Thermochronology of the Miocene Arabia-Eurasia Collision Zone of Southeastern Turkey GEOSPHERE; V
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Research Paper GEOSPHERE Thermochronology of the Miocene Arabia-Eurasia collision zone of southeastern Turkey GEOSPHERE; v. 14, no. 5 William Cavazza1, Silvia Cattò1, Massimiliano Zattin2, Aral I. Okay3, and Peter Reiners4 1Department of Biological, Geological and Environmental Sciences, University of Bologna, 40126 Bologna, Italy https://doi.org/10.1130/GES01637.1 2Department of Geosciences, University of Padua, 35131 Padua, Italy 3Eurasia Institute of Earth Sciences, Istanbul Technical University, Maslak 34469, Istanbul, Turkey 4Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA 9 figures; 3 tables CORRESPONDENCE: william .cavazza@ unibo.it ABSTRACT ocean, and has been linked to mid-Cenozoic global cooling, Red Sea rifting, extension in the Aegean region, inception of the North and East Anatolian CITATION: Cavazza, W., Cattò, S., Zattin, M., Okay, The Bitlis-Pütürge collision zone of SE Turkey is the area of maximum in- strike-slip fault systems, and development of the Anatolian-Iranian continental A.I., and Reiners, P., 2018, Thermochronology of the Miocene Arabia-Eurasia collision zone of southeast- dentation along the >2400-km-long Assyrian-Zagros suture between Arabia and plateau (e.g., Şengör and Kidd, 1979; Dewey et al., 1986; Jolivet and Faccenna, ern Turkey: Geosphere, v. 14, no. 5, p. 2277–2293, Eurasia. The integration of (i) fission-track analyses on apatites, ii( ) (U-Th)/He 2000; Barazangi et al., 2006; Robertson et al., 2007; Allen and Armstrong, 2008; https:// doi .org /10 .1130 /GES01637.1. analyses on zircons, (iii ) field observations on stratigraphic and structural rela- Yılmaz et al., 2010). The age of the continental collision has been the topic of tionships, and (iv) preexisting U-Pb and Ar-Ar age determinations on zircons, much debate, with proposed ages ranging widely from the Late Cretaceous to Science Editor: Raymond M. Russo amphiboles, and micas provides for the first time an overall picture of the the Pliocene (Hall, 1976; Berberian and King, 1981; Şengör et al., 1985; Yılmaz, Associate Editor: Michael L. Williams thermo chronometric evolution of this collisional orogen. The data set points to 1993; Alavi, 1994; Jolivet and Faccenna, 2000; Agard et al., 2005; Robertson Received 17 November 2017 ubiquitous latest Cretaceous metamorphism of a passive margin sedimentary et al., 2007; Allen and Armstrong, 2008; Okay et al., 2010; McQuarrie and van Revision received 26 May 2018 sequence and its igneous basement not only along the suture zone but across Hinsbergen, 2013). Exact determination of the timing of the continental col- Accepted 3 July 2018 the entire width of the Anatolia-Tauride block north of the suture. During the lision is crucial not only for understanding the evolution of the Bitlis- Zagros Published online 7 August 2018 early Paleogene the basement complex of the Bitlis and Pütürge massifs along collisional orogen but also for elucidating the chronology and causative the suture was rapidly exhumed due to extensional tectonics in a back-arc set- mechanisms of more general syn- and post-collisional processes like (i ) the ting and eventually overlain by Eocene shallow-marine sediments. The entire development of large-scale strike-slip systems accommodating plate conver- Oligocene is characterized by a rather flat thermochronometric evolution in gence and (ii ) the development of continental plateaux. In the Bitlis-Pütürge the Bitlis orogenic wedge, contrary to the widely held belief that this epoch massifs of southeastern Turkey, i.e., the area of maximum continental inden- marked the inception of the Arabia-Eurasia collision and was characterized by tation, high-temperature radiometric systems indicate a discrete episode of widespread deformation. Deposition of a thick Oligocene sedimentary succes- high-pressure–low-temperature (HP-LT ) metamorphism in the latest Creta- sion in the Muş-Hınıs basin occurred in a retroarc foreland setting unrelated to ceous (Hempton, 1985; Okay et al., 1985; Oberhänsli et al., 2010, 2012, 2013; continental collision. During the Middle Miocene, the Bitlis-Pütürge orogenic Rolland et al., 2012; Topuz et al., 2017) which has been interpreted as the result wedge underwent a significant and discrete phase of rapid growth by both of the collision between Eurasia and either Arabia or a smaller microplate. The frontal accretion, as shown by cooling/exhumation of the foreland deposits only low-temperature thermochronometric data set available for the same re- on both sides of the orogenic prism, and underplating, as shown by cooling/ gion (Okay et al., 2010) (based on fission-track analyses on apatite in samples OLD G exhumation of the central metamorphic core of the orogenic wedge. We con- from both the basement units and the sedimentary cover) points to a discrete clude that