Structure and deformation history of the Bitlis suture near Lake Hazar, southeastern Turkey MARK R. HEMPTON* Department of Geological Sciences, State University of New York at Albany, Albany, New York 12222 ABSTRACT north. During middle to late Eocene, conver- followed by a later phase of continental collision gence caused thrust stacking of the Elazig, in the Miocene. French geologists do not accept Detailed mapping of the Bitlis suture zone Maden, and Puturge Complexes; second- the concept of a Bitlis suture (Ricou and others, near Lake Hazar shows that it is composed of generation deformation in the Puturge Com- 1974, 1979; Delaune-Mayere and others, 1977; three tectonostratigraphic units which crop plex; and first-generation deformation in the Ricou and Marcoux, 1979). They propose that out as distinct north-dipping thrust slices. Maden Mélange. Continued convergence thrust sheets composing the zone emanated as From south to north, these are the Puturge with the Arabian plate in the late Miocene large nappes from near the Pontide Mountains, Metamorphic Complex, the Maden Mélange, caused kink banding in the Puturge and several hundred kilometres to the north. Dewey and the Elazig Igneous Complex. The Pu- Maden Complexes. Since the late Miocene, and Sengor (1979), Sengor (1979), and Sengor turge Metamorphic Complex consists of pre- this convergence has been accommodated by and Yilmaz (1981) refined the model of Dewey Tertiary, continental-margin sediments shortening and thickening along numerous and others (1973) by relating the geology of the metamorphosed to the greenschist facies dur- internal faults. Bitlis suture zone to the regional geology of the ing the Campanian-Maastrichtian and de- entire eastern Mediterranean area and offering formed by four generations of structures. INTRODUCTION more detailed paleogeographic interpretations. These are, in sequence (1) isoclinal folds and All the models proposed to explain the struc- a transposition foliation, (2) open folds, cren- The Bitlis suture zone is a belt of high strain tural and tectonic evolution of the Bitlis su- ulation cleavage, and north-dipping thrust and rapid uplift that marks the convergent ture zone suffer from a limited data base, over- faults, (3) kink bands, and (4) small-displace- boundary between the Arabian platform to the simplifications, and unclear paleogeographic ment faults. The Maden Mélange represents south and a collage of continental fragments, implications. The biggest problem for construct- middle Eocene, back-arc-basin sediments island arcs, and ophiolitic mélange to the north ing well-constrained tectonic models is the lack and volcanics metamorphosed to the green- (Dewey and others, 1973; Sengor and Yilmaz, of reliable data from this rugged and inhospita- schist facies and deformed by three genera- 1981). The zone strikes east across southeastern ble terrain. Clearly, there is a need for large-scale tions of structures: (1) a north-dipping Turkey, forming the Tauride Mountains, which mapping to clarify key lithological and struc- cleavage, (2) kink bands, and (3) small- merge into the Zagros Mountains in Iran tural details with which to test and constrain displacement faults. The Elazig Igneous (Fig. 1). Based on regional mapping, Ketin tectonic scenarios. I conducted a detailed map- Complex comprises an imbricated Maastrich- (1959, 1966) delineated major lithologic units ping project (scale 1:10,000) across 450 km2 of tian-early Eocene island arc and young within the Taurides. He recognized that thrust- the suture near Lake Hazar (Hempton, 1982a). marginal-basin terrain. Thrust faults between ing was south-directed and had progressed from This area was chosen because major units of the units are north-dipping, listric, and form a north to south. Ketin proposed that the strongest suture and their interrelationships are well ex- thin-skinned system. "orogenic movement" occurred in the Late Cre- posed (Fig. 1). The purpose of this paper is to These features suggest the following de- taceous but was followed by a "paroxysmal report the results of this mapping and to exam- formational and tectonic history. The Puturge movement" in the Oligocene. Reconnaissance ine their implications for the deformation history Metamorphic Complex was generated by mapping and borehole studies by Rigo de Righi and tectonic development of this part of the Bit- isoclinal folding and metamorphism of sedi- and Cortesini (1964) delineated an Upper Cre- lis suture zone. ments composing the Arabian continental taceous ophiolitic assemblage within the pre- margin during Campanian-Maastrichtian Tertiary Arabian platform. They constructed a TECTONOSTRATIGRAPHIC ophiolite obduction to the south. The Elazig detailed cross section of the