Southwest Pacific Rim Gold-Copper Systems: Structure, Alteration, and Mineralization

This is a revised adaption of the manual used for the short course of the same name presented, at the SME/SEG Meeting in Phoenix in March, 1996, with modifications in response to reviewers’ comments.

Where possible, the terms used throughout this book are technically correct and in common use by field geologists working in mineral exploration. However, the terminology may not always be in strict agreement with some geological literature, to which the readers are referred.

This workshop demonstrates and describes ore deposit styles as well as exploration and conceptual exploration models as aids to the exploration and evaluation of southwest Pacific Rim magmatic arc mineral resources. However, careful consideration of the nature of these exploration models is necessary before any reliance can be placed upon them.

Exploration geologists compare, contrast and classify mineral occurrences in order to build up empirical patterns from data such as field observations. Deposit models are developed as empirical descriptions of individual deposits, or, what is of more use to the exploration geologist, styles of deposits. Exploration models are derived from interpretations, focusing upon those characteristics of a deposit model which aid in the discovery of ore deposits of a particular style. Progressively lateral interpretations depart from rigorously reviewed science and so become conceptual exploration models. Such a conceptualization may give the explorationist a competitive advantage (Henley and Berger, 1993) in the increasingly difficult search for ore deposits. These models may also assist in ranking projects and aid in the abandonment of lower order targets.

Conceptual exploration models evolve through their application to exploration examples, and are refined by research, many being abandoned during this process. Although luck plays a part, the competitive nature of the search for ore bodies encourages explorationists to be the first to develop or utilize a conceptual exploration model. The very innovative nature which makes a conceptual exploration model of use to the explorationist, precludes the lengthy process of rigorous evaluation of many of the concepts by exhaustive research studies.

It is important that models must not be applied rigidly, but should be modified to become project-specific. Greatcare must be taken to abandon or nlodify inappropriate models. It is intended in this manual to outline to explorationists, the processes involved in the derivition of conceptual exploration models, rather than in the rigid application of existing models. Structure and petrologv are tools which the explorationist may use in the development of conceptual exploration models.