Fire conditions and source materials recorded in scoria from an intentional fire at Store Tovstrup Iron Age house, Central Jutland, Denmark

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Fire conditions and source materials recorded in scoria from an intentional fire at Store Tovstrup Iron Age house, Central Jutland, Denmark. / Thy, Peter; Barfod, Gry H.; Christensen, Lotte Bach; Hansen, Astrid Skou.

In: Journal of Archaeological Science: Reports, Vol. 21, 10.2018, p. 702-711.

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Thy, Peter ; Barfod, Gry H. ; Christensen, Lotte Bach ; Hansen, Astrid Skou. / Fire conditions and source materials recorded in scoria from an intentional fire at Store Tovstrup Iron Age house, Central Jutland, Denmark. In: Journal of Archaeological Science: Reports. 2018 ; Vol. 21. pp. 702-711.

Bibtex

@article{44fa769a1068464fa5ff0e34c6043f98,
title = "Fire conditions and source materials recorded in scoria from an intentional fire at Store Tovstrup Iron Age house, Central Jutland, Denmark",
abstract = "The composition, mineralogy, and textures preserved in scoria from ancient fires provide constraints on the firing temperature, the source and nature of the fire, and its potential social and cultural implications. Analyses of four scoria fragments preserved in a posthole of an Iron Age longhouse at Store Tovstrup, West Denmark, by scanning electron microscopy, electron microprobe, and laser ablation ICP-MS show these to consist of rounded quartz and orthoclase grains, gas vesicles, and carbonaceous material bonded together by a silicate- and potassium-rich (SiO2 67–69 wt{\%} and K2O 11–14 wt{\%}) melt (now glass). Given the presence of vesicles and carbonaceous material, the fire is indicated to have occurred under restricted air-flow and to have involved decomposition of biomass and soil. The initiation of melting occurred during what was presumably an event of short duration. Simplified ternary phase equilibria point to localized melting initiated around 700–800 °C and continuing to about 1000 °C. The main structure succumbed to char at lower temperatures. Calculations suggest that a mixture of 50{\%} sandy soil, 41{\%} barley straw, and 9{\%} oak branches best explains the low Al2O3, Fe2O3, and Na2O concentrations in the melt phase. The scoria at Store Tovstrup most likely originated from a short duration burning with restricted air-flow resulting in the collapse and charring of daub walls. The fire was intentional and set after the house had been cleared of household goods.",
keywords = "Burning, Central Jutland, Daub composition, Geochemistry, Pre-Roman longhouse, Silicate scoria, Temperature",
author = "Peter Thy and Barfod, {Gry H.} and Christensen, {Lotte Bach} and Hansen, {Astrid Skou}",
year = "2018",
month = "10",
doi = "10.1016/j.jasrep.2018.08.032",
language = "English",
volume = "21",
pages = "702--711",
journal = "Journal of Archaeological Science: Reports",
issn = "2352-409X",
publisher = "Elsevier BV",

}

RIS

TY - JOUR

T1 - Fire conditions and source materials recorded in scoria from an intentional fire at Store Tovstrup Iron Age house, Central Jutland, Denmark

AU - Thy, Peter

AU - Barfod, Gry H.

AU - Christensen, Lotte Bach

AU - Hansen, Astrid Skou

PY - 2018/10

Y1 - 2018/10

N2 - The composition, mineralogy, and textures preserved in scoria from ancient fires provide constraints on the firing temperature, the source and nature of the fire, and its potential social and cultural implications. Analyses of four scoria fragments preserved in a posthole of an Iron Age longhouse at Store Tovstrup, West Denmark, by scanning electron microscopy, electron microprobe, and laser ablation ICP-MS show these to consist of rounded quartz and orthoclase grains, gas vesicles, and carbonaceous material bonded together by a silicate- and potassium-rich (SiO2 67–69 wt% and K2O 11–14 wt%) melt (now glass). Given the presence of vesicles and carbonaceous material, the fire is indicated to have occurred under restricted air-flow and to have involved decomposition of biomass and soil. The initiation of melting occurred during what was presumably an event of short duration. Simplified ternary phase equilibria point to localized melting initiated around 700–800 °C and continuing to about 1000 °C. The main structure succumbed to char at lower temperatures. Calculations suggest that a mixture of 50% sandy soil, 41% barley straw, and 9% oak branches best explains the low Al2O3, Fe2O3, and Na2O concentrations in the melt phase. The scoria at Store Tovstrup most likely originated from a short duration burning with restricted air-flow resulting in the collapse and charring of daub walls. The fire was intentional and set after the house had been cleared of household goods.

AB - The composition, mineralogy, and textures preserved in scoria from ancient fires provide constraints on the firing temperature, the source and nature of the fire, and its potential social and cultural implications. Analyses of four scoria fragments preserved in a posthole of an Iron Age longhouse at Store Tovstrup, West Denmark, by scanning electron microscopy, electron microprobe, and laser ablation ICP-MS show these to consist of rounded quartz and orthoclase grains, gas vesicles, and carbonaceous material bonded together by a silicate- and potassium-rich (SiO2 67–69 wt% and K2O 11–14 wt%) melt (now glass). Given the presence of vesicles and carbonaceous material, the fire is indicated to have occurred under restricted air-flow and to have involved decomposition of biomass and soil. The initiation of melting occurred during what was presumably an event of short duration. Simplified ternary phase equilibria point to localized melting initiated around 700–800 °C and continuing to about 1000 °C. The main structure succumbed to char at lower temperatures. Calculations suggest that a mixture of 50% sandy soil, 41% barley straw, and 9% oak branches best explains the low Al2O3, Fe2O3, and Na2O concentrations in the melt phase. The scoria at Store Tovstrup most likely originated from a short duration burning with restricted air-flow resulting in the collapse and charring of daub walls. The fire was intentional and set after the house had been cleared of household goods.

KW - Burning

KW - Central Jutland

KW - Daub composition

KW - Geochemistry

KW - Pre-Roman longhouse

KW - Silicate scoria

KW - Temperature

U2 - 10.1016/j.jasrep.2018.08.032

DO - 10.1016/j.jasrep.2018.08.032

M3 - Journal article

VL - 21

SP - 702

EP - 711

JO - Journal of Archaeological Science: Reports

JF - Journal of Archaeological Science: Reports

SN - 2352-409X

ER -