The geochemical environment can be classified into two types based on the conditions of temperature, pressure and chemistry. They are,
1. Endogenic Environment.
2. Exogenic Environment.
The Endogenic Environment is the deep-seated environment in which forces driven by earth's internal heat predominate. Since rock formation often takes place in this environment, it is also called the "Primary Environment". Metamorphic conditions, magmatic, igneous conditions, activities in the vicinity of plate boundaries and sometimes deep seated sedimentary conditions are geological activities that are prominent in the endogenic environment. The endogenic environment can be characterized by,
- high temperature
- high pressure
- lack of free oxygen
- lack of free water and CO2
- restricted movement of fluids
The Exogenic Environment is the surficial environment in which forces are mainly driven by solar energy. It is also termed the "Secondary Environment". Geological activities present in the exogenic environment are, weathering, erosion, transportation and sedimentation. The exogenic environment can be characterized by,
- low temperature
- low pressure
- abundant free oxygen
- abundant water and CO2
- free movement of solutions
These two environments are connected to each other and material gets transported from one to another creating a closed system. Driven by the natural forces described above this dynamic system can be simplified and depicted in the diagram below. A good understanding of this cycle can help decision making in the mineral exploration process.
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| the geochemical cycle(Image from "Geochemistry in Mineral Exploration" by Rose et al) |
