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1.
Recent field campaign in the southern Menderes Massif in southwestern Turkey revealed that the so-called ‘core of the massif’ comprises two distinct types of granitoid rocks: an orthogneiss (traditionally known as augen gneisses) and leucocratic metagranite, where the latter is intrusive into the former and the structurally overlying ‘cover’ schists. These differ from one another in intensity of deformation, degree of metamorphism and kinematics. The orthogneiss display penetrative top-to-the-N–NNE fabrics formed under upper-amphibolite facies conditions during the Eocene main Menderes metamorphism (MMM), whereas foliation and stretching lineation exists in the leucocratic metagranites but are not strongly developed. The leucocratic metagranites show evidence of syn- to post-emplacement deformation in a series of weakly developed top-to-the-S–SSW fabrics formed under lower greenschist-facies (?) conditions. Leucocratic metagranite bodies occur all along the augen gneiss–schist contact in the southern Menderes Massif; they are emplaced as sheet-like bodies into country rocks (previously deformed and metamorphosed during a top-to-the-N–NNE Alpine orogeny) along a ductile extensional shear zone, located between orthogneisses and metasediments, which was possibly active during emplacement. The data presently available indicate that emplacement and associated ductile extensional deformation occurred during Late Oligocene–Early Miocene time. These results confirm previous contentions that there are Tertiary granites in this part of the Menderes Massif.  相似文献   

2.
《Sedimentary Geology》2005,173(1-4):373-408
The Alaşehir (Gediz) Graben exemplifies clastic sedimentation in a long-lived continental half-graben in a semi-arid setting, developed within relatively incompetent metamorphic rocks. Early Miocene to Recent rift-related sediments are exhumed on both flanks of the graben, allowing detailed three-dimensional study. During the Early Miocene, small fan-delta lobes were shed northwards from the rugged Menderes Metamorphic Massif into a bordering lacustrine basin. During Early to Mid-Miocene time, large alluvial fans prograded northwards into this basin. Through-drainage to the Aegean Sea was established as the basin widened and filled. Discrete lobes of coarse alluvial fan sediments of latest Miocene(?)–Pliocene age, also shedding northwards, are likely to have been climatically influenced. Quaternary alluvium party infills the modern Alaşehır rift basin.The sedimentary information can be used to test two alternative tectonic models for the Alaşehır Graben. In the first model, an E–W graben bounded by high-angle faults was active during latest Miocene(?)–Recent time, whereas earlier Miocene sedimentation was controlled by N–S faulting related to a N–S compressional stress regime. In the second hypothesis, the Alaşehır Graben was initiated much earlier, in the Early Miocene and was then either continuously or episodically active until Recent. Our results, especially facies and palaeocurrent data from alluvial sediments, indicate that clastic sedimentation was controlled by mainly E–W faulting in a N–S stress regime. Assuming the Early Miocene clastic sediments are correctly dated, this supports the second (long-lived extension) model. However, rather than steady-state extension for ca. 15 Ma, the sedimentary evidence and regional context are consistent with a pulsed extension model, whereby initial Early to Mid-Miocene extension and related clastic sedimentation was followed by a second phase of extension in latest Miocene(?)–Pliocene time. The driving force of initial, Early Miocene extension was probably gravity spreading towards a south-Aegean subduction zone, whereas the inferred second extension pulse is seen as being triggered by westward “tectonic escape” of Anatolia towards the extending Aegean back-arc region.  相似文献   

3.
《Geodinamica Acta》2013,26(3-4):255-282
The Lycian molasse basin of SW Turkey is a NE-SW-oriented basin that developed on an imbricated basement, comprising the allochthonous Mesozoic rocks of the Lycian nappes and Palaeocene-Eocene supra-allochthonous sediments. The imbricated basement has resulted from a complex history related to the emplacement of different tectonic units from Late Cretaceous to Late Eocene. Following imbrication, extensional collapse of the Lycian orogen resulted in extensive emergent areas, some of which coincide with present-day mountains. These were surrounded by interconnected depressions, namely, the Kale-Tavas, Çardak-Dazk?r? and Denizli subbasins.

