A GEOLOGICAL AND PETROLOGICAL OVERVIEW OF THE HISTORY OF KIRA MOUNTAIN: AN APPROACH TO THE SIMILARITY AND DIFFERENCE OF KARACADAG

The volcanism of Kıra Mountain, at south of the Bitlis Zagros suture zone (BZK), was erupted from different joint systems by young extensional tectonic regime. The main geological and petrographic features of the Late Miocene Kıra Mountain volcanics were investigated as well as the major oxide, trace element and rare earth element geochemical characteristics. The Kıra Mountain volcanic products are classified as basanite, tephrite and trachy-basalt and show alkaline character above the alkaline-subalkaline separation line. Nonetheless, the peripherals associated with these volcanics starts with the Miocene aged Şelmo Formation. This formation is accompanied by Oligocene Germik Formation and Eocene Gercus Formations. The Karacadag volcanics are adjacent to the Lower, Middle and Late-Cambrian Sadan, Koruk and Sosink Formations, respectively, predominantly the Precambrian Derik Formation. In addition to these formations, Late Cretaceous Karababa and Karbogaz Formations, Late Cretaceous-Paleocene Germav Formation, Eocene Midyat Formation and Eocene Şelmo Formations are also contiguous. The phenocrysts of the Karacadag volcanics include olivine, clinopyroxene, plagioclase and opaque minerals. In the Kıra Mountain volcanics, olivine, plagioclase and opaque minerals are accompanied by sanidine and pyroxene. As reported by the geochemical and petrographical studies, The Karacadag volcanics are mainly classified as basalt and trachy-basalt, tephrite, basanite and hawaiite. Moreover these lavas are mainly alkaline and present subalkaline transition. The Karacadag volcanics erupted in three different stages with different phases, and the Kıra mountain volcanics were found to be identical with the Siverek stage.


Introduction
After the closing of the Tethys Ocean in the Middle Miocene (approximately 11-12 Ma, [13,14,15]), the deformation and compression effect in Anatolia, which started with the Arabian plate dipping under the Eurasian plate, continues effectively today. As a result of this collision to the north of the Bitlis-Zagros suture zone (BZK), volcanic units such as Mount Ararat, Mount Nemrut, Mount

Figure 1 Mapping of Kıra Mount and Karacadag in Southeast Anatolia and the spread of two volcanism (The dispersion of Karacadag volcanism is modified from [12])
The Kıra Mountain lavas, which can be traced from Batman center, erupted Eocene aged limestones (Hoya formation), sedimentary rocks with Oligocene gypsum-shale-evaporites (Germik formation) and Miocene aged conglomerate-claystone-shales (Şelmo formation) along the stretching cracks. In this study, it is aimed to present the geochemical and petrographical data of the Kıra Mountain and the Karacadag volcanism. Additionally, the mantle resource areas are evaluated in the light of the available data.

Analytical techniques
In addition to the geological and topographical maps of the study area and its surroundings, more than 100 representative samples were collected by using satellite data. Thin sections were prepared in different university laboratories for petrographical studies from selected samples. Thin sections were examined by Leica DM750P brand under polarized microscope and detailed petrographic determinations were made especially mineralogical composition and textural features. For geochemical data, major oxides, trace elements and rare earth element analyzes were performed at the laboratories of ACME (Canada) and Istanbul Technical University. Each sample was weighed between 0.1g and 1g and subjected to a solution of HCF: HNO3: HF (3:1:0.5) acid mixture at a temperature of 180 °C and a pressure of 20 bar at the Berghof brand microwave. Fully soluble analyte solutions were analyzed on a Perkin Elmer ELAN DRC-e brand ICP-MS, Perkin Elmer Analyst 700 AAS device. Multi-element ICP-MS calibration solutions at 10mg/L concentration were used as calibration solutions.

Kıra mount volcanics
The volcanics which can be traced along the Beşiri (Batman) district and nearby villages have a plateau basalt character and layer thickness reaches 40m. Considering the land spread (about 23 km2), there are no pyroclastic material exits. The color and textural characteristics of basaltic magma show occasional changes, and the presence of aggregates with gas porosity or column shape is noteworthy. Volcanites, where limited samples of basalt lava morphology are observed, can be distinguished from Karacadag volcanics in the field observations with abundant fractures and widespread discontinuities.
In the scope of phenocrystalline, feldspar minerals (sanidine and plagioclase) are added to olivine, pyroxene and opaque minerals. Minerals are generally not euhedral, but they offer examples of alteration at different scales. Opaque minerals are commonly found in sections, while the feldspar bars in the matrix give typical basaltic texture samples ( Figure 3).

