The discovery of a low-angle normal fault in the Taurus Mountains: the İvriz detachment and implications concerning the Cenozoic geology of southern Turkey

The İvriz detachment fault has been determined on the southern border of the Ulukışla basin separating the metamorphic Bolkar Group of the Taurus Mountains and the Paleocene-Lower Eocene Halkapınar formation of basin deposits. The fault dips towards the north and has kinematic indicators (asymmetric grain/grain aggregate porphyroclasts, oblique foliation, and S-C fabrics), suggesting a top-to-the-N-NE sense of shearing.

Turkish Journal of Earth Sciences Turkish J Earth Sci (2017) 26: 189-205 © TÜBİTAK doi:10.3906/yer-1610-11 http://journals.tubitak.gov.tr/earth/ Research Article The discovery of a low-angle normal fault in the Taurus Mountains: the İvriz detachment and implications concerning the Cenozoic geology of southern Turkey* 1, 1 Gürol SEYİTOĞLU *, Veysel IŞIK , Esra GÜRBÜZ , Alper GÜRBÜZ Department of Geological Engineering, Tectonics Research Group, Ankara University, Gölbaşı, Ankara, Turkey Department of Geological Engineering, Aksaray University, Aksaray, Turkey Department of Geological Engineering, Ömer Halisdemir University, Niğde, Turkey Received: 18.10.2016 Accepted/Published Online: 07.07.2017 Final Version: 24.08.2017 Abstract: The İvriz detachment fault has been determined on the southern border of the Ulukışla basin separating the metamorphic Bolkar Group of the Taurus Mountains and the Paleocene-Lower Eocene Halkapınar formation of basin deposits The fault dips towards the north and has kinematic indicators (asymmetric grain/grain aggregate porphyroclasts, oblique foliation, and S-C fabrics), suggesting a top-to-the-N-NE sense of shearing The clastic material originating from the Bolkar Group in the sedimentary units of the Ulukışla basin demonstrates that the detachment fault could have been be active during Latest Cretaceous-Eocene times The İvriz detachment may have initiated as part of a high-angle breakaway fault (the Aydos main breakaway fault) in the south of the Ulukışla basin The breakaway fault then rotated to a low-angle normal fault and its northern continuation played an important role in the exhumation of the Central Anatolian Crystalline Complex This implies that the Upper Cretaceous-Eocene sedimentary basins in central Anatolia were supradetachment basins rather than collision- or arc-related basins as previously suggested Key words: Ulukışla basin, Taurus Mountains, detachment fault, extensional tectonics, Central Anatolian Crystalline Complex Introduction A detachment surface is one of the main tectonic elements on highly extended terrains Well-defined examples are reported on the core complexes in the Basin and Range Province of the western United States and in the Aegean extensional province (i.e Aegean Sea, Greece, western Turkey) (e.g., Davis, 1980; Wernicke, 1981; Lister et al., 1984; Bozkurt and Park, 1994; Hetzel et al 1995; Gessner et al., 2001; Işık and Tekeli, 2001; Işık et al., 2004; Jolivet and Brun, 2010) Detachment faults are low-angle normal faults separating mostly high-to medium-grade metamorphic rocks from basin deposits and/or low-grade metamorphic rocks (e.g., Davis and Lister, 1988; Lister and Davis, 1989) The extensional nature of a detachment fault is shown by a transition from ductile to brittle conditions (e.g., Işık et al., 2003) The initiation mechanisms and evaluations of detachment faults have been discussed elsewhere (e.g., Lister and Davis, 1989; Malavieille, 1993; Fletcher et al., 1995; Buck, 1988; Wernicke and Axen, 1988; Seyitoğlu et al., 2002, 2004; Ring et al., 2003; Tirel et al 2008; van Hinsbergen, 2010) Central Turkey is one of the key areas in deciphering Alpine orogeny, which includes the rocks of metamorphic * Correspondence: seyitoglu@ankara.edu.tr massifs (e.g., Kırşehir, Niğde, Akdağmadeni), oceanic crust (e.g., İzmir-Ankara-Erzincan), variable intrusions (e.g., Aaỗửren, ĩỗkapl, Baranada), and basin deposits (e.g., Tuzgửlỹ, Ulukla, Sivas, Çankırı) There have been numerous studies