The Lycian molasse sequence contains a relatively complete record of the tectonic history of the Lycian orogenic collapse from which it was derived. The sequence is characterised by interdependence between tectonism and sedimentation, the latter of which includes fining-and coarsening-upward sedimentary cycles with syn-depositional intrabasinal unconformities.

The Denizli subbasin consists of thick, coarse-grained wedges of alluvial fans and fine-grained fan-delta deposits formed in a shallowmarine environment. Some areas of the fan deltas were colonised by corals, red algae and foraminifera, forming patch reefs.

The first phase of extensional collapse in the region is marked by the Lycian orogenic collapse, which may have been initiated by the beginning of the Oligocene (Rupelian), following the main Menderes metamorphism. Starting in the latest Early Miocene or in the Middle Miocene, the area of the molasse basin was subject to deformation with the Lycian nappes, and to erosion as well. At that time, the Lycian nappes, with some ophiolitic assemblages, were thrust over the molasse deposits and thus, NE-SW-trending folds were formed. The molasse deposits and thrust-related deformational structures were then unconformably covered by Upper Miocene continental deposits which belong to the neotectonic period of SW Turkey. The second phase of extensional collapse is marked by granitic intrusions and the formation of Miocene detachment-related extensional basins. This phase may have been related to the exhumation of the gneissic core of the Menderes Massif, from which fragments were derived and incorporated into the upper parts of the Denizli subbasin during the Aquitanian.  相似文献   

4.
The Mesozoic platform sequence of the Menderes Massif consists of thick succession of detrital and carbonate rocks. In this sequence there are mafic metavolcanic rocks at two different levels. The first level of mafic metavolcanic intercalations is in the Late Triassic detrital-rich series located in the ÇaltayL Formation, which is the lowermost unit of the Mesozoic platform. The second level of the mafic metavolcanic rocks is located in the Late Cretaceous-(?)Paleocene Selçuk Formation laying on top of the platform sequence. The ÇaltayL Formation, which is composed of mica-schists, thinly-bedded cherts, calc-schist and mafic volcanic intercalations unconformably overlie the BayLndLr Formation, which consists of mica-schists, phyllites, and white quartzites of Palaeozoic or probably older age. The mafic volcanic rocks in the ÇaltayL Formation are alkaline basalts with within plate characteristics and are formed during an intraplate extension. The ÇaltayL Formation is conformably overlain by the KayaaltL Formation represented by calc-schists, dolomitic marbles, and rudist- and emery-bearing massive marbles in ascending order. The Selçuk Formation overlies the KayaaltL Formation and consists of a mica-schist matrix with allochthonous blocks of mafic volcanic rocks, metaperidotites, metagabbros and massive marbles. The mafic volcanic rocks in the Selçuk Formation are tholeiitic basalts and are petrologically similar to mid-oceanic basalts. The geological and geochemical characteristics of the mafic metavolcanic rocks in the ÇaltayL Formation indicate that during the Late Triassic, the Menderes platform was segmented, probably by the opening of a branch of the Neotethyan Ocean. Between the Late Triassic and the Late Cretaceous, the Menderes carbonate platform was built up. During the Latest Cretaceous-Early Paleocene, a slab of oceanic crust obducted on this platform and provided slices of mafic metavolcanic rocks into the Selçuk Formation.  相似文献   

5.
The Büyük Menderes and Gediz (Ala?ehir) grabens are two significant segments of the Western Anatolian extensional province. They merge around Buldan-Sar?caova in the east. Outcropping Neogene sedimentary units in this area display a rather complex structure. This paper summarizes the importance and meaning of the data obtained during a detailed investigation of the Neogene units and aims to improve our understanding of the neotectonic evolution of Western Anatolia. The Buldan-Sar?caova Neogene sequence is composed of three different sedimentary units: (1) the Lower Unit, (2) the Middle Unit, and (3) the Upper Unit. The Lower Unit crops out on the Buldan horst which is located between the Büyük Menderes and Ala?ehir grabens. The sequence starts as a coarse conglomerate and sandstone (?salar Formation) and continues as lagoonal-lacustrine mudstone, interbedded with coal seams and shales (Bostanyeri Formation) and also with lacustrine limestones. The age of this succession is Lower-Middle Miocene. The development of the basin is structurally controlled by NNW-trending normal faults. The Middle Unit begins with a conglomerate–mudstone sequence (K?z?lburun Formation), followed by a sandstone–mudstone–marl sequence (Sarayköy Formation). A lacustrine limestone–marl unit occurs at the top (Aktepe Formation). Some thin gypsum lenses and layers are observed in the Sarayköy Formation. The unit contains some brackish-water fossils. The rocks of the Middle Unit crop out mostly at the low altitudes of the Buldan horst, i.e. the southeast piedmont, around the junction of the Büyük Menderes and the Gediz grabens. The Middle Unit was deposited in fluvial and lacustrine environments during the Late Miocene–Pliocene period. These rocks were formed in response to the uplift of the Buldan horst. The Upper Unit, which is composed of conglomerates, was deposited within the Büyük Menderes Graben–Gediz Graben depressions as alluvial fill.  相似文献   

