Cappadocian Geology

Geology of the İdiş Dağı - Avanos

The basement rocks of the study area constitute Mesozoic aged Asigedigi Metamorphics, that represent the uppermost unit of the Central Anatolian Metamorphics and consist of platform type meta-carbonates. İdiş Dağı Syenitoid, composed of quartz syenite, alkali feldspar quartz syenite and quartz monzonite intruded the Asigedigi Metamorphics, and generated contact metamorphic zones. Karahıdır Volcanics are found as dykes cutting the İdiş Dağı Syenitoids and as blocks in the Göynük Volcaniclastic Olistostrome. Göynük Volcaniclastic Olistostrome unconformably covers the basement rocks. It is formed within a fault-controlled extensional basin in Uppermost Cretaceous-Lower Paleocene period, and includes the olistoliths of the Karahıdır Volcanics and İdiş Dağı Syenitoids. The late Lower Paleocene-Upper Paleocene Yeşilöz Formation consists of the Saytepe Conglomerate Member and the Asaftepe Member and represents the terrestrial and lacustrine depositional environment. Middle Eocene Mucur Formation characterising shallow marine (reefal) deposition transgressively overlies the basement rocks. It is suggested that in the Early Miocene, a compressional system effected the İdiş Dağı Area, and the basement rocks were thrusted over the Tertiary cover units. The neotectonic period started in Late Miocene in the study area. In this period a new tensional system became effective, Ürgüp and Asarcık Formations are deposited within the basins which are controlled by the Central Kızılırmak Fault Zone. The Quaternary aged travertine occurrences and talus deposits are also related to this fault zone. The Karataş Volcanics and Kızılırmak River terraces of Quaternary of age are mainly controlled by the Central Kızılırmak Fault Zone.

Source:

Bulletin of the Mineral Research and Exploration Institute of Turkey. 119; Pages 41-58. 1997

Publisher:

Maden Tetkik ye Arama Enstitüsü. Ankara, Turkey. 1997

Authors:

Köksal, Serhat; Göncüoğlu, M. Cemal

Reference Source:

GeoRef, Copyright 1998, American Geological Institute

ISSN:

0026-4563

Engineering geological properties and durability assessment of the Cappadocian tuff

Some of the unique landforms, the so-called fairy chimneys, which were formed within the Cappadocian tuff of central Turkey, were used as dwellings in the past and contain culturally valuable wall paintings. However, these structures are undergoing chemical and physical deterioration due to atmospheric effects. For conservation studies, an understanding of the engineering geological properties of the tuff is essential. The Cappadocian tuff is almost fresh, with local discoloration, is moderately weak to very weak, and has low unit weight, very high porosity, and high deformability. Discontinuity surveys revealed two dominant joint sets, which not only controlled the formation but also control the structural stability of the fairy chimneys. Various methods used for the durability assessment of the Cappadocian tuff indicate poor to very poor durability. Due consideration must be given to reduction due to moisture, poor to very poor durability, and the adverse effects of joints on the structural stability of the fairy chimneys.

Source:

Engineering Geology. 47; 1-2, Pages 175-187. 1997

Publisher:

Elsevier. Amsterdam, Netherlands. 1997

Authors:

Topal, T; Doyuran, V.

Reference Source:

GeoRef, Copyright 1998, American Geological Institute.
Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands

ISSN:

0013-7952

Neogene ignimbrites of the Nevşehir plateau (central Turkey);
stratigraphy, distribution and source constraints

In Anatolia (Turkey), extensive calc-alkaline volcanism has developed along discontinuous provinces from Neogene to Quaternary times as a consequence of plate convergence and continental collision. In the Nevşehir plateau, which is located in the Central Anatolian Volcanic Province, volcanism consists of numerous monogenetic centres, several large stratovolcanoes and an extensive, mainly Neogene, rhyolitic ignimbrite field. Vent and caldera locations for the Neogene ignimbrites were not well known based on previous studies. In the Neogene ignimbrite sequence of the Nevşehir plateau, we have identified an old group of ignimbrites (Kavak ignimbrites) followed by five major ignimbrite units (Zelve, Sarımaden Tepe, Cemilköy, Gordeles, Kızılkaya) and two smaller, less extensive ones (Tahar, Sofular). Other ignimbrite units at the margin of the plateau occur as outliers of larger ignimbrites whose main distributions are beyond the plateau. Excellent exposure and physical continuity of the units over large areas have allowed establishment of the stratigraphic succession of the ignimbrites as, from bottom to top: Kavak, Zelve, Sarımaden Tepe, Cemilköy, Tahar, Gordeles, Sofular, Kızılkaya. Our stratigraphic scheme refines previous ones by the identification of the Zelve ignimbrite and the correlation of the previously defined Akköy ignimbrite with the Sarımaden Tepe ignimbrite. Correlations of distant ignimbrite remnants have been achieved by using a combination a field criteria:

1. sedimentological characterisitics;
2. phenocryst assemblage;
3. pumice vesiculation texture;
4. presence and characteristics of associated plinian fallout deposits; and
5. lithic types.

The correlations significantly enlarge the estimates of the original extent and volume of most ignimbrites: volumes range between 80 km (super 3) and 300 km (super 3) for the major ignimbrites, corresponding to 2500-10.000 km (super 2) in areal extent. The major ignimbrites of the Nevşehir plateau have an inferred source area in the Derinkuyu tectonic basin which extends mainly between Nevşehir and the Melendiz Dağı volcanic complex. The Kavak ignimbrites and the Zelve ignimbrite have inferred sources located between Nevşehir and Derinkuyu, coincident with a negative gravity anomaly. The younger ignimbrites (Sarımaden Tepe, Cemilköy, Gordeles, Kızılkaya) have inferred sources clustered to the south between the Erdaş Dağı and the Melendiz Dağı volcanic complex. Evidence was found of collapse structures on the northern and southern flanks of the Erdaş Dağı volcanic massif, and of a large updoming structure in the Şahınkalesi Tepe massif. The present-day Derinkuyu tectonic basin is mostly covered with Quaternary sediments and volcanics. The fault system which bounds the basin to the east provides evidence that the ignimbrite volcanism and inferred caldera formation took place in a locally extensional environment while the basin was already subsiding. Drilling and geophysical prospecting are necessary to decipher in detail the presently unknown internal structure of the basin and the inferred, probably coalesced or nested, calderas within it.

Source:

Journal of Volcanology and Geothermal Research. 63; 1-2, Pages 59-87. 1994

Publisher:

Elsevier. Amsterdam, Netherlands. 1994

Authors:

Le Pennec, J.L,; Bourdier, J.L.; Froger, J.L.; Temel, A.; Camus, G.; Gourgaud, A.

Reference Source:

GeoRef, Copyright 1998, American Geological Institute
Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands

ISSN:

0377-0273