A GENERAL REVIEW OF THE GEOLOGY OF TURKEY Cahit ERENTÖZ I. INTRODUCTION : Since the publication of the book these belts show common features, and «Geology of Turkey» (Türkiye Jeolojisi) their features vary as of the Tertiary. by Dr. N. EGERAN and Dr. E. LAHN in The depressions and culminations 1948, there has been no detailed publi- on the axis of these longitudinal belts cation on the general stratigraphy of are crossing transversals, particularly Turkey. Most of the later publications in the N. - S. direction of Anatolia (the are confined to detailed studies of va- Çanakkale - Menderes transversal, the rious regions. Antalya transversal, the Istanbul trans- We have compiled various data in versal, the Tuzgölü transversal, the a very general manner, together with Kızılırmak transversal, the Malatya those that have come out since 1948, transversal and the Van transversal) to introduce before the sessions of the (32). «Symposium on Applied Geology in the The Central Anatolian orogenous Middle East», held on Nov. 14, 1955 complex, situated between the Pontides in Ankara. However, we were not able folded belts in the north and the Tau- to read it in detail and had opportu- rides folded belts in the south, has nity only to show some geological maps. formed important units in Central For this reason we have decided Anatolia. to publish this documentary compil- With the exception of Ağrı Dağı ation in the present bulletin. (Mt. Ararat) in Eastern Anatolia, We have given just a few refe- reaching an elevation of 5,165 meters, rences, since it is impossible to give all the other mountain ranges vary here the names of all books and papers between 3,000-4,500 meters in height. published to this day. III. STRATIGRAPHY : II GEOGRAPHIC POSITION : 1 - Old Substratum In general, Turkey consists of lon- The oldest formation known in gitudinal mountain ranges, extending Turkey, determined by means of fossils, along the Black Sea and the Mediter- is the Cambrian, which is found on ranean shores, and of the high Anato- Mazı Dağı, in the vicinity of the town lian plateaus between these ranges. of Mardin, district of Derik, in South- The littoral mountain ranges have eastern Anatolia. The old strata of this formed large orogenous folded belts. region is exposed under the Upper Practically up to the Upper Cretaceous, Cretaceous limestones through a fault. 40 This series is, from the bottom to the sometimes chalco-schists and now and top, as follows (40) : then quartz veins are found. The marb- Red, brown quartz - porphyry les form the uppermost part of the metamorphic series; granitic contacts Dark-red sandstone are clearly observed in these marbles. Conglomerate and sandstone with The crystalline schist gravels of the volcanic elements Istranca massif form the elements of Red, clayey sandstone the basal conglomerate of the Istanbul Dark-grey, massive limestone Silurian, which proves that the age of Conglomerate and fine sandstone the massif is older than the Silurian (16). Metamorphosed limestone and do- The metamorphic series located at lomite Eskişehir, Kütahya -Balıkesir, in the Schist, schistose sandstone, glauco- south of Çanakkale, at Kazdağ and at nitic schist Uludağ (Bursa), are crossed by grani- tic plutons and other intrusions. The In sandstones, constituting the up- granites are in contact with marbles permost levels of this series, Trilobites on one side and with gneiss and amphi- have been found. These belong to the bolites on the other; particularly at Lower and Middle Cambrian, and the the marble contacts large skarn and series with volcanic elements beneath scheelite occurrences are found. The are Algonkian. granitic intrusion has taken place du- Leaving aside this oldest fossil-bear- ring the last stage of the crystalline ing strata, the old substratum in the schist folding. These series are found other regions of Turkey is the crystal- towards the north, in Kapıdağı and line schist series which has undergone the isles of Marmara (22). metamorphism. On the other hand, the old crystal- Many authors maintain that the line schist formations) which continue Thracian Block in Thrace (the old towards the east from the Pontides and strata of the Rodop, Istranca, Ergene, which constitute practically the core Çatalca massifs) is a continuation of of the principal range, have been also the Anatolian Block. These crystalline crossed by chloritic schists, basic and schist series are encountered in places at acidic intrusions. Of these formations, Uludağ, in the region of Kütahya-Ba- the Tokat - Yıldızeli granites have an lıkesir and south of Çanakkale, at the economic value. Menderes massif, in Central Anatolia, Speaking of the old substratum, and even continue towards east. the Menderes Massif in Western Ana- The Istranca massif, forming the tolia is worth mentioning. This massif principal heights of the Thracian Block, has undergone strong metamorphism consists of gneiss, mica-schist, quart- and contains various gneiss, mica- zite, phyllite and marble. The gneiss schists, quartzites, marbles, phyllites, is the core of the massif, which is co- amphibolites and chalco-schists. Phylli- vered in the north by more metamor- tes and marbles form the upper part phic rocks and in the south by Ter- of this series. The eastern extensions tiary formations. This massif is crossed of the massif are covered by the Cent- in many places by a granitic batholith ral Anatolian Neogene and the northern and by aplite veins. The gneiss is fre- and southern parts by Paleozoic and quently alternating with mica - schists; Mesozoic formations. 