that particularly discuss the late Mesozoic-early Cenozoic tectonic evolution of central Turkey and related deformations within the scope of the process of closing the Neotethys Ocean and its various branches Therefore, the origins of central Anatolian sedimentary basins have been generally accepted as having developed through collisional and postcollisional compressional tectonics over years (e.g., Şengör and Yılmaz, 1981; Görür et al., 1984, 1998; Gürer and Aldanmaz, 2002) Especially in the last decade, however, evidence of extensional tectonics that controlled the development of these basins as well as the exhumation process of the Central Anatolian Crystalline Complex (CACC; i.e the Kırşehir-Niğde Massif) has been brought forward and discussed by several scientists (e.g., Whitney and Dilek, 1997; Gautier et al., 2002, 2008; Jaffey and Robertson, 2005; Işık et al., 2008, 2014; Işık, 2009; Lefebvre et al., 2015) Our study suggests the existence of a low-angle normal fault named here as the İvriz detachment, located between 189 SEYİTOĞLU et al / Turkish J Earth Sci the Ulukışla basin and the Bolkar Group of the Taurus Mountains in south-central Turkey In this paper, first, the geological setting of the area will be presented and then the description of the detachment surface will be given Finally the implications of the detachment faulting on the regional geology will be discussed Geological setting The Taurus Mountains extend all along southern Turkey and have been recognized as a linear structure since the Eratosthenes map (c 194 B.C.) Several tectonic units constitute the complex structure of the Taurus Mountains (Blumenthal, 1941; Brunn et al., 1971; Özgül, 1971, 1976, 1997; Demirtaşlı et al., 1975) The central part of the mountains is mainly composed of the PermianCretaceous recrystallized limestone marble, slate, and schist intercalations (i.e the Bolkar Group of Demirtaşlı et al., 1984) that represent the low-grade metamorphic rocks of the Taurides in Figure The Ulukışla basin (e.g., Oktay, 1982; Demirtaşlı et al., 1984; Clark and Robertson, 2002, 2005) is located between the central Taurus Mountains and the CACC (Figure 2) The basin fill is considerably well dated according to the paleontological data of previous authors (e.g., Demirtaşlı et al., 1975, 1984; Gỹl et al., 1984; Nazik and Gửkỗen, 1989; Alan et al., 2007; Gürer et al., 2016; Figure 3) The detailed descriptions of the formations can be found in the works of Demirtaşlı et al (1975, 1984) and Alan et al (2007) The Upper Cretaceous-middle Eocene basin fill is composed of the Dedeli, Güneydağı, Halkapınar, and Ulukışla formations Ophiolitic olistoliths of the Dedeli formation, clastic rocks of Halkapınar formation that originated from the Bolkar Group, and volcanic material in the Ulukışla formation are the prominent features of the Upper Cretaceous-middle Eocene basin fill (Figures and 3) The unconformably overlain Delimahmutlu and Hasangazi formations constitute the middle Eocene units (Figure 3) The Upper Eocene-Lower Oligocene gypsum and anhydrite unit is known as the Kabaktepe formation (Clark and Robertson, 2005; Meijers et al., 2016) The Upper Oligocene-Lower Miocene Aktoprak formation is composed of conglomerate, sandstone, marl, and limestone Upper Miocene-Pliocene fluviolacustrine deposits of the İnsuyu formation overlie the earlier units with an angular unconformity (Figures and 3) Quaternary alluvium, fluvial, and lacustrine sediments unconformably cover the previous units On top of the Taurus Mountains, Lower PaleoceneLower Eocene sedimentary units unconformably overlie the Bolkar Group (Demirtaşlı et al., 1984) (Figure 1) Similar to other central Anatolian basins, the Ulukışla basin has been interpreted by many scientists as a foreland and/or forearc or intraarc basin (e.g., Şengör and Yılmaz, 1981; Oktay, 1982; Görür et al., 1984, 1998; Gürer et 190 al., 2016), formed during the Neo-Tethys closure The southern margin of the Ulukışla basin is mapped as a thrust fault verging towards the north, especially on its eastern side (Demirtaşlı