GNGTS 2017 - 36° Convegno Nazionale

730 GNGTS 2017 S essione 3.3 magnetization is an important feature of ArchaeoMag , which could be used, in some circumstances, to estimate the age of firing events and help reconstructions of the historical development of a settlement. In fact, when firing is the only event responsible for the acquisition of NRM and it is possible to establish that the artifact has not been moved since that time, we can compare the model NRM declination and inclination with existing master curves of palaeosecular variations, obtaining an age for the magnetization event (e.g., Vigliotti, 2006). Finally, ArchaeoMag allows to export the magnetized blocks as a georeferenced text file that can be subsequently loaded in a GIS and integrated with other data sets for the study area. For example, it is possible to combine or compare magnetization maps with resistivity or GPR data to build an integrated archaeological model. It should be noted that the integration of magnetic anomalies with other geophysical data is not generally a correct procedure, because of the displacement of the objects with respect to the anomaly peaks. Conversely, the exported ArchaeoMag blocks provide a model of true archaeological features in their correct position. Conclusion. In the previous sections, we have presented a new approach to the use of magnetic data in archaeological geophysics, which provides a greater quantity of information and allows an easy integration with other geophysical data. In this approach, total field data are acquired, filtered, and reduced to archaeological anomalies according to standard procedures. Then, an interactive forward modelling software, ArchaeoMag , is used to create and edit magnetization models of buried settlements. In addition, it allows to distinguish between induced and NRM components of magnetization, thereby allowing a fine calibration of the model and possibly a dating of firing events. In the present version, three basic shapes and one composite object can be created using the ArchaeoMag GUI: Dipoles, rectangular prisms, general vertical prisms, and stairways. Each object can have specific magnetization parameters, size, and burial depth. The shapes can be easily edited, moved, rotated, or resized according to a trial–and–error procedure to obtain a better fit of the model anomalies to the observed values. Finally, ArchaeoMag allows to load topographic data, in order to generate model anomalies that can be directly compared with the observed data even in the case of rugged relief. References Bevan B.W.; 2002: The magnetic properties of archaeological materials, Geosight Tech. Report No. 5, 2 nd edition, 13 pp., DOI: 10.13140/RG.2.1.3505.5603. Powell A.J., McDonnell J.G., Batt C.M. & Vernon R.W.; 2002: An assessment of the magnetic response of an iron- smelting site, Archaeometry, 44(4), 651-665. Schettino A., Çondi D., Perna R., Pierantoni P.P. & Ghezzi A.; 2017: Searching for the Antigonea theatre: Amagnetic survey in an ancient Epirus city, Archaeological Prospection, 24, 3–15, DOI: 10.1002/arp.1549. Tabbagh J.; 2003: Total field magnetic prospection: are vertical gradiometer measurements preferable to single sensor survey? Archaeological Prospection, 10(2), 75-81. Vigliotti L.; 2006: Secular variation record of the Earth’s magnetic field in Italy during the Holocene: constraints for the construction of a master curve, Geophys. J. Int., 165(2), 414-429. AMBIGUITÀ PER L’INVERSIONE DELLA SCALING FUNCTION: UN CONFRONTO CON L’INVERSIONE DEL CAMPO DI GRAVITÀ M. Singh Chauhan 1 , M. Fedi 1 , M.l K. Sen 2 1 University Federico II, Napoli 2 The University of Texas, Austin, USA Introduzione. Possiamo distinguere molti tipi di ambiguità nell’interpretazione dei campi di potenziale (ad esempio, Fedi et al. , 2005). Il primo è inerente e deriva dalla terza identità di Green (ad esempio, Blakely, 1996; Parker, 1977). L’ambiguità di campionamento si origina