scholarly journals A new Middle Miocene mammalian fauna from Mordoğan (Western Turkey)

PalZ ◽  
2003 ◽  
Vol 77 (2) ◽  
pp. 293-302 ◽  
Author(s):  
Tanju Kaya ◽  
Denis Geraads ◽  
Vahdet Tuna
Keyword(s):  
Middle Miocene ◽  
Mammalian Fauna ◽  
Western Turkey

scholarly journals A new Middle Miocene mammalian fauna from Mordoğan (Western Turkey)

PalZ ◽  
2004 ◽  
Vol 78 (1) ◽  
pp. 231-231
Author(s):  
Tanju Kaya ◽  
Denis Geraads ◽  
Vahdet Tuna
Keyword(s):  
Middle Miocene ◽  
Mammalian Fauna ◽  
Western Turkey

Precise U–Pb ages of syn-extensional Miocene intrusions in the central Menderes Massif, western Turkey

2006 ◽  
Vol 144 (2) ◽  
pp. 235-246 ◽  
Author(s):  
JOHANNES GLODNY ◽  
RALF HETZEL
Keyword(s):  
Shear Zone ◽  
Continental Crust ◽  
Late Miocene ◽  
Large Scale ◽  
Middle Miocene ◽  
Convincing Evidence ◽  
Western Turkey ◽  
Crustal Rocks ◽  
Menderes Massif ◽  
Tectonic Exhumation

Western Turkey is an area which has experienced large-scale extension of continental crust. Here we report precise crystallization ages of two intrusions in the central Menderes Massif, the Turgutlu and Salihli granodiorites, using U–Pb dating. Both intrusions occur in the southern footwall of the seismically active Alaşehir graben and were emplaced syntectonically in an extensional top-to-the-NNE shear zone which was active at retrograde greenschist-facies conditions. The U–Pb ages of 16.1 ± 0.2 Ma (monazite, Turgutlu granodiorite) and 15.0 ± 0.3 Ma (allanite, Salihli granodiorite) document that tectonic exhumation of middle-crustal rocks in the central Menderes Massif was already underway at the Early to Middle Miocene transition. Combined with published geochronological, structural and sedimentological data, the new U–Pb ages point to a continued extension since at least 16 Ma. There is no convincing evidence for a late Miocene/Pliocene phase of tectonic shortening.

The role of the flexural rotation/rolling hinge model in the tectonic evolution of the Alaşehir graben, western Turkey

2002 ◽  
Vol 139 (1) ◽  
pp. 15-26 ◽  
Author(s):  
GÜROL SEYİTOĞLU ◽  
OKAN TEKELİ ◽  
İBRAHİM ÇEMEN ◽  
ŞEVKET ŞEN ◽  
VEYSEL IŞIK
Keyword(s):  
Tectonic Evolution ◽  
Middle Miocene ◽  
Hanging Wall ◽  
Fault System ◽  
Sequential Process ◽  
Western Turkey ◽  
Extensional Structure ◽  
Hinge Model ◽  
Sedimentary Unit

The Alaşehir graben is a well-defined prominent extensional structure in western Turkey, generally trending E–W and containing four sedimentary units. At the beginning of graben formation during Early–Middle Miocene times, the first fault system was active and responsible for the accumulation of the first and second sedimentary units. In Pliocene times, a second fault system developed in the hanging wall of the first system and a third sedimentary unit was deposited. The recently active third fault system separates older graben fill and a fourth sedimentary unit. Activity on each fault system caused the rotation and uplift of previous systems, similar to the ‘flexural rotation/rolling hinge’ model, but our field observations indicate that the rotated first fault system is also active, allowing exhumation of larger amounts of rock units. This paper documents that graben formation in western Turkey is a sequential process. Its different periods are represented by three fault systems and associated sedimentation. Consequently, recent claims using age data from only the second and/or third sedimentary units to determine the timing of graben formation are misleading.

scholarly journals Faunal turnover of the Miocene mammalian faunas of Sub-Saharan Africa and the middle Miocene paleoenvironmental change

1992 ◽  
Vol 6 ◽  
pp. 218-218
Author(s):  
Hideo Nakaya
Keyword(s):  
East Africa ◽  
Late Miocene ◽  
Half Life ◽  
Middle Miocene ◽  
Sub Saharan Africa ◽  
Mammalian Fauna ◽  
Faunal Turnover ◽  
Mammalian Faunas ◽  
Open Land ◽  
Sub Saharan