et al., 1984) In contrast, Dilek et al (1999) proposed that the southern margin of the Ulukışla basin is a north-dipping high-angle normal fault called the Bolkar Frontal Fault Zone, which was active during Oligo-Miocene times (figure in Dilek et al., 1999) In the footwall of this fault zone, the Horoz granitoid (47.17 ± 0.69 Ma: Ar/Ar hornblende; 54.3 ± 1.7 Ma; 50.44 0.28 Ma: Ar/Ar biotite, Kuỗu et al., 2010; 56.1 Ma: U-Pb zircon, Kadıoğlu and Dilek, 2010; 49.1 ± 1.0 Ma to 50.6 ± 2.4 Ma: U-Pb zircon, Parlak et al., 2013) added pebbles to the middle Eocene clastic rocks of the Ulukışla basin (Sarıfakıoğlu et al., 2012) (Figure 2) Clark and Robertson (2002, 2005) evaluated the subsidence history of the basin fill and geochemistry of the volcanic rocks and suggested that the Ulukışla basin developed in an extensional or transtensional setting between the Bolkar Carbonate Platform and the Niğde-Kırşehir massif Alpaslan et al (2004, 2006) documented the sodic alkaline and ultrapotassic nature of the volcanism in the Ulukışla basin and suggested a postcollisional, extension-related geodynamic setting The northern edge of the Ulukışla basin is bordered by the Niğde metamorphic massif, which has been evaluated as a core complex of the Oligocene-Miocene (Whitney and Dilek, 1997; Fayon et al., 2001) However, Gautier et al (2002) indicated the Early-Middle Eocene sedimentary units, which unconformably cover the southern Niğde massif, including the pebbles of this massif Thus, they suggested that the massif must have been at the surface before Eocene times or at least at the beginning of the Eocene Gautier et al (2002) defined a detachment on top of the Niğde dome Whitney et al (2003) documented pervasive top-to-the-NNE shearing overprinted by topto-the south shearing and presented new geochronological data indicating that the migmatites of the Niğde massif are cut by the ĩỗkapl granite, which shows coeval emplacement with the Late Cretaceous extension Gautier et al (2008) accept that the Niğde massif is a Cordillerantype core complex that developed along a detachment having top-to-the-NE/ENE sense of shearing (location in Figure 1) The opening of the Ulukışla basin and the shearing along the detachment on the Niğde core complex were evaluated as unrelated events (Gautier et al., 2008) On the other hand, considerable isotopic dating data have been published recently concerning the CACC To the north of the Niğde massif, on the northern side of the CACC, the Kerkenez granitoid of the Yozgat batholith has extensional mylonitic shear zones dated 71.6 ± 0.3 Ma and 71.7 ± 0.2 Ma (Ar/Ar, hornblende), showing a top-to-theNW shear sense (Işık et al., 2008) (location in Figure 1) SEYİTOĞLU et al / Turkish J Earth Sci Figure Simplified geological map of the Central Anatolian Crystalline Complex and middle Taurides based on a 1:500,000 scale geological map of Turkey by the MTA [1] Top-to-the-NE sense of shear on a detachment on the Niğde massif (Gautier et al., 2002, 2008), [2] top-to-the-NW sense of ductile shear from the Yozgat batholith (Işık et al., 2008), [3] top-to-the-SW sense of ductile shear on the Emizözü shear zone (Işık, 2009), [4] Kaman detachment and top-to-the-NW sense of shear (Lefebvre, 2011; Lefebvre et al., 2011), [5] top-to-the-NE sense of shear of the Hırkadağ detachment (Lefebvre, 2011; Advokaat et al., 2014; Lefebvre et al., 2015), [6] top-to-the-N-NE sense of shear on the İvriz detachment (this paper), [7] location of the hypothetical Aydos main breakaway fault (this paper), [8] NE stretching lineations in the SE of Altınekin (Eren, 2000) NM: Niğde massif, AD: Akdağ massif, KM: Kırşehir massif, YB: Yozgat batholith, AG: Aaỗửren granitoid, BA: Baranada quartz-monzonite, HM: Hrkada massif 191 SEYİTOĞLU et al / Turkish J Earth Sci Figure Geological map of the Ulukışla basin (modified from Atabey et al., 1990; Ulu, 2009; Alan et al., 2011a, 2011b; Gürbüz, 2016; the faults are after Yetiş, 1978; Demirtaşlı et al., 1984; Whitney and Dilek, 1997; Koỗyiit, 2003) and location of the İvriz detachment To the NW of the