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