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1.
The Sivas Basin is one of several Central Anatolian basins. It developed mainly after the closure of the northern branch of Neotethys. Its location between the Kirsehir Massif and the Taurides implies that it should not be confused with the Inner Tauride ocean located south of the Eastern Taurides. The basement of the Sivas Basin consists of ophiolitic nappes and melanges that were thrust toward the margins of the continental blocks present in this area—the Pontide belt to the north and the Anatolide-Tauride platform to the south. The basin was initiated by tectonic subsidence at the end of the Cretaceous, and it can be compared to a foreland basin during Paleocene and early to middle Eocene time. It was emergent during late Eocene and Oligocene time, although it continued to subside. A transgression in some parts of the basin occurred during the Oligocene and early Miocene (maximum flooding). During the Pliocene, it was affected by regional compression directed toward the NNW, which resulted from convergence of the Arabian and Eurasian plates. This basin may have developed as an intracontinental basin within the Tauride platform and probably never had an oceanic basement. As a result of this work, the general paleogeographic organization of Central Anatolia and Northern Tethys during the Mesozoic should to be revised.  相似文献   

2.
The paleogeography of the Eastern Pontides was defined by the Paleotethys ocean to the north and a continental assemblage to the south, prior to Carboniferous time. The S-dipping subduction of Paleotethys beneath Gondwana caused the development of arc magmatism, mostly active in the Early Carboniferous. Cessation of magmatism during Late Carboniferous-Early Permian time was accompanied by the deposition of platform carbonates, which were rifted to open a back-arc oceanic basin (Karakaya ocean) during the Triassic.

Accompanying closure of this Triassic basin, the Ladinian-Late Triassic products of Neotethys, opening in the south, transgressively overlay the basement in the Keban continent to the south. However, transgression reached the northern region (Pontide continent) during Liassic time, because of a topographic high created by southward subduction of the Paleotethys ocean as well as closure of the Karakaya ocean.

During the late Cenomanian/Turonian to Eocene, an island arc evolved as a result of N-dipping subduction of Neotethys. The ophiolite-melange association was obducted onto the Pontide continent as a retrocharriage process in the Turonian-Maastrichtian, Paleocene, and the end of the early Eocene, and onto the Keban continent in Campanian-Maastrichtian and pre-late Lutetian time.

A continental-lacustrine environment developed, and partial melting of the thickened crust initiated the development of volcanic units in the Miocene. The region was affected by right-lateral strike-slip faulting (the North Anatolian fault) and a NE-SW-trending left-lateral strike-slip fault system (the Northeast Anatolian fault).  相似文献   

3.
The G?ksun(Kahramanmaras)ophiolite(GKO),cropping out in a tectonic window bounded by the Malatya metamorphic unit on both the north and south,is located in the EW-trending lower nappe zone of the southeast Anatolian orogenic belt(Turkey).It exhibits a complete oceanic lithospheric section and overlies the Middle Eocene Maden Group/Complex with a tectonic contact at its base.The ophiolitic rocks and the tectonically overlying Malatya metamorphic(continental)unit were intruded by I-type calc-alkaline Late Cretaceous granitoid(~81-84 Ma).The ultramafic to cumulates in the GKO are represented by wehrlite,plagioclase wehrlite,olivine gabbro and gabbro.The crystallization order for the cumulate rocks is as follows:olivine±chromian spinel→clinopyroxene→plagioclase.The major and trace element geochemistry as well as the mineral chemistry of the ultramafic to mafic cumulate rocks suggest that the primary magma generating the GKO is compositionally similar to that observed in the modern island-arc tholeiitic sequences.The mineral chemistry of the ultramafic to mafic cumulates indicates that they were derived from a mantle source that was previously depleted by earlier partial melting events.The highly magnesian olivine(Fo77-83),clinopyroxene(Mg#of 82-90)and the highly Ca-plagioclase(An81-89)exhibit a close similarity to those,which formed in a supra-subduction zone(SSZ)setting.The field and the geochemical evidence suggest that the GKO formed as part of a much larger sheet of oceanic lithosphere,which accreted to the base of the Tauride active continental margin,including the ispendere,K?mürhan and the Guleman ophiolites.The latter were contemporaneous and genetically/tectonically related within the same SSZ setting during the closure of the Neotethyan oceanic basin(Berit Ocean)between the Taurides to the north and the Bitlis-Pütürge massif to the south during the Late Cretaceous.  相似文献   

