Chapter 2 Flashcards
branch of geology focused on understanding the materials and processes that shape the Earth’s structure and surface.
Physical Geology
It encompasses the study of rocks, minerals, and landforms, and investigates the physical processes driving geological change.
Physical Geology
Earth’s Structure: Layers of the Earth
Crust
Mantle
Core
Thicker (about 30-70 km) and less dense. Composed mainly of granitic rocks.
Continental Crust
Continental Crust: Thicker (about __-__ km) and less dense than oceanic crust. Composed mainly of __________ rocks.
30-70 km
granitic
Thinner (about 5-10 km) and denser. Composed primarily of basaltic rocks.
Oceanic Crust
Oceanic Crust: Thinner (about _-__km) and denser than continental crust. Composed primarily of ________ rocks.
5-10
basaltic
Extends to about 410 km below the surface. Includes the lithosphere (rigid outer layer) and the asthenosphere (partially molten and ductile layer).
upper mantle
Upper Mantle: Extends to about ____ km below the surface. Includes the _______ (rigid outer layer) and the _________ (partially molten and ductile layer).
410
lithosphere
asthenosphere
Extends from 410 km to about 2,900 km. Composed of more solid, high-pressure minerals like perovskite and ferropericlase.
Lower Mantle
Lower Mantle: Extends from _____km to about __________km. Composed of more solid,_________ minerals like perovskite and ferropericlase.
410
2,900
high-pressure
Liquid layer extending from about 2,900 km to 5,150 km.
Outer Core
Composed mainly of iron and nickel, and is responsible for Earth’s magnetic field.
Outer Core
Solid layer at the center of the Earth, extending from 5,150 km to about 6,371 km.
Inner Core
Composed primarily of iron and nickel and remains solid due to immense pressure.
Inner Core
are fundamental components of Earth’s materials, playing a crucial role in the composition, structure, and processes of the planet. They are naturally occurring, inorganic solid with a specific chemical composition and a crystalline structure.
Minerals
are naturally occurring, meaning they form through natural geological processes without human intervention.
Minerals
They are inorganic, composed of elements and compounds not associated with biological life.
Minerals
They are solid at room temperature and have a crystalline structure, which means they have an internal atomic arrangement that forms a crystal lattice, giving them specific shapes and physical properties. Each mineral has a defined chemical formula that can vary slightly due to impurities or substitutions.
Minerals
Many minerals come from ___________, the molten rock beneath the Earth’s surface. When magma ________, mineral crystals are formed. How and where magma cools determine the _______of the mineral crystals.
magma
cool
size
molten rock beneath the Earth’s surface
magma
When magma cools slowly beneath the Earth’s crust, __________crystals form.
large
When magma cools rapidly beneath the Earth’s surface, ________ crystals form.
small
earth’s crust and slowly = _________
earth’s surface and rapidly =________
large
small
Crystals may also form from compounds dissolved in a liquid such as water.
Evaporation
When the liquid _________, or changes to a gas, it leaves behind the minerals as crystals. Halite, or rock salt, forms in this way.
evaporates
are the most abundant mineral group, characterized by the presence of silicon and oxygen.
silicates
composed of silicon and oxygen, is a major component of many rocks, and is known for its hardness and resistance to weathering.
quartz
is a group of minerals containing aluminum silicates, including orthoclase and plagioclase, which are important in granite and other igneous rocks.
feldspar
is a group of silicate minerals with a layered structure, including muscovite and biotite, known for their cleavage and use in electrical insulators.
mica
are minerals containing carbonate ions (CO₃²⁻). Common examples include calcite (CaCO₃) and dolomite (CaMg(CO₃)₂).
carbonate
found in limestone and marble, plays a significant role in the carbon cycle and is used as a building material.
calcite
are minerals where oxygen is combined with one or more metals. Examples include hematite (Fe₂0₃) and magnetite (Fe₃O₄).
oxides
is an iron oxide that is a primary ore of iron and is used in pigments and various industrial applications.
hematite
are minerals containing sulfur combined with metals.
sulfide
often referred to as “fool’s gold,” is an iron sulfide mineral with a metallic luster and is used in the production of sulfuric acid.
pyrite
are minerals that contain halogen elements like fluorine, chlorine, bromine, or iodine.
halides
commonly known as rock salt, is used for road de-icing and as a seasoning in food.
halite
are minerals composed of a single element.
native element
a native metal, is used in jewelry, electronics, and as a financial asset.
gold
Minerals containing silicon and oxygen (e.g., quartz, feldspar, mica).
silicate
Minerals containing carbon and oxygen (e.g., calcite, dolomite).
carbonate
Minerals where oxygen is combined with metal elements (e.g., hematite, magnetite).
oxides
physical properties of minerals
density
luster
cleavage
color
streak
fracture
hardness
measure of the mass of a material divided by its volume. Relates to the composition of the mineral and to the patter in which the mineral’s atoms are arranged.
density
Example: Galena has a high density (specific gravity of around 7.5), making it much heavier than minerals with similar colors like Pyrite, which has a specific gravity of around 5.
density
is the term used to describe how mineral surfaces reflect light and can be categorized as metallic, vitreous, pearly, etc.
luster
Example: Pyrite has a metallic luster and a golden-yellow color, often mistaken for gold.