6.
The central Menderes Massif (western Turkey) is characterized by an overall dome-shaped Alpine foliation pattern and a N-NNE-trending stretching lineation. A section through the southern flank of the central submassif along the northern margin of Büyük Menderes graben has been studied. There, asymmetric non-coaxial fabrics indicate that the submassif has experienced two distinct phases of Alpine deformation: a top-to-the N-NNE contractional phase and a top-to-the S-SSW extensional event. The former fabrics are coeval with a regional prograde Barrovian-type metamorphism at greenschist to upper-amphibolite facies conditions. This event, known as the main Menderes metamorphism, is thought to be the result of internal imbrication of the Menderes Massif rocks along south-verging thrust sheets during the collision of the Sakarya continent in the north and the Anatolide-Tauride platform in the south across the Gzmir-Ankara suture during the (?)Palaeocene-Eocene. Top-to-the S-SSW fabrics, represented by a well-developed ductile shear band foliation associated with inclined and/or curved foliation, asymmetric boudins, and cataclasites, were clearly superimposed on earlier contractional fabrics. These fabrics are interpreted to be related to a low-grade (greenschist?) retrogressive metamorphism and a continuum of deformation from ductile to brittle in the footwall rocks of a south-dipping, presently low-angle normal fault that accompanied Early Miocene orogenic collapse and continental extension in western Turkey. A similar tectono-metamorphic history has been documented for the northern flank of the dome along the southern margin of the Gediz graben with top-to-the N-NNE extensional fabrics. The exhumation of the central Menderes Massif can therefore be attributed to a model of symmetric gravity collapse of the previously thickened crust in the submassif area. The central submassif is thus interpreted as a piece of ductile lower-middle crust that was exhumed along two normal-sense shear zones with opposing vergence and may be regarded as a typical symmetrical metamorphic core complex. These relationships are consistent with previous models that the Miocene exhumation of the Menderes Massif and Cycladic Massif in the Aegean Sea was a result of bivergent extension.  相似文献   

7.
The orientation, asymmetry and cross-cutting relationships of the structures along the contact zone between the Lycian nappes and the Menderes Massif suggest the presence of three deformation phases in the Milas region of southwest Turkey. The first deformation phase (D1) is characterized by a ductile deformation with top-to-the-NE sense of shear. Structural data of the first deformation measured along the uppermost part of the Menderes Massif and the base of the Lycian nappes suggest that the lowermost unit of the Lycian nappes was emplaced initially from southwest to northeast onto the Menderes Massif during the Early Eocene. The second deformation phase (D2) is also ductile in nature and is characterized by an E–W-trending stretching lineation with a bivergent sense of shear, which is probably related to the load of the overlying nappes. A third deformation phase (D3) is characterized by south-dipping normal faults with top-to-the-S sense of movement. This third deformation phase can be related to southward movement of the Lycian nappes along a low-angle décollement zone. The tectonic contact between the Menderes Massif and the Lycian nappes and their strongly-deformed rocks are unconformably covered by approximately flat-lying, coal-bearing Early–Middle Miocene sedimentary rocks, which constrains the upper time limit for all three deformation phases.  相似文献   

