FORAMINIFERA FROM THE EXOTIC PERMO-CARBONIFEROUS LIMESTONE BLOCKS IN THE KARAKAYA COMPLEX, NORTHWESTERN TURKEY

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Geology of the Paleotetis units at the northern part of Edremit Bay

İnceleme alanı Kuzeybatı Anadolu’da Biga Yarımadası’nın güneyinde, Edremit Körfezi ve kuzeyinde yer alan Kazdağ ve çevresini kapsar. Kazdağ Grubu, amfbolit-granulit fasiyesinde metamorfik bir istiftir.  Kazdağ Grubu üzerinde, bir sıyrılma fayı dokanağı ile yeşil şist fasiyesinde metamorfik birimlerden oluşan Karakaya Karmaşığı bulunur. Kazdağ Grubu, okyanus kabuğu, üzerinde gelişen okyanus platosu çökel ve volkanikleri, Karakaya Karmaşığı, riftt çökelleri, denizaltı-dağı, denizaltı platosu, hendek çökelleri, dalma-batma gerisi havza çökelleri temsil eden bir eklenir prizmadır. Kazdağ Grubu ve Karakaya Karmaşığı Paleotetis Okyanusu’nun Permo-Karbonifer’de oluşumu ve Triyas’ta kapanmasının hemen hemen tüm aşamalarını temsil eder. Anahtar Kelimeler: Paleotetis, Kazdağ Grubu, Karakaya Karmaşığı, jeodinamik evrim.Study area is located to the south of the Biga Peninsula, NW Anatolia. It includes the Edremit Bay and the Kazdağ Group to the north. The rock groups represent a geological period starting from the Carboniferous to present. On the basement a metamorphic series in amphibolite-granulite facies take place. These series form the Kazdağ Group itself and are made up of the Babadağ Formation, Sarıkız Formation, Kavurmacılar Formation and Altınoluk Formation. A detachment fault and the metamorphic Karakaya complex (green schist facies) take place on the Kazdağ Group. To the east, the Karakaya Complex starts with the Fazlıca, Kınar and Kalabak units, which contain shale, schist, fillate, basalt and marble, on a Palaeozoic granodiorite basement. These units are overlain by the units of Nilüfer, which is made up of tectonically thrusted spilits, and Tepeoba, which is made up of felsic fillate and tuffs, respectively. The unit Hodul passes laterally into the unit Nilüfer and it is made up of arkozic sandstone, rare spilit and chert alternations. On top of these formations, the unit Çal is located with a tectonic contact and it contains Permian-Trias limestone blocks in a size of a mountain. The study area forms the pieces of Palaeotethys ocean dominated between Carboniferous and Triassic. The rocks of the Kazdağ Group form the Laurassia part of the ocean crust while the Karakaya Complex represents the southern environments of the south-dipping oceanic crust. These environments include the sea-mount (Nilüfer unit), accretional prism (Hodul unit), marginal basin (Tepeoba unit) and passive Cimmeria margin of this basin (Fazlıca+Kınar+Kalabak). The Laurassia and Sakarya continents collided during Middle-late Triassic and the units between these continents formed the Karakaya Complex in the form of tectonic slices.Keywords: Paleotethys, Kazdağ Group, Karakaya Complex, geodynamic evolution

Thermochronology of the Miocene Arabia-Eurasia collision zone of southeastern Turkey

The Bitlis-Piitiirge collision zone of SE Turkey is the area of maximum indentation along the > 2400-km-long Assyrian-Zagros suture between Arabia and Eurasia. The integration of (1) fission-track analyses on apatites, (ii) (U-Th)/He analyses on zircons, (iii) field observations on stratigraphic and structural relationships, and (iv) preexisting U-Pb and Ar-Ar age determinations on zircons, amphiboles, and micas provides for the first time an overall picture of the thermochronometric evolution of this collisional orogen. The data set points to ubiquitous latest Cretaceous metamorphism of a passive margin sedimentary sequence and its igneous basement not only along the suture zone but across the entire width of the Anatolia-Tauride block north of the suture. During the early Paleogene the basement complex of the Bitlis and Piitiirge massifs along the suture was rapidly exhumed due to extensional tectonics in a back-arc setting and eventually overlain by Eocene shallow-marine sediments. The entire Oligocene is characterized by a rather flat thermochronometric evolution in the Bitlis orogenic wedge, contrary to the widely held belief that this epoch marked the inception of the Arabia-Eurasia collision and was characterized by widespread deformation. Deposition of a thick Oligocene sedimentary succession in the Mu-Hinis basin occurred in a retroarc foreland setting unrelated to continental collision. During the Middle Miocene, the Bitlis-Piitiirge orogenic wedge underwent a significant and discrete phase of rapid growth by both frontal accretion, as shown by cooling/exhumation of the foreland deposits on both sides of the orogenic prism, and underplating, as shown by cooling/exhumation of the central metamorphic core of the orogenic wedge. We conclude that continental collision started in the mid-Miocene, as also shown by coeval thick syntectonic clastic wedges deposited in flexural basins along the Arabian plate northern margin and contractional reactivation of a number of preexisting structures in the European foreland

