Metamorphic rocks 2

From GeoClasses

Topics from chapter 6

causes of metamorphism

geothermal gradients during conditions of erosion and deposition

• see fig. 6.2
• temperature
  • geothermal gradient
• pressure (stress)
  • confining pressure vs. directed pressure
• metasomatism (fluids)

metamorphic rock textures

• see fig. 6.4
• foliated rocks:
  • slate, phyllite, schist, gneiss, (migmatite)
• non-foliated (granoblastic) rocks:
  • hornfels, quartzites, marbles, greenstones, amphibolite, granulite
• porphyroblasts
• see table 6.1
• pictures of all the metamorphic rock types

Metamorphic series from least metamorphosed to most the order is shale-slate-phyllite-schist.

• more than you ever wanted to know about metamorphism and metamorphic rocks
  • high P, low T = subduction
  • high T, high P = regional metamorphism = continent collision
    • regional met. creates foliated rocks: shale - slate - schist - gneiss
  • high T, low P = contact metamorphism = intrusion
    • contact met. creates nonfoliated rocks: limestone to marble, sandstone to quartzite
• minerals found in rock types (see table 3.5)

metamorphic environments

• regional metamorphism (Franciscan Complex, CA example)
• contact metamorphism (Brisbane, Australia)
• low-grade (burial) metamorphism
• high-pressure and ultra-high-pressure metamorphism
• shock metamorphism

mapping metamorphism

metamorphic map of the Alps

• mapping metamorphic grade
  • metamorphic facies
  • mineral isograds
  • see fig. 6.7, table 6.2

metamorphic processes

• orogeny
• prograde vs retrograde (see fig. 6.9)
• ocean-continent convergence settings
  • melange
  • exhumation
• continent-continent collision setting
  • effect of climate