Petrology-Finals Exam Reviewer

A broad scientific discipline focused on the study of all kinds of sedimentary rocks, including composition, characteristics, and origins.

Sedimentary Petrology

Rocks that form at low temperatures and pressures due to deposition by water, wind, or ice, characterized by layers and distinct textures.

Sedimentary Rocks

The breakdown of rock through chemical alteration, physical, and biological processes when exposed to the atmosphere, hydrosphere, and biosphere.

Weathering

The physical breakdown of rocks without changing their chemical composition, often through processes like freezing, thawing, heating, or pressure.

Mechanical Weathering

The breakdown of minerals through chemical reactions with water, other chemicals, or gases, leading to stability in minerals.

Chemical Weathering

The process of moving rock and soil caused by agents like gravity, ice, water, and wind.

Erosion

The physical, chemical, and biological processes that transform sediments into sedimentary rock.

Diagenesis

Sedimentary rocks formed from mechanical weathering products and classified according to texture and composition.

Siliciclastic Rocks

Sedimentary rocks composed mainly of the mineral calcite formed through chemical and biochemical processes.

Carbonate Rocks

Prograding depositional bodies that form where a river drains into a lake or sea.

Delta

General term for sediment transported and deposited by glaciers.

Glacial Drift

Rocks that are formed from pre-existing rocks subjected to higher pressure and temperature conditions.

Metamorphic Rocks

Planar fabric in rocks due to the preferred orientation of minerals, often seen in metamorphic rocks.

Foliation

Metamorphism that occurs through heat transfer from hot magma to surrounding cooler rocks.

Contact Metamorphism

Metamorphism that occurs in a large area under high temperature and pressure conditions due to tectonics.

Regional Metamorphism

A large crystal or mineral that has grown in a finer-grained matrix in metamorphic rocks.

Porphyroblast

A high-grade metamorphic rock that is predominantly composed of OH-free minerals.

Granulite

A group of minerals that form during low-grade metamorphic processes, often having a porous structure.

Zeolite

Formation of the Red Sea and Atlantic Ocean

Divergent plate boundaries

-Oceanic-continental convergence (Oceanic Nazka – S American plate)

-Oceanic-oceanic convergence (Pacific plate – Philippine plate)

-Continental-continental convergence (Indian plate- Eurasian plate)

Convergent plate boundaries

The San Andreas fault zone, and Gulf of Aqaba fault

Transform or shear plate boundaries

the study of the subsolid changes that a rock undergoes when exposed to physicochemical conditions dinerent from those prevailing near the surface of the Earth

Metamorphic petrology

defined by characteristic mineral assemblages specific to particular bulk-rock compositions

Metamorphic facies

Minerals recrystallize into new forms stable under the new conditions. Grain size may increase (coarsening) with increasing metamorphic grade

Recrystallization

refer to the transformation of minerals into new mineral phases that are stable under the new metamorphic conditions

Phase Change

refers to the changes in shape and structure that occur due to the application of differential stress during metamorphism

Deformation

the property of a rock to split along a regular set of sub-parallel, closely-spaced planes

Cleavage

A preferred orientation of inequant mineral grains or grain aggregates produced by metamorphic processes

Schistosity

Either a poorly-developed schistosity or segregated into layers by metamorphic processes

Gneissose structure

means that a metamorphic rock has one or more metamorphic minerals that grew much larger than the others

Porphyroblastic

metamorphic rock composed predominantly of calcite or dolomite. The protolith is typically limestone or dolostone.

marble

: a metamorphic rock composed predominantly of quartz. The protolith is typically sandstone

Quartzite

: a comprehensive term for any isotropic rock (a rock with no preferred orientation)

Granofels

type of granofels that is typically very fine- grained and compact, and occurs in contact aureoles.

Hornfels

a contact metamorphosed and silica metasomatized carbonate rock containing calc- silicate minerals, such as grossular, epidote, tremolite, vesuvianite, etc. Tactite is a synonym.

Skarn:

: a high grade rock of pelitic, mafic, or quartzo-feldspathic parentage that is predominantly composed of OH-free minerals.

Granulite

: a low-grade metamorphic rock that typically contains chlorite, actinolite, epidote, and albite.

Greenschist/Greenstone

a metamorphic rock dominated by hornblende + plagioclase. may be foliated or non-foliated

Amphibolite

: an ultramafic rock metamorphosed at low grade, so that it contains mostly serpentine

Serpentinite

: a blue amphibole-bearing metamorphosed mafic igneous rock or mafic graywacke. This term is so commonly applied to such rocks that it is even applied to non-schistose rocks

Blueschist

: a green and red metamorphic rock that contains clinopyroxene and garnet (omphacite + pyrope).

Eclogite

: a composite silicate rock that is heterogeneous on the 1-10 cm scale, commonly having a dark gneissic matrix (melanosome) and lighter felsic portions (leucosome).

Migmatite

Indicates the intensity of metamorphism a rock has undergone. It is typically classified into low-grade, medium-grade, and high-grade metamorphism based on mineral assemblages and textures.

METAMORPHIC GRADES