Lithogeochemical Alteration Studies

These studies combine petrographic analyses with lithogeochemical whole-rock and trace element data to quantitatively define the intensity, distribution, zoning, and paragenetic sequence of chemical and mineralogical alteration and their relationships to mineralization.

Economic mineralization is often genetically and spatially associated with chemical and mineralogical alteration. Such alteration can be detected and quantitatively assessed using computer-assisted techniques (DePangher, 1988). These techniques take advantage of easily obtainable petrographic and whole-rock chemical analyses of drill core and rock samples whose full information potential is otherwise rarely tapped.

Why Look at Alteration?

• Alteration is often more areally extensive than mineralization and thereby provides a larger target for exploration.
• Alteration zoning can indicate the direction toward associated mineralization.
• Alteration anomalies are often highly correlated with mineralization because the two are often genetically linked.

Benefits of Alteration Studies

• Geologic mapping and core logging can be improved by determining the intensity, distribution, zoning, and paragenesis of chemical and mineralogical alteration.
• Geologic interpretation can be improved by reconstructing pre-alteration geology, even in areas of complex structure overprinted by intense alteration or metamorphism.
• Exploration can be improved by identifying alteration fingerprints that indicate the type and probability of mineralization.

Summary

Alteration assessments of this type can produce a wealth of chemical, mineralogic, and geologic information that is useful in exploration and cannot be obtained by any other techniques. Decades worth of data can be cost-effectively evaluated in a short time. Exploration tools are produced which do not become obsolete and can be easily and effectively used with a minimum amount of training.