Quaternary International. 2016, V. 414, p. 244-257
Fecha de publicación :
Recent archaeomagnetic studies carried out on Mid-to Late Holocene burnt anthropogenic cave sediments
have shown that under certain conditions, these materials are suitable geomagnetic field recorders.
Archaeomagnetic analyses carried out on these contexts constitute a rich source of information
not only for geophysical purposes -in terms of reconstructing the variation of Earth's magnetic field in
the past- but also from the archaeological point of view, for example by archaeomagnetic dating. Here,
we report three different archaeomagnetic applications to the study of burnt cave sediments: (i)
archaeomagnetic dating; (ii) determining palaeotemperatures and (iii) assessing post-depositional
processes. The first case study is a dating attempt carried out on a Late Holocene (Bronze Age) burnt
level from El Mirador Cave (Burgos, Spain). Using the directional European secular variation curve,
several dating intervals were obtained for the last burning of this combustion feature. Considering the
archaeological evidence and the independent radiometric (14C) dating available the possible ages obtained
are discussed. This is the first archaeomagnetic dating obtained in these contexts so far. The
second case study is an application of the method to determine the last heating temperatures reached by
the carbonaceous facies of these fires. Stepwise thermal demagnetization of oriented samples can be
used to quantitatively estimate heating temperatures. An intermediate normal polarity component
interpreted as a partial thermo-remanence (pTRM) with maximum unblocking temperatures of 400
e450 C was systematically identified, revealing the last heating temperatures experienced by this facies.
These temperatures were confirmed with partial thermomagnetic curve experiments. Finally, archaeomagnetic
analyses on a partially bioturbated burning event were performed in order to evaluate until
what spatial extent the burnt sediments were affected by post-depositional mechanical alteration processes.
For each case study, the archaeological implications are discussed highlighting the potential of
archaeomagnetic methods to retrieve archaeological information.
Fumiers Holocene Thermoremanent magnetization Secular variation Ashes Bronze Age