Niğde massif, in the Aaỗửren granitoid, the Emizửzỹ ductile shear zone with a top-to-the-SW sense of shear is found (Işık, 2009) (location in Figure 1) The age of this ductile shear is estimated at around 78–71 Ma (Işık, 2009) (Figure 1) Köksal et al (2012) later published an intrusion age for the Aaỗửren granitoid in the range of 84.1 1.0 Ma and 73.6 ± 0.4 Ma (U-Pb, zircon) The Kaman detachment has been recognized between the marbles of the CACC and the ophiolitic rocks, with topto-the-W-NW normal shearing (Lefebvre et al., 2011) (location in Figure 1) The intrusion of the Baranadağ quartz-monzonite postdated the ductile deformation, and it is claimed that movement on the Kaman detachment has ceased The cooling period of the Baranadağ quartzmonzonite is 69–72 Ma and apatite fission track ages of 57– 60 Ma have been provided (Boztuğ and Jonckheere, 2007; Boztuğ et al., 2009) 40Ar/39Ar dating of 72.11 ± 1.46 Ma andesite has been reported in the basin fill of the AyhanBüyükkışla basin, which is related to the exhumation of the CACC’s Hırkadağ massif (Advokaat et al., 2014; Lefebvre et al., 2015) (location in Figure 1) Recent studies using paleomagnetic reconstructions suggest that the CACC experienced nearly E-W extensional exhumation above 192 an eastward-dipping subduction during late Cretaceous times (Lefebvre, 2011; Lefebvre et al., 2013, 2015; Nairn et al., 2013; van Hinsbergen et al., 2016) Field observations 3.1 İvriz detachment The İvriz detachment is observed to the southern margin of the Ulukışla basin as a significant north-dipping low-angle normal fault at İvriz village (location in Figures 1, 2, and 4) The detachment surface separates the metamorphic Bolkar Group from the nonmetamorphic Halkapınar formation and ophiolitic mélange (Figures and 6) In the footwall of the İvriz detachment, the metamorphic Bolkar Group is mainly composed of marble and mylonitic marble Calc-silicate phyllites and schists are also present in the footwall Fine to coarse-grained marble represents the structurally lowest rocks of the footwall Marble is the most widespread and thickest rock unit in the study area It is mainly composed of calcite and dolomite, with up to 10% quartz, opaque minerals, and feldspar Marbles and schists/phyllites away from the detachment show mylonitic foliation defined principally by recrystallized and/or elongated carbonate minerals SEYİTOĞLU et al / Turkish J Earth Sci Figure The generalized stratigraphy of the Ulukışla basin (after Demirtaşlı et al., 1984; Alan et al., 2007; Gürbüz, 2016) and traces of broken feldspars, plus recrystallized quartz, sericite, and chlorite Mylonitic foliation within the study area strikes nearly east-west, with moderate dips to the north The development of mylonite and ultramylonite in which carbonates are ductily deformed, but where there is also a fracturing of feldspar grains, suggests temperatures not in excess of 450 °C Kinematic indicators in the mylonites of the study include asymmetric grain/ grain aggregate porphyroclasts, oblique foliation, and S-C fabrics, which suggest a top-to-the-N-NE sense of shear (Figures 6a and 6b) The İvriz detachment is characterized by a zone of brittle deformation in which footwall rocks are pervasively fractured and brecciated The zone of brittle deformation (cataclastic zone) is up to ~50 m in thickness in the study area, in which mylonitic marbles and calc- silicate schists/phyllites are pervasively fractured and turned into breccia (Figure 6c) Breccia is characterized by mainly angular rock fragments with lesser amounts of precipitated secondary minerals, such as calcite Although the main brittle deformation is attributed to the İvriz detachment, mesoscale faults are seen in the cataclastic zone Down-dipping slickenlines on the İvriz detachment are also typical A Paleocene-Eocene sequence (i.e the Halkapınar formation) that consists of conglomerate and sandstone lies directly above the fault surface (Figure 6d) Clastic components are polygenetic, containing marble, recrystallized limestone, mylonitic marble, phyllite, and