41 This old massif, which plunges un- towards the east. This Silurian is ge- der the Taurides beyond the Muğla nerally comprised of conglomerate, district, reappears now and then and sandstone, arkosic and mainly quartzitic constitutes the core of the sedimentary series. According to recent surveys, strata along the Taurus Mountains. Graptolites have been found in the Finally, it forms towards east the Niğ- black schists, constituting the lower de Complex in the foreland of the levels of these series in the eastern Taurides. The old Kırşehir or Kızılır- creeks of Çengelköy (47). mak massif, covering large areas north of this complex, is a continuation of In the Zonguldak basin and south- the same complex to the north. east of Ereğli, there exist the Grapto- lite-bearing Silurian strata. The strata The Kırşehir massif consists of consist of marly schists, phyllites and gneiss, mica-schist, quartzite, phyllites dark-red sandstones (11; 40). and marbles, also strongly metamor- phosed. Since the acidic and basic in- The black schists and the siliceous trusions are intermixed here, it is not schists beneath the Mesozoic strata, possible to see everywhere which intru- west of Muğla in Southern Anatolia, sion is older than the other. However, are considered to be of Silurian age. during recent surveys (Dr. BUCHARDT, There is much resemblance between 1953-1954), the contact influences of these schists and the fossiliferous Silu- the acidic intrusions on the radiolarite, rian strata of the Istanköy Island. greenstone and plaquetted limestone complex have been observed. It is pre- From the Taurus range as far as sumed that these plaquetted limestones, Adana no definite fossil - bearing Silu- containing Globotruncana, and the rian is observed. However, during re- acidic intrusions have taken place af- cent surveys, Graptolite-bearing Silurian ter the Maestrichtian and before the formation has been established along Eocene. Very rich scheelite occurrences the Kozan - Saimbeyli road, north of have been observed in the large skarn Adana. This graptolitic series found in bands, formed at the contact points of dark-grey, black schists, lies unconfor- the marbles with acidic intrusions. mably, especially under the Devonian Furthermore, the fluorite veins, related and the Permo - Carboniferous strata mostly to syenites, give unique radioac- (48). The fossil - bearing black schists tive evidences of the area. of the Silurian continue to the north as far as Pınarbaşı (18). On the other hand, Metamorphic series constitute the it has been known for some time that principal substratum of the Bitlis massif, the greyish-grey, black, thick, micaceous south of the Lake Van, in Eastern sanstones, quartz, and schists, located Anatolia. Here, also, are found various between Fevzipaşa and Bahçe, are Si- gneisses, amphibolites and mica-schists. lurian. Quartzites are alternating in these se- ries. Marbles are also found in the 3 — Devonian upper levels. The Devonian covers quite an ex- 2 - Silurian tensive area in Turkey. The Devonian The Silurian strata in Istanbul, at sea has flooded almost the whole of Pendik, on Sedef Island and to the the country, turning the old massifs east of Çengelköy cover a large area into islands. 42 The Devonian covers large areas Towards the east, in the Taurus in the Istanbul region. The Lower range, the Brachiopod, Polyp-bearing Devonian consists mostly of quartzites, strata in the shore-line formations of limestones and secondarily of graywacke the Alanya massif belong to the Upper and schists; the Middle Devonian, of Devonian. These Devonian strata, abun- nodular limestones and of siliceous dant in fossils and almost resembling schists; and the Upper Devonian, of each other, continue to the east in the alternating clayey schists, graywacke depressions and culminations of the Tau- and conglomerates. The Upper Devo- rus mountains. Two thirds of the Pa- nian schists, so far named as the Thrace leozoic formations outcropping on the series, have been considered as Car- Taurus belts are Devonian in age and boniferous, according to the recent belong mostly to the Upper Devonian. surveys (46). These formations alternate with bluish- grey or light - coloured limestones, The Devonian of Istanbul extends bluish-black, calcareous schists, marly to Şile, Adapazarı, Karadeniz Ereğlisi, schists and sandstones (6, 8). These Bartın, Kastamonu and further east series extend to the Malatya massif, and shows similar facies in parts.