4.
《Geodinamica Acta》2001,14(1-3):147-158
Central Anatolia has undergone complex Neotectonic deformation since Late Miocene–Pliocene times. Many faults and intracontinental basins in this region were either formed, or have been reactivated, during this period. The eastern part of central Anatolia is dominated by a NE–SW-trending, left lateral transcurrent structure named the Central Anatolian fault zone located between Sivas in the northeast and west of Mersin in the southwest. Around the central part, it is characterized by transtensional depressions formed by left stepping and southward bending of the fault zone.Pre-Upper Miocene basement rocks of the region consist of the central Anatolian crystalline complex and a sedimentary cover of Tertiary age. These rock units were strongly deformed by N–S convergence. The entire area emerged to become the site of erosion and formed a vast plateau before the Late Miocene. A NE–SW-trending extensional basin developed on this plateau in Late Miocene–Early Pliocene times. Rock units of this basin are characterized by a thick succession of pyroclastic rocks intercalated with calcalkaline–alkaline volcanics. The volcanic sequence is unconformably overlain by Pliocene lacustrine–fluviatile deposits intercalated with ignimbrites and tuffs. Thick, coarse grained alluvial/colluvial fan deposits of marginal facies and fine grained clastics and carbonates of central facies display characteristic synsedimentary structures with volcanic intercalations. These are the main lines of evidence for development of a new transtensional Hırka–Kızılırmak basin in Pliocene times. Reactivation of the main segment of the Central Anatolian fault zone has triggered development of depressions around the left stepping and southward bending of the central part of this sinistral fault zone in the ignimbritic plateau during Late Pliocene–Quaternary time. These transtensional basins are named the Tuzla Gölü and Sultansazlığı pull-apart basins. The Sultansazlığı basin has a lazy S to rhomboidal shape and displays characteristic morphologic features including a steep and stepped western margin, large alluvial and colluvial fans, and a huge composite volcano (the Erciyes Dağı).The geometry of faulting and formation of pull-apart basins can be explained within the framework of tectonic escape of the wedge-like Anatolian block, bounded by sinistral East Anatolian fault zone and dextral North Anatolian transform fault zone. This escape may have been accomplished as lateral continental extrusion of the Anatolian Plate caused by final collision of the Arabian Plate with the Eurasian Plate.  相似文献   

5.
The Southeast Anatolian orogen is a part of the eastern Mediterranean-Himalayan orogenic belt. Development of the Southeast Anatolian orogen began with the first ophiolite obduction onto the Arabian platform during the Late Cretaceous, and it continued until the Miocene. Its lingering effects continue to be discernible at present. During the Late Cretaceous-Miocene interval, three major deformational phases occurred, related to Late Cretaceous, Eocene, and Miocene nappe emplacements. The Miocene nappes are composed of ophiolites and metamorphic massifs.

For a decade, field studies in the region have shown that strike-slip tectonics played a role complementary to the major horizontal effects of the nappe movement, as indicated by: (1) fault systems active during the Eocene; (2) different Eocene rock units composed of coeval continental and deep-sea deposits and presently tectonically juxtaposed; and (3) other stratigraphic and structural data obtained across the present strike-slip fault zones.

These strike-slip faults possibly resulted from oblique subduction of the mid-oceanic ridge underneath the northerly situated Yuksekova ensimatic island-arc complex, causing a gradual cessation of the island-arc system. The subduction also led to the development of a back-arc pull-apart basin, i.e., the Maden basin, which opened on the upper plate. The geologic history in Southeast Anatolia resembles the development of the San Andreas fault system and subsequent tectonic evolution.  相似文献   

6.
Tethyan evolution of Turkey: A plate tectonic approach   总被引：9，自引：0，他引：9  
The Tethyan evolution of Turkey may be divided into two main phases, namely a Palaeo-Tethyan and a Neo-Tethyan, although they partly overlap in time. The Palaeo-Tethyan evolution was governed by the main south-dipping (present geographic orientation) subduction zone of Palaeo-Tethys beneath northern Turkey during the Permo-Liassic interval. During the Permian the entire present area of Turkey constituted a part of the northern margin of Gondwana-Land. A marginal basin opened above the subduction zone and disrupted this margin during the early Triassic. In this paper it is called the Karakaya marginal sea, which was already closed by earliest Jurassic times because early Jurassic sediments unconformably overlie its deformed lithologies. The present eastern Mediterranean and its easterly continuation into the Bitlis and Zagros oceans began opening mainly during the Carnian—Norian interval. This opening marked the birth of Neo-Tethys behind the Cimmerian continent which, at that time, started to separate from northern Gondwana-Land. During the early Jurassic the Cimmerian continent internally disintegrated behind the Palaeo-Tethyan arc constituting its northern margin and gave birth to the northern branch of Neo-Tethys. The northern branch of Neo-Tethys included the Intra-Pontide, Izmir—Ankara, and the Inner Tauride oceans. With the closure of Palaeo-Tethys during the medial Jurassic only two oceanic areas were left in Turkey: the multi-armed northern and the relatively simpler southern branches of Neo-Tethys. The northern branch separated the Anatolide—Tauride platform with its long appendage, the Bitlis—Pötürge fragment from Eurasia, whereas the southern one separated them from the main body of Gondwana-Land. The Intra-Pontide and the Izmir—Ankara oceans isolated a small Sakarya continent within the northern branch, which may represent an easterly continuation of the Paikon Ridge of the Vardar Zone in Macedonia. The Anatolide-Tauride platform itself constituted the easterly continuation of the Apulian platform that had remained attached to Africa through Sicily. The Neo-Tethyan oceans reached their maximum size during the early Cretaceous in Turkey and their contraction began during the early late Cretaceous. Both oceans were eliminated mainly by north-dipping subduction, beneath the Eurasian, Sakaryan, and the Anatolide- Tauride margins. Subduction beneath the Eurasian margin formed a marginal basin, the present Black Sea and its westerly prolongation into the Srednogorie province of the Balkanides, during the medial to late Cretaceous. This resulted in the isolation of a Rhodope—Pontide fragment (essentially an island arc) south of the southern margin of Eurasia. Late Cretaceous is also a time of widespread ophiolite obduction in Turkey, when the Bozkir ophiolite nappe was obducted onto the northern margin of the Anatolide—Tauride platform. Two other ophiolite nappes were emplaced onto the Bitlis—Pötürge fragment and onto the northern margin of the Arabian platform respectively. This last event occurred as a result of the collision of the Bitlis—Pötürge fragment with Arabia. Shortly after this collision during the Campanian—Maastrichtian, a subduction zone began consuming the floor of the Inner Tauride ocean just to the north of the Bitlis—Pötürge fragment producing the arc lithologies of the Yüksekova complex. During the Maastrichtian—Middle Eocene interval a marginal basin complex, the Maden and the Çüngüş basins began opening above this subduction zone, disrupting the ophiolite-laden Bitlis—Pötürge fragment. The Anatolide-Tauride platform collided with the Pontide arc system (Rhodope—Pontide fragment plus the Sakarya continent that collided with the former during the latest Cretaceous along the Intra Pontide suture) during the early to late Eocene interval. This collision resulted in the large-scale south-vergent internal imbrication of the platform that produced the far travelled nappe systems of the Taurides, and buried beneath these, the metamorphic axis of Anatolia, the Anatolides. The Maden basin closed during the early late Eocene by north-dipping subduction, synthetic to the Inner-Tauride subduction zone that had switched from south-dipping subduction beneath the Bitlis—Pötürge fragment to north dipping subduction beneath the Anatolide—Tauride platform during the later Palaeocene. Finally, the terminal collision of Arabia with Eurasia in eastern Turkey eliminated the Çüngüş basin as well and created the present tectonic regime of Turkey by pushing a considerable piece of it eastwards along the two newly-generated transform faults, namely those of North and East Anatolia. Much of the present eastern Anatolia is underlain by an extensive mélange prism that accumulated during the late Cretaceous—late Eocene interval north and east of the Bitlis—Pötürge fragment.  相似文献   