8.
The Iraqi territory could be divided into four main tectonic zones; each one has its own characteristics concerning type of the rocks, their age, thickness and structural evolution. These four zones are: (1) Inner Platform (stable shelf), (2) Outer Platform (unstable shelf), (3) Shalair Zone (Terrain), and (4) Zagros Suture Zone. The first two zones of the Arabian Plate lack any kind of metamorphism and volcanism.The Iraqi territory is located in the extreme northeastern part of the Arabian Plate, which is colliding with the Eurasian (Iranian) Plate. This collision has developed a foreland basin that includes: (1) Imbricate Zone, (2) High Folded Zone, (3) Low Folded Zone and (4) Mesopotamia Foredeep.The Mesopotamia Foredeep, in Iraq includes the Mesopotamia Plain and the Jazira Plain; it is less tectonically disturbed as compared to the Imbricate, High Folded and Low Folded Zones. Quaternary alluvial sediments of the Tigris and Euphrates Rivers and their tributaries as well as distributaries cover the central and southeastern parts of the Foredeep totally; it is called the Mesopotamian Flood Plain. The extension of the Mesopotamia Plain towards northwest however, is called the Jazira Plain, which is covered by Miocene rocks.The Mesopotamia Foredeep is represented by thick sedimentary sequence, which thickens northwestwards including synrift sediments; especially of Late Cretaceous age, whereas on surface the Quaternary sediments thicken southeastwards. The depth of the basement also changes from 8 km, in the west to 14 km, in the Iraqi–Iranian boarders towards southeast.The anticlinal structures have N–S trend, in the extreme southern part of the Mesopotamia Foredeep and extends northwards until the Latitude 32°N, within the Jazira Plain, there they change their trends to NW–SE, and then to E–W trend.The Mesozoic sequence is almost without any significant break, with increase in thickness from the west to the east, attaining 5 km. The sequence forms the main source and reservoir rocks in the central and southern parts of Iraq. The Cenozoic sequence consists of Paleogene open marine carbonates, which grades upwards into Neogene lagoonal marine; of Early Miocene and evaporitic rocks; of Middle Miocene age, followed by thick molasses of continental clastics that attain 3500 m in thickness; starting from Late Miocene. The Quaternary sediments are very well developed in the Mesopotamia Plain and they thicken southwards to reach about 180 m near Basra city; in the extreme southeastern part of Iraq.The Iraqi Inner Platform (stable shelf) is a part of the Arabian Plate, being less affected by tectonic disturbances; it covers the area due to south and west of the Euphrates River. The main tectonic feature in this zone that had affected on the geology of the area is the Rutbah Uplift; with less extent is the Ga’ara High.The oldest exposed rocks within the Inner Platform belong to Ga’ara Formation of Permian age; it is exposed only in the Ga’ara Depression. The Permian rocks are overlain by Late Triassic rocks; represented by Mulussa and Zor Hauran formations, both of marine carbonates with marl intercalations. The whole Triassic rocks are absent west, north and east of Ga’ara Depression. Jurassic rocks, represented by five sedimentary cycles, overlie the Triassic rocks. Each cycle consists of clastic rocks overlain by carbonates, being all of marine sediments; whereas the last one (Late Jurassic) consists of marine carbonates only. All the five formations are separated from each other by unconformable contacts. Cretaceous rocks, represented by seven sedimentary cycles, overlie the Jurassic rocks. Marine clastics overlain by marine carbonates. Followed upwards (Late Cretaceous) by continental clastics overlain by marine carbonates; then followed by marine carbonates with marl intercalations, and finally by marine clastics overlain by carbonates; representing the last three cycles, respectively.The Paleocene rocks form narrow belt west of the Ga’ara Depression, represented by Early–Late Paleocene phosphatic facies, which is well developed east of Rutbah Uplift and extends eastwards in the Foredeep. Eocene rocks; west of Rutbah Uplift are represented by marine carbonates that has wide aerial coverage in south Iraq. Locally, east of Rutbah Uplift unconformable contacts are recorded between Early, Middle and Late Eocene rocks. During Oligocene, in the eastern margin of the Inner Platform, the Outer Platform was uplifted causing very narrow depositional Oligocene basin. Therefore, very restricted exposures are present in the northern part of the Inner Platform (north of Ga’ara Depression), represented by reef, forereef sediments of some Oligocene formations.The Miocene rocks have no exposures west of Rutbah Uplift, but north and northwestwards are widely exposed represented by Early Miocene of marine carbonates with marl intercalations. Very locally, Early Miocene deltaic clastics and carbonates, are interfingering with the marine carbonates. The last marine open sea sediments, locally with reef, represent the Middle Miocene rocks and fore reef facies that interfingers with evaporates along the northern part of Abu Jir Fault Zone, which is believed to be the reason for the restriction of the closed lagoons; in the area.During Late Miocene, the continental phase started in Iraq due to the closure of the Neo-Tethys and collision of the Sanandaj Zone with the Arabian Plate. The continental sediments consist of fine clastics. The Late Miocene – Middle Pliocene sediments were not deposited in the Inner Platform.The Pliocene–Pleistocene sediments are represented by cyclic sediments of conglomeratic sandstone overlain by fresh water limestone, and by pebbly sandstone.The Quaternary sediments are poorly developed in the Inner Platform. Terraces of Euphrates River and those of main valleys represent pleistocene sediments. Flood plain of the Euphrates River and those of large valleys represent Holocene sediments. Residual soil is developed, widely in the western part of Iraq, within the western marginal part of the Inner Platform.  相似文献   

