along a large-scale thrust, reactivated as a Miocene top-east extensional shear zone. The focus of Day 2 is on high-pressure assemblages in northern Samos. The following three days explore the Anatolide Belt in western Turkey where the Mend-eres nappes—also known as the Menderes Massif—form the tectonic footwall below the Cycladic Blueschist Unit. The outcrops in western Anatolia include the Cycladic Blueschist Unit in the area around Selçuk (Day 3) and sections across the Bozdağ and Aydm Mountains including the Kuzey and Güney detachment faults and the Cycladic Menderes Thrust (Days 4 and 5). Outcrops on Day 6 showcase structures along the southern margin of the Menderes Massif in the Milas–Selimiye area.

Abstract Samos is not one of the typical Aegean “turtle-back–shaped core-complex type” islands like Ios or Mykonos, for example. The general structure of Samos is dominated by steep faults, and the overall architecture of the islands is best described as a horst. The topography of Samos is rugged and dominated by the sheer cliffs of 1433-m-high Mount Kerkis in the western part of the island (Fig.7). The geology of Samos consists of a number of metamorphosed nappes, one non-metamorphosed nappe, and a Miocene graben. The island offers a look at an exceptionally complete nappe stack of the Central Hellenides, ranging from the high-pressure–metamorphosed Basal Unit (as part of the External Hel-lenides), all the way up to the ophiolitic Selçuk Nappe and the non-metamorphosed Cycladic Ophiolite Nappe. This field guide is concerned with the two structurally lowest units, the Basal Unit and the overlying Cycladic Blueschist Unit, as well as the Tertiary sediments.

Abstract The Menderes Massif is a complex geological terrane. Despite much research progress in the past ten years, there are still substantial unresolved issues regarding its tectonic and meta-morphic history. Although we would like to outline some key controversies here, we recommend the review section in Bozkurt and Oberhänsli’s 2001 editorial article (Bozkurt and Oberhänsli, 2001) and van Hinsbergen et al. (2010) for an attempt to reconcile local structure with geodynamics. The pre-Miocene tectonics of the Menderes Massif have been interpreted in terms of a large-scale recumbent fold (Okay, 2001; Gessner et al., 2002), a series of nappes stacked during south-directed thrusting (Ring et al., 1999a; Gessner et al., 2001c), and a series of north-directed thrusts that subsequently collapsed either in a bivergent fashion (Hetzel et al., 1998) or through top-to-south extension (Bozkurt and Park, 1994; Bozkurt, 2007). The key controversies are focused on which structures are related to the kinematics of early Tertiary Alpine crustal shortening, which ones are related to late Tertiary crustal extension, and how this fits with the observed large-scale architecture of the massif. Whereas the role of Miocene to Pliocene normal fault systems bounding the Gediz and Büyük Menderes Grabens

Abstract This field-trip guide explores the tectonics of Samos and the Menderes Massif, two fascinating areas within the eastern Mediterranean section of the Tethyan orogen. The guide includes detailed outcrop descriptions, maps, and diagrams to explore along-strike variations in the Hellenide-Anatolide orogen, including the architecture of the Early Tertiary Alpine nappe stack and its strong Miocene extensional overprint. The suggested itinerary is based on the 2010 Geological Society of America Field Forum: “Significance of Along-Strike Variations for the 3-D Architecture of Orogens: The Hellenides and Anatolides in the Eastern Mediterranean.” The outcrop descriptions begin with Day 1 in Samos, where, atypically for the N-S stretched Aegean region, Miocene extension is E-W. The focus of Day 2 is on high-pressure assemblages in northern Samos. The following three days explore the Anatolide Belt in western Turkey, where the Menderes nappes—also known as the Menderes Massif—form the tectonic footwall below the Cycladic Blueschist Unit.

Abstract We apply low-temperature thermochronology, Rb/Sr geochronology, petrological data, and structural mapping to constrain the timing and kinematics of the Ios metamorphic core complex. Top-to-north extension in the lower plate Headland Shear Zone was active at 18–19 Ma under metamorphic conditions of 475–610 °C and 0.65–1.1 GPa. The South Cyclades Shear Zone/Ios Detachment Fault (SCSZ/IDF) system shows top-to-south extensional shear active at c. 19 Ma at 380–550 °C, with local top-to-north bands. Extensional shear above the SCSZ/IDF is dominantly top-to-south to top-to-SW. PT estimates from an eclogite boudin constrain Eocene high-pressure metamorphism to 430–560 °C and 1.21±0.42 GPa to 0.66±0.37 GPa. Similar low-temperature thermochronometric ages across Ios demonstrate that ductile extensional movement ceased by c. 15 Ma. Exhumation to shallow crustal levels took place between c. 15 and 9 Ma at cooling rates of up to 120 °C Ma −1 with a slow down to <20 °C Ma −1 between 12 and 9 Ma, most likely accommodated by extensional slip at rates of c. 3 km Ma −1 along the top-to-SW Coastal Fault System. We propose a model of bivergent extension for exhumation of the Ios core complex between 19 and 9 Ma, with Ios forming a secondary antithetic top-to-south to top-to-SW extensional fault system to a more dominant top-to-north Naxos/Paros detachment system.