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| Titel |
Geology and Tectonic Evolution of the Kazdağ Massif (NW Anatolia) |
| VerfasserIn |
B. Erdogan, E. Akay, A. Hasözbek, M. Satir, W. Siebel |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022892
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| Zusammenfassung |
| Abstract
In the northwestern part of Anatolia along the Izmir-Ankara Suture Zone, the Kazdağ and Uludağ metamorphic massifs form an E-W trending belt between the Sakarya Continent in the north and the Menderes Massif in the south. Internal succession of these two massifs have been described as metamorphic complexes consisting of various kinds of micaschists, quartz mica schist, gneisses, amphibolites and marbles. In the Kazdağ metamorphics, metaophiolites have been described additionally (Okay et al., 1991; Yaltırak and Okay, 1994; Okay et al., 1996; Duru et al., 2004).
These metamorphic complexes were considered to form the basement of the Sakarya Continent tectonically overlain by the Early Permian (Topuz et al., 2004) to Late Triassic (Okay and Monie, 1997; Okay et al., 2002) Karakaya Complex. This old basement and the Karakaya Complex were suggested to be unconformably overlain by Liassic and younger platform limestones and detritals (Altıner et al., 1991). In the literature, it has also been suggested that the Kazdağ Massif had experienced polyphase metamorphism, first during Carboniferous time, second during Early Triassic and third during Tertiary (Bingöl, 1971; Okay et al., 1996; Okay and Satır, 2000).
In this study we mapped the Kazdağ Massif on 1/25000 scale, studied its internal stratigraphy and structures and performed some petrologic analyses and radiogenic age determinations. Stratigraphically in the lower part of the Kazdağ metamorphic sequence, there is a part of an oceanic crust represented by metaultramafic rocks and gabbroic metacumulates. Geochemistry of these banded metagabbros show a mid-oceanic affinity. This oceanic crust is overlain, along an unconformity, by a platform type marble succession. At the base of the marbles, there is a basal conglomerate, clasts of which derived from the underlying ultramafic sequence. Thick white marble sequence is overlain along a gradational boundary with a metadetrital succession consisting of quartz mica schist and mica schists that are partly converted into migmatites. There are mafic metavolcanic intervals along the lower gradational zone and within various levels of the metadetrital unit and some marble lenses. The platform sequence resembles to the Mesozoic platform of the Sakarya continent and the underlying oceanic crust might be a part of a Paleotethys Ocean.
The Kazdağ succession had been subjected to high-grade migmatitic metamorphism accompanied by syntectonic granite emplacements. Zircons of these metagranites yielded U-Pb ages of 27.6 ± 6.8 Ma and 207Pb/206 Pb evaporation ages of 30 Ma. The metadetrital sequences and migmatites show scattered 207Pb/206 Pb zircon evaporation ages ranging from 301.4 ± 2.8 Ma, 274.9 ± 3.1 Ma, 169.3 ± 3.5 Ma indicating mixed ages with strong Alpine imprints.
After metamorphism the Kazdağ metamorphic sequence was internally imbricated by southward compression and the ultramafic sequence thrust on the top of the platform sequence. During this southward thrusting two different nappes emplaced successively on top of the Kazdağ metamorphics from the north. The first nappe consists of a part of Karakaya Complex and the second one, at the top, consists of the Çetmi Melange.
Our mapping results clearly show that all these nappe packages including the internally imbricated Kazdağ metamorphics are cut by undeformed young granites of 18-24 Ma age (Okay and Satır, 2000).
Exhumation of the Kazdağ metamorphics was a result of the southerly imbrication which occurred after the emplacement of the syntectonic metagranites (29-30 Ma) and before the intrusion of the cross cutting young granites (~ 21 Ma) The present topographic relief of the mountain was the result of younger vertical movements dissipated among numerous E-W trending high angle normal faults observed on its southern slope facing to Edremit Bay.
References
Altiner , D., Koçyiğit, A., Farinacci, A., Nicosia, U. and Conti, M.A. (1991) Jurassic-Lower Cretaceous stratigraphy and paleogeographic evolution of the southern part of the northwestern Anatolia. Geologica Romana 27, 13-80
Bingöl, E. (1971) Classification of age determination methods and application of Rb/Sr and K/Ar methods in Kazdağ. Bulletin of the Mineral Research and Exploration Institute of Turkey 14, 1-16 (in Turkish)
Duru, M., Pehlivan, Ş., Şentürk, Y., Yavaş, F. ve Kar, H. (2004) New results on the lithostratigraphy of the Kazdağ Massif in northwest Turkey. Turkish Journal of Earth Sciences 13, 177-186
Okay, A.I and Monie, P. (1997) Early Mesozoic subduction in the eastern Mediterranean: Evidence from Triassic eclogite in northwest Turkey. Geology 25, 595-598
Okay, A.I and Satır, M. (2000) Coeval plutonism and metamorphism in a latest Oligocene metamorphic core complex in northwestern Turkey. Geological Magazine 137, 495-516
Okay, A.I, Siyako, M and Burkan, K.A. (1991) Geology and tectonic evolution of the Biga Peninsula, northwestern Turkey. Bulletin of the Technical University of İstanbul 44, 191-256
Okay, A.I, Monod, O and Monie, P. (2002) Triaasic blueschists and eclogites from northwestern Turkey: vestiges of the Paleo-Tethyan subduction. Lithos 64, 155-178
Okay, A.I, Satır, M., Maluski, H., Sıyako, M., Monie, P., Metzger, R., Akyüz, S., (1996) Paleo- and Neo-Tethyan events in northwestern Turkey: Geologic and geochronologic constrains. The Tectonic Evolution of Asia, 420-441
Topuz, G, Altıner, D, Satır, M, and Schwartz, W.H. (2004) Low-grade metamorphic rocks from the Pulur Complex, NE Turkey: implications for the pre-Liassic evolution of the Eastern Pontides. International Journal of Earth Science, 93, 72-91
Yaltırak C. and Okay A.İ (1994) Geology of the Paleo-Tethyan units in the north of Edremit Bay. Bulletin of the Technical University of İstanbul , 3/1, 67-79 (in Turkish) |
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