7.
Kadir Dirik 《Geodinamica Acta》2013,26(1-3):147-158
Abstract

Central Anatolia has undergone complex Neotectonic deformation since Late Miocene-Pliocene times. Many faults and intracontinental basins in this region were either formed, or have been reactivated, during this period. The eastern part of central Anatolia is dominated by a NE-SW-trending, left lateral transcurrent structure named the Central Anatolian fault zone located between Sivas in the northeast and west of Mersin in the southwest. Around the central part, it is characterized by transtensional depressions formed by left stepping and southward bending of the fault zone. Pre-Upper Miocene basement rocks of the region consist of the central Anatolian crystalline complex and a sedimentary cover of Tertiary age. These rock units were strongly deformed by N-S con- vergence. The entire area emerged to become the site of erosion and formed a vast plateau before the Late Miocene. A NE-SW- trending extensional basin developed on this plateau in Late Miocene-Early Pliocene times. Rock units of this basin are characterized by a thick succession of pyroclastic rocks intercalated with calcalkaline-alkaline volcanics. The volcanic sequence is uncon- formably overlain by Pliocene lacustrine-fluviatile deposits interrelated with ignimbrites and tuffs. Thick, coarse grained alluvial/colluvial fan deposits of marginal facies and fine grained elastics and carbonates of central facies display characteristic synsedimentary structures with volcanic intercalations. These are the main lines of evidence for development of a new transtensional H?rka— k?zd?rmak basin in Pliocene times. Reactivation of the main segment of the Central Anatolian fault zone has triggered development of depressions around the left stepping and southward bending of the central part of this sinistral fault zone in the ignimbritic plateau during Late Pliocene-Quaternary time. These transtensional basins are named the Tuzla Gölü and Sultansazl??? pull-apart basins. The Sultansazl??? basin has a lazy S to rhomboidal shape and displays characteristic morphologic features including a steep and stepped western margin, large alluvial and colluvial fans, and a huge composite volcano (the Erciyes Da??).

The geometry of faulting and formation of pull-apart basins can be explained within the framework of tectonic escape of the wedgelike Anatolian block, bounded by sinistral East Anatolian fault zone and dextral North Anatolian transform fault zone. This escape may have been accomplished as lateral continental extrusion of the Anatolian Plate caused by final collision of the Arabian Plate with the Eurasian Plate. © 2001 Éditions scientifiques et médicales Elsevier SAS  相似文献   

8.
The volcanosedimentary units of Late Mesozoic-Tertiary age that outcrop in the Southeast Anatolian orogenic belt are commonly referred to as the Maden complex. There is a long-lasting controversy over its definition, age, stratigraphic and structural position, and the origin, and thus, the orogenic evolution. To solve this problem, large strips across the Southeast Anatolian orogenic belt have been studied extensively, and different rock groups which were regarded previously as the Maden unit have been differentiated. Their major characteristics and differences have been identified. The Maden unit sensu stricto is here redefined as a volcanosedimentary succession of Middle Eocene age representing a short-lived back-arc basin which reached the stage of an embryonic ocean. Presently, the Maden group occurs mainly within the lower nappe stack of the nappe zone of the Southeast Anatolian orogen. It rests stratigraphically on an amalgamated nappe package consisting of the different metamorphic tectonic units and, in turn, is overlain tectonically by the upper nappe units.  相似文献   