In contrast, Talc has a pearly luster and is greasy to the touch.
luster
refers to the flat, smooth planes along which some minerals break and also to the shape of the resulting fragments.
cleavage
Example: Mica exhibits perfect cleavage in one direction, allowing it to split into thin, flexible sheets. Halite has cubic cleavage, breaking into cubic pieces.
cleavage
refers to the hue of a mineral which can vary due to impurities and exposure to environmental factors.
color
Example: Quartz can appear in various colors, including clear (rock crystal), purple (amethyst), and pink (rose quartz), depending on the presence of trace elements or inclusions.
color
is the color of the residue produced by scratching a mineral on a non-glazed porcelain plate.
streak
Different specimens of the same mineral may vary in color, but the streak color is always the _______.
same
is the tendency of mineral breaks unevenly or irregularly.
fracture
Example: Quartz typically exhibits a conchoidal fracture, with smooth, curved surfaces. Olivine often has a granular or uneven fracture.
fracture
measures a mineral’s resistance to scratching, often assessed using Mohs scale (e.g., talc is 1, diamond is 10).
hardness
a German mineralogist, worked out a scale of hardness.
Friedrich Mohs
is relative and allows geologists to rank minerals according to their hardness; it is not an absolute scale.
The Mohs scale
In the Moh’s Scale, since Quartz is harder than Calcite, ___________leaves powder resdue.
Calcite
are fundamental to understanding geology, as they are the Earth’s building blocks and provide insights into geological processes, history, and resource management.
rocks
are naturally occurring aggregates of one or more minerals, mineraloids, or organic materials. They form through various geological processes and are categorized based on their origin and composition.
rocks
rocks vs minerals: which is organic and inorganic?
minerals = inorganic
rocks = organic
are formed from the cooling and solidification of molten magma or lava.
igneous rocks
Texture of these rocks can range from coarse-grained (granite) to fine-grained (basalt), depending on the cooling rate.
igneous rocks
two types of igneous rocks
intrusive (plutonic) rocks
extrusive (volcanic) rocks
Formed from magma that cools slowly beneath the Earth’s surface, allowing crystals to grow
Intrusive (plutonic) rocks
Formed from lava that cools quickly at the Earth’s surface, resulting in smaller crystals.
extrusive (volcanic) rocks
In Igneous rocks:
___________= magma cools slowly, larger crystals
___________= lava cools quickly, smaller crystals
intrusive (plutonic)
extrusive (volcanic)
rocks that consist mostly of silicate minerals
igneous rocks
Igneous rocks four basic types of textures
glassy
fine-grained (basalt)
course-grained (granite)
porphyritic
formed from the accumulation and compaction of sediments or from the precipitation of minerals from water.
sedimentary rocks
Often have a layered or stratified appearance due to the accumulation of sediments. Mineral composition includes minerals like calcite, gypsum, and various clays
sedimentary rocks
breakdown of older rocks under the conditions found in Earth’s surface environment.
sedimentary rocks
Rocks of any kind, when exposed at Earth’s surface, slowly deteriorate due to the processes of ________________
weathering
most abundant sedimentary rock
limestone
three types of sedimentary rocks:
clastic rocks
chemical rocks
organic rocks
Composed of fragments of other rocks or minerals that have been cemented together. Examples include sanstone (from sand-sized particles) and shale (from clay-sized particles).
clastic rocks
Formed from the evaporation of water and subsequent precipitation of minerals. Formed when a sea or lake dries up, leaving large amounts of minerals that were dissolved in water. (Ex.: Rock salt and gypsum)
chemical rocks
Formed from the accumulation of organic materials such as plant debris. Examples include coal (from plant material) and oil shale (from organic-rich sediment). Limestones are often but not always organic rocks. Deposits of limestone may be formed from the shells of creatures when they die.
organic rocks
three types of sediments
(clastic sediments
organic sediments
crystalline sediments)
whole particles formed by the breakdown of rocks and were transported and deposited as whole particles
clastic sediments
sediments that are formed biologically such as seashells
organic sediments
sediments that are formed by precipitation of salt out of water
crystalline sediments
are the rocks that are drilled to find gas and oil. They are the source and reservoir rocks for gas and oil.
