APPLICATION OF ISOTOPE GEOCHEMISTRY IN GEOSCIENCE

APPLICATION OF ISOTOPE GEOCHEMISTRY IN GEOSCIENCE

Isotopes do not fractionate during partial melting or fractional crystallization processes. So they will reflect the characteristics of the mantle source. Isotope geochemistry is an aspect of geology based upon study of the natural variations in the relative abundances of isotopes of various elements. While stable isotope geochemistry, is concerned with variation of the isotropic compositions of light elements arising from chemical fractionations rather than nuclear processes.

Isotope geochemistry; low temperature application:

The isotropic composition of a given element in living tissue depends on the source of that element like atmospheric CO₂ versus dissolved CO₂, seawater O₂ versus meteoric water O₂. The isotropic composition of fossil material will depend on any isotropic changes associated with diagenesis, included microbial decomposition. In this point, how this way is inverted to provide insights into the food sources of fossil organisms including man will be show. Low temperature application shows that isotope ratios of carbon and nitrogen are fractionated during primary production of organic matter. This application showed that the relationship between the isotropic geochemistry related to the geoscience or geology. Where is the application used into the rocks to find the fossil.

Isotope geochemistry; high temperature application:

Stable isotopes have a number of uses in high temperature geochemistry such as igneous and metamorphic geochemistry. This application used of the temperature dependency of fractionation factors. The translational and rotation contributions to the partition function do not vary with temperature. Then, one of the principles used of stable isotopes is as geothermometers. Like conventional chemical geothermometers, stable isotope geothemometers are based on temperature dependence of the equilibrium constant. For example, calculated oxygen isotope fractionation for several mineral pairs as a function of temperature. So, this application is much related to the geoscience.

Application of isotope geochemistry of natural gases and carbon:

There are two fundamental of isotopes, stable and unstable (radioactive) species. Stable isotopes were not subject to radioactive decay, which is their abundance in nature is controlled by biological and physical processes like equilibrium reactions in the case of the stable isotopes of carbon (¹²C and ¹³C). Meanwhile, unstable isotopes experience to radioactive decay. It known as the half-life and these isotopes used in age dating, for example, ¹⁴C. Carbon that occurred in wide variety of compounds, from highly oxidized inorganic materials like CO₂ and sedimentary carbonate rocks to highly reduce organic substances in the biosphere. Isotope equilibrium exchange reactions in the inorganic carbon system (atmospheric CO_2- dissolved bicarbonate-solid carbonate) lead to an enrichment of ¹³C in carbonate rocks. In the other hand, kinetic isotope effects during photosynthesis concentrate ¹²C in organic matter. For distinguishing natural gases from different sources, stable isotope geochemistry was provided a powerful method.

Application of isotope geochemistry to igneous petrogenesis:

One of the most fundamental applications of isotopes to igneous systems is to use radiogenic isotopes as “clocks” to date the crystallization ages of rocks. Isotropic compositions of igneous rocks provided a wealth of information about the processes and timescales involved in their formation. Numerous isotope systems, individually combined, have provided a detailed understanding of a range of igneous processes from the formation and early evolution of earth’s interior to ongoing processes. The application to some of the most fundamentally important processes in igneous petrology, included constrain on the timing of crust mantle differentiation, timescales of magma formation and ascent, and the processes and timescales of magma evolution. Crystallization ages of meteorites and the oldest terrestrial minerals constrain the age of the earth and formation evolution of ancient continental crust. Knowledge of the crystallization ages of young volcanic rocks is necessary to determine of eruption recurrence intervals. Radiogenic, stable and cosmogenic isotope systems also play fundamental roles as tracers of diverse igneous processes.

Application of isotope geochemistry in petroleum geoscience:

Petroleum system is a natural system that encompasses a pod of petroleum source rocks and all related oil and gas which included all the geologic elements and processes that are essential if a hydrocarbon accumulation is to exist. Essential elements of a petroleum such as a petroleum source rock, a petroleum reservoir rock, a seal rock and an overburden rock. Meanwhile, essential processes of petroleum such as trap formation and generation migration accumulation of petroleum. Modern isotope and biomarker analyses on the molecular level readily allow the identification and separation of multiple sources of oils in a petroleum system, where oils were inherit the molecular and isotropic character of the parent oil. Stable isotope applications in liquids; to correlation of whole oils, bitumens and kerogen, and quantitative estimates of oil co-sources.

Discussion

Overall in this application used in the geoscience. Firstly, isotropic composition of fossil material will depend on any isotropic changes associated with diagenesis to provide insights into the food sources of fossil organisms. There are several reasons for the controversy, but all ultimately relate to the extremely complex geological history of the area. Then, high temperature geochemistry such as igneous and metamorphic geochemistry, which is his application used of the temperature dependency of fractionation factors. The nature of chemical bond is of primary importance in determining isotope fractionations. For example, comparison of quartz-mineral fractionation factors estimated from the difference in oxygen site potential and experimentally observed fractionation. 

Next, carbon that occurred in wide variety of compounds, from highly oxidized inorganic materials like CO2 and sedimentary carbonate rocks to highly reduce organic substances in the biosphere. Sedimentary carbonates and organic matter possess distinct stable carbon isotope compositions because of the operation of two different reaction mechanisms. Applications of isotopes to igneous systems used radiogenic isotopes as “clocks” to date the crystallization ages of rocks. Thus, provides a critical link to volcanic hazard assessment and eruption forecasting. For petroleum geoscience, where it related to the exploration, development, production and field abandonment of petroleum.

This will provide a general overview of first principals concerning stable isotope geochemistry in the earth sciences.