Taurides, showing FRAMEWORK arc developed on the deformed margin be- numerous north-dipping thrust sheets, and pro- cause of subsequent southward subduction of posed two deformation events—an "Alpine di- In the Lake Hazar region, the Bitlis suture oceanic lithosphere. The arc migrated to the astrophism" and a late Miocene phase of gravity zone consists of the following tectonostrati- north, opening a back-arc basin. By the early gliding. Dewey and others (1973) synthesized graphic units, outcropping as distinct north- Eocene, the back-arc basin was filling with the available data within a plate-tectonic dipping thrust slices north of the frontal thrust volcaniclastics of the Maden Mélange, and framework and proposed that the Bitlis suture and transected by the East Anatolian Fault. the Elazig arc collided with a continent to the zone began to form in the late Miocene as the From south to north these are (1) the Puturge convergent boundary between the continental Complex, (2) the Maden Mélange, and (3) the plates of Arabia and Eurasia. Based on limited Elazig Complex (Figs. 1, 2, 3). These units are •Present address: Bellaire Research Center, Shell mapping, Hall (1976) proposed that "initial su- Development Company, P.O. Box 481, Houston, major components of the suture zone over most Texas 77001. turing" began in the Late Cretaceous and was of its length. Subordinate tectonostratigraphic Geological Society of America Bulletin, v. 96, p. 233-243, 7 figs., 1 table, February 1985. 233 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/96/2/233/3444937/i0016-7606-96-2-233.pdf by guest on 29 September 2021 234 M. R. HEMPTON 39 00 Figure 1. Sketch map of Bitlis suture near Lake Hazar, illustrating distribution and structural relationships of major tectonostratigraphic units. Horizontally ruled areas represent Upper Cretaceous to Paleocene sediments, including the Simaki Formation. Black areas represent tectonic slivers of Guleman serpentinite. Rectangle near Lake Hazar shows area of Figure 2. Index map shows frontal thrust of Bitlis suture (barbed) and area of Figure 1. units include the Guleman serpentinite and the base, and amphibolites that have undergone sists of a multiply deformed, low-grade meta- Simaki Formation. In the following sections, metamorphism in the greenschist and almandine- morphic terrain, at least 2,730 m thick, which each of these units is considered in detail. Each amphibolite fades (Altinli and others, 1963; contains 80% metapelite, 15% metaquaitzite, section briefly summarizes reported data and Perincek, 1979). Sengor and others (1979) and 5% recrystallized limestone (Fig. 2). then describes and interprets salient lithological showed that it is multiply deformed. Rigo de The metapelite unit forms the lower 1,780 m and structural data generated by this study. Righi and Cortesini (1964) noted that a recrystal- of the exposed complex and includes phyllite, lized limestone contains Permian-Carboniferous; slate, quartz-muscovite schist, calcschist, and Puturge Metamorphic Complex fossils. They suggested that the Puturge Meta- very low-grade, thinly interbedded metapielite morphic Complex was the product of regional (Fig. 4). Replicate whole-rock, K-Ar age The Puturge Metamorphic Complex crops metamorphism during "Alpine diastrophism." dates obtained from an unweathered, coarse- out in the southern third of the map area, south Because the complex is unconformably overlain grained mica schist yield an average of of the East Anatolian fault. Previous studies of by the middle Eocene Maden Complex, it must 71.2 ± 3.6 Ma. The mica schist contains 2.5% this unit in other localities reported that it con- be pre-middle Eocene (Hempton, 1982a). potassium, and 90% of all argon is radiogenic tained mica schist, clayey schist, quartz-bearing Mapping of the Puturge Metamorphic Com- 40AR. This indicates a Campanian-Maastiich- schist, quartzite, calcschist, marble, meta-dia- plex within the study area shows that it con- tian minimum age of recrystallization and cool- Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/96/2/233/3444937/i0016-7606-96-2-233.pdf by guest on 29 September 2021 BITLIS SUTURE, TURKEY 235 ing. The recrystallized limestone unit outcrops oping metapelite. (2) In many exposures, west-oriented, irregular shapes, which indicate above the metapelite unit as irregular and elon- first-generation structures are overprinted by a that they formed from isoclinal recumbent folds. gate discontinuous bodies surrounded by meta- second generation of structural elements includ- These folds have been subsequently deformed pelite (Figs. 2 and 3). These bodies strike ing folds (F2), a foliation (S2), and a lineation on by more open folds, whose vertical axial sur- northwest, dip northeast,