9.
The Malatya Basin is situated on the southern Taurus-Anatolian Platform. The southern part of the basin contains a sedimentary sequence which can be divided into four main units, each separated by an unconformity. From base to top, these are: (1) Permo-Carboniferous; (2) Upper Cretaceous–Lower Paleocene, (3) Middle-Upper Eocene and (4) Upper Miocene. The Upper Cretaceous–Tertiary sedimentary sequence resting on basement rocks is up to 700 m thick.The Permo-Carboniferous basement consist of dolomites and recrystallized limestones. The Upper Cretaceous–Lower Paleocene transgressive–regressive sequence shows a transition from terrestrial environments, via lagoonal to shallow-marine limestones to deep marine turbiditic sediments, followed upwards by shallow marine cherty limestones. The marine sediments contain planktic and benthic foraminifers indicating an upper Campanian, Maastrichtian and Danian age. The Middle-Upper Eocene is a transgressive–regressive sequence represented by terrestrial and lagoonal clastics, shallow-marine limestones and deep marine turbidites. The planktic and benthic foraminifers in the marine sediments indicate a Middle-Upper Eocene age. The upper Miocene sequence consists of a reddish-brown conglomerate–sandstone–mudstone alternation of alluvial and fluvial facies.During Late Cretaceous–Early Paleocene times, the Gündüzbey Group was deposited in the southern part of a fore-arc basin, simultaneously with volcanics belonging to the Yüksekova Group. During Middle-Late Eocene times, the Yeşilyurt Group was deposited in the northern part of the Maden Basin and the Helete volcanic arc. The Middle-Upper Eocene Malatya Basin was formed due to block faulting at the beginning of the Middle Eocene time. During the Late Paleocene–Early Eocene, and at the end of the Eocene, the study areas became continental due to the southward advance of nappe structures.The rock sequences in the southern part of the Malatya Basin may be divided into four tectonic units, from base to top: the lower allochthon, the upper allochthon, the parautochthon and autochthonous rock units.  相似文献   

10.
《Sedimentary Geology》2005,173(1-4):15-51
The Ulukışla Basin, the southerly and best exposed of the Lower Tertiary Central Anatolian Basins, sheds light on one of the outstanding problems of the tectonic assembly of suture zones: how large deep-water basins can form within a zone of regional plate convergence. The oldest Ulukışla Basin sediments, of Maastrichtian age, transgressively overlie mélange and ophiolitic rocks that were emplaced southwards onto the Tauride microcontinent during the latest Cretaceous time. The Niğde-Kirşehir Massif forming the northern basin margin probably represents another rifted continental fragment that was surrounded by oceanic crust during Mesozoic time. The stratigraphic succession of the Ulukışla Basin begins with the deposition of shallow-marine carbonates of Maastrichtian–Early Palaeocene age, then passes upwards into slope-facies carbonates, with localised sedimentary breccias and channelised units, followed by deep-water clastic turbidites of Middle Palaeocene–Early Eocene age. This was followed by the extrusion of c. 2000 m of basic volcanic rocks during Early to Mid Eocene time. After volcanism ended, coral-bearing neritic carbonates and nummulitic shelf sediments accumulated along the northern and southern margins of the basin, respectively. Deposition of the Ulukışla Basin ended with gypsum deposits including turbidites, debris flows, and sabkhas, followed by a regional Oligocene unconformity.The Ulukışla Basin is interpreted as the result of extension (or transtension) coupled with subsidence and basic volcanism. After post-volcanic subsidence, the basin was terminated by regional convergence, culminating in thrusting and folding in Late Eocene time. Comparisons of the Ulukışla Basin with the adjacent central Anatolian basins (e.g. Tuzgölü, Sivas and Şarkişla) support the view that these basins formed parts of a regional transtensional (to extensional) basin system. In our preferred hypothesis, the Ulukışla Basin developed during an intermediate stage of continental collision, after steady-state subduction of oceanic crust had more or less ended (“soft collision”), but before the opposing Tauride and Eurasian continental units forcefully collided (“hard collision”). Late Eocene forceful collision terminated the basinal evolution and initiated uplift of the Taurus Mountains.  相似文献   

11.
In northwest Anatolia, there is a mosaic of different morpho-tectonic fragments within the western part of the right-lateral strike-slip North Anatolian Fault (NAF) Zone. These were developed from compressional and extensional tectonic regimes during the paleo- and neo-tectonic periods of Turkish orogenic history. A NE-SW-trending left-lateral strike-slip fault system (Adapazari-Karasu Fault) extends through the northern part of the Sakarya River Valley and began to develop within a N–S compressional tectonic regime which involved all of northern Anatolia during Middle Eocene to early Middle Miocene times. Since the end of Middle Miocene times, this fault system forms a border between a compressional tectonic regime in the eastern area eastwards from the northern part of the Sakarya River Valley, and an extensional tectonic regime in the Marmara region to the west. The extension caused the development of basins and ridges, and the incursions of the Mediterranean Sea into the site of the future Sea of Marmara since Late Miocene times. Following the initiation in late Middle Miocene times and the eastward propagation of extension along the western part of the NAF, a block (North Anatolian Block) began to form in the northern Anatolia region since the end of Pliocene times. The Adapazari-Karasu Fault constitutes the western boundary of this block which is bounded by the NAF in the south, the Northeast Anatolian Fault in the east, and the South Black Sea Thrust Fault in the north. The northeastward movement of the North Anatolian Block caused the formation of a marine connection between the Black Sea and the Aegean/Mediterranean Sea during the Pleistocene.  相似文献   