quartzite, which are similar to those within the underlying footwall rock (Figure 6e) 193 SEYİTOĞLU et al / Turkish J Earth Sci Figure A-A’ cross section (upper part) See Figure for location and legend (a) A field photo of the İvriz detachment; (b) interpreted version of the field photo of the İvriz detachment Further to the east, the İvriz detachment can be followed around Kayasaray, where the ophiolites and olistoliths are found on the hanging wall (Figures 2, 7, and 8) 3.1.1 The age of İvriz detachment Based on its fossil content, the age of the Halkapınar formation, which is in the hanging wall of the İvriz detachment, is Paleocene-Early Eocene (Demirtaşlı et al., 1975, 1984; Sirel, 1981, personal communication, 2013; Alan et al., 2007; Gürbüz, 2016) (Figure 3) Immediately NW of İvriz, the Halkapınar formation contains conglomerates that contain cobbles/pebbles 194 of the Bolkar Group (Figures and 4), and the dipping of beds gradually decreases upwards Further to the north, towards relatively lower stratigraphical levels, the Halkapınar formation contains block-sized materials composed of ophiolites and recrystallized limestones of the Bolkar Group The provenance analysis of Clark and Robertson (2005; page 24) also indicates that the Upper Cretaceous-Paleocene units contain grains of the Bolkar Group These stratigraphical restrictions are consistent with the Paleocene-Eocene isotopic dating of the Horoz granitoid (see above) that shows an intrusive contact with the Bolkar Group in brittle conditions SEYİTOĞLU et al / Turkish J Earth Sci Figure Detailed geological map of the İvriz detachment around İvriz village For location see Figure Black dashed line shows the location of Figure This evidence indicates that during Latest CretaceousEarly Eocene times, the Bolkar Group was exhumed by normal faulting on the İvriz detachment 3.2 Synsedimentary faulting and deformation of the Ulukışla basin fill The Upper Cretaceous-middle Eocene units of the Ulukışla basin are deformed by several thrust faults (Figure 9), but careful examination in the field demonstrates that the units contain synsedimentary normal faults (Figure 10), indicating that its deposition occurred under an extensional tectonic regime This observation is supported by the İvriz detachment determined in this study and by the alkaline character of volcanism that developed simultaneously with the Ulukışla formation (e.g., Alpaslan et al., 2004, 2006) The synsedimentary normal faults in the Upper Cretaceous-middle Eocene sequence are overprinted by thrust faults (Figure 10), indicating a postmiddle Eocene contraction This contraction affected the eastern continuation of the İvriz detachment surface and the Bolkar Group thrusts onto the Ulukışla basin fill around Maden village (Figures 2, 11, and 12) The Upper Oligocene-Lower Miocene Aktoprak formation is limited by a north-dipping normal fault A drag-fold syncline developed on the hanging wall of this normal fault (Figure 7) The Aktoprak formation is deformed by thrust faulting near Yeniyıldız village (Figure 2) The intensity of deformation is different in the Upper Cretaceous-middle Eocene units (several folds and thrusts) and the Upper Oligocene-Lower Miocene sequence (overall a single drag fold syncline) Therefore, it can be said that the Ulukışla basin fill was affected by two different contractional events during post-middle Eocene and post-Oligocene times These data concur with the dating of the Savcılı thrust, further north in central Anatolia (Işık et al 2014) Discussion In the earlier studies mentioned before, the CACC magmatism and the development of surrounding basins are generally accepted as collision or arc-related Increasing evidence of extensional exhumation data from the CACC together with the reported İvriz detachment in the southern margin of the Ulukışla basin create an obligation to reopen discussion of the regional geology The observation of the İvriz detachment in the south of the Ulukışla basin can be explained as follows (Figures 13 and 14) The İvriz detachment had a high-angle origin and