Search

In this study, we investigated the chemical and physical properties of the volcanic rocks used as building stones in historical places and monuments. The chemical weathering effect of salt crystallization on these stones was measured on the laboratory conditions (in most cases, used samples were very small). For this purpose, the dry weight loss (DWL) test was conducted. The rocks of dacite, andesite and tuffs of volcanic origin have different durability against salt crystallization. The most stable rocks are dacites (DWL 2.06%) which were used in the construction of Hittite monuments at Eflatun. The durability of the stones is closely related to their chemical, mineralogical, petrographical and mechanical properties. The stones used in the historical buildings are generally much more stable than present-day building stones.

Many Neo-Tethyan ophiolitic bodies are well exposed as thrust-slices in Central Anatolia and are predominantly represented by massive hornblende gabbros, most of which are cut by Supra Subduction Zone (SSZ) plagiogranites. The allochthonous gabbros are distinct from their autochthonous counterparts, with their mineralogy including both igneous hornblende, relict diopside rimmed by replacement hornblende and their chemical composition corresponding mostly to gabbro rather than diorite. The results of major and trace element analyses of forty-two samples, and REE analyses of nine samples, indicate that the hornblende gabbros are SSZ-type and formed from a wet magma by high-degree partial melting of peridotite possibly coupled with contamination by predominantly neighbouring-slab derived fluids within an intra-oceanic back-arc basin. The mafic magmas then underwent high-level fractional crystallization involving titaniferous magnetite, diopside, tschermakite and possibly olivine. Emplacement was followed by extensive ocean–floor metamorphism, which has induced crystallization (or recrystallization) of chlorite, biotite, amphiboles and mobilisation of most of the major elements such as alkali and alkali earth elements, and some LREE.

Salda Golu (Lake), in southern Turkey, is a highly alkaline (pH > 9) freshwater lake in which composite stromatolites several metres high are formed by microbially induced precipitation of hydromagnesite. The magnesium and carbonate in the lake waters were dissolved during passage through ultramafic rocks. Precipitation is brought about by the flora of diatoms and cyanobacteria forming the surface of the stromatolites, but does not occur in direct contact with cells. Stromatolites have previously been reported from environments ranging from fully marine through brackish water to a variety of freshwater lacustrine and fluvial situations. The principal importance of these structures lies in their novel mineralogy. Hydromagnesite Mg4(OH)2(CO3)3· 3H2O is commonly regarded as a low-temperature hydrothermal mineral.