İzmir‐Ankara suture as a Triassic to Cretaceous plate boundary – data from central Anatolia

The İzmir‐Ankara suture represents part of the boundary between Laurasia and Gondwana along which a wide Tethyan ocean was subducted. In northwest Turkey, it is associated with distinct oceanic subduction‐accretion complexes of Late Triassic, Jurassic and Late Cretaceous ages. The Late Triassic and Jurassic accretion complexes consist predominantly of basalt with lesser amounts of shale, limestone, chert, Permian (274 Ma zircon U‐Pb age) metagabbro and serpentinite, which have undergone greenschist facies metamorphism. Ar‐Ar muscovite ages from the phyllites range from 210 Ma down to 145 Ma with a broad southward younging. The Late Cretaceous subduction‐accretion complex, the ophiolitic mélange, consists of basalt, radiolarian chert, shale and minor amounts of recrystallized limestone, serpentinite and greywacke, showing various degrees of blueschist facies metamorphism and penetrative deformation. Ar‐Ar phengite ages from two blueschist metabasites are ca. 80 Ma (Campanian). The ophiolitic mélange includes large Jurassic peridotite‐gabbro bodies with plagiogranites with ca. 180 Ma U‐Pb zircon ages. Geochronological and geological data show that Permian to Cretaceous oceanic lithosphere was subducted north under the Pontides from the Late Triassic to the Late Cretaceous. This period was characterized generally by subduction‐accretion, except in the Early Cretaceous, when subduction‐erosion took place. In the Sakarya segment all the subduction accretion complexes, as well as the adjacent continental sequences, are unconformably overlain by Lower Eocene red beds. This, along with the stratigraphy of the Sakarya Zone indicate that the hard collision between the Sakarya Zone and the Anatolide‐Tauride Block took place in Paleocene

Multiple Orbitoides d’Orbigny lineages in the Maastrichtian? Data from the Central Sakarya Basin (Turkey) and Arabian Platform successions (Southeastern Turkey and Oman)

The standard reconstruction of species of Orbitoides d'Orbigny into a single lineage during the late Santonian to the end of the Maastrichtian is based upon morphometric data from Western Europe. An irreversible increase in the size of the embryonic apparatus, and the formation of a greater number of epi-embryonic chamberlets (EPC) with time, is regarded as the main evolutionary trends used in species discrimination. However, data from Maastrichtian Orbitoides assemblages from Central Turkey and the Arabian Platform margin (Southeastern Turkey and Oman) are not consistent with this record. The Maastrichtian Besni Formation of the Arabian Platform margin in Southeastern Turkey yields invariably biconvex specimens, with small, tri- to quadrilocular embryons and a small number of EPC, comparable to late Campanian Orbitoides medius (d'Archiac). The upper Maastrichtian Tarakli Formation from the Sakarya Basin of Central Turkey contains two distinct, yet closely associated forms of Orbitoides, easily differentiated by both external and internal features. Flat to biconcave specimens possess a small, tri- to quadrilocular embryonic apparatus of Orbitoides medius-type and a small number of EPC, whereas biconvex specimens possess a large, predominantly bilocular embryonic apparatus, and were assigned to Orbitoides ex. interc. gruenbachensis Papp-apiculatus Schlumberger based on morphometry. The flat to biconcave specimens belong to a long overlooked species Orbitoides pamiri Meric, originally described from the late Maastrichtian of the Tauride Mountains in SW Turkey. This species is herein interpreted to be an offshoot from the main Orbitoides lineage during the Maastrichtian, as are forms that we term Orbitoides 'medius', since they recall this species, yet are younger than normal occurrence with the accepted morphometrically defined lineage. The consistent correlation between the external and internal test features in O. pamiri implies that the shape of the test is not an ecophenotypic variation, but appears to be biologically controlled. We, therefore, postulate that more than one lineage of Orbitoides exists during the Maastrichtian, with a lineage that includes O. 'medius' and O. pamiri displaying retrograde evolutionary features