12.
《Geodinamica Acta》2001,14(1-3):177-195
The east Anatolian plateau and the Lesser Caucasus are characterised and shaped by three major structures: (1) NW- and NE-trending dextral to sinistral active strike-slip faults, (2) N-S to NNW-trending fissures and /or Plio-Quaternary volcanoes, and (3) a 5-km thick, undeformed Plio-Quaternary continental volcano-sedimentary sequence accumulated in various strike-slip basins. In contrast to the situation in the east Anatolian plateau and the Lesser Caucasus, the Transcaucasus and the Great Caucasus are characterised by WNW-trending active thrust to reverse faults, folds, and 6-km thick, undeformed (except for the fault-bounded basin margins) continuous Oligocene-Quaternary molassic sequence accumulated in actively developing ramp basins. Hence, the neotectonic regime in the Great Caucasus and the Transcaucasus is compressional–contractional, and Oligocene-Quaternary in age; whereas it is compressional–extensional, and Plio-Quaternary in age in the east Anatolian plateau and the Lesser Caucasus.Middle and Upper Miocene volcano-sedimentary sequences are folded and thrust-to-reverse-faulted as a result of compressional–contractional tectonic regime accompanied by mostly calc-alkaline volcanic activity, whereas Middle Pliocene-Quaternary sequences, which rest with angular unconformity on the pre-Middle Pliocene rocks, are nearly flat-lying and dominated by strike-slip faulting accompanied by mostly alkali volcanic activity implying an inversion in tectonic regime. The strike-slip faults cut and displace dykes, reverse to thrust faults and fold axes of Late Miocene age up to maximum 7 km: hence these faults are younger than Late Miocene, i.e., these formed after Late Miocene. Therefore, the time period between late Serravalian (∼ 12 Ma) continent–continent collision of Arabian and Eurasian plates and the late Early Pliocene inversion in both the tectonic regime, basin type and deformation pattern (from folding and thrusting to strike-slip faulting) is here termed as the Transitional period.Orientation patterns of various neotectonic structures and focal mechanism solutions of recent earthquakes that occurred in the east Anatolian plateau and the Caucasus fit well with the N–S directed intracontinental convergence between the Arabian plate in the south and the Eurasian plate in the north lasting since Late Miocene or Early Pliocene in places.  相似文献   

13.
《Sedimentary Geology》2005,173(1-4):121-150
The hitherto poorly known Mut basin occupies a position that is critical to our understanding of the later Cenozoic history of south central Turkey. The biostratigraphic and sedimentological study reported here reveals an extended and complex pattern of basin evolution and enables the history of this basin to be compared in detail with that of adjacent south Turkish basins.The oldest basin fill deposits are demonstrated to be Oligocene to earliest Miocene in age and comprise alluvial redbeds, thick lacustrine deposits and thin lagoonal sediments mainly supplied from northern (Tauride) sources This mainly terrestrial megasequence resulted from an early Oligocene phase of crustal extension, leading to rapid “trap-door” subsidence and the formation of narrow E–W trending troughs. This phase was terminated by a minor marine incursion and through reactivation of basement faults during renewed extension in the earliest Miocene.The overlying Miocene succession, thus, rests with local angular discordance upon tilted and gently deformed Oligocene (and older) rocks. Subsequent subaerial erosion created an irregular pre-Burdigalian palaeotopography that strongly influenced the nature, thickness and distribution of the early Miocene basin fill. In palaeotopographic depressions, the Miocene sequence commences with alluvial fan, braidplain and meander belt redbeds formed in river systems that flowed mainly south and southeast. These pass up (and laterally) into more extensive lagoonal and shallow marine mixed clastic/carbonate units yielding late Burdigalian to early Langhian microfaunas, marking the inception of the main Miocene marine transgression in this area. Episodic northwards marine advance led to isolation of the northerly source of siliciclastic detritus and resulted in periodic onlap of mid- to inner-shelf fine-grained carbonates (with thin clastic intercalations) that include isolated coralgal build-ups, calcarenite mounds and sand-waves. At the peak of Miocene transgression (mid-Serravallian), thick reefal limestones were deposited far to the north and also formed on top of basement highs forming the southern and eastern flanks of the basin. Significant influxes of coarse and fine siliciclastics from the north attest to periodic progradational events that are more conspicuous and protracted in the late Serravallian and Tortonian. However, muddy deeper shelf conditions prevailed throughout the middle Miocene in the central part of the basin, while stronger currents and unstable slopes characterise the constricted marine strait in the southeast of the basin near Silifke.In terms of their sequential arrangement, palaeoenvironmental and tectonic evolution the Oligo-Miocene sediments of the Mut basin closely resemble coeval sequences in the adjacent Ecemis–Aktoprak and Karsanti–northern Adana basins and share a similar history, involving complex interplay between regional tectonics and eustasism. Deeper water Oligo-Miocene sequences in the ‘outboard troughs,’ such as the southern Adana basin and the Kyrenia–Misis–Andirin complex, yield more subtle signatures of these tectonic and eustatic events. The differences between these basins are attributable to the influence of regional kinematic elements generated during the reorganisation of plate boundaries in the northeast Mediterranean that followed final suturing of the Arabian and Anatolide plates in the mid-Cenozoic.  相似文献   

