A Special Issue Devoted to the Early to Middle Archean Mineral Deposits ofthe North Pilbara Terrain, Western Australia

Abstract

The Archean eon is a highly mineralized eon in geological time, producing a significant proportion of the world’s Au, Cu, Zn, and Ni. However, much of this mineralization is concentrated within the period from 2740 to 2620 Ma, a time characterized by extensive crustal growth and mineralization and referred to by Barley et al. (1998) as the Archean Numerous papers have been written about Late Archean mineral deposits and their tectonic environments, yet this Late Archean bonanza comprises only 120 m.y. of an eon that spanned from 4000 to 2500 Ma. By comparison, the period prior to the Late Archean bonanza is poorly mineralized and its metallogenesis has not been as comprehensively described, in part because few rocks of this age have been preserved. To understand the evolution of mineralizing processes through time, however, it is essential to document the characteristics of mineral deposits and their environments during the Early to Middle Archean, as well as in the Late Archean bonanza. The North Pilbara terrain (previously known as the Pilbara block) of Western Australia is one of the best preserved regions of Early to Middle Archean crust on Earth and as such offers an ideal opportunity to record mineralizing processes prior to the Late Archean. In 1995, Geoscience Australia (then the Australian Geological Survey Organisation) joined with the Geological Survey of Western Australia in the North Pilbara National Geoscience Mapping Accord project to document the geology …