Coated Grains

Coated grains have always attracted attention, at first of naturalists, and later of geologists, and the interest in these peculiar bodies was re lated both to their intriguing form and their significance in facies inter pretation and sedimentology and to their relevance to accumulations of hydrocarbons and other mineral deposits. This resulted in numerous publications on this subject, and the intention of this volume is to sum marize the present state of knowledge on coated grains. The idea of the book was to unite some general papers with papers reporting case studies of both recent and ancient coated grains. The organization of the book follows this intention. The papers presented in this volume have been invited by the editor; the theme of the book merits a few words of personal history. The development of studies of coated grains during the last two decades has not only resulted in a great increase in knowledge of recent and ancient environments of coated grain formation, but also numerous important and controversial questions of classification, environmental significance, mineralogical composition etc. of ancient coated grains have arisen. To answer these questions, in 1978 I started the study of many ancient and recent occurrences of coated grains at the Institut fUr Geologie, Ruhr-UniversiUH Bochum, following the invitation of Hans Fiichtbauer and sponsored by the Alexander von Humboldt-Stiftung.

Inhalt
I Approaches.- I.1 Classification of Coated Grains.- I.2 Classification of Coated Grains: Discussion.- I.3 Origin of Coated Grains: Trace Element Constraints.- I.4 Carbon and Oxygen Isotope Composition of Recent and Ancient Coated Grains.- I.5 Neritic Macroid Genesis, an Ecological Approach.- I.6 Accretionary Lapilli in Volcanic Ash Falls: Physical Factors Governing Their Formation.- II Ooids.- II.1 Calcareous Ooids: A Synopsis.- II.2 Ferriferous Ooids.- II.3 Cortical Fabrics in Calcite and Aragonite Ooids.- II.4 Relict Sand Bodies and Bedforms of the Northern Bahamas: Evidence of Extensive Early Holocene Sand Transport.- II.5 The Joulters Ooid Shoal, Great Bahama Bank.- II.6 Holocene Lacustrine Ooids from Pyramid Lake, Nevada.- II.7 Subrecent High-Sr Aragonitic Ooids from Hot Springs Near Tekke Ilica (Turkey).- II.8 Coated Grains Along the Dead Sea Shore.- II.9 Structural and Geochemical Features of Jurassic Oolitic Limestones in the Veneto Region (NE Italy).- II.10 Sedimentary Characteristics of Oolitic Carbonates from the Jialing-Jiang Formation [Lower Triassic (T12J1)], South Sichuan Basin, China.- II.11 Ooid Zonation as Indication for Environmental Conditions in a Givetian-Frasnian Carbonate Shelf-Slope Transition.- II.12 Ooids and Oolites of the Proterophytic Boomplaas Formation, Transvaal Supergroup, Griqualand West, South Africa.- III Rhodoids.- III.1 Description and Classification of Rhodoliths (Rhodoids, Rhodolites).- III.2 The Occurrence and Ecology of Recent Rhodoliths A Review.- III.3 Rhodoids in Temperate Carbonates from the Cenozoic of New Zealand.- III.4 Early Permian Coated Grains from a Lagoonal Environment, Laborcita Formation, Sacramento Mountains, Southcentral New Mexico, U.S.A..- IV Oncoids.- IV.1 Oncoids: Comment to Recent Developments.- IV.2 Cyanoliths (Cyanoids): Oncoids Formed by Calcified Cyanophytes.- IV.3 Algal Micro-Reefs Coated Grains from Freshwater Environments.- IV.4 Brackish-Water Oncoids Composed of Blue-Green and Red Algae from a Pleistocene Terrace Near Corinth, Greece.- IV.5 Environmental Significance of Freshwater Oncoids, Eocene Guarga Formation, Southern Pyrenees, Spain.- IV.6 Depositional Environment, Diagenesis and Reservoir Properties of Oncolitic Packstones, Macaé Formation (Albian-Cenomanian), Campos Basin, Offshore Rio de Janeiro, Brazil.- IV.7 Albian Pelagic Phosphate-Rich Macrooncoids from the Tatra Mts (Poland).- IV.8 Oncoids and Stromatolites in the Rosso Ammonitico Sequences (Middle-Upper Jurassic) of the Venetian Alps, Italy.- IV.9 Pelagic Oncoids and Ooids in the Middle-Upper Jurassic of Eastern Sardinia.- IV.10 Depositional Environments of Some Upper Jurassic Oncoids.- IV.11 Carnian Oncolites of the Northern Calcareous Alps and the Drau Range (Austria).- IV.12 Girvanella Oncoids From Middle to Upper Triassic Allochthonous Boulders of the Dolomite Alps, Northern Italy.- IV.13 Triassic Oncoids from Central Balkanides (Bulgaria).- IV.14 The Genesis of Algal Nodule Limestones from the Upper Carboniferous (San Emiliano Formation) of N.W. Spain.- IV.15 Morphogenesis of Oncoids in the Lower Carboniferous Llanelly Formation of South Wales.- V Vadoids.- V.1 Vadoids.- V.2 Recent Travertine Pisoliths (Pisoids) from Southeastern Idaho, U.S.A..- V.3 Pisoids in the Caliche Profiles of Tarragona (N.E. Spain).- V.4 Pisoliths (Pisoids) in Quaternary Travertines of Tivoli, Italy.- V.5 Quaternary Pisoids of Lau, Fiji.- V.6 Pisoids and Pisolite Facies (Permian), Guadalupe Mountains, New Mexico and West Texas.- V.7 Vadose Pisolites of the Tongying Formation (Upper Sinian System) in Southwest China.- V.8 A Proterozoic Calcrete in the Amos Formation, McArthur Group, Northern Territory, Australia.- VI Contrasted Occurrences.- VI.1 Coated Grains from the Great Barrier Reef.- VI.2 Coated Grains Fades in the Lower Cretaceous of the Outer Dinarides (Yugoslavia).- VI.3 Coated Grains in Contrasted Environmental Situations: Norian and Lower Liassic of Northern Apennines.- VI.4 Coated Grains from the Zechstein Limestone (Upper Permian) of Western Poland.- VI.5 Unusual Algal-Crystalline Carbonate Coated Grains from the Capitan Reef (Permian, Guadalupian), New Mexico, USA.- VI.6 Contrasted Occurrence of Lower Devonian Coated Grains, Northeastern Armorican Massif, France.- VI.7 Accretionary Lapilli and Other Spheroidal Rocks from the Archaean Swaziland Supergroup, Barberton Mountain Land, South Africa.- Author Index.