14.
This paper presents several types of new information including U–Pb radiometric dating of ophiolitic rocks and an intrusive granite, micropalaeontological dating of siliceous and calcareous sedimentary rocks, together with sedimentological, petrographic and structural data. The new information is synthesised with existing results from the study area and adjacent regions (Central Pontides and Lesser Caucasus) to produce a new tectonic model for the Mesozoic–Cenozoic tectonic development of this key Tethyan suture zone.

The Tethyan suture zone in NE Turkey (Ankara–Erzincan–Kars suture zone) exemplifies stages in the subduction, suturing and post-collisional deformation of a Mesozoic ocean basin that existed between the Eurasian (Pontide) and Gondwanan (Tauride) continents. Ophiolitic rocks, both as intact and as dismembered sequences, together with an intrusive granite (tonalite), formed during the Early Jurassic in a supra-subduction zone (SSZ) setting within the ?zmir–Ankara–Erzincan ocean. Basalts also occur as blocks and dismembered thrust sheets within Cretaceous accretionary melange. During the Early Jurassic, these basalts erupted in both a SSZ-type setting and in an intra-plate (seamount-type) setting. The volcanic-sedimentary melange accreted in an open-ocean setting in response to Cretaceous northward subduction beneath a backstop made up of Early Jurassic forearc ophiolitic crust. The Early Jurassic SSZ basalts in the melange were later detached from the overriding Early Jurassic ophiolitic crust.

Sedimentary melange (debris-flow deposits) locally includes ophiolitic extrusive rocks of boninitic composition that were metamorphosed under high-pressure low-temperature conditions. Slices of mainly Cretaceous clastic sedimentary rocks within the suture zone are interpreted as a deformed forearc basin that bordered the Eurasian active margin. The basin received a copious supply of sediments derived from Late Cretaceous arc volcanism together with input of ophiolitic detritus from accreted oceanic crust.

Accretionary melange was emplaced southwards onto the leading edge of the Tauride continent (Munzur Massif) during latest Cretaceous time. Accretionary melange was also emplaced northwards over the collapsed southern edge of the Eurasian continental margin (continental backstop) during the latest Cretaceous. Sedimentation persisted into the Early Eocene in more northerly areas of the Eurasian margin.

Collision of the Tauride and Eurasian continents took place progressively during latest Late Palaeocene–Early Eocene. The Jurassic SSZ ophiolites and the Cretaceous accretionary melange finally docked with the Eurasian margin. Coarse clastic sediments were shed from the uplifted Eurasian margin and infilled a narrow peripheral basin. Gravity flows accumulated in thrust-top piggyback basins above accretionary melange and dismembered ophiolites and also in a post-collisional peripheral basin above Eurasian crust. Thickening of the accretionary wedge triggered large-scale out-of-sequence thrusting and re-thrusting of continental margin and ophiolitic units. Collision culminated in detachment and northward thrusting on a regional scale.

Collisional deformation of the suture zone ended prior to the Mid-Eocene (~45?Ma) when the Eurasian margin was transgressed by non-marine and/or shallow-marine sediments. The foreland became volcanically active and subsided strongly during Mid-Eocene, possibly related to post-collisional slab rollback and/or delamination. The present structure and morphology of the suture zone was strongly influenced by several phases of mostly S-directed suture zone tightening (Late Eocene; pre-Pliocene), possible slab break-off and right-lateral strike-slip along the North Anatolian Transform Fault.

In the wider regional context, a double subduction zone model is preferred, in which northward subduction was active during the Jurassic and Cretaceous, both within the Tethyan ocean and bordering the Eurasian continental margin.  相似文献   

15.
Volcanic activity in the Ayas-Güdül-Celtikci region began by Oligocene (?)-early Miocene time and persisted until the end of early Pliocene time. It commenced with andesitic breccias and lavas at the base of the series and evolved through the deposition of ignimbritic and laharic volcanic material toward intermediate levels of the succession. Caldera formation followed this period of volcanic activity. Ephemeral lakes covering the region caused the subaqueous extrusion of the latest lavas during this period of activity. Afterward, limnic and fluvial sedimentation Occurred in the region during a period of volcanic quiescence. This mid-late Miocene deposition was followed by new basaltic activity. The volcanism was controlled by conjugate fault sets, N45W and N15E, representing pure-shear stress in a N20W direction, from the late Oligocene to the end of the early Pliocene. Normal dip-slip faults having a N55E trend were created by local N25W tension, presumably because of the North Anatolian fault, after early Pliocene time.  相似文献   

16.
Compressional or extensional troughs occupied by at least two sedimentary fills of dissimilar age, origin, facies, internal structure, and deformation pattern are herein termed superimposed basins. The lower and older fill of such basins is inherited from the latest compressional paleotectonic regime, and therefore is highly deformed (folded to thrust faulted). In contrast, the upper fill (neotectonic fill) is nearly flat, or undeformed, resting on the erosional surface of the lower fill with an angular unconformity. Superimposed basins occur mostly in or adjacent to recently active extensional terrains and recent strike-slip fault zones cutting across suture zones.