operated as a main breakaway fault, termed here as the Aydos main breakaway fault, that controlled deposition of the Ulukışla basin fill during the latest CretaceousEocene times (location in Figures and 13a) During the Paleocene-Eocene, the basin fill overlapped the main breakaway fault The remnant of this overlapped unit can 195 SEYİTOĞLU et al / Turkish J Earth Sci Figure a) Simplified geological cross-section of the border between the Taurus Mountains and the Ulukışla basin showing the detailed nature of the İvriz detachment fault with locations of photomicrograph and photographs labeled as b, c, d, and e b) Photomicrograph in crossed polarized light of oblique foliation (of) and S-foliation (S) and mylonitic foliation (mf) creating the kinematic indicator called S-C fabric in mylonitic marble Note that oblique foliation and S-C fabric suggest a top-to-the-north sense of shearing c) Field photograph of breccia below the detachment fault surface d) Photograph of the detachment fault surface and contact between the fault and the overlying conglomerate Notice the striations on the fault surface e) Close-up field view of conglomerate with mostly gray and light brown clasts of the Bolkar Group 196 SEYİTOĞLU et al / Turkish J Earth Sci Figure Kayasaray cross-section of the İvriz detachment For location and legend see Figure Figure a) Uninterpreted field photo of the İvriz detachment east of İvriz at Kayasaray; b) interpreted photo be observed on top of the Taurus Mountains today Later, the high-angle main breakaway transformed into the lowangle normal fault, the İvriz detachment, probably due to a rolling hinge mechanism like in western Turkey (i.e the Alaşehir type rolling hinge mechanism: Seyitoğlu et al., 2002, 2014) (Figure 13b) Its lateral northwest continuation probably creates the Altınekin stretching lineations (Eren 2000) (location in Figure 1) Along the north-northeast continuation of the up-bulged Aydos main breakaway, the CACC exhumed as an asymmetrical core complex, likely 197 SEYİTOĞLU et al / Turkish J Earth Sci Figure Deformed Paleocene-Eocene units in the Ulukışla basin See Figure for location and legend Figure 10 Field photo of synsedimentary normal faults overprinted by thrusting in Paleocene-Eocene units of the Ulukışla basin Location is at the north of Kolsuz; see Figure Figure 11 Cross-section of Maden and Gümüşköy that shows the southern margin of the Ulukışla basin For location and legend see Figure formed as an elliptical dome shape in map view (Lefebvre, 2011) (Figures 14a–14c) Top-to-the-SW movement on the Emizözü ductile shear zone (Işık, 2009) (location in Figure 1) and top-to-NNE shearing overprinted by top-tosouth shearing in the Niğde massif (Whitney et al., 2003) (location in Figure 1; Figure 14c) are possibly related 198 to the slight southward slip on the main breakaway fault because of the doming of the CACC The correlation of metamorphic grade between the footwall of the İvriz detachment (this paper) and the Niğde massif (e.g., Gautier et al., 2008) indicates that relatively deeper sections of the crust exhumed in the Figure 12 Field photo of thrust fault cutting the İvriz detachment near Maden village at the southern margin of the Ulukışla basin SEYİTOĞLU et al / Turkish J Earth Sci 199 SEYİTOĞLU et al / Turkish J Earth Sci Figure 13 The regional tectonic interpretation of the İvriz detachment K: Kaman detachment (Lefebvre, 2011; Lefebvre et al., 2011), Y: Yozgat batholith ductile shear zone (Işık et al., 2008), H: Hırkadağ detachment (Lefebvre, 2011; Advokaat et al., 2014; Lefebvre et al., 2015), E: Emizözü ductile shear zone (Işık, 2009), N: Niğde detachment (Gautier et al., 2002, 2008), A: Altınekin stretching lineations (Eren, 2000), I: İvriz detachment (this paper) CACC: Central Anatolian Crystalline Complex, STZ: Savcılı Thrust Zone (Işık et al., 2014) Figure 14 The Aydos main breakaway fault Development of the İvriz detachment and its role in the exhumation of the CACC 200 SEYİTOĞLU et al / Turkish J Earth Sci Figure 14 (Continued) 201 SEYİTOĞLU et al / Turkish J Earth Sci north