continental collision started in the mid-Miocene, as also shown by phase of rapid mid-Miocene cooling/exhumation interpreted as the onset of coeval thick syntectonic clastic wedges deposited in flexural basins along the the Arabia-Eurasia hard collision. The results by Okay et al. (2010) do not rule Arabian plate northern margin and contractional reactivation of a number of out the possibility that the documented episode of Miocene cooling was only OPEN ACCESS preexisting structures in the European foreland. the last stage of a longer thermochronometric evolution and that the collision could have started somewhat earlier. This paper advances the state of the knowledge on this crucial area by integrating new apatite fission-track (AFT) INTRODUCTION and ZrHe data (this study) with other radiometric data from the literature (U-Pb on zircon and Ar-Ar on amphiboles and micas). The data ultimately provides a The >2400-km-long Bitlis-Zagros (Assyrian) suture zone in the Middle East more complete picture of the thermo-tectonic evolution of selected segments This paper is published under the terms of the (Fig. 1) marks the continental collision between Arabia and Eurasia. This is a of the Arabia-Eurasia collision zone. The results of this study indicate that the CC-BY-NC license. major event in Earth’s history, which isolated the Mediterranean and the Indian basement complex of the Bitlis and Pütürge massifs along the Assyrian suture © 2018 The Authors GEOSPHERE | Volume 14 | Number 5 Cavazza et al. | The Miocene Arabia-Eurasia collision zone of southeastern Turkey Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/14/5/2277/4338386/2277.pdf 2277 by guest on 27 September 2021 Research Paper 30° E 40° E 50° E E e u r a s i a n P l a t GCGC Black Sea LCLC 40° N NNANAFA P F EPE SASSASA Z SZSZ IZ SZS CaspianCCasp SeaSe İAEAESZ aspian SeSea SkSSkZkZ AF KMKM EAEAF g. 2 lis Suture Zo gg. 2 A ATAT Bit ne l b o r z Z a g r b i a n P o Mediterranean SeSea A r a l a t s F e a S >5000 m DSFDSD 30° N 4000 m 3000 m 2000 m 1000 m Subduction Zone 500 m Thrust 200 m Strike-slip fault 0 m 400 km Fault Figure 1. Overall tectonic sketch map of the Middle East. The box indicates the area shown in Figure 2. AT—Anatolide-Tauride terrane; IZ—Istanbul zone; SkZ—Sakarya zone; KM—Kirşehir Massif; NAF—North Anatolian fault; EAF—Eastern Anatolian fault; EP—Eastern Pontides; IAESZ—Izmir-Ankara-Erzincan suture zone; SASZ—Sevan-Akera suture zone; GC—Greater Caucasus; LC—Lesser Caucasus; DSF—Dead Sea fault. GPS vectors from Le Pichon and Kreemer (2010). experienced the following thermochronometric evolution during the Ceno- GEOLOGICAL FRAMEWORK zoic: (i ) cooling/exhumation between ca. 65 and 55 Ma probably resulting from backarc extension; (ii ) stable temperatures during the Oligocene except for The Bitlis-Pütürge Massif of southeastern Anatolia (Fig. 2) is a 500-km-long the Muş-Hınıs retroarc foreland basin, where the sediments being deposited arcuate belt of allochthonous metamorphic rocks bordering the Arabian Plat- underwent progressive burial; and (iii ) rapid cooling/exhumation during the form to the south, from which it is separated by a narrow belt of Upper Cre- Miocene, marking the collision between the Arabian and Eurasian plates. taceous to Early Miocene mélange made of flysch and ophiolitic units (Hall, GEOSPHERE | Volume 14 | Number 5 Cavazza et al. | The Miocene Arabia-Eurasia collision zone of southeastern Turkey Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/14/5/2277/4338386/2277.pdf 2278 by guest on 27 September 2021 Research Paper 39° N Karlıova E u r a s i a n P l a t e M u ş B′ B a s i 255 n Muş L a k e V a n 136 138 145 142 Bitlis 38° N C′ 140 151 A′ Maden B 155 159 Pütürge r a b i a n P l A a t e Hakkari 40° E 42° 44° 149 A 100 km E C E Eurasian and Anatolian Plates Cretaceous sedimentary rocks, Bitlis-Pütürge collision zone Thrust fault volcanics and granitoids Plio-Quaternary Eocene-to-Miocene Normal or undefined fault alluvium and volcanics Cretaceous accretionary complex ophiolitic mélange Miocene continental siliciclastics, Jurassic Strike-slip fault carbonates and volcanics Arabian Plate limestone and marble Sample Oligocene Paleozoic-to-recent Paleozoic clastics and evaporite sediments and volcanics schist, phyllite and marble Melazgirt-1 well Paleocene-Eocene Lower Miocene Paleozoic gneiss, metagranitoid Trace of cross-section clastics and limestone limestone and amphibolite Figure 2. Geological sketch map of the Bitlis-Pütürge collision zone of southeastern Turkey (after Bilgic, 2002; Günay and Şenel, 2002; Şenel and Ercan, 2002; Tarhan, 2002). 1976; Perinçek, 1990; Yılmaz, 1993; Okay, 2008). The massif is made of a Pre- The present-day structural configuration of the Bitlis orogenic wedge is cambrian basement and an overlying Phanerozoic sequence (Çağlayan et al., largely the result of south-verging post-Eocene thrusting, as shown by per- 1984; Göncüoğlu and Turhan, 1984; Okay et al., 1985).