Within the framework of neotectonics, recent geologic studies such as field geologic mapping, measured stratigraphic sections, aerial photography, and remote-sensing studies conducted in Turkey have shown that a number of well-developed and preserved superimposed basins occur along and adjacent to the North Anatolian transform fault (NATF), obliquely crossing the late Tertiary Izmir-Ankara-Erzincan suture zone (IAESZ). One such superimposed basin is the Refahiye, previously and erroneously interpreted to be a strike-slip basin of Pliocene age. In contrast, this study demonstrates that it is a well-preserved superimposed basin consisting of a combination of both an early-formed, early-middle Miocene piggy-back basin (the older Refahiye basin) and a newly developing strike-slip basin (the Kova basin). The Refahiye basin, located on the southern block of the Niksar-Erzincan segment of the Northern Anatolian fault master strand (NAFMS), contains two fills: (1) lower-middle Miocene latest paleotectonic fill (lower fill), and (2) Plio-Quaternary neotectonic fill (upper fill). The lower fill consists mostly of fluvial red clastics approximately 1 km thick with intercalations of gypsum lenses and shallow-marine reefal limestone of early-middle Miocene age. It is intensely folded, thrust-faulted, and not confined the present-day configuration of the Refahiye basin. The lower fill and its deformational structures, such as folds and thrust faults, are crossed and displaced dextrally by an active strike-slip fault system, the NATE In contrast, the upper fill, which rests on the erosional surface of the lower fill with an angular unconformity, consists of Plio-Quaternary terrace conglomerates, Quaternary imbricated gravels, and fine-grained Quaternary plain sediments (mostly silt and clay); these were deposited within a newly developing strike-slip basin—the Kova pull-apart basin—superimposed on the lower fill of the Refahiye basin. The upper fill is undeformed and nearly flat-lying. All these characteristics reveal that the present configuration of the Refahiye basin is a superimposed basin, herein termed the Refahiye superimposed basin.  相似文献   

17.
吐哈盆地中央构造带正反转演化特征   总被引：5，自引：3，他引：5  
吐哈盆地中央构造带由火焰山构造和七克台构造组成。中央构造带形成于三叠纪晚期至侏罗纪早期,表现为伸展构造特征,生长断层上盘地层厚度明显大于下盘,并于断层上盘所在的台北凹陷形成沉降中心。晚侏罗世,由于拉萨陆块与欧亚大陆的碰撞作用导致吐哈盆地由伸展盆地转变为挤压盆地,中央构造带也于此时发生构造反转,由早期的伸展正断层转变为挤压逆断层。发生于55Ma的喜山构造事件对天山地区产生了深刻的影响,但影响时间略有滞后,大致发生在晚渐新世至早中新世,中央构造带即在此次构造事件中强烈变形,逆冲出露于地表。  相似文献   

18.
The Sea of Marmara Basin (SMB) is connected to the fully marine Mediterranean by the Dardanelles strait and to the brackish Black Sea by the Thracian Bosporus. This linkage to two different marine realms with contrasting water chemistry has been a prime control on the sedimentary history of the SMB, which in turn was controlled by its tectonics. Isolation from any of these realms resulted in drastic changes in its paleoceanographic conditions and made it a part either of the global ocean system or of a brackish-marine environment, depending on the realm from which the connection was severed.

The SMB represents the inundated part of the northwestern Anatolian graben system that resulted from the interaction between the North Anatolian fault (NAF) zone and the present N-S extensional tectonic regime of the Aegean. The geologic history of this basin began during the late Serravallian when the NAF was initiated. The first inundation of the basin coincided in both time and space with this initiation. The invading sea was the Mediterranean, which stayed there for a short period and subsequently was replaced by the Paratethys during the late Miocene. Paratethyan conditions prevailed in the basin until the latest Pliocene, when the second flooding from the Mediterranean occurred through the Dardanelles. Owing to glacio-eustatic sea-level changes during the Pleistocene, Paratethyan/Black Sea and Mediterranean conditions alternated. In the last (Würm) glaciation, the SMB was completely isolated and turned into a euxinic lacustrine environment, similar to the Black Sea at that time. Following the Würm glaciation, the Mediterranean Sea broke its way once more into the SMB and filled it with salt water. When sea level in the basin rose above the Bosporous sill at 7.5 Ka B.P., the present dual flow regime was established.  相似文献   

