The Central Anatolian segment of the Alpine-Himalayan orogen contains "interior" basins, the largest of which is the Tuzgölü (Salt Lake) basin (>20,000 km2). It is bounded on the east by the Tuzgölü (Salt Lake) fault zone and on the west by the Yeniceoba and Cihanbeyli fault zones. Structural, stratigraphic, and sedimentologic evidence suggests that the Tuzgölü basin started as a fault-controlled basin during late Maastrichtian tectonism when the present-day northwest-trending faults that bound the basin were initiated. These faults may have been formed as normal faults suggesting extension or strike-slip faults with a normal component of movement indicating a large transtension at the time of their initiation. The late Maastrichtian faults were reactivated as strike-slip faults in response to late Eocene compression in the region that produced the Central Anatolian thrust belt to the north and the late Eocene south-dipping thrust faults of the Ulukisla basin to the south. This reactivation is suggested by structurally repeated and missing Paleocene-Eocene deposits in some of the basin's wildcat wells. The late Eocene regression in the Tuzgölü basin was caused by the combined effects of Eocene shortening and a large environmental change. Late Eocene evaporites suggest that the basin was dry before the start of the Neotectonic period, while during the Neotectonic itself the Tuzgölü fault zone was reactivated again, predominantly as a normal fault with a right-lateral strike-slip component. This is evidenced by (1) a major unconformity between the post-Eocene Koçhisar Formation of the Tuzgölü basin and the underlying Eocene rock units; (2) a well-developed rollover anticline observed on seismic reflection profiles; and (3) a right-step along the Tuzgölü fault zone seen in the field.

In the Central

The Central Anatolian Crystalline Complex (CACC) or Kırşehir Block is part of the metamorphosed leading edge of the Tauride-Anatolide Carbonate Platform. It contains oceanic remnants derived from the Neotethys Ocean (İzmir-Ankara-Erzincan branch) which separate it from the Sakarya microcontinent. Two tectonic units are distinguished: an amphibolite facies Mesozoic ‘basement’, dominated by platform marbles, over which is thrust a younger fragmented Upper Cretaceous ophiolite sequence. Three metabasite horizons were sampled to reconstruct the development of the oceanic components: (1) fragmented Upper Cretaceous (90-85 Ma) stratiform ophiolitic members comprising gabbros, sheeted dykes, basalt lavas and pelagic sediments thrust over all other units; (2) a tectonised admixture of basite, ultramafic and felsic blocks in an ophiolitic mélange (Upper Cretaceous matrix) thrust over the basement metamorphic rocks; and (3) amphibolites concordant with ‘basement’ marbles and minor pelagics of the largely (?)Triassic Kaleboynu Formation in the lower part of the carbonate platform.Metabasalts and metagabbros from isolated fragments of the stratiform ophiolites form geochemically coherent groups and indicate the influence of a subduction component during their development. It is considered that the suprasubduction zone ophiolites record the association of a tholeiitic arc and an adjacent back-arc basin with more mid-ocean ridge basalt (MORB)-like compositions.Metabasite blocks within the tectonised ophiolitic mélange slice are MORB like, together with minor ocean island basalt (OIB) and island arc basalts, and may be tectonically related to ophiolitic units within the accretionary wedge of the Ankara Mélange.Concordant amphibolites of the Kaleboynu Formation are largely OIB types and reflect an early ensialic rifting stage of the Tauride-Anatolide Carbonate Platform. Small ocean basins also developed at this time, as recorded by the presence of MORB and associated pelagics.The CACC block, together with parts of the Ankara Mélange, are considered to represent oceanic lithosphere (comprising both early spreading centre and latter subduction-influenced crust) and continental carbonate platform that were subsequently ejected from an accretionary-subduction complex on collision with the Sakarya microcontinent.

No abstract

The Central Anatolian Crystalline Complex (CACC), situated between the northern and southern oceanic strands of Neotethys, contain a number of little-studied ophiolitic bodies of late Cretaceous age that have a bearing on the Mesozoic development of this region. The pillow lavas and sheeted dykes of the Safikaraman Ophiolite were originally a comagmatic differentiated series of vesicular, aphyric and olivine-poor, plagioclase-clinopyroxene phyric tholeiites, but now exhibit gmenschist facies assemblages. A set of late dolerite dykes cross-cutting the whole volcanic sequence are more chemically evolved and were probably derived from a different source. Relative to N-MORB the lavas and dykes are enriched in some LIL elements (K, Rb, Cs, U, Th and St) and depleted in HFS elements (Nb, Ta, Hf, Zr, Ti and Y) and light REE. In terms of immobile elements the ophiolitic basalts have the broad chemical characteristics of island arc tholeiites that were formed in a supra-subduction zone setting, whereas the late dykes are more akin to N-MORB. In this respect the Sarikaraman Ophiolite is similar to other ophiolites found in the eastern Mediterranean region and emphasizes the preservation of this particular environment in the CACC. If all the Central Anatolian Ophiolites (of which the Sarikaraman Ophiolite is one example) were derived via southward thrusting from the Vardar-Izmir-Ankara-Erzincan Ocean branch to the north, age relationships suggest that this segment of ocean crust was relatively short-lived before obduction onto the CACC.