GEOTHERMOMETRY GEOBAROMETRY PARAGENESIS ZONING DATING OF MINERALS. The estimation of the temperature of formation of a mineral or a mineral assemblage is called geothermometry.Download Now An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.Since parent uranium atoms change into daughter atoms with time at a known rate, their relative abundance leads directly to the absolute age of the host mineral.Just as the use of the fossil record has allowed a precise definition of geologic processes in approximately the past 600 million years, absolute ages allow correlations back to Earth’s oldest known rocks formed more than 4 billion years ago.In fact, even in younger rocks, absolute dating is the only way that the fossil record can be calibrated.Without absolute ages, investigators could only determine which fossil organisms lived at the same time and the relative order of their appearance in the correlated sedimentary rock record.When these regions are later exposed in uptilted portions of ancient continents, a history of terrestrial rock-forming events can be deduced.Episodes of global volcanic activity, rifting of continents, folding, and metamorphism are defined by absolute ages.
Similarly, in geology, if distinctive granitic pebbles can be found in the sediment beside a similar granitic body, it can be inferred that the granite, after cooling, had been uplifted and eroded and therefore was not injected into the adjacent rock sequence.
Any feature, including colour variations, textures, fossil content, mineralogy, or any unusual combinations of these can be used.
It is only by correlations that the conditions on different parts of Earth at any particular stage in its history can be deduced.
Although with clever detective work many complex time sequences or relative ages can be deduced, the ability to show that objects at two separated sites were formed at the same time requires additional information.
A coin, vessel, or other common artifact could link two archaeological sites, but the possibility of recycling would have to be considered.