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New luminescence ages for the Galería Complex archaeological site: resolving chronological uncertainties on the acheulean record of the Sierra de Atapuerca, northern Spain.

Demuro M, Arnold LJ, Parés JM, Pérez-González A, Ortega AI, Arsuaga JL, Bermúdez de Castro JM, Carbonell E - PLoS ONE (2014)

Bottom Line: For the majority of samples dated, however, the new luminescence ages are significantly (∼50%) younger than previously published polymineral thermoluminescence (TL) chronologies, suggesting that the latter may have overestimated the true burial age of the Galería deposits.Galería Complex may be correlative with other Middle Pleistocene sites from Atapuerca, such as Gran Dolina level TD10 and unit TE19 from Sima del Elefante, but the lowermost archaeological horizons are ∼100 ka younger than the hominin-bearing clay breccias at the Sima de los Huesos site.Our results suggest that both pIR-IR and single-grain TT-OSL dating are suitable for resolving Middle Pleistocene chronologies for the Sierra de Atapuerca karstic infill sequences.

View Article: PubMed Central - PubMed

Affiliation: Institute for Photonics and Advanced Sensing, School of Chemistry and Physics, The University of Adelaide, Adelaide, Australia; Centro Nacional de Investigación sobre la Evolución Humana, Burgos, Spain.

ABSTRACT
The archaeological karstic infill site of Galería Complex, located within the Atapuerca system (Spain), has produced a large faunal and archaeological record (Homo sp. aff. heidelbergensis fossils and Mode II lithic artefacts) belonging to the Middle Pleistocene. Extended-range luminescence dating techniques, namely post-infrared infrared stimulated luminescence (pIR-IR) dating of K-feldspars and thermally transferred optically stimulated luminescence (TT-OSL) dating of individual quartz grains, were applied to fossil-bearing sediments at Galería. The luminescence dating results are in good agreement with published chronologies derived using alternative radiometric dating methods (i.e., ESR and U-series dating of bracketing speleothems and combined ESR/U-series dating of herbivore teeth), as well as biochronology and palaeoenvironmental reconstructions inferred from proxy records (e.g., pollen data). For the majority of samples dated, however, the new luminescence ages are significantly (∼50%) younger than previously published polymineral thermoluminescence (TL) chronologies, suggesting that the latter may have overestimated the true burial age of the Galería deposits. The luminescence ages obtained indicate that the top of the basal sterile sands (GIb) at Galería have an age of up to ∼370 thousand years (ka), while the lowermost sub-unit containing Mode II Acheulean lithics (base of unit GIIa) was deposited during MIS 9 (mean age = 313±14 ka; n = 4). The overlying units GIIb-GIV, which contain the richest archaeopalaeontological remains, were deposited during late MIS 8 or early MIS 7 (∼240 ka). Galería Complex may be correlative with other Middle Pleistocene sites from Atapuerca, such as Gran Dolina level TD10 and unit TE19 from Sima del Elefante, but the lowermost archaeological horizons are ∼100 ka younger than the hominin-bearing clay breccias at the Sima de los Huesos site. Our results suggest that both pIR-IR and single-grain TT-OSL dating are suitable for resolving Middle Pleistocene chronologies for the Sierra de Atapuerca karstic infill sequences.

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Selected examples of dose-response curves and signal decay curves.(a-d) TT-OSL single-grain measurements and (e-f) pIR-IR225 measurements of the Galería samples.
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pone-0110169-g004: Selected examples of dose-response curves and signal decay curves.(a-d) TT-OSL single-grain measurements and (e-f) pIR-IR225 measurements of the Galería samples.

Mentions: Representative TT-OSL decay curves and sensitivity-corrected dose-response curves are shown in Figure 4a-d for two accepted grains from unit GIIIa (sample ATG10-7). These two grains were measured from the same single-grain disc but display very different luminescence sensitivities; one has a relatively bright TT-OSL signal (Tn intensity >1500 cts/0.02 s) (Figure 4d), while the other displays a dimmer Tn luminescence intensity of ∼200 cts/0.02 s (Figure 4b). The latter is representative of the majority of grains measured for these samples. In both cases, the TT-OSL signals decay rapidly to background and the dose-responses are well represented by a single-saturating exponential function (Figure 4a, c). Samples collected from the lowermost units at Galería, i.e., unit GI (ATG10-4), layer TG7 at the base of GIIa (ATG10-9 and ATG10-10) and the base of TZ (ATZ10-4), display distinctly different TT-OSL brightness characteristics. Further details of these differences are provided in the Supporting Information. The dose-saturation properties of the accepted grains permit finite De determination over very high dose ranges. A pooled distribution of characteristic saturation dose (D0) values for the accepted grains of all nine samples is shown in Figure S3 in File S1. Grains with dose-response curves that are best characterised by a single saturating exponential function (n = 270) yielded D0 values ranging between 250 Gy and 10,000 Gy. Additionally, ∼23% of the accepted grains produced linear dose-response curves over the administered dose range (highest dose-point  = 900–1200 Gy). All of the accepted grains had De values that are lower than their corresponding 2*D0 value; i.e., they are well below the commonly cited threshold for precise burial dose determination.