9.
Southwestern Turkey experienced a transition from crustal shortening to extension during Late Cenozoic, and evidence of this was recorded in four distinct basin types in the Mu?la–Gökova Gulf region. During the Oligocene–Early Miocene, the upper slices of the southerly moving Lycian Nappes turned into north-dipping normal faults due to the acceleration of gravity. The Kale–Tavas Basin developed as a piggyback basin along the fault plane on hanging wall blocks of these normal faults. During Middle Miocene, a shift had occurred from local extension to N–S compression/transpression, during which sediments in the Eskihisar–T?naz Basins were deposited in pull-apart regions of the Menderes Massif cover units, where nappe slices were already eroded. During the Late Miocene–Pliocene, a hiatus occurred from previous compressional/transpressional tectonism along intermountain basins and Yata?an Basin fills were deposited on Menderes Massif, Lycian Nappes, and on top of Oligo–Miocene sediments. Plio-Quaternary marked the activation of N–S extension and the development of the E–W-trending Mu?la–Gökova Grabens, co-genetic equivalents of which are common throughout western Anatolia. Thus, the tectonic evolution of the western Anotolia during late Cenozoic was shifting from compressional to extensional with a relaxation period, suggesting a non-uniform evolution.  相似文献   

10.
《Geodinamica Acta》2013,26(3-4):239-253
The precise ages of the sedimentary successions within two prominent NE-SW-trending basins, the Gördes Basin and the Selendi Basin, are critical to an understanding of the Neogene evolutionary setting of western Turkey and associated calc-alkaline magmatism. Early radiometric dating was not always sufficiently precise to resolve alternative interpretations. During this study, high-precision Ar40-Ar39 radiometric ages were determined on single crystals of biotite and sanidine from silicic tuffs and associated intrusive rocks. Finegrained tuffaceous sediments near the top of the sedimentary succession in the Selendi Basin gave ages of 18.89 ± 0.58 Ma to 16.42 ± 0.09 Ma. Coarser-grained tuffaceous sediments near the top of the equivalent sedimentary succession in the Gördes Basin to the NW yielded ages of 18.78 ± 0.3 Ma to 17.04 ± 0.35 Ma. Associated intrusive rocks were dated at 20.86 ± 0.08 Ma to 17.62 ± 0.07 Ma. An andesitic body on the northern margin of the Gediz (Ala?ehir) Graben further south gave ages of 16.08 ± 10.91 to 14.65 ± 0.06 Ma.

