Ophiolites in earth history: introduction

Abstract

Ophiolites record significant evidence for tectonic and magmatic processes from rift-drift through accrefionary and collisional stages of continental margin evolution in various tectonic settings. Structural, petrological and geochemical features of ophiolites and associated rock units provide essential information on mantle flow field effects, including plume activities, collision-induced aesthenospheric extrusion, crustal growth via magmatism and tectonic accretion in subductionaccretion cycles, changes in the structure and composition of the crust and mantle reservoirs through time, and evolution of global geochemical cycles and seawater compositions. Ophiolite studies over the years have played a major role in better understanding of mid-ocean ridge and subduction zone processes, mantle dynanlics and heterogeneity, magma chamber processes, fluid flow mechanisms and fluid-rock interactions in oceanic lithosphere, the evolution of deep biosphere, the role of plate tectonics and plume tectonics in crustal evolution during the Precambrian and the Phanerozoic, and mechanisms of continental growth in accretionary and coltisional mountain belts. Through multi-disciplinary investigations and comparative studies of ophiolites and modern oceanic crust and using advanced instrumentation and computational facilities, the international ophiolite community has gathered a wealth of new data and syntheses from ophiolites around the world during the last 10 years. The purpose of this book is to present the most recent data, observations and ideas on different aspects of 'ophiolite science' through case studies and to document the mode and nature of igneous, metamorphic, tectonic, sedimentological and/or biological processes associated with the evolution of oceanic crust in different tectonic settings in Earth's history. It comprises 32 papers collected in six sections on temporal relations anaongst ophiolite genesis, mantle plume events and orogeny in Earth history; Tethyan ophiolites in the AlpineHimalayan orogenic system; magmatic, metamorphic and tectonic processes in ophiolite genesis; hydrothermal and biogenic alteration of oceanic crust; mechanisms of ophiolite emplacement; and regional occurrences of ophiolites and their geodynamic implications.