Abstract
In this preliminary work a paleontological search method, based on the geophysical methodology known as Ground Penetrating Radar (GPR), is described. GPR is a non-destructive methodology and it uses, for the localisation of buried structures, short time duration electromagnetic (EM) pulses lasting from about 1 ns to about 30 ns. Therefore it is characterised by a wide frequencies band ranging from 10 MHz to some GHz. Such a methodology results to be useful in the localisation of the EM discontinuities in the subsurface with high resolution. The geophysical investigation was undertaken with the purpose of verifing the resolution capability of the GPR technique for the location of paleontological finds with consequent saving in both excavation time and costs. In this paper the results of some tests carried out on biomicrite samples (with known position of the fossils) are reported. The tests have been performed on three biomicrite samples: ! glauconitic biomicrite, which is a variety of the Pietra Leccese, with a fragment of Cetotheride maxillary (Cetacea – Mysticete); ! biomicrite with cetacean vertebrae (Scaldiceto); ! normal biomicrite with part of Psephophorus Poligonus (Chelonide); all the samples date from the Middle Upper Miocene. Due to the samples thickness, it has been necessary to use antennae with frequencies of 1000 MHz and 1500 MHz, with particular attention on the data acquisition (parameters and geometries of acquisition). The data were visualized in 3D space not only by the standard time slice technique, but also by the iso-amplitude surface of the complex trace amplitude. The immediacy in revealing the spatial position of highly reflecting bodies, such as the anomaly related to the fossil remains in the tests on the samples, makes 3D visualization technique very attractive in paleontological applications of GPR. The results obtained from the different situations encountered in this work are very interesting. The satisfactory performance of the GPR method in the paleontological research is confirmed. Introduction The opportunity to find underground structures, such as fossil remains, is particularly stimulating for paleontoligists, in order to work in wide areas, where the existance of those remains is just an hypothesis. The GPR is a fast and cost-effective electromagnetic (EM) method which, in favourable conditions, i.e. mainly resistive non-magnetic environments, can provide valuable information on the shallow subsurface. Since it is based on the propagation and reflection of EM waves, it is sensitive to variations of the EM parameters in the subsoil, expecially the dielectric constant and the electric conductivity (Davis and Annan, 1989). Despite its relatively low penetration depth (expecially with high-frequency antennae and in moderately conductive environments), the GPR resolution capability (also depending on frequency and soil properties), by far greater than that obtained by other geophysical methods, makes this technique suitable for high-resolution shallow studies like archaeological applications and shallow stratigraphy mapping. The advantages to use the GPR technique for the finding of archeologically and geologically interesting underground structures have already been exposed by several authors (D. G. Smith et
Published Version
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