Burial and thrust-related very low-grade metamorphism in the Upper Paleozoic meta-sedimentary rocks at the Kangal-Alacahan area, Sivas
Abstract: Kangal formation meta-clastics of Middle Devonian-Lower Carboniferous have different lithologic, textural and mineralogu: features related to sedimentary burial and thrust, from bottom to top, in the Kangal-Alacahan area. Kınalar member (slates and lessmeta-siltstone, with chlorite-mica pod) contain phyllosilicates (2M, illitelmuscovite, lib chlorite, mixed-layer paragonite-muscoviteP-M, paragonite, pyrophyllite, kaolinite/dickite, mixed-layer chlorite-vermiculite-C-V, mixed-layer chlorite-smectite-C-S), calcite,quartz, goethite and chloritoid, in order of decreasing abundance. IC values are indicative of low epizonal-high anchizonal conditions. Quartz, phyllosilicates (2Ml+lMd illitelmuscovite, kaolinite/dickite), feldspar and geothite are present in the anchimeta-sandstone and anchimeta-shale and/or slates of Bakırtepe member, which represents middle anchizone IC values. The anchimeta-shale,anchimeta-siltstone, anchimeta-limestone, anchimeta-sandstone and slates with chlorite-mica pod in the Düzce member mainly consist of phyllosilicates (2M1+Md illitelmuscovite, lib chlorite, M-P, paragonite, kaolinite/dickite, pyrophyllite, CIV, CIS), quartz, calcite and geothite. IC measurements of meta-clastics show high-grade anchizone. Höyük member is commonly composed of crystallized limestone, and rarely sandstone and shale that corresponds to low anchimetamorphic or high diagenetic degree. The unit includes calcite, quartz, phyllosilicates (illitelmuscovite, chlorite and kaoliniteldickite) and goethite. The index minerals related to thrustsuch as P-M, paragonite, pyrophyllite and chloritoid are found in the allochthonous Kangal formation that appears as an indicatorto distinguish allochthonous and autochthonous units. In addition, paragenetic relationships suggest that meta-sedimentary rocks aremetamorphosed in anticlockwise P-T-t (pressure-temperature-time) path and then clockwise P-T-t path as a result of burial and thrusttectonics, respectively.