New luminescence ages for the Galería Complex archaeological site: resolving chronological uncertainties on the acheulean record of the Sierra de Atapuerca, northern Spain.

Demuro M, Arnold LJ, Parés JM, Pérez-González A, Ortega AI, Arsuaga JL, Bermúdez de Castro JM, Carbonell E - PLoS ONE (2014)

Selected examples of dose-response curves and signal decay curves.(a-d) TT-OSL single-grain measurements and (e-f) pIR-IR225 measurements of the Galería samples.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206284&req=5

pone-0110169-g004: Selected examples of dose-response curves and signal decay curves.(a-d) TT-OSL single-grain measurements and (e-f) pIR-IR225 measurements of the Galería samples.
Mentions: Representative TT-OSL decay curves and sensitivity-corrected dose-response curves are shown in Figure 4a-d for two accepted grains from unit GIIIa (sample ATG10-7). These two grains were measured from the same single-grain disc but display very different luminescence sensitivities; one has a relatively bright TT-OSL signal (Tn intensity >1500 cts/0.02 s) (Figure 4d), while the other displays a dimmer Tn luminescence intensity of ∼200 cts/0.02 s (Figure 4b). The latter is representative of the majority of grains measured for these samples. In both cases, the TT-OSL signals decay rapidly to background and the dose-responses are well represented by a single-saturating exponential function (Figure 4a, c). Samples collected from the lowermost units at Galería, i.e., unit GI (ATG10-4), layer TG7 at the base of GIIa (ATG10-9 and ATG10-10) and the base of TZ (ATZ10-4), display distinctly different TT-OSL brightness characteristics. Further details of these differences are provided in the Supporting Information. The dose-saturation properties of the accepted grains permit finite De determination over very high dose ranges. A pooled distribution of characteristic saturation dose (D0) values for the accepted grains of all nine samples is shown in Figure S3 in File S1. Grains with dose-response curves that are best characterised by a single saturating exponential function (n = 270) yielded D0 values ranging between 250 Gy and 10,000 Gy. Additionally, ∼23% of the accepted grains produced linear dose-response curves over the administered dose range (highest dose-point  = 900–1200 Gy). All of the accepted grains had De values that are lower than their corresponding 2*D0 value; i.e., they are well below the commonly cited threshold for precise burial dose determination.

Bottom Line: For the majority of samples dated, however, the new luminescence ages are significantly (∼50%) younger than previously published polymineral thermoluminescence (TL) chronologies, suggesting that the latter may have overestimated the true burial age of the Galería deposits.Galería Complex may be correlative with other Middle Pleistocene sites from Atapuerca, such as Gran Dolina level TD10 and unit TE19 from Sima del Elefante, but the lowermost archaeological horizons are ∼100 ka younger than the hominin-bearing clay breccias at the Sima de los Huesos site.Our results suggest that both pIR-IR and single-grain TT-OSL dating are suitable for resolving Middle Pleistocene chronologies for the Sierra de Atapuerca karstic infill sequences.

View Article: PubMed Central - PubMed

Affiliation: Institute for Photonics and Advanced Sensing, School of Chemistry and Physics, The University of Adelaide, Adelaide, Australia; Centro Nacional de Investigación sobre la Evolución Humana, Burgos, Spain.

ABSTRACT
The archaeological karstic infill site of Galería Complex, located within the Atapuerca system (Spain), has produced a large faunal and archaeological record (Homo sp. aff. heidelbergensis fossils and Mode II lithic artefacts) belonging to the Middle Pleistocene. Extended-range luminescence dating techniques, namely post-infrared infrared stimulated luminescence (pIR-IR) dating of K-feldspars and thermally transferred optically stimulated luminescence (TT-OSL) dating of individual quartz grains, were applied to fossil-bearing sediments at Galería. The luminescence dating results are in good agreement with published chronologies derived using alternative radiometric dating methods (i.e., ESR and U-series dating of bracketing speleothems and combined ESR/U-series dating of herbivore teeth), as well as biochronology and palaeoenvironmental reconstructions inferred from proxy records (e.g., pollen data). For the majority of samples dated, however, the new luminescence ages are significantly (∼50%) younger than previously published polymineral thermoluminescence (TL) chronologies, suggesting that the latter may have overestimated the true burial age of the Galería deposits. The luminescence ages obtained indicate that the top of the basal sterile sands (GIb) at Galería have an age of up to ∼370 thousand years (ka), while the lowermost sub-unit containing Mode II Acheulean lithics (base of unit GIIa) was deposited during MIS 9 (mean age = 313±14 ka; n = 4). The overlying units GIIb-GIV, which contain the richest archaeopalaeontological remains, were deposited during late MIS 8 or early MIS 7 (∼240 ka). Galería Complex may be correlative with other Middle Pleistocene sites from Atapuerca, such as Gran Dolina level TD10 and unit TE19 from Sima del Elefante, but the lowermost archaeological horizons are ∼100 ka younger than the hominin-bearing clay breccias at the Sima de los Huesos site. Our results suggest that both pIR-IR and single-grain TT-OSL dating are suitable for resolving Middle Pleistocene chronologies for the Sierra de Atapuerca karstic infill sequences.

Show MeSH
Related in: MedlinePlus