TAVŞANLI ZONU: ANATOLİD-TORİD BLOKU'NUN DALMA-BATMAYA UĞRAMIŞ KUZEY UCU

Tavşanlı Zonu, Anatolid-Torid Bloku'nun kuzey ucunda yer alan ve Kretase'de yüksek basınç-düşük sıcaklık koşullarında metamorfizma geçirmiş kesimini oluşturur. Kuzeyden Izmir-Ankara Kenedi, güneyden Afyon Zonu kayaları tarafından sınırlanan Tavşanlı Zonu başlıca dört tektonik üniteden oluşmuştur. En altta düzenli bir stra- tigrafik istif sunan ve Geç Kretase'de (~80 my) ~24 kbar basınç, 430-500 °C sıcaklıkta metamorfizma geçirmiş olan Orhaneli Grubu yer alır. Orhaneli Grubu kendi içinde alttan üste doğru mikaşist, mermer ve metabazit-meta- çört-fillat ardalanmasından meydana gelmiştir. Orhaneli Grubu üzerinde tektonik dokanaklarla ofiyolitli melanj veya doğrudan ofiyolit kütleleri oturur. Ofiyolitli melanjı oluşturan bazalt, çört, pelajik şeyl, kireçtaşı gibi kayalar düşük sıcaklıklarda bir başlangıç mavişist metamorfizması geçirmiştir. Tektonik istifin en üst üyesini oluşturan ofi- yolit kütlesinin büyük bir kesimi (>%90) peridotitlerden yapılmıştır. Peridotitlere az oranlarda gabro, piroksenit gibi kayalar eşlik eder. Peridotit kütleleri izole diyabaz daykları tarafından kesilmiştir. Tavşanlı Zonu'nun batı kesim- lerinde tüm bu birimler Alt-Orta Eosen granodiyoritleri tarafından kesilir, doğu kesimlerinde ise Erken Eosen yaşlı denizel kireçtaşları, ofiyolit ve mavişistleri uyumsuzlukla örter. Anatolid-Torid Bloku'nun kuzey ucu Kampa- niyen'de bir okyanus içi dalma-batma zonuna girerek YB/DS koşullarında deforme olmuş ve metamorfizma geçir- miştir. Mavişistler, dalma-batma olayı sürerken, kıta-kıta çarpışması gerçekleşmeden, Maastrihtiyen ve Pa- leosen'de, tabanda bindirme fayı, tavanda normal fay arasında bir tektonik dilim olarak yüzeye çıkmıştır. Tavşanlı Zonu tektonik konumu ve jeolojik olayların zamanlaması açısından Umman doğusunda bulunan Semail ofiyolitine ve altındaki mavişist ve eklojitlere büyük benzerlik sunar

DENİZLİ'NİN GÜNEYİNDE MENDERES MASİFİ VE LİKYA NAPLARININ JEOLOJİSİ

Honaz dağı bölgesi üst üste duran tektonik birimlerden oluşmuştur. Batıda, bu tektonik istifin en altında monoton yeşil metaşeylden oluşan yaşı belirsiz Honaz şeyli yer alır. Honaz şeylinin üzerinde tektonik bir dokanakla masif beyaz kireçtaşı ve ince tabakalı çörtlü kireçtaşı ve şeylden oluşan, hafif bir metamorfizma geçirmiş, Menderes masifinin Mesozoyik örtü birimi yer alır. Menderes masifi üzerinde tektonik dokanakla Likya naplarına ait Sandak birimi bulunur. Mesozoyik yaşta dolomit ve kireçtaşından oluşan Sandak biriminin üzerinde ise ofiyolit yer almaktadır. Bütün bu birimler Honaz antiklinali diye adlandırılan, doğuya devrik büyük bir antiklinal oluşturur; Honaz antiklinalinin devrik kanadı altında, tektonik bir dokanakla, Göbecik tepe birimi adı verilen Geç Kretase - Orta/Geç Eosen yaşta pelajik bir sedimanter istif yer almaktadır. Göbecik tepe birimi Honaz dağı bölgesinde nispî otokton birimi teşkil etmektedir. Honaz dağı bölgesindeki birimlerde Geç Kretase, Orta Eosen ve Geç Eosen/Oligosen tektoniğinin izi görülür. Ofiyolitin, Sandak birimi üzerine yerleşmesi muhtemelen Geç Kretasede olmuş, Sandak biriminin Menderes masifi üzerine bindirmesi muhtemelen Orta Eosende, tüm bu birimlerin Göbecik tepe birimi üzerine yerleşmesi ve Honaz antiklinalinin oluşması Geç Eosen/Oligosende meydana gelmiştir