Karacadag volcanics
Karacadag volcanism, which is located in a very wide geography (about 10 000 km2) covering different provinces of Mardin and Şanlıurfa, mainly in Diyarbakır, has been active in three main stages [3,4]. The most widely distributed and relatively oldest Siverek stage (2.7 Ma-11 Ma/constitutes 80% of the volcanism) was the north-south direction from the south of Ergani to Viransehir. The Karacadag stage (1 Ma-1,9 Ma/constitutes 15% of the volcanism) composes the main body of Karacadag and contains pyroclastic aggregates in some places. The youngest member, the Ovabag stage (0,01 Ma-0,4 Ma/constitutes 5% of volcanism), has reached the SE directional surface, not in the form of a whole, but in several parts of the opening cracks. The phenocrysts of these volcanics include olivine, pyroxene (clinopyroxene), feldspar (plagioclase) and opaque minerals [10,11,12].

Geochemical properties
The major oxides, trace elements and REE of the Kıra Mountain volcanics and the Karacadag volcanic complex (Table 1 and Table 2) were evaluated in the TAS diagram proposed by Le Bas et al. (1986) [9]. (Data related to the Karacadag volcanites are described in [3,10,11,12] ). The main oxide changes reflect a characteristic of the sodic composition rich in TiO2, which is commonly seen around the Mediterranean when both volcanic products are considered together. The samples belonging to Karacadag show a wide distribution up to basalt and trachy-andesite including trachy-basalt, tefrite, phonotephrite, basanite, basaltic trachy-andesite, and alkaline character except for a few examples according to Irvine and Baragar 1971 [6] (Figure 4).  Although it is noteworthy that the Kıra Mountain lavas are falling into the trachy-basalt, tephrite, phonotephrite, and basanite range, it is determined that they have an alkaline character such as Karacadag products. In order to examine the main oxide data carefully, Kıra Mountain volcanics show lower values of SiO2, Al2O3, MgO, CaO, Na2O, K2O and TiO2 compared to Karacadag products whereas Fe2O3 and MnO data are considered as equivalent on average. With respect to the P2O5 and Cr2O3 values, an enrichment is observed.
It is seen that the rising basalts, mostly Siverek stage volcanics and Karacadag stage volcanites, predominantly alkaline character Karacadag products imply the Nb/La (>1) and Nb/Yb ratios showing a scattered trend and the OIB type as the asthenospheric mantle. In contrast, the lower Nb/La (<1) and low Nb/Yb (<8) values of the Kıra Mountain volcanics indicate that the mantle source they derive is

Discussion
To take regionally, the collision of the Arabian and Anatolian plate, which controls the neotectonics Turkey is one of two main events and has played a decisive role in terms of the dynamics of this case. This movement formed an in-plate volcanism that started in Late Miocene and continued until Quaternary and thus formed Karacadag and Kıra Mountain. Karacadag lava coming out of the opening cracks and reaching the surface in the direction of NW-SE is in line with the Kıra Mountain lava. The Karacadag products also show formations in the N-S direction. While the Kıra Mountain volcanites are classified as tephrite, phono-tephrite, trachy-basalt and basanite, the Karacadag magma also offers a wide distribution extending from basalt to trachy-andesite. Karacadag products are similar to OIB and are predominantly of asthenospheric mantle origin. In contrast, the magma forming the Kıra Mountain marks a mixed lithospheric-astenospheric mantle composition.

Conclusion
On the basis of the stratigraphic location of the region for many years, the Kıra Mountain volcanics have been evaluated as Pliocene and some have been accepted as Quaternary in literature studies. Nonetheless, in the light of the current geological data, with the effect of the stress regime developed due to neotectonic deformation in the region, mantle uplift was realized and basaltic products were exposed in plateau basalt form spreading in Diyarbakır and Batman regions. Although the Kıra Mountain lavas exhibit similar mineral paragenesis, they can be distinguished from the Karacadag Volcanites by their abundant fractures and widespread discontinuities in the field surveys as well as by their distinctive color distribution in different shades. Considering the unique contribution of analysis data, it is quite clear that the Late Miocene aged Kıra Mountain volcanites were found in the Karacadag volcanites which correspond to Siverek stage periodically, exhibit different geochemical characteristics and derived from different types of magma.