In evolutionary paleontology of terrestrial biotas, the Miocene is the most important age especially for evolution of hominids and mammalian faunas. The modern mammalian fauna appeared from the end of this age in Eurasia. In Sub-Saharan Africa, the assemblage of the late Miocene mammalian faunas was very poor, and these faunas were represented by only few faunas. Therefore, this incompleteness of the late Miocene East African faunas, it is very difficult to analyze faunal turnover of Sub-Saharan mammalian faunas and compare with Eurasian and Sub-Saharan faunas of this age.The paleontological contribution of the Japan and Kenya joint expedition to the Samburu Hills, northern Kenya covered this gap of mammalian evolution in Sub-Saharan Africa.In this work, the Miocene mammalian faunas in Sub-Saharan Africa is examined the half-life (Kurtén 1959, 1972, 1988) of each faunal assemblages (sets).Assemblage of the mammalian faunas from early Miocene was comparatively stable and had long half life in Sub-Saharan Africa on the basis of the results of this work.However, mammalian assemblage changed drastically at the middle Miocene (Astaracian) in Sub-Saharan Africa.A great number of early to middle Miocene mammalian taxa were extinct and the modern mammalian taxa appeared in this period. The half life of middle and late Miocene mammalian faunas is shortened compared with the early Miocene faunas in the East Africa. This geological event of faunal turnover occurred by the immigration and divergence of open land taxa.It is evident that the rise of open land taxa is related to the environmental change for the plateau phonolite and basalt volcanism in the middle Miocene East Africa (Pickford 1981) and the worldwide warm and arid event (savannitisation) of continental temperate zone in the middle to late Miocene (Liu 1988). In the middle Miocene (16 Ma) Pacific region, it has been proposed that the tropical event is recognized from shallow marine faunas of the Southwestern Japan (Tsuchi 1986). African and Eurasian land connection was also established before the middle Miocene (16 Ma±) (Bernor et al. 1987).The Astaracian faunal turnover in Sub-Saharan Africa is considered to be caused by immigration and diversity of open country mammalian taxa and that was related to the worldwide middle Miocene warm event and the plateau volcanism in middle Miocene East Africa. Furthermore, the Pleistocene and modern taxa and their direct ancestors of Sub-Saharan Africa appeared from the late Miocene faunas of East Africa. It has been made clear that the Namurungule Fauna is the forerunner of the modern Sub-Saharan mammalian fauna of savanna environments.As mentioned before, the Hominid Fossil was found from the Namurungule Formation (late Miocene) of northern Kenya. The savannitisation in the Sub-Saharan Africa began in middle Miocene. The origin of hominid bipedalism seems to be closely related to the environmental change from forest to open land (Foley 1984). Human evolution in East Africa is accelerated by the savannitisation of Sub-Saharan Africa which commenced earlier than that of Eurasia and continued throughout the Neogene.

Progressive development of the Büyük Menderes Graben based on new data, western Turkey

2009 ◽  
Vol 146 (5) ◽  
pp. 652-673 ◽  
Author(s):  
ÖMER FEYZİ GÜRER ◽  
NURAN SARICA-FILOREAU ◽  
MUZAFFER ÖZBURAN ◽  
ERCAN SANGU ◽  
BÜLENT DOĞAN
Keyword(s):  
Middle Miocene ◽  
Normal Fault ◽  
Structural Data ◽  
Detachment Fault ◽  
Normal Faults ◽  
Tectonic Event ◽  
Alluvial Deposits ◽  
Western Turkey ◽  
Northern Margin ◽  
The North

AbstractOblique and normal fault systems exposed in the Büyük Menderes Graben (BMG) region record two successive and independent complex tectonic events. The first group tectonic event is defined by an E–W extension related to N–S contraction and transpression. This group is responsible for the development of NW- and NE-trending conjugate pairs of oblique faults which controlled Early–Middle Miocene basin formation. Between the Early–Middle Miocene and Plio-Quaternary strata exists an unconformity, indicating a period of folding, uplift and severe erosion associated with N–S shortening. The second group of events was the change in tectonic regime from E–W extension to N–S extension which controlled the formation of the Büyük Menderes Graben by three progressive pulses of deformation. The first pulse of extensional deformation was initially recorded in the region by the exhumation of the deep part of the Menderes Massif (MM) with the development of the E-trending Büyük Menderes Detachment Fault (BMDF). The minimum age of this pulse is constrained by the older Plio-Quaternary fluviatile deposits of the Büyük Menderes Graben that range in age from the Plio-Pleistocene boundary interval to Late Pleistocene. The second pulse, which is marked by the rapid deposition of alluvial deposits, initiated the formation of approximately E–W-trending high-angle normal faults synthetic and antithetic to the Büyük Menderes Detachment Fault, on the northern margin during Holocene times. These faults are interpreted as secondary steeper listric faults that merge with the main Büyük Menderes Detachment Fault at depth. The third pulse was the migration of the Büyük Menderes Graben depocentre to the present day position by diachronous activity of secondary steeper listric faults. These steeper faults are the most seismically active tectonic elements in western Turkey. According to the stratigraphic and structural data, the N–S extension in the Büyük Menderes Graben region produced a progressive deformation phase with different pulses during its Plio-Quaternary evolution, with migration of deformation from the master fault to the hangingwall. The formation of diachronous secondary synthetic and antithetic steeper faults on the upper plate of the Büyük Menderes Detachment Fault, hence the southward migration of the deformation and of the Büyük Menderes Graben depocentre, should be related to the evolution of detachment in the region. The presence of the seismically active splays of secondary faults implies an active detachment system in the region. This young Plio-Quaternary N–S extension in the Büyük Menderes Graben may be attributed to the combined effects of the two continuing processes in Aegean region. The first process is back-arc spreading or probably the roll-back of African slab below the south Aegean Arc, which seems to be responsible for the change in the stress tensor from E–W extension to N–S extension. The second and later event is the southwestward escape of the Anatolian block along its boundary fault, that is, the North Anatolian fault (NAF).

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