Metamorphic Rocks … on the Road to Something New…

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A R O U N D and/or Pressure and/or Extreme Heat Heat Extreme W E G O Metamorphic Rocks on the road to something new… Regents Earth Science with Ms. Connery To metamorphose something means to change something from one form to another How do metamorphic rocks form? metamorphism metamorphism extreme heat foliated extreme non-foliated pressure deformation contact mineral metamorphism alignment regional You know it’s metamorphosed if change has occurred! Metamorphism happened here because layers were originally horizontal BEFORE FOLDING AFTER DEFORMED (FOLDED) from EXTREME PRESSURE of TECTONIC PRESSURE REGIONAL METAMORPHISM APPLIED Extreme heat of igneous magma intrusion causes CONTACT METAMORPHISM YOUNGEST SED. LAYER OLDEST SED. LAYER Contact metamorphism A R O U N D and/or Pressure and/or Extreme Heat Heat Extreme W E G O Overview of Metamorphic Rocks “REGIONAL” metamorphism • Change caused by from extreme heat and pressure • REGIONAL metamorphism means change at a LARGE scale over LARGE area IGNEOUS METAMORPHIC ESRTs - Regional metamorphism • NO MELTING…just rearranging and lining up the same mineral crystals • Grade of metamorphism depends on how long the process goes on • Deeper with more heat & pressure & longer time more change occurs Regional metamorphism… Rocks show an increase in foliation & deformation as metamorphism continues Foliation when the minerals align perpendicular to the pressure being applied Which way was the pressure applied? Foliation - minerals align or “line up” perpendicular to the pressure Scheme for Metamorphic Rock Identification Increased pressure from regional metamorphism causes foliation to slate progress shale phyllite gneiss schist Increased pressure from regional metamorphism changes bituminous to ANTHRACITE coal This metamorphic rock is NOT FOLIATED - it doesn’t have mineral alignment but it’s harder than bituminous. What’s different? http://www.mii.org/mineral_photos_by_type.htm#meta How does the heat of contact metamorphism changes sedimentary limestone to METAMORPHIC MARBLE? http://www.mii.org/mineral_photos_by_type.htm#meta HEAT - Contact metamorphism 1 - Existing Rock = LIMESTONE 3- Limestone changed to MARBLE at edges 2 - Diorite (igneous rock) intrusion at 1000s of degrees 3 - Limestone changed to MARBLE at edges 1 - Existing Rock = LIMESTONE http://geology.about.com/library/bl/images/blcontactmet.htm HEAT - Contact metamorphism • Extreme heat of contact of an existing rock with an igneous (magma) intrusion or lava causes some existing rock to melt and become part of the magma. • Along the edges (contact zone) where not quite hot enough to melt the existing rock, it “changes” the rock through recrystallization (but not melting!). Let’s ID some Metamorphic Rocks! Conceptual Model: Extreme heat of Contact metamorphism.

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Metamorphic Rocks.Pdf
Metamorphism & Metamorphic Rocks (((adapted from Brunkel, 2012) Metamorphic Rocks . Changed rocks- with heat and pressure . But not melted . Change in the solid state . Textural changes (always) . Mineralogy changes (usually) Metamorphism . The mineral changes that transform a parent rock to into a new metamorphic rock by exposure to heat, stress, and fluids unlike those in which the parent rock formed. granite gneiss Geothermal gradient Types of Metamorphism . Contact metamorphism – – Happens in wall rock next to intrusions – HEAT is main metamorphic agent . Contact metamorphism Contact Metamorphism . Local- Usually a zone only a few meters wide . Heat from plutons intruded into “cooler” country rock . Usually forms nonfoliated rocks Types of Metamorphism . Hydrothermal metamorphism – – Happens along fracture conduits – HOT FLUIDS are main metamorphic agent Types of Metamorphism . Regional metamorphism – – Happens during mountain building – Most significant type – STRESS associated with plate convergence & – HEAT associated with burial (geothermal gradient) are main metamorphic agents . Contact metamorphism . Hydrothermal metamorphism . Regional metamorphism . Wide range of pressure and temperature conditions across a large area regional hot springs hydrothermal contact . Regional metamorphism Other types of Metamorphism . Burial . Fault zones . Impact metamorphism Tektites Metamorphism and Plate Tectonics . Fault zone metamorphism . Mélange- chaotic mixture of materials that have been crumpled together Stress (pressure) . From burial
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