Radiometric dating geologic time and the age of the earth
Another technological development is the ICP-MS (Inductively Coupled Plasma Mass Spectrometer), which is able to provide the isotopic age of the minerals zircon, titanite, rutile, and monazite.These minerals are common to many igneous and metamorphic rocks.For example, the XRF (X-Ray Fluorescence) spectrometer can quantify the major and trace element abundances of many chemical elements in a rock sample down to parts-per-million concentrations.This geochemical method has been used to differentiate successive stages of igneous rocks in the plate-tectonic cycle.Between 18 he elucidated the complex sequence of chemical reactions attending the precipitation of salts (evaporites) from the evaporation of seawater.Van ’t Hoff’s aim was to explain the succession of mineral salts present in Permian rocks of Germany.At greater depths the temperature effect should become dominant, and response to stress should result in flow rather than fracture of rocks. Rubey, demonstrated that fluids in the pores of rock may reduce internal friction and permit gliding over nearly horizontal planes of the large overthrust blocks associated with folded mountains.More recently the Norwegian petrologist Hans Ramberg performed many experiments with a large centrifuge that produced a negative gravity effect and thus was able to create structures simulating salt domes, which rise because of the relatively low density of the salt in comparison with that of surrounding rocks.
These experiments are carried out at elevated temperatures and pressures that simulate those operating in different levels of Earth’s crust. Bridgman developed a technique for subjecting rock samples to high pressures similar to those deep in the Earth.
Because the rock chips brought up in oil wells are so small, a high-resolution instrument known as a scanning electron microscope had to be developed to study the microfossils.
The classification of microfossils of organisms that lived within relatively short time spans has enabled Mesozoic-Cenozoic sediments to be subdivided in remarkable detail.
A radiometric dating technique that measures the ratio of the rare earth elements neodymium and samarium present in a rock sample was used to produce the estimate.
Also, by extrapolating backward in time to a situation when there was no lead that had been produced by radiogenic processes, a figure of about 4.6 billion years is obtained for the minimum age of the Earth.