Geochronology

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[Technique]----Geochronology has been applied to rocks since the beginning of the 19th century to date rocks formation (e.g. Holmes, 1913). The thermal effects on radioisotopic ages were recognized a few decades later (Hurley, 1954). Using this fundamental discovery, the concept of comparing dates constrained with different radiometric techniques the cooling history of rocks was intuited starting from the early 1960s in few interesting pioneering work both in the Alps (Amstrong et al., 1966) and the Himalaya (Krummenacher, 1961). Armstrong et al., (1966), used Rb-Sr and K-Ar on biotite, white mica, and sanidine minerals to define their ages as the time of the cooling of the rocks during Alpine metamorphism. They also predicted, using different isotopic systems with two different closure temperatures, how the two system can be different and can be used to infer the rate of cooling of a certain region. Later, a work by Wagner et al.(1979), used apatite fission tracks data to constrain the exhumation rate of the Bergell intrusive body (Central Alps) and to recursively restore the original position of a set of boulders found in the Po plain (Italy), eroded during late Oligocene.[Extracting erosion and exhumation patterns from detrital thermochronology: an example from the eastern Himalaya. VU, Amsterdam PhD Manuscipt by Gemignani, L., 2018].