Trondhjemites, Dacites, and Related Rocks

Developments in Petrology, 6: Trondhjemites, Dacites, and Related Rocks focuses on the geology, geochemistry, and petrology of several kinds of trondhjemites, dacites, and genetically related rocks. The selection first elaborates on the definition, environment, and hypotheses of origin of trondhjemite; a review of the mineralogy and chemistry of tertiary-recent dacitic, latitic, rhyolitic, and related salic volcanic rocks; and some trace elements in trondhjemites and their implications to magma genesis and paleotectonic setting. Discussions focus on tectonic environments and trace element patterns, selection and reliability of trace elements, interrelationships between mineralogy and chemistry, and regional variations of dacitic and rhyolitic magmas. The publication then tackles strontium isotope geochemistry of late Archean to late Cretaceous tonalites and trondhjemites; Archean gray gneisses and the origin of the continental crust in West Greenland; and metamorphic development of early Archean tonalitic and trondhjemitic gneisses in Saglek Area, Labrador. The book examines the petrology, geochemistry, and origin of the Sparta quartz dioritetrondhjemite complex; reconnaissance geochemistry of Devonian island-arc volcanic and intrusive rocks in West Shasta District, California; and origin of the Twillingate trondhjemite in North-Central Newfoundland. The selection is highly recommended for geologists and geochemists wanting to explore trondhjemites, dacites, and genetically related rocks.

PrefaceContributorsChapter 1. Trondhjemite: Definition, Environment and Hypotheses of Origin Abstract Trondhjemite: Definition Major-Element Character Occurrence Hypotheses of Origin Comments on Archean Gray Gneiss Complexes Relation to Subduction Acknowledgments ReferencesChapter 2. A Review of the Mineralogy and Chemistry of Tertiary-Recent Dacitic, Latitic, Rhyolitic, and Related Salic Volcanic Rocks Abstract Introduction Chemistry Phenocryst Mineralogy Interrelationships Between Mineralogy and Chemistry Regional Variations of Dacitic and Rhyolitic Magmas Acknowledgments References AppendicesChapter 3. Some Trace Elements in Trondhjemites - Their Implications to Magma Genesis and Paleotectonic Setting Introduction Selection and Reliability of Trace Elements Tectonic Environments and Trace Element Patterns Models of Trondhjemite Genesis Conclusions ReferencesChapter 4. Strontium Isotope Geochemistry of Late Archean to Late Cretaceous Tonalites and Trondhjemites Abstract Introduction Samples and Criteria Data Results Conclusions Acknowledgments ReferencesChapter 5. Oceanic Plagiogranite Revisited Abstract Introduction Keratophyre and Plagiogranite Nomenclature Petrography Intergrowths Chemistry Summary ReferencesChapter 6. Archean Gray Gneisses and the Origin of the Continental Crust: Evidence from the Godthåb Region, West Greenland Abstract Introduction The Nuk Gneisses Origin of the Nuk Magmas Comparison with Younger Tectonic Environments A Model for the Generation of the Nuk Gneisses The Amitsoq Gneisses Conclusions Acknowledgments ReferencesChapter 7. Metamorphic Development of Early Archean Tonalitic and Trondhjemitic Gneisses: Saglek Area, Labrador Abstract Introduction Geological Setting Geological Relations in the Saglek Area Meta-Plutonic Rocks: The Uivak Gneisses Supracrustal Rocks Petrology Geochemistry Discussion and Origin of the Uivak Gneisses Implications for Archean Crustal Development Acknowledgments ReferencesChapter 8. Geochemistry of Archean Trondhjemitic and Tonalitic Gneisses from Scotland and East Greenland Abstract Introduction Geochemistry Discussion ReferencesChapter 9. The Role of Tonalitic and Trondhjemitic Rocks in the Crustal Development of Swaziland and the Eastern Transvaal, South Africa Introduction General Geologic Setting of Swaziland and Eastern Transvaal Geology of the Tonalitic-Trondhjemitic Suites Geochemistry of the Tonalite-Trondhjemite Suites Origin of the Tonalite-Trondhjemite Suites Summary and Discussion ReferencesChapter 10. Petrochemistry and Tectonic Setting of Plutonic Rocks of the Superior Province in Manitoba Abstract Introduction Terminology Regional Geology Regional Geophysics Age of Plutonism Petrochemistry Tectonic Setting Summary and Conclusions Acknowledgments ReferencesChapter 11. The Oxygen-Isotope Geochemistry of Archean Granitoids Abstract Introduction Analytical Methods The Oxygen Isotopie Composition of Archean Granitoids - A Review d180 Results for Granitoids from Northwestern Ontario Conclusions Acknowledgments ReferencesChapter 12· Archean Trondhjemites of the Southwestern Big Horn Mountains, Wyoming: A Preliminary Report Abstract Introduction Geology Ages of the E-1 and E-2 Events Major- and Minor-Element Abundances Acknowledgments ReferencesChapter 13. Four Low-K Siliceous Rocks of the Western U.S.A. Introduction Webb Canyon Gneiss Rocks of Wilson Creek Area, Wind River Mountains Trondhjemite, Rigging Area, Idaho Jurassic Plutons, Trinity Alps, Klamath Mountains Acknowledgments ReferencesChapter 14.