The INGV Paleomagnetism Laboratory is located in the Rome branch in Via di Vigna Murata, 605. Inside, by measuring the magnetic properties of rocks, information is acquired on the characteristics of the earth's magnetic field over the course of the geological past, with a considerable variety of geodynamic, stratigraphic, environmental and volcanic applications. We asked Aldo Winkler, head of the Paleomagnetism Laboratory, to explain the research activities and the main instruments used within the Lab.
When was the laboratory born?
The first instruments were set up at the L'Aquila headquarters starting from 1990, where they remained until 1991. Between 1992 and 1993, a magnetically shielded room was designed and built at the Rome headquarters, where the laboratory was gradually transferred and expanded. The current configuration of the room was achieved in 2006, with a shielded volume of 50 m3, suitable for hosting two cryogenic magnetometers.
What is Paleomagnetism?
Paleomagnetism is a very versatile geophysical discipline, which deals with the study of the "fossil" magnetization of rocks; it provided crucial evidence for the seafloor spreading hypothesis, proving the theory of plate tectonics.
What are its applications?
Historically, among its best-known applications, we can mention the discovery of the inversions of the earth's magnetic field, as well as the reconstruction of the displacement undergone by the lithospheric plates over the course of geological times.
Currently, the activities we carry out in the laboratory mainly concern the study of marine and lake cores for paleoclimatic and magnetostratigraphic investigations, the integrated analysis of paleomagnetic, tectonic and geophysical data to reconstruct the evolution of mountain ranges, the reconstruction of variations in the earth's magnetic field during its periods of instability (excursions, polarity reversals), the paleomagnetic dating of lavas and ignimbrites produced by active volcanoes and the study of the magnetic properties of atmospheric fine particles.
What activities do you carry out in the laboratory?
The rock samples, acquired during the sampling phases, are measured, treated and analyzed in the laboratory set up in the room shielded from static magnetic fields, which makes it possible to reduce the intensity of the magnetic field inside it down to a few thousandths of the earth's magnetic field local, equal to about 45.000 nanoTesla (nT).
The shielded room houses two cryogenic magnetometers and all the instruments that must operate without the influence of magnetic fields; this instrumentation is further shielded with particular metals suitable for insulating them also from variable magnetic fields. Other instruments, which do not require shielding, are housed outside the shielded room and in another room belonging to the laboratory.
What are the main tools you use?
Among the main instruments used in the Paleomagnetism Laboratory of the INGV are the two cryogenic magnetometers with DC SQUID sensors, to measure and progressively demagnetize the remaining magnetization of discrete and continuous paleomagnetic samples, the ovens for the thermal demagnetization of rock samples, with maximum applicable temperature 700°C, and magnetic susceptibility meters, its anisotropy and its variability with the temperature and the applied magnetic field.