title: The origin and determination of silica types in the silica occurrences from Altintaş region (Uşak-Western Anatolia) using multianalytical techniques.
abstract: The studied area is located in Western Anatolia and situated on the NE-SW directed Uşak-Güre cross-graben that developed under a crustal extensional regime during the Late Miocene-Pliocene. Silica occurrences have been mostly found as mushroom-shaped big caps. They also show sedimentary structures such as stratification. Silica occurrences are milky white, yellowish white, yellow to chocolate brown and rarely pale blue, bluish gray in color and have no crystal forms in hand specimen. Some of the silica samples show conchoidal fracture. Silica minerals are mostly chalcedony, low-quartz (α-quartz) and sporadically opal-CT in spectras, according to confocal Raman spectrometry. The silica samples have enrichment of Fe (1000-24,600 ppm), Ca (100-10,200 ppm), P (4-3950 ppm) and Mn (8-3020 ppm). Other striking elements in fewer amounts are Ba (0.9-609.6 ppm), Ni (15.7-182.3 ppm) and Co (18.6-343.1 ppm). In chondrite-normalized spider diagram, silica samples display partial enrichment in LIL elements (Rb, Ba, Th). The δ(18)O (‰ V-SMOW) values for silica samples vary from 18.4‰ to 22.8‰ and are similar to low temperature hydrothermal silica. Confocal Raman spectrometry and oxygen isotope indicate that the silica minerals may precipitate from host fluid which is relatively has low temperatures hydrothermal solutions derived from the residual melt of basaltic magma.
authors.affiliation: Pamukkale University Faculty of Engineering, Department of Geological Engineering, Kinikli Campus, 20017 Denizli, Turkey. Electronic address: tkoralay@pau.edu.tr.
authors.forename: Tamer
authors.initials: T
authors.lastname: Koralay
authors.affiliation: Ankara University, Geological Engineering Department, Tandoğan, 06100 Ankara, Turkey. Electronic address: kadi@ankara.edu.tr.
authors.forename: Yusuf Kağan
authors.initials: YK
authors.lastname: Kadıoğlu
mesh_terms: D001464:Barium / Q000032:analysis; D002118:Calcium / Q000032:analysis; D019015:Geologic Sediments / Q000737:chemistry; D005844:Geology / Q000379:methods; D007501:Iron / Q000032:analysis; D008903:Minerals / Q000032:analysis / Q000737:chemistry*; D010103:Oxygen Isotopes; D010758:Phosphorus / Q000032:analysis; D011791:Quartz; D012822:Silicon Dioxide / Q000032:analysis* / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013059:Spectrum Analysis, Raman; D014421:Turkey; D014961:X-Ray Diffraction
chemical_list: D008903:Minerals; D010103:Oxygen Isotopes; D011791:Quartz; D001464:Barium; D010758:Phosphorus; D012822:Silicon Dioxide; D007501:Iron; D002118:Calcium
keywords: Altıntaş–Uşak region; Confocal Raman spectrometer; Hydrothermal solution; Oxygen isotopes; Silica occurrences