Laboratory Details

Ar-Ar Geochronology Laboratory - Pisa

Time is a fundamental parameter in the earth sciences whose knowledge is essential for estimating the length and rate of geological processes. The 40Ar-39Ar method, variant of the K-Ar method, is based on the radioactive decay of the naturally occurring parent 40K (half-life 1.25 Ga) to the daughter 40Ar over geological time.

The 40Ar-39Ar method, applied to K-bearing systems (minerals or glass), represents one of the most powerful geochronological tools currently available to constrain the timing of geological processes. It can be applied to a wide range of geological problems and to rocks ranging in age from a few thousand years to the oldest rocks available.

The development of the laser extraction technique has expanded fields of application, including among others: (1) the study of the relationship between mineral-textural information and Ar isotope records in minerals; (2) dating fault-generated and impact-related pseudotachylytes; (3) dating deformation; (4) the study of the provenance of detrital phases in clastic sediments; (5) dating the recent past (as young as Pleistocene to Holocene) by analyzing high-potassium volcanogenic minerals; (6) dating clay minerals from sediments and shallow faults; (7) direct measurements of argon diffusion in minerals and of argon partition coefficients between minerals and silicate melts.

In the recent years, improved precision thanks to a new generation of multi-collector noble gas mass spectrometers, together with the development of new detectors, generated a renewed and growing interest in the 40Ar-39Ar dating technique. Recent instrumental advances allow geochronological analyses on increasingly smaller samples, with improved analytical precision, up to an order of magnitude. A new generation noble gas mass spectrometer has recently been installed at the 40Ar–39Ar Geochronology Laboratory of the Instituto di Geoscience e Georisorse (https://www.youtube.com/watch?v=B0I5xxzX-qY).