Presence and tectonic significance of Cretaceous rudist species in the so-called Permo-Carboniferous G�ktepe Formation, central Menderes metamorphic massif, western Turkey

Abstract

A schist sequence of the central Menderes Massif, in which lenses of fossiliferous marbles are found, is observed in the southern flank of the Aydın Mountain, north of Köşk (Aydın), around Egrikavak village. These rocks have been considered as Permo-Carboniferous in age and are included in the Göktepe Formation of earlier studies. However, some rudist species are described from thickly bedded gray marbles that have a concordant contact with the overlying schist sequence. Although the rudists have been metamorphosed, it is observed that some contain fossils are well enough preserved to determine the following rudist fauna: Hippurites lapeirousei (GOLDFUSS), Hippurites nabresinensis FUTTERER, Hippurites cf. colliciatus WOODWARD. This rudist fauna dates the schist sequence as SantonianCampanian. The schist sequence is overlain by a thick tectonostratigraphic pile of orthogneiss which has been interpreted as the Pan-African metamorphic core of the Menderes Massif. A widespread cataclastic and mylonitic zone is present between the underlying rudist-bearing marbles and the structurally overlying orthogneiss sequence. The existing kinematic studies in the footwall and hangingwall of this tectonic contact reveal two different phases of deformations, a contractional phase followed by an extensional phase. During the contractional event, which occurred at 36 Ma, the orthogneiss sequence was thrust faulted northwards over the schist sequence. This thrust fault was later reactivated as a low-angle normal fault beneath a supradetachment sedimentary basin of Early-Middle Miocene age. The fossil discoveries of this study and the existing kinematic studies reveal that a new structural model for the central Menderes Massif in which the tectonometamorphic units form a major southward closing recumbent fold needs to be reviewed.

Neotethyan closure history of western Anatolia: a geodynamic discussion

“…4). The lowermost, Bayindır Unit consists of greenschist-facies metasedimentary rocks, including rudist-bearing carbonate (Özer and Sözbilir 2003). Muscovite from schist of the Bayindır Unit yielded an Ar-Ar age of 36 ± 2 Ma (Lips et al 2001).…”

Granitoid rocks of the southern Menderes Massif (southwestern Turkey): field evidence for Tertiary magmatism in an extensional shear zone

“…Although the former event is attributed to the southward transport of Lycian Nappes above the massif area (Ş engör and Yılmaz 1981;Ş engör et al 1984), the top-to-the-NNE kinematics of MMM fabrics and ductile fabrics in HP-LT metasediments of the Lycian Nappes are incompatible with this long-standing assumption (Bozkurt 1995;Hetzel et al 1998;Bozkurt and Park 1999;Bozkurt 2001b;Lips et al 2001;RimmelØ et al 2003). The later event is associated with the subsequent exhumation of the Menderes Massif along originally high-angle but presently low-angle normal faults during the Miocene times (e.g., Bozkurt and Park 1994, 1997a, 1997bHetzel et al 1995aHetzel et al , 1995bHetzel et al , 1998Verge 1995;Bozkurt 2000Bozkurt , 2001bBozkurt and Oberhänsli 2001a;Bozkurt and Satır 2000;Gessner et al 2001aGessner et al , 2001bGökten et al 2001;Işık and Tekeli 2001;Lips et al 2001;Seyitoglu et al 2002;Bozkurt and Sözbilir 2003;Özer and Sözbilir 2003).…”

“…Fossil evidence indicates Permian and Carboniferous ages for marbles in the upper parts of the schist cover and Triassic to Middle Palaeocene ages for carbonates in the marble cover. The readers are referred to recent literature for further reading about the stratigraphy of the Menderes Massif (e.g., Bozkurt and Oberhänsli 2001a;Özer et al 2001;Güngör and Erdogan 2002;Okay 2001Okay , 2002Özer and Sözbilir 2003 and references therein). The age of the core rocks will be discussed below (see section on 'Current Problem').…”

Source of arsenic based on geological and hydrogeochemical properties of geothermal systems in Western Turkey

“…Ring et al, 1999;Gessner et al, 2001;Lips et al, 2001;Ozer and Sözbilir, 2003). According to these studies, the massif is made up of four tectonoctratigraphic units which are, from bottom to top, rudist-bearing metamorphic rocks of the Bayındır unit, a highgrade metamorphic unit intruded by Pan-African and Triassic granites, the metasedimentary Bozdag unit, the gneiss-dominated Cine unit with Pan-African granitic protoliths, and the Selimiye metasedimentary unit of the Permo-Triassic age (Gessner et al, 2001;Okay, 2001;Ozer and Sözbilir, 2003).…”