Iron Formation Facts And Problems

Iron-Formation: Facts and Problems

The present volume is an intellectual agglomeration covering a variety of topics in diagenesis. It starts with the diagenesis of marine pore waters and soft-sediment deformations, followed by two chapters on sandstones - one on climatic influence in terrestrial sandstone diagenesis and the other on the deep-sea volcaniclastic sandstones. Diagenesis of carbonates is treated next, with one chapter on compactional diagenesis and another devoted to a case study (Aymestry Limestone Beds, UK). There are two chapters on the origin and migration of oil: (a) maturation of organic matter, and (b) relation of diagenesis to mineralization and hydrocarbon reservoir development, followed by a chapter on sedimentary ore genesis - banded iron-formation. In conclusion there are two chapters on paleosols. This book will be of interest to geologists, geochemists and petroleum engineers.

"The history of Earth's early atmosphere, hydrosphere, and biosphere, from Hadean through Proterozoic time, is one of geology's enduring puzzles. Ore deposits provide important insights into this history because they contain elements and minerals that are highly sensitive to the geochemical environment in which they form. Just what these minerals tell us remains a matter of considerable debate, however. When and how did life develop, an oxygen-rich atmosphere form, and sulfate dominate the ocean? This volume contains reports on these questions from both sides of the aisle for iron and manganese formations, uranium paleoplacers and hydrothermal deposits, and exhalative sulfides and oxides."--Publisher's website.

Manganese mineralization is diverse in occurence, origin, mineralogy and geochemistry. This volume includes a review of the range of terrestrial Mn deposits and their relative abundance through geological time. Experimental and modelling approaches to Mn geochemistry and mineralogy can further aid our understanding of the formational and depositational processes involved and thereby our interpretation of deposit metallogenesis.

As a final product of the International Geological Correlation Program (IGCP) Project 217, this volume brings together significant advances in the understanding of Proterozoic crustal evolution. This IGCP Project focussed on nine research objectives: 1) Comparison of Archean and Proterozoic supracrustal assemblages to more fully understand differences between Archean and post-Archean tectonic regimes; 2) To more fully understand the geochemical differences between Archean and post-Archean sediments and to evaluate the various factors that control sediment composition; 3) From combined U/Pb zircon and whole-rock Sm/Nd studies, to see if the apparent 2.4-2.0 continental crust "generation gap" is real; 4) To employ new techniques in the dating of individual zircons to more fully understand Proterozoic tectonic history and the role of crustal reworking; 5) From trace element ratios and Nd isotopic data from basalts, to better understand Proterozoic mantle evolution; 6) To encourage more detailed studies of the anorogenic granite-anorthosite association to better understand its origin and significance in terms of crustal evolution; 7) From combined Nd, Pb, and Sr isotopic data, to more precisely estimate the amount of new continental crust formed during the Proterozoic; 8) To encourage joint P-T and geochronological studies of Proterozoic and high-grade terranes to better understand Proterozoic orogenesis: and 9) To try and understand why hydrothermal precious metal deposits are relatively rare in the Proterozoic compared to both the Archean and the Phanerozoic. The book should be of interest to professionals in the geosciences (especially geochemists, petrologists and structural geologists) and graduate students in the same fields.

In this book the editors strive to cover all primary (i.e. non-applied) topics in Precambrian geology in a non-partisan way, by using a large team of international authors to present their datasets and highly divergent viewpoints. The chapters address: celestial origins of Earth and succeeding extraterrestrial impact events; generation of continental crust and the greenstone-granite debate; the interaction of mantle plumes and plate tectonics over Precambrian time; Precambrian volcanism, emphasising komatiite research; evolution and models for Earth's hydrosphere and atmosphere; evolution of life and its influence on Precambrian ocean chemistry and chemical sedimentation; sedimentation through Precambrian time; the application of sequence stratigraphy to the Precambrian rock record. Each topic is introduced and a non-partisan closing commentary provided at the end of each chapter. The final chapter blends the major geological events and rates at which important processes occurred into a synthesis, which postulates a number of "event clusters" in the Precambrian when significant changes occurred in many natural systems and geological environments. Also available in paperback, ISBN: 0-444-51509-7