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Petrology of Oceanic Crust

Petrology of Oceanic Crust. Mark Gorenc John Solder. Components of Oceanic Lithosphere. Layer 1 (>1 km) Sediment Layer Layer 2 ( up to 2.8 km) Pillow Basalts, Sheeted Dikes Layer 3 (up to 5 km) Gabbro. Mid Oceanic Ridge Basalts. Heterogeneous Basalts Textures controlled by

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Petrology of Oceanic Crust

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  1. Petrology of Oceanic Crust Mark Gorenc John Solder

  2. Components of Oceanic Lithosphere • Layer 1 (>1 km) • Sediment Layer • Layer 2 ( up to 2.8 km) • Pillow Basalts, Sheeted Dikes • Layer 3 (up to 5 km) • Gabbro

  3. Mid Oceanic Ridge Basalts Heterogeneous Basalts • Textures controlled by cooling Histories • Heterogeneous mantle • Fractionation • Tholeiites • Phenocryst Rich Basalts • Plagioclase, Olivine

  4. MOR Metamorphism • Hydrothermal Metasomatism • Low Grade – mostly Zeolite and Greenschist • Olivine & Pyroxene => Hydrated Silicates

  5. Tale of Two Circulation Systems • Active - High T, alteration of fresh basalt and underlying magma chamber • Greenschist and Prehnite-PumpellyiteFacies • Cholrite, Actinolite, Talc, Albite, and Epidote • Passive – Lower T, alteration of sediments • Basalt cools over millions of years as evidenced by continued hydrothermal circulation • Zeolite Facies=> Hydrated Clays, Calcite, Cholrite, and Zeolites

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