Combined with published radiometric age data, these new results confirm an Early Miocene age for the clastic sedimentary fills of the Gördes and Selendi basins. The results from the Gediz Graben are consistent with its formation in Early Miocene time, earlier than the Late Miocene or Plio-Quaternary ages suggested in some interpretations.  相似文献   

11.
The Kazda?? metaophiolite crops out in the Kazda?? (Ida) Mountains in the Biga Peninsula in northwestern Turkey. It is in stratigraphic contact with the high–grade metamorphic rocks of the Kazda?? Massif. Metaophiolitic and high–grade metamorphic rocks are tectonically overlain by low–grade metamorphic units of the Permo‐Triassic Karakaya Complex of the Sakarya Zone. Late Oligocene‐Early Miocene granites intruded these tectonic units (Okay and Sat?r, 2000; Duru et al. 2012). In the Kazda?? metaophiolitic sequence, upper mantle peridotites are represented by metaharzburgite and metadunite, whereas the mantle transition zone metaperidotites are composed of metadunite, metapyroxenite and minor plagioclase‐bearing metalherzolite. The upper part of the metadunites in the mantle transition zone show intercalation with metagabbros. Gabbros of oceanic crust experienced amphibolite facies metamorphism and are transformed into amphibolite, garnet amphibolite and migmatitic gabbros. The metagabbros and amphibolites display MORB‐ and IAT‐like geochemical features. The Kazda?? metaophiolite is conformably overline by basal conglomerates and hemi‐pelagic carbonate rocks continuing upward into forearc‐type flysch–like detrital sedimentary rocks interspersed with mafic volcanic intervals. These cover units underwent high–grade metamorphism into gneisses, migmatites, amphibolites and marbles in a compressional regime during the Alpine orogeny. New U–Pb zircon data from the metagabbros show two crystallization peaks at ～52 Ma and ～73 Ma. This has implications for the age of subduction of the Izmir–Ankara–Erzincan Ocean, generally assumed to be northward under the Sakarya Zone. During the Triassic to Middle Eocene, progressive overthrusting of the Sakarya Zone via a N–S compresional regime created by the Alpine orogeny onto subduction–accretion‐ and forearc‐units resulted in high–grade metamorphic conditions in the Biga Peninsula.  相似文献   

12.
The Menderes Massif, in western Anatolia, has been described as a lithological succession comprising a basal ‘Precambrian gneissic core of sedimentary origin’ overlain in sequence by ‘Palaeozoic schist’ and ‘Mesozoic-Cenozoic marble’ forming the envelope. The boundary between core and schist envelope was interpreted as a major unconformity, the ‘Supra-Pan-African unconformity’. By contrast, our field observations and geochemical data show that around the southern side of Besparmak Mountain, north of Selimiye (Milas), the protoliths of highly deformed, mylonitized augen gneisses are granitoid rocks intrusive into the adjacent Palaeozoic metasedimentary schists. The field relationships indicate the age of intrusion to be younger than late Permian and there is no evidence for the existence of either an exposed Precambrian basement or the ‘Supra-Pan-African unconformity’ in this sector of the Menderes Massif.  相似文献   

13.
《Geodinamica Acta》2002,15(5-6):277-288
A close relationship between formation of approximately upright folds with axes normal to the extension direction and ramp/flat extensional geometries is established for well exposed Neogene syn-extensional rocks on the presently low-angle Gediz detachment fault, along the southern margin of the Gediz Graben region of western Anatolia, Turkey. Three unconformity-bounded sedimentary sequences and several metamorphic extensional allochthons were mapped in the upper-plate of the Gediz detachment. The oldest sedimentary sequence consists of deformed and folded strata of sandstones and conglomerates that are regarded as being deposited in a supra-detachment basin during the Miocene–Early Pliocene. This unit rests unconformably on the extensional allochthonous, but directly in fault contact with the lower-plate mylonitic rocks. The younger slightly tilted Late Pliocene–Pleistocene sedimentary sequences are post-detachment units that are controlled by EW-trending high-angle normal faults. The youngest alluvium comprises the undeformed present-day basin fill of the Gediz Graben. The supra-detachment sedimentary rocks contain a number of kilometric-scale longitudinal folds that are nearly parallel to the east-west-trending fault system of the Gediz Graben. The folds have a steeply inclined bisecting surface, an interlimb angle of 130–150°, and a plunge of <10°. These folds may be interpreted to form as a result of bending in the underlying Gediz detachment fault. The bending may have an alternation of ramp and flat geometries on which a hanging-wall syncline and rollover anticline formed, respectively. This study again shows the importance of local geology in understanding of some spectacular structures of the extensional basins.  相似文献   

