TY - JOUR

T1 - Geochemical signatures of soapstones from the Nuuk area, southern West Greenland – their use for fingerprinting of archaeological artefacts

AU - Keulen, Nynke

AU - Poulsen, Majken D.

AU - Frei, Robert

N1 - Funding Information: Fieldwork and geochemical analyses were paid by Geocenter Bevilling 2016/12. Rebekka Knudsen, Kisser Thors?e, Morten Meldgaard, and others at GEUS Nuuk are thanked for discussions. Mikkel Myrup and Bo Albrechtsen gave an excellent introduction into the archaeological history of soapstone in the Nuuk area. We were inspired by the earlier SOAP project and discussions with Martin Appelt to apply for this project. The Greenlandic Ministry of Mineral Resources is gratefully acknowledged for organising the small-scale mining workshop that let to this project. H.-C. Olsen is thanked for discussion of Nuuks soapstone occurrences. Olga Nielsen and Toni Larsen are cordially thanked for laboratory support. Toby Leeper is acknowledged for keeping the mass spectrometers in perfect running conditions and for help in the mass spectrometrical analyses of the samples. Sara Salehi, Simon M. Thaarup, Henrik Stendal, and Mikkel Myrup for collecting or donating samples. Matthias Husted assisted in digitizing the literature data collection. We thank the editor Marcos Martin?n-Torres and two anonymous reviewers for the constructive comments provided that improved an earlier version of this manuscript. Publisher Copyright: © 2022 Elsevier Ltd

PY - 2022/4

Y1 - 2022/4

N2 - Soapstone was mined and traded by the Palaeo- and Neo-Eskimo cultures (Saqqaq, Dorset, and Thule) as well as the Norse and Moravian cultures living in Greenland through time. We collected soapstone from outcrops around Nuuk, which hold large quantities of Greenland's high-quality soapstone, and analysed their whole-rock geochemistry, Sm–Nd and Rb–Sr isotopes for fingerprinting geological and archaeological purposes. Fieldwork showed that the quality of soapstone in the Nuuk area varies widely; however, a correlation exists with the age and metamorphic history of the rocks. Soapstone in the Nuuk area is derived from Archaean ultramafic rocks and yield high Mg, Cr, Ni and low Fe, V, K concentrations and are depleted in Ca. Soapstones from Nuuk have very high Rb concentrations and average to low Sr concentrations compared to other Archaean ultramafic rocks, leading to very high and irregular 87Rb/86Sr and 87Sr/86Sr ratios. A very poorly constrained Rb–Sr errorchron for unmetasomatised samples from the Nuuk area has a slope corresponding to an age of 3.05 ± 0.33 Ga. Soapstone samples from Nuuk, both affected and unaffected by metasomatism give a147Sm/144Nd isochron age of 2.95 ± 0.06 Ga. This is regarded as the age of metsomatism, and tectono-metamorphic overprinting, which affected the precursors to the soapstone. The best quality soapstones occur in the areas dominated by Eoarchaean gneisses. The ca. 2.95 Ga overprinting is uncommonly old for soapstones worldwide. Soapstone, and hence archaeological artefacts created from this soapstone, may likely be fingerprinted to the Nuuk area.

AB - Soapstone was mined and traded by the Palaeo- and Neo-Eskimo cultures (Saqqaq, Dorset, and Thule) as well as the Norse and Moravian cultures living in Greenland through time. We collected soapstone from outcrops around Nuuk, which hold large quantities of Greenland's high-quality soapstone, and analysed their whole-rock geochemistry, Sm–Nd and Rb–Sr isotopes for fingerprinting geological and archaeological purposes. Fieldwork showed that the quality of soapstone in the Nuuk area varies widely; however, a correlation exists with the age and metamorphic history of the rocks. Soapstone in the Nuuk area is derived from Archaean ultramafic rocks and yield high Mg, Cr, Ni and low Fe, V, K concentrations and are depleted in Ca. Soapstones from Nuuk have very high Rb concentrations and average to low Sr concentrations compared to other Archaean ultramafic rocks, leading to very high and irregular 87Rb/86Sr and 87Sr/86Sr ratios. A very poorly constrained Rb–Sr errorchron for unmetasomatised samples from the Nuuk area has a slope corresponding to an age of 3.05 ± 0.33 Ga. Soapstone samples from Nuuk, both affected and unaffected by metasomatism give a147Sm/144Nd isochron age of 2.95 ± 0.06 Ga. This is regarded as the age of metsomatism, and tectono-metamorphic overprinting, which affected the precursors to the soapstone. The best quality soapstones occur in the areas dominated by Eoarchaean gneisses. The ca. 2.95 Ga overprinting is uncommonly old for soapstones worldwide. Soapstone, and hence archaeological artefacts created from this soapstone, may likely be fingerprinted to the Nuuk area.

KW - Eoarchaean

KW - Geoarchaeology

KW - Godthåbsfjord (Nuup Kangerlua)

KW - Provenance

KW - Rb–Sr isotope Geochemistry

KW - Sm/Nd isochron age

KW - Steatite/soapstone

U2 - 10.1016/j.jas.2022.105552

DO - 10.1016/j.jas.2022.105552

M3 - Journal article

AN - SCOPUS:85124528133

VL - 140

JO - Journal of Archaeological Science

JF - Journal of Archaeological Science

SN - 0305-4403

M1 - 105552

ER -