Sediments and sedimentary rocks as hosts to giant metallic deposits have already been invoked in several earlier chapters like oceanic sediments (Chapter 5); sediments in island arcs and Andeantype continental margins (Chapters 5 and 6, respectively), sedimentary rocks in the volcanosedimentary orogens (Chapter 9) and in early Precambrian greenstone belts (Chapter 10), in Proterozoic-style intracratonic settings (Chapter 11) and in rift settings (Chapter 12). In all these chapters the sediments or sedimentary rocks, and processes that formed them, have been treated as second-order divisions, subordinated to the firstorder categories like volcanism, magmatism and hydrothermal activity based on geotectonic and lithotectonic premises.