14.
《Geodinamica Acta》1999,12(1):25-42
The Early Eocene to Early Oligocene tectonic history of the Menderes Massif involves a major regional Barrovian-type metamorphism (M1, Main Menderes Metamorphism, MMM), present only in the Palaeozoic-Cenozoic metasediments (the so-called “cover” of the massif), which reached upper amphibolite faciès with local anatectic melting at structurally lower levels of the cover rocks and gradually decreased southwards to greenschist facies at structurally higher levels. It is not present in the augen gneisses (the so called “core” of the massif), which are interpreted as a peraluminous granite deformed within a Tertiary extensional shear zone, and lie structurally below the metasediments. A pronounced regional (S1) foliation and approximately N-S trending mineral lineation (L1) associated with first-order folding (F1) were produced during D1 deformation coeval with the MMM. The S1 foliation was later refolded during D2 by approximately WNW-ESE trending F2 folds associated with S2 crenulation cleavage. It is now commonly believed that the MMM is the product of latest Palaeogene collision across Neo-Tethys and the consequent internal imbrication of the Menderes Massif area within a broad zone along the base of the Lycian Nappes during the Early Eocene-Early Oligocene time interval. However, the meso- and micro-structures produced during D1 deformation, the asymmetry and change in the intensity and geometry of the F2 folds towards the Lycian thrust front all indicate an unambiguous non-coaxial deformation and a shear sense of upper levels moving north. This shear sense is incompatible with a long-standing assumption that the Lycian Nappes were transported southwards over the massif causing its metamorphism. It is suggested here that the MMM results from burial related to the initial collision across the Neo-Tethys and Tefenni nappe emplacement, whereas associated D1 deformation and later D2 deformation are probably related to the northward backthrusting of the Lycian nappes.  相似文献   

15.
The Argillite Sequence located at the base of the sedimentary cover on the continental slope of the Sea of Japan was studied by petrographic, palynological, and X-ray diffraction methods. Two spores-pollen complexes were distinguished in it: the Late Oligocene reflecting cooling and the Early Miocene corresponding to initiated warming. The data obtained indicate that the sequence is composed of terrigenous silty-clayey sediments that accumulated in shallow coastal-marine settings. The global sea-level rise at the Early-Middle Miocene transition, combined with the regional tectonic processes, determined the basin deepening, owing to which the argillite sequence was overlain by thick Middle Miocene diatomaceous-clayey sediments. Due to tectonic movement along existing faults in the terminal Late Miocene, the argillite sequence occurring initially at depths of at least 400–500 m was locally exhumed to the basin bottom.  相似文献   

16.
We review the geology of the Gyeonggi Massif, Gyeonggi Marginal Belt, and Taebaeksan Basin of the Korean Peninsula, which are relevant to the 2018 Winter Olympic sites. Neoarchaean–Palaeoproterozoic gneisses and schists of the Gyeonggi Massif underwent two distinct collisional orogenies at the Palaeoproterozoic (1.88–1.85 Ga) and Triassic (245–230 Ma). These basement rocks are structurally overlain by a suite of Mesoproterozoic to Early Permian supracrustal rocks of the Gyeonggi Marginal Belt, consisting primarily of medium-pressure schists and amphibolites metamorphosed at ~270–250 Ma. In contrast, sedimentary successions in the Taebaeksan Basin, commonly fossiliferous, consist primarily of Early Cambrian–Middle Ordovician Joseon Supergroup and Late Carboniferous–Early Triassic Pyeongan Supergroup. The ‘Great Hiatus’ between the two supergroups is characteristic for the North China Craton. The marked contrast in tectonometamorphic evolution between the Taebaeksan Basin and Gyeonggi Marginal Belt suggests an existence of major suture in-between, which is most likely produced by the Permian–Triassic continental collision between the North and South China cratons. Finally, recent tectonics of the Korean Peninsula is governed by the opening of East Sea/Sea of Japan during the Late Oligocene–Early Miocene. This back-arc rifting event has resulted in an exhumation of the Taebaek Mountain Range, estimated to be 22 ± 3 Ma on the basis of apatite (U–Th)/He ages. Thus, high topography in the 2018 Winter Olympic sites is the consequence of Tertiary tectonics associated with the opening of a back-arc basin.  相似文献   

17.
The Mugla province is one of the major marble producing regions located in the southern flank of the Menderes Massif in SW Turkey. The Menderes Massif is a regionally metamorphosed massif with an old Pan-African core and cover successions from the Permo–Carboniferous to Paleocene. There are four major metamorphic carbonate horizons in the cover successions exploited for the marble production. These horizons are located within the Permo–Carboniferous, Triassic, Upper Cretaceous and Paleocene successions along the southern flank of the Menderes Massif. Here the world wide known marbles with names such as the Mugla Black, the Milas White, Veined, Pearl, Aubergine, Lilac and Lemony, the Mugla White and the Aegean Bordeaux are found.

