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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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Photos showing the location of the luminescence dating samples and the types of deposits investigated at Galería.(a) and (c) show the sampling positions in unit GIII; (b) shows the stratigraphic sequence sampled at Covacha Zarpazos (northern wall); (d) sampling of the upper guano in unit GIIa (level TN2A); (e) and (f) shows sampling of the lower part of unit GIIa (level TG7).
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pone-0110169-g003: Photos showing the location of the luminescence dating samples and the types of deposits investigated at Galería.(a) and (c) show the sampling positions in unit GIII; (b) shows the stratigraphic sequence sampled at Covacha Zarpazos (northern wall); (d) sampling of the upper guano in unit GIIa (level TN2A); (e) and (f) shows sampling of the lower part of unit GIIa (level TG7).

Mentions: Access and permission to collect samples in Atapuerca was granted by the Junta de Castilla y León, Spain. Ten samples were collected from units GI to GIV, as shown in Figure 2b and Figure 3 and Table 1. Units, or lenses within units, dominated by homogenous sandy silts and clays were targeted for sampling. We specifically avoided locations that were affected by cementation, carbonate/calcite growth and (where possible) those with non-homogenous compositions/grain sizes to minimise the potential effects of beta-dose heterogeneity (see Table S1 in File S1 for lithological descriptions of each sample). One sample was collected from unit GIV (AT10-2) and two were collected from GIIIb (ATG10-1 and ATG10-3), within fine silts and clays towards the northern (Zarpazos) side of the profile (Figure 3a, c). During sampling of sub-unit GIIIb, care was taken to avoid layers that were predominantly composed of small limestone gravels and cemented calcitic sands. Specifically, samples ATG10-1 and ATG10-3 were collected from two thin (<10 cm) layers of sandy silts and clays corresponding to GSU 2 and GSU 7, respectively, which intercalate gravelly layers towards the central northern sectors. The base of GIII (GIIIa) was sampled within a massive horizon of homogenous fine silt and clay preserved in the centre of the profile (ATG10-7; Figure 3a). Three samples were collected from GIIa; one from the upper guano layer in sub-unit TN2A, which is underlain directly by red clays and fine silts (ATG10-8; Figure 3d), and another two samples from the base of GIIa within TG7, which is composed of brown/yellow sandy silt and clay (samples ATG10-9 and ATG10-10; Figure 3e-f). Two samples were collected from a level at Zarpazos that lies directly below the archaeo-palaeontological levels at Galería (i.e., below GII) and is stratigraphically correlated as lying at the top of unit GI (samples ATZ10-3 and ATZ10-4; Figure 3b). The upper part of unit GI (GIb) was sampled in the central sector of Galería (sample ATG10-4) within a horizon bracketed by the palaeomagnetic reversal and an overlaying speleothem that has been dated to >350 ka and 318±60 ka by U-series and ESR, respectively.


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)

Photos showing the location of the luminescence dating samples and the types of deposits investigated at Galería.(a) and (c) show the sampling positions in unit GIII; (b) shows the stratigraphic sequence sampled at Covacha Zarpazos (northern wall); (d) sampling of the upper guano in unit GIIa (level TN2A); (e) and (f) shows sampling of the lower part of unit GIIa (level TG7).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0110169-g003: Photos showing the location of the luminescence dating samples and the types of deposits investigated at Galería.(a) and (c) show the sampling positions in unit GIII; (b) shows the stratigraphic sequence sampled at Covacha Zarpazos (northern wall); (d) sampling of the upper guano in unit GIIa (level TN2A); (e) and (f) shows sampling of the lower part of unit GIIa (level TG7).
Mentions: Access and permission to collect samples in Atapuerca was granted by the Junta de Castilla y León, Spain. Ten samples were collected from units GI to GIV, as shown in Figure 2b and Figure 3 and Table 1. Units, or lenses within units, dominated by homogenous sandy silts and clays were targeted for sampling. We specifically avoided locations that were affected by cementation, carbonate/calcite growth and (where possible) those with non-homogenous compositions/grain sizes to minimise the potential effects of beta-dose heterogeneity (see Table S1 in File S1 for lithological descriptions of each sample). One sample was collected from unit GIV (AT10-2) and two were collected from GIIIb (ATG10-1 and ATG10-3), within fine silts and clays towards the northern (Zarpazos) side of the profile (Figure 3a, c). During sampling of sub-unit GIIIb, care was taken to avoid layers that were predominantly composed of small limestone gravels and cemented calcitic sands. Specifically, samples ATG10-1 and ATG10-3 were collected from two thin (<10 cm) layers of sandy silts and clays corresponding to GSU 2 and GSU 7, respectively, which intercalate gravelly layers towards the central northern sectors. The base of GIII (GIIIa) was sampled within a massive horizon of homogenous fine silt and clay preserved in the centre of the profile (ATG10-7; Figure 3a). Three samples were collected from GIIa; one from the upper guano layer in sub-unit TN2A, which is underlain directly by red clays and fine silts (ATG10-8; Figure 3d), and another two samples from the base of GIIa within TG7, which is composed of brown/yellow sandy silt and clay (samples ATG10-9 and ATG10-10; Figure 3e-f). Two samples were collected from a level at Zarpazos that lies directly below the archaeo-palaeontological levels at Galería (i.e., below GII) and is stratigraphically correlated as lying at the top of unit GI (samples ATZ10-3 and ATZ10-4; Figure 3b). The upper part of unit GI (GIb) was sampled in the central sector of Galería (sample ATG10-4) within a horizon bracketed by the palaeomagnetic reversal and an overlaying speleothem that has been dated to >350 ka and 318±60 ka by U-series and ESR, respectively.

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