The reason for the relatively shallow layers of the crustal exhumation along the İvriz detachment is probably the rolling hinge mechanism of the Aydos main breakaway fault in the south of the Ulukışla basin The stratigraphy of the Ulukışla basin has an Upper Cretaceous-Middle Eocene transgressive sequence and Upper Eocene-Lower Oligocene gypsum units (Figure 3) The transition from deep sedimentary environment to shallow conditions towards the Late Paleogene could be related to the exhumation of the Niğde massif that created shallow sedimentary conditions for the northern margin of the Ulukışla basin (Figure 14d) Post-Eocene contractional structures can be seen in both the CACC and inside the Ulukışla basin as well as on its southern margin (Figures 13c, 14e, and 14f) This hypothesis indicates the formation of an asymmetrical core complex with top-to-the-NE shearing for the CACC and evaluates the central Anatolian basins as supradetachment basins There is no need for a subduction under the CACC to explain igneous activity as previous studies suggested (e.g., Lefebvre, 2011; van Hinsbergen et al., 2016) During the core complex formation, delamination of the lithosphere can create synand postexhumation magmatic activity (e.g Cordilleran, western US – Wells and Hoisch, 2008; Liaonan, northern China – Ji et al., 2015) Discovery of the İvriz detachment in the Taurus Mountains may be a missing part of a puzzle regarding the exhumation of the CACC Conclusion This paper documents the first records of a low-angle normal fault in the Taurus Mountains The İvriz detachment separates the metamorphic Bolkar Group from the ophiolitic rocks and sedimentary fill of the Ulukışla basin Geological relationships indicate that the İvriz detachment operated during latest Cretaceous-Eocene times Discovery of the İvriz detachment would change the perception of the tectonic style in south and central Anatolian sedimentary basins from collision/arc-related basins to supradetachment basins and opens up the possibility for more meaningful explanations of the exhumation history of the CACC, including the Niğde massif Acknowledgments This study was partly supported by ASÜBAP (Aksaray University, Scientific Research Projects, Grant No: 201371) The authors are grateful to A Yıldız (ASÜ), N Kazancı, and E Sirel (AÜ) for their contributions and fruitful discussions, and the three reviewers for their criticisms that improved the manuscript significantly EG acknowledges support from the Scientific and Technological Research Council of Turkey (TĩBTAK BDEB 2211-A) References Advokaat EL, van Hinsbergen DJJ, Kaymakỗ N, Vissers RLM, Hendriks BWH (2014) Late Cretaceous extension and Palaeogene rotation-related contraction in Central Anatolia recorded in the Ayhan-Büyükkışla basin Int Geol Rev 56: 1813-1836 Alan İ, Bakırhan B, Elibol H (2011a) MTA Genel Mỹdỹrlỹỹ, 1:100 000 ửlỗekli Tỹrkiye Jeoloji Haritaları Serisi, Karaman-N32 Paftası, No:165 Ankara, Turkey: MTA Jeoloji Etütleri Dairesi (in Turkish) Alan İ, Şahin Ş, Bakırhan B 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Tectonic controls on metamorphism, partial melting, and intrusion: timing and duration of regional metamorphism and magmatism in the Niğde Massif, Turkey Tectonophysics 376: 37-60 Yetiş C (1978) Çamardı (Niğde ili) yakın ve uzak dolayının jeoloji incelemesi ve Ecemiş Yarılım kuşağının Maden boğazı-Kamışlı arasındaki özellikleri PhD, İstanbul University, İstanbul, Turkey (in Turkish) 205 ... exhumation along the İvriz detachment is probably the rolling hinge mechanism of the Aydos main breakaway fault in the south of the Ulukışla basin The stratigraphy of the Ulukışla basin has an... photo of the İvriz detachment east of İvriz at Kayasaray; b) interpreted photo be observed on top of the Taurus Mountains today Later, the high-angle main breakaway transformed into the lowangle normal. .. regional geology The observation of the İvriz detachment in the south of the Ulukışla basin can be explained as follows (Figures 13 and 14) The İvriz detachment had a high-angle origin and operated as