Link between Petrology and Chronology

Meaning of chronological data for petrological studies was reviewed. Mizutani and Shibata (1983) estimated duration of lithification after initial deposition of sediment as 17 million years using a combination of radiolarian fossil and 87Rb-87Sr whole rock isochron ages. Harayama (1992) reported a youngest exposed granitoid pluton on Earth from the Northern Alps, central Japan, based on the K-Ar hornblende and biotite ages， Rb-Sr biotite age，and fission track zircon age. Metamorphic rocks generally record ages of many equilibrium stages during metamorphic evolution. Katayama (2004) confirmed five stages of zircon growth in ultra-high pressure metamorphic rocks from the Kokchetav massif，and estimated their exhumation speed as 0.5-0.6 cm/year using Secondary Ion Mass Spectrometry.
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