The geology of the Ağvanis metamorphic rocks and neighbouring formations

The area studied is located in Northeast Anatolia between the Pontide and Tauride orogenic belts. The metamorphic rocks called Ağvanis Group are bounded to the north and south by faults of the North Anatolian Fault Zone; in the east and west they are unconformably overlain by sedimentary rocks of Eocene and younger age. The Ağvanis Group consists mainly of metabasic rocks with lesser amounts of marble, phyllite, metadacite and metaacidic plutonic rocks. The major metaacidic pluton is the Gökseki metatrondhjemite which forms a large sheet. Metamorphic and surrounding rocks are cut by hundreds of dacite sills, stocks and a quartz-diorite pluton related to Paleocene acid magmatism. The western part of the Ağvanis Group forms a WNW-ESE trending large anticlinorium whereas in the east N-S trending antiform and synforms, probably as part of older structural elements, are preserved. Metamorphic rocks of the Ağvanis Group have undergone regional metamorphism in greenschist facies; a contact metamorphism superimposed on the regional metamorphism has developed around the quartz-diorite pluton. In terms of lithology, stratigraphy and type of metamorphism rocks of the Ağvanis Group resemble those of the Tokat Massif and probably constitute, like the Tokat Massif, the basement to the Pontide Mesozoic sequence. Hacıören Formation of Liassic age consisting of volcano-clastic sediments occurs to the north of the Ağvanis metamorphic rocks; whereas to the northeast of the Ağvanis metamorphic rocks there is the newly described Taşdemir Formation consisting of olistostromes of Paleocene age. Taşdemir Formation is tectonically overlain by the Boynuktepe Group which forms a nappe of Jurassic-Cretaceous limestones. Eocene sandstones lie unconformably on the Ağvanis metamorphic rocks and on the Taşdemir Formation. The youngest rocks in the area are terrigenous deposits probable of Oligomiocene age and poorly consolidated sandstone conglomerate, clay, marn and basalts of Neogene age

Late Oligocene—Early Miocene shortening in the Thrace Basin, northern Aegean

Late Cenozoic was a period of large-scale extension in the Aegean. The extension is mainly recorded in the metamorphic core complexes with little data from the sedimentary sequences. The exception is the Thrace Basin in the northern Aegean, which has a continuous record of Middle Eocene to Oligocene marine sedimentation. In the Thrace Basin, the Late Oligocene–Early Miocene was characterized by north-northwest (N25°W) shortening leading to the termination of sedimentation and formation of large-scale folds. We studied the stratigraphy and structure of one of these folds, the Korudağ anticline. The Korudağ anticline has formed in the uppermost Eocene–Lower Oligocene siliciclastic turbidites with Early Oligocene (31.6 Ma zircon U–Pb age) acidic tuff beds. The turbidites are underlain by a thin sequence of Upper Eocene pelagic limestone. The Korudağ anticline is an east-northeast (N65°E) trending fault-propagation fold, 9 km wide and 22 km long and with a subhorizontal fold axis. It is asymmetric with shallowly-dipping northern and steeply-dipping southern limbs. Its geometry indicates about 1 km of shortening in a N25°W direction. The folded strata are unconformably overlain by Middle Miocene continental sandstones, which constrain the age of folding. The Korudağ anticline and other large folds in the Thrace Basin predate the inception of the North Anatolian Fault (NAF) by at least 12 myr. The Late Oligocene–Early Miocene (28–17 Ma) shortening in the Thrace Basin and elsewhere in the Balkans forms an interlude between two extensional periods, and is probably linked to changes in the subduction dynamics along the Hellenic trench.TÜBİTAKİTÜ-BAPTÜBAFreie Universität Berlin (1008