Early Precambrian Basic Magmatism

Basic magmatic rocks make up approximately three-quarters of the crust ofthe present day Earth. Because we can observe and study the volcanic products of present day tectonic regimes comprehensively, we can shed light on ancient tectono-magmatic provinces, and thereby deduce the petrogenesis and evolution of the oldest basic rocks. This is the primary objective of this book. The book was conceived in order to provide a comprehensive review of the basic rocks produced during the first half of the Precambrian, i.e. the Archaean and early Proterozoic, to about 1.8 Ga years ago. Two major questions are addressed. First, what basic magmas were generated during the early Precambrian: were these magmas globally uniform, and to what extent were prevailing tectonic controls and compo- sitions analogous to those of the present day? Clearly, this can be answered only by bringing together fundamental information about all relevant basic magmatic events. Second, is there any systematic temporal variation in the nature of basic suites, and what implications might such variations have on our interpretations of early Earth history? Are there important differences between early Archaean, late Archaean, Proterozoic and modern basic magmatic suites? The book uses two approaches to address these questions. Early chapters examine the fundamental characteristics of these basic rocks, whilst later chapters assess regional distribution and development by providing an overview of each major early Precambrian craton.

Table of Contents:
1 Introduction: basic magmatism and crustal evolution.- 1.1 Early thermal and magmatic history of the Earth.- 1.2 Early Precambrian oceans and greenstone belts.- 1.3 Continental crust and the major basic intrusions.- I General Aspects.- 2 Archaean basic magmas.- 3 Geochemical characteristics of Precambrian basaltic greenstones.- 4 Early Precambrian layered intrusions.- 5 Noritic magmatism.- 6 Mantle evolution.- 7 Lunar magmatism.- 8 Mineralisation associated with early Precambrian basic magmatism.- II Regional Syntheses.- 9 Early Precambrian basic rocks of the USA.- 10 Early Precambrian basic rocks of the Canadian Shield.- 11 Early Precambrian basic rocks of Greenland and Scotland.- 12 Early Precambrian basic rocks of the Baltic Shield.- 13 Early Precambrian basic rocks of China.- 14 Early Precambrian basic rocks of Australia.- 15 Early Precambrian basic rocks of India.- 16 Early Precambrian basic rocks of Africa.- 17 Early Precambrian basic rocks of South America.- References.