19.
The Mid-Tertiary (Mid-Eocene to earliest Miocene) Misis–Andırın Complex documents tectonic-sedimentary processes affecting the northerly, active margin of the South Tethys (Neotethys) in the easternmost Mediterranean region. Each of three orogenic segments, Misis (in the SW), Andırın (central) and Engizek (in the NE) represent parts of an originally continuous active continental margin. A structurally lower Volcanic-Sedimentary Unit includes Late Cretaceous arc-related extrusives and their Lower Tertiary pelagic cover. This unit is interpreted as an Early Tertiary remnant of the Mesozoic South Tethys. The overlying melange unit is dominated by tectonically brecciated blocks (>100 m across) of Mesozoic neritic limestone that were derived from the Tauride carbonate platform to the north, together with accreted ophiolitic material. The melange matrix comprises polymict debris flows, high- to low-density turbidites and minor hemipelagic sediments.The Misis–Andırın Complex is interpreted as an accretionary prism related to the latest stages of northward subduction of the South Tethys and diachronous continental collision of the Tauride (Eurasian) and Arabian (African) plates during Mid-Eocene to earliest Miocene time. Slivers of Upper Cretaceous oceanic crust and its Early Tertiary pelagic cover were accreted, while blocks of Mesozoic platform carbonates slid from the overriding plate. Tectonic mixing and sedimentary recycling took place within a trench. Subduction culminated in large-scale collapse of the overriding (northern) margin and foundering of vast blocks of neritic carbonate into the trench. A possible cause was rapid roll back of dense downgoing Mesozoic oceanic crust, such that the accretionary wedge taper was extended leading to gravity collapse. Melange formation was terminated by underthrusting of the Arabian plate from the south during earliest Miocene time.Collision was diachronous. In the east (Engizek Range and SE Anatolia) collision generated a Lower Miocene flexural basin infilled with turbidites and a flexural bulge to the south. Miocene turbiditic sediments also covered the former accretionary prism. Further west (Misis Range) the easternmost Mediterranean remained in a pre-collisional setting with northward underthrusting (incipient subduction) along the Cyprus arc. The Lower Miocene basins to the north (Misis and Adana) indicate an extensional (to transtensional) setting. The NE–SW linking segment (Andırın) probably originated as a Mesozoic palaeogeographic offset of the Tauride margin. This was reactivated by strike-slip (and transtension) during Later Tertiary diachronous collision. Related to on-going plate convergence the former accretionary wedge (upper plate) was thrust over the Lower Miocene turbiditic basins in Mid–Late Miocene time. The Plio-Quaternary was dominated by left-lateral strike-slip along the East Anatolian transform fault and also along fault strands cutting the Misis–Andırın Complex.  相似文献   

20.
The Sivas Basin extends over a major crustal structure underlying the contact zone between the Tauride and Pontide belts. The Kirsehir block, a continental crustal element lying between the main belts, introduces a subordinate suture in front of the Pontides—the Inner Tauride suture. The junction of the two main sutures occurs between Hafikand Imranli. Four structural zones have been considered. The northern basement of the basin, which includes both the Kirsehir continental crust and thrust sheets of ophiolite and pelagic sediments, forms an imbricate stack with an Eocene cover. The Eocene cover shows two distinct sequences: marine neritic and continental basalts overlying the Kirsehir basement, and deltaic and basinal deposits lying to the southeast. Southward tectonic stacking of the entire pile has occurred repeatedly since Oligocene time. The Sivas Basin proper is separated from the Kirsehir basement by the Kizilirmak Basin. This new structural unit consists of nearly undeformed, middle Miocene sandstones and conglomerates and a Pliocene lacustrine limestone.

The Sivas Basin proper corresponds to a fold-and-thrust belt involving an Oligocene deltaic plain with intervening large-scale evaporitic stages and subsequent lower Miocene shallow-marine deposits. Three distinct tectonic domains are considered—(1) an eastern A domain, characterized by a hinterland of deep imbricate and rare northward thrusts; (2) a transitional B domain, corresponding to a series of lateral thrust branches propagating to the southwest; this domain later was deformed by the (3) C domain, displaying a foreland-dip type of stacking. The Caldag-Tecer-Gurlevik ridge forms a structural entity of topographic highs along the southern margin of the Sivas fold-and-thrust belt. Three Eocene-cored anticlinoria arranged along an E-W relay zone fold a passive-roof composite allochthon including ophiolitic elements together with Upper Cretaceous to Eocene limestone and conglomerate. The sole of this allochthon consists of Oligocene gypsum. The Kangal Basin, a large syncline cored by Pliocene continental deposits, corresponds to the southernmost unit. The boundary with the Caldag-Tercer-Gurlevik ridge is partially concealed by a lower Miocene continental basin, overlain by a N-vergent thrust of a lower Mesozoic limestone of the Taurus platform. If the southeastward propagation of thrusting in the Sivas thrust belt and related northward thrusts at a variety of scales is considered to represent the main thrust over the undeformed Kizilirmak basin, a comparison with modern analog structural features and analog models yields a coherent interpretation of this basin in terms of its forearc-prism evolution. At a larger scale, the Sivas Basin should be considered as a piggyback basin developed along the northward-rotated rear of the Tauride wedge and the synchronous southward thrusting of the Kirsehir-Pontide wedge. At least in early Miocene time, the Inner Tauride and Erzincan sutures corresponded to a single intracontinental thrust zone along which part of the displacement of the southern front of the Tauride has been progressively transferred.  相似文献   

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