Mineral Deposits as an Indicator of Tectonic Processes

Yasushi Watanabe

Institute for Geo-Resources and Environment, AIST, Japan

INTRODUCTION

Mineral deposition is a physical and chemical process that is related to tectonic, magmatic, and geologic environments. This results in the occurrence of a specific type of mineral deposits in a specific tectonic, magmatic and geologic setting as a metallogenic province. Porphyry Cu and epithermal Au deposits have been long regarded as representative mineral deposit types in subduction-related magmatic arcs, and Kuroko-type massive sulfide deposits as a product of arc-related rifting (Sawkins, 1990; Uyeda and Nishiwaki, 1980; Fig. 1). However, tectonic regimes can change within a few million years in the same regions, and also change laterally along the magmatic arcs. These result in mixed occurrence of different deposit types in the same regions, or change of the deposit type along the magmatic arcs, making the tectonic setting of each deposit type unclear.

Recent detailed studies on metallogenesis, geochronology and tectonic regime have revealed that epithermal Au and porphyry Cu deposits occur in limited time spans, related to dynamic tectonic and volcanic processes in the magmatic arcs (John, 2001; Watanabe, 2002, in prep.; Sillitoe and Hedenquist, 2003; Garwin et al., 2005). Therefore, as one of the indicators of tectonic processes, this relationship can be utilized to reconstruct paleo magmatic-tectonic processes for the magmatic belts that were significantly deformed, metamorphosed, and amalgamated into continental blocks.