Detailed geological studies were carried out in selected marble quarries representing the different stratigraphic levels to determine the geological parameters affecting the marble production in the southern flank of the Menderes Massif in SW Turkey. The geological parameters such as bedding, joints, schist interlayers and mica filled joints affecting the block production from the marble beds are considered to be primary features. The presence of dolomite bands and lenses, abnormal sized calcite crystals and emery minerals which affect the slab and the production qualities and appearances are considered to be secondary geological parameters. The primary and secondary geological parameters affecting the marble productions at different stratigraphical levels in SW Turkey, are determined and the practical aspects of these findings are discussed.  相似文献   


18.
《Lithos》2003,71(1):19-46
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19.
《Geodinamica Acta》2013,26(3-4):317-331
The Küçük Menderes Graben (KMG) is part of the horst-graben system of southwestern Anatolia (Turkey), bounded by the Bozda? horst in the north and the Ayd?n horst in the south. The Plio-Quaternary evolution of the KMG has been evaluated using the nature of the Miocene-Quaternary fill sediments and palaeostress analysis of slip data measured in different parts of the graben.

The graben is composed of five subbasins—the Kiraz, Ödemi?, Bay?nd?r, Da?k?z?lca-Torbal? and Selçuk—that are connected to each other through narrow Quaternary troughs. The Da?k?z?lca, Kiraz and Selçuk basins bear Miocene and younger sequences whereas the other subbasins are largely filled by Quaternary sediments. The maximum thickness of the Quaternary fill reaches about 270 m in the Ödemi? and Bay?nd?r subbasins.

The calculated slip results indicate multidirectional extension, three successive deformational periods, and possible counterclockwise rotation in the KMG during the post-Miocene period. The first phase was a strike-slip regime under N-S compression, followed by a second phase of deformation which resulted in ENE-WSW extension with strike-slip components. The final phase of deformation was NE-SW extension which constituted the final evolution of the KMG.

The graben gained its present morphological configuration via the onset of E-W-trending, high-angle normal faulting imposed on the regionwide synformal structure during the Plio-Quaternary. The KMG evolved as a result of rifting during the Plio-Quaternary which followed Late Miocene unroofing of the Menderes Massif and the evolution of the Büyük Menderes and Gediz grabens.  相似文献   

20.
The Alaçam region of NW Turkey lies within the Alpine collision zone between the Sakarya continent and the Menderes platform. Four different tectonic zones of these two continents form imbricated nappe packages (including the Afyon zone), intruded by the Alaçam granite. Newly determined U-Pb zircon ages of this granite are 20.0 ± 1.4 and 20.3 ± 3.3 Ma, indicating early Miocene emplacement. Rb-Sr biotite ages of the granite are 20.01 ± 0.20 and 20.17 ± 0.20 Ma, suggesting fast cooling at a shallow crustal level. Geochemical characteristics show that the Alaçam granite is similar to numerous EW-trending plutons in NW Anatolia.

Gneissic granites of the Afyon tectonic zone were intruded by the Miocene Alaçam granite and have been interpreted in earlier studies as sheared parts of the Alaçam granite, which formed along a crustal-scale detachment zone under an extensional regime. We determined a U-Pb zircon age of 314.9 ± 2.7 Ma for a gneissic granite sample of the Afyon zone, demonstrating that these rocks are unrelated to the Miocene Alaçam granite. The early Miocene granitic plutons bear post-collisional geochemical features and are interpreted as products of Alpine-type magmatism along the Izmir–Ankara suture zone in NW Turkey, and seem to have no genetic relation to the detachment zone.  相似文献   

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