Geochemistry of Permian–Triassic low-grade (meta-)sandstones from NW and central NE Anatolia, Turkey: implications for provenance and tectonic setting

• Published in: Arabian journal of geosciences 2022-12, Vol.15 (23), Article 1693
• Main Authors: Tetiker, Sema, Yalçın, Hüseyin
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Anomalies; Apatite; Basalt; Biotite; Calcite; Chlorite; Chondrites; Earth and Environmental Science; Earth science; Earth Sciences; Feldspars; Geochemistry; Goethite; Haematite; Heavy minerals; Hematite; Igneous rocks; Isotopes; Limestone; Mica; Minerals; Muscovite; Original Paper; Orthoclase; Permian; Plagioclase; Quartzite; Sandstone; Schist; Schists; Sedimentary rocks; Sediments; Silica; Silicates; Tectonics; Titanium dioxide; Trace elements; Triassic; Weathering; Zircon
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-022-10972-z

The Permian–Triassic Karakaya Complex (KC), related to the Palaeotethys, is located within the Sakarya Terrane in northern Turkey and is subdivided into two parts, the Lower Karakaya (LKC) and Upper Karakaya (UKC). UKC units usually consist of meta(sandstone) strata. This study contributes to their provenance and geotectonic settings by revealing the petrographic and geochemical properties of (meta-)sandstones in the UKC units from the northwest and central northeast Anatolia. KC (meta-)sandstones have middle-to-poor sorting; are unmatured; have microlamination, mineral orientation, and slaty and crenulation cleavages; and have muscovite/biotite-chlorite stack/pod structures. Sandstones contain polycrystalline and monocrystalline quartz, feldspar (plagioclase, orthoclase, and rare microcline), rock fragments (basalt, granite, quartzite, schist, phyllite, and limestone), heavy minerals (muscovite, biotite, zircon, epidote, apatite, hematite, and goethite), matrix (chlorite and sericite), and cement (calcite and silica). Plagioclase Alteration Index (PIA), Chemical Index of Alteration (CIA), and Chemical Index of Weathering (CIW) values of (meta-)sandstones indicate that the silicates had an intermediate degree of chemical weathering/alteration. The total REE concentrations of (meta-)sandstones are 38–276 ppm, and they show 193–10 (La-Lu) times the enrichments with negative Eu anomalies in comparison with chondrites. The Al 2 O 3 /TiO 2 ratios of the UKC sandstones indicate that the sediments were derived from felsic and intermediate igneous rocks. The major and trace element geochemistry of the KC sandstones was associated with an active margin setting. (Meta-)sandstones from the LKC-UP and UKC units were largely derived from magmatic and sedimentary sources that indicate extensional basins, respectively.