Orhan Kavak

Early activity of the largest Cenozoic shield volcano in the circum-Mediterranean area: Mt. Karacadag, SE Turkey

Volcanic activity at Mt. Karacadag, SE Turkey, developed between ~11 and ~0.01 Ma. In this paper we investigate the oldest products (older than 2.6 Ma) that created a large volcanic plateau and a N-S aligned volcanic edifice in the form of a shield volcano. These igneous rocks are mildly alkaline to transitional olivine-clinopyroxene phyric basalts with minor hawaiites, basanites and very rare differentiated lithologies (mugearites and benmoreites). The poor correlation of major elements with MgO in these lavas is qualitatively consistent with polybaric depths of magma production, variable degrees of partial melting (from ~2 to ~10 %), heterogeneous mantle sources and differences in the fractionating crystal assemblage. Primitive mantle-normalized patterns resemble typical anorogenic magma compositions, with peaks at HFSE (Nb, Ta, Hf, Zr) and high HFSE/LILE ratios. REE contents are compatible with derivation of the basanites from a mixed garnet-spinel facies peridotite after ~2 % partial melting. Alkali basalts are compatible with higher degrees of melting (between 5 and 10 %) from the same type of source. Initial 87 Sr/ 86 Sr ratios range from 0.70349 to 0.70522 while those of 143 Nd/ 144 Nd range from 0.512853 to 0.512659. Early-stage lavas show higher 87 Sr/ 86 Sr and lower 143 Nd/ 144 Nd compared to plateau-stage lavas. The Sr-Nd isotopic variations and their relation with major and trace elements cannot be explained by AFC-like (Assimilation and Fractional Crystallization) processes involving average crustal lithologies. More likely, the Sr-Nd isotopic ratios are related to the existence of heterogeneous mantle sources with only minor involvement of AFC-like processes. The Cenozoic lavas in a 200 x 800 km area between the Karasu Valley and the Syria-Iraq-Turkey border in south-eastern Anatolia form a distinct igneous province which can be characterised on the basis of Sr-isotope signatures. The lithospheric mantle beneath this area is characterized by anomalously enriched 87 Sr/ 86 Sr compositions (up to 0.7055) as well as more isotopically depleted compositi o ns ( 87 Sr/ 86 Sr down to 0.7030).

Determination of environmental exposure to asbestos (tremolite) and mesothelioma risks in the southeastern region of Turkey.

Abstract In this study, the authors examined the concentrations and mineralogical analyses of asbestos, and investigated mesothelioma risk in southeastern Anatolia, Turkey. They used a gravimetric dust sampler to collect samples from 2 villages and 2 asbestos mines (1 active). Samples were then evaluated by an X-ray diffractometer and an electron microscope. The authors found high concentrations of asbestos in an active mine (4.9 fibers[f]/cm3) and at a house that was plastered with asbestos (1.24 f/cm3) and had a very active population. They found a low concentration (0.0042 f/cm3) in indoor measurements taken in Armutova village, and an even lower concentration (0.000081 f/cm3) in the inactive mine environment. Outdoor measurements included a low concentration of 0.007 f/cm3 in the village environment, and a high concentration of 1.17 f/cm3 on the mine road during the passing of a sheep herd. The people in the region are continuously exposed to asbestos during normal activities. This cumulative exposure to asbestos carries sufficient risks for mesothelioma development.

The geochronology and origin of mantle sources for late cenozoic intraplate volcanism in the frontal part of the Arabian plate in the Karacadağ neovolcanic area of Turkey. Part 2. The results of geochemical and isotope (Sr-Nd-Pb) studies

A geochemical and isotope-geochemical (Sr-Nd-Pb) study has been carried out for the Karacadağ neovolcanic area, which is situated within the frontal part of the Arabian plate. The obtained data and the results of petrological modeling show that the petrogenesis of parental magmas in the Karacadağ neovolcanic area involved two compositionally different mantle sources; one consisted of garnet-bearing peridotites of the asthenosphere mantle and the other was spinel-bearing peridotites of the enriched subcontinental lithosphere mantle. During early stages in the evolution of the magmatic system, deep-seated asthenospheric magmas were ascending to the surface while intensively interacting with the melts that had been generated at upper mantle depths. The interaction gradually diminished, so that the later effusive rocks mostly have compositions that are similar to those of the primitive asthenospheric magmas. It is shown that a significant (up to 17–18 wt % of the mantle melt) assimilation of crustal material could take place only during the initial phases of the magmatism. Periodic replenishment of the magma chambers by primitive magmas, which resulted in an observable high degree of homogeneity in the composition of young effusive rocks, was also of importance in the petrogenesis of lavas during the evolution of volcanic activity.

The geochronology and origin of mantle sources for late cenozoic intraplate volcanism in the frontal part of the Arabian plate in the Karacadağ neovolcanic area of Turkey. Part 1. The results of isotope-geochronological studies

This paper considers results from isotope-geochronological (K-Ar) studies of the products of Neogene-Quaternary volcanism in the Karacadağ area, which is situated within the northern frontal part of the Arabian plate. It was found that magmatic activity has been evolving at this location for at least the last 11–10 Myr and was distinctly discrete in character. Three stages of volcanism have been identified: (I) Early or Miocene, ∼11–6.7 Ma; (II) Middle or Pliocene-Early Quaternary, 4–1 Ma; and (III) Late or Late Quaternary, 0.4–0.1 Ma. The most recent manifestations of magmatic activity in the region date back to about 100000 years ago.An analysis of the spatial distribution of volcanic centers of different ages in the Karacadağ neovolcanic area shows that the magmatism of that region involved a lateral migration of activity from northwest to southeast along a major regional tectonic fault. The migration was caused by the movement of local tension zones where the lithosphere was thinner and deep-seated mantle magmas were ascending.