2 D3. Advances in Geoarchaeology

Monday, 26 October 2020
1:30 PM - 5:30 PM
Meeting Rooms

PROBING EVER DEEPER AND EVER OLDER IN GOLEMA PEŠT, NORTH MACEDONIA: PLEISTOCENE SEDIMENTARY ANALYSES FOR ESR DATING UPPER-LOWER PALEOLITHIC DEPOSITS

Paper number: 2-12
Program: Technical Sessions
Time: 3:50 PM – 4:00 PM

Authors

Abstract

Located about 3.5 km from Zdunje, and 65 km SW of Skopje, Golema Pešt hosts the only Middle Paleolithic archaeological site known in Macedonia. In the Treska River Valley, the cave overlooks the reservoir Lake Kozjak. Opening at 460 m amsl, the cave averages ~ 31 m long, and 18 m wide, with a mouth 12 m wide by 3.5 m high. Golema Pešt contains > 21 flatly lying, silty-sandy matrix-supported gravel layers with éboulis clasts reaching > 5.5 m deep. In Sondage 2, Layers 2-6 yielded ~ 6300 Middle Paleolithic artefacts and ~ 4,900 vertebrate fossils, but Upper Paleolithic tools were found in the upper part of Layer 2, and older tools and fauna have been found in Layers 6-20 in Sondage 1. Electron spin resonance (ESR) can date mammalian teeth from ~ 5-10 ka to ~ 2-4 Ma, with ~ 2-5% precision. In caves, accurate ESR ages require accurate sedimentary dose rates, because most layers can contain 2-10 nonhomogenoeusly distributed sedimentary components each with a different dose rate. To estimate the time-averaged sedimentary dose rates, the water concentrations now and in the past must be modelled. To measure the modern water concentrations, 30 sediment samples from Sondage 5, which was opened for the first time in 2019, were gently heated at ~ 50oC to measure the change in sedimentary mass. In Sondage 5, the modern water concentrations ran­ged from 2 wt% to > 22 wt%, depending on the sample's mineralogy. Layer 2b had the highest water concentrations at 18.6 ± 4.4 wt%, but interesting the hearth in Layer 2 had only 2.0 wt% water concentration. To find the individual sedimentary dose rates, > 125 sedimentary samples from Layers 1b-20c in Sondages 1, 2, and 5 were analyzed for their U, by delay neutron counting, and their Th and K concentrations by standard NAA with γ counting. To calculate the volumetrically averaged sedimentary dose rates, the mean individual dose rates for each layer and component were averaged based on their volumetric contribution to the sediment in the sphere around each tooth, using a 3 mm sphere for β, and a 30 cm sphere for γ, radiation. Using these new volumetric sedimentary dose rates allow the calculation of more precise and accurate ESR ages for teeth from Golema Pešt.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-351486

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