The proxy data reported here are measured from a sediment core collected from Lake Sardarya (28° 38' 03" N, 61° 00' 44" E, 2675 m a.s.l.) situated on the western slope of Taftan volcano, southeastern Iran. The core is 550 cm long and was collected in May 2017. To determine total organic (TOC) and inorganic carbon (TIC) contents, we used Fourier-transform infrared spectroscopy (FTIRS) analyses of the samples in a diffuse reflectance mode with a VERTEX 70 FTIRS spectrometer (BrukerOptik GmbH, Germany) equipped with a diffuse reflectance accessory (Praying Mantis Harrick Inc., USA). Sample pretreatment, IR spectroscopy measurement conditions and processing procedures applied to the raw spectra are described by Vogel et al. (2016). The pretreatment for all samples consisted of drying and grinding 50 mg smaller than 63 mm. Additionally, the Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analysis was used to estimate biogenic silica (BSi) content. For DRIFTS analyses, 11 (±0.1) mg of the sample was mixed with 500 (±0.5) mg of potassium bromide (KBr). Finally, the BSi content was determined using the calibration model by Meyer-Jacob et al. (2014), which is based on synthetic sediment mixtures with defined BSi concentrations.

Biogenic silica, total organic (TOC) and inorganic carbon (TIC): 77 samples, analysed at Dept. of Geosciences, University of Bremen (17.08.2017)