HR: 1340h
AN: GP23A-0161    [Abstracts]
TI: Archaeomagnetic studies in Mesoamerica using non-conventional materials
AU: * Soler-Arechalde, A
EM: anesoler@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria s/n, Mexico, DF 04510 Mexico
AU: Gogichaishvili, A
EM: avto@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria s/n, Mexico, DF 04510 Mexico
AU: Urrutia-Fucugauchi, J
EM: juf@geofisica.unam.mx
AF: Instituto de Geofisica, UNAM, Ciudad Universitaria s/n, Mexico, DF 04510 Mexico
AB: For the first time results of an archaeomagnetic study of mural paintings and unburned lime-plasters from Mesoamerica are presented. The magnetic measurements show that at least four murals (sites: Cacaxtla, Cholula and Templo Mayor) retain a remanent magnetization carried by a mixture of hematite and magnetite grains. In most specimens, a characteristic magnetization is successfully isolated by alternating field demagnetization. The mean directions are reasonably well determined for each murals and within the range of secular variation during the last centuries. Studied Mesoamerican murals apparently retain the direction of the magnetic field at the time they were painted and are therefore an invaluable source of information concerning its secular variation. Lime-plaster samples were selected from two archaeological excavation projects in the Teopancazco residential compound of Teotihuacan and the large multi-stage structure of Templo Mayor in Tenochtitlan, where chronological information is available. The intensity of remanent magnetization and low-field susceptibility are weak reflecting low relative content of magnetic minerals. NRM directions are well grouped and alternating field demagnetization shows single or two-component magnetizations. Rock-magnetic experiments point to fine-grained titanomagnetites with pseudo-single domain behavior. Anisotropy of magnetic susceptibility measurements document a depositional fabric, with normal to free-surface minimum AMS axes. Characteristic mean site directions were correlated to the paleosecular variation curve for Mesoamerica. Our results suggest that archaeomagnetic dating can be applied to mural paintings and lime-plasters, which are materials widely employed in Mesoamerica.
DE: 1503 Archeomagnetism
DE: 1522 Paleomagnetic secular variation
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting