METAMORPHISM , METAMORPHIC ROCKS, & HYDROTHERMAL ROCKS
Jan 19, 2016
METAMORPHISM , METAMORPHIC ROCKS, & HYDROTHERMAL ROCKS
Introduction
Metamorphism increase in Pressure; increase in TemperatureBurialContactRegional
Metamorphic rock Pre-existing rock Parent rock
Factors Controlling the Characteristics of Metamorphic Rocks
Composition of Parent RockTemperature
Geothermal gradient Stability of minerals
Pressure Confining pressure Lithostatic pressure
Factors Controlling the Characteristics of Metamorphic Rocks
Foliation Slaty cleavage Phyllitic Schistose Gneissic texture
Foliation
Foliation
Factors Controlling the Characteristics of Metamorphic Rocks
Fluids Hot water Trigger metamorphic chemical reactions
Time
Metamorphic Grades
Classification of Metamorphic Rocks
Nonfoliated Named on the basis of its composition
Example - quartzite,marble
Foliated Determine type of foliation
Example -• slaty• schistose
Classification
A- SlateC- PhylliteD- SchistE- GneissF- Migmatite
Classification
Types of Metamorphism
Regional MetamorphismTakes place at considerable depth
and high temperatures Basalt => greenschist- actinolite, and
sodium-rich plagioclase Basalt => amphibole schist -
hornblende, plagioclase feldspar, and garnet
Types of Metamorphism
Contact Metamorphism (thermal metamorphism) Narrow zone of contact Shale => hornfels Limestone => MARBLE Sandstone => QUARTZITE
Quartz grains welded togetherRecrystallized
Types of Metamorphism
Progressive Metamorphism Progressively greater temperature and
pressure Shale => Slate => Phyllite => Schist
=> Gneiss => Migmatite
Plate Tectonics and Metamorphism
Geothermal gradientIsotherm
Hydrothermal Activity
Hydrothermal Processes
Hydrothermal Minerals => Hydrothermal Rock
VeinHyrothermal Activity at
Diverging Plate BoundariesOre Deposits at Diverging Plate
Boundaries
Hydrothermal Processes
Hydothermal Rocks and Minerals disseminated ore deposits
Sources of Water Groundwater Water Trapped in Sediments Hydrous Minerals