sedimentary rocks
process that bonds the loose grains into a solid sedimentary rock. The most common cement is the mineral calcite.
natural cementation
sedimentary rocks often consist of three parts when examined under a microscope:
- sediment ___________
- ____________ ___________ that bonds the grains
- spaces called ____________that is usually filled with fluids
- sediment grains
- natural cement that bonds the grains
- spaces called pores that is usually filled with fluids
rocks that are
made of the fragments of
previously existing rocks
clastic rocks
clastic rocks classification according to size and shape
conglomerate
sandstone
shale
made of rounded pebbles cemented together
clay, mud or sand and make up 1/3 of the rock. The pebbles
conglomerates are smooth and rounded because they have been
worn down by the action of water.
conglomerate
rocks made of small and fine grains are called
____________. At least half the particles in a clastic rock must be sand
sized in order for it to be considered a sandstone. In a sandstone,
the grains are cemented together by minerals such as quartz, calcite
and hematite, that harden.
sandstones
describe all the clastic rocks that are made of particles
smaller than sand. It forms from small particles of mud and clay
that settle to the bottom of quiet bodies of water such as swamps.
shale
come from organisms. (ex. coal)
organic rocks
T or F
Limestone are often but not always organic rocks. Deposits of
limestone may be formed from the shells of creatures when they die.
T
T or F
Limestone are always organic rocks. Deposits of
limestone may be formed from the shells of creatures when they die.
F
water precipitates two ways to form
_______ sedimentary rocks; by the process of evaporation and through
the life processes of marine organism.
chemical sedimentary rocsk
Formed when a sea or lake dries up, leaving large amounts - of
minerals that were dissolved in water. (Ex.: Rock salt and
gypsum)
chemical sedimentary rocks
In chemical sedimentary rocks:
Halite and gypsum are examples of ________________.
________________ - Chert, jasper and flint all form from silica that is left
behind when water evaporates.
evaporites
silicates
-rock is often classified according to the grain size.
-the size of the grains controls the size of the _______ ________ and the quality of the oil or gas reservoir
-Larger grains have _________pores between them. It is ___________ for fluids, such as gas and oil, to flow through larger pores and into a well
- ____________ grains in sedimentary rocks are classified by their diameters in
millimeters
pore spaces
larger
easier
clastic
is an important clue as to how a sedimentary
rock was formed.
lithology (rock composition)
Sedimentary structures such as ___________, _________, and ______________
help to visualize the environment in which the rock was deposited.
Sedimentary structures such as ripple marks, mud cracks, and flow marks
help to visualize the environment in which the rock was deposited.
Sedimentary rocks are most readily recognized from a distance by their distinctive layering, called _____________.
It is caused by the deposition of different sedimentary materials, one layer above the other.
Sedimentary rocks are most readily recognized from a distance by their distinctive layering, called bedding. Bedding is caused by the deposition of different sedimentary materials, one layer above the other.
come from Greek word meta means change and morphe means form and a result from changes to pre-existing rocks; these changes occur when the minerals that compose the rock are changed or rearranged or both.
metamorphic rocks
It is formed from the alteration of preexisting rocks (igneous, sedimentary, or other metamorphic rocks) through heat, pressure, and/or chemical processes.
metamorphic rocks
The changes typically occur at temperatures in excess of 200°C, which distinguishes _________________ rocks from the lower-temperature weathering and lithification processes that form sedimentary rocks.
metamorphic
Distinguished from igneous rocks because the temperatures that change the former are not high enough to cause the rock to melt.
metamorphic rocks
the changing of one type of rock into another as a result of heat, pressure, and chemical reactions
metamorphism
new minerals form and align perpendicular to the applied pressure if present
metamorphism
Have a layered or banded appearance due to the alignment of mineral grains under pressure. Examples include schist and slate.
foliated rocks
the mineral crystals are arranged in parallel
foliated rocks
Do not exhibit layering and are often formed from rocks that do not have a significant alignment of mineral grains. Examples include marble (from limestone) and quartzite (from sandstone).
non-foliated rocks
the rocks are not banded and do not break into layers
unfoliated rocks
is described by salt content in parts per thousand (ppt).
groundwater
contains so little salt (0-1 ppt) that it can be used for drinking water,
freshwater
are subsurface waters that contain more salt than seawater (35-300 ppt)
brines
are mixtures of freshwaters and brines (1-35 ppt).
brackish waters
is the natural, continuous process that forms, breaks down, and reforms rock through geological, chemical, and physical processes.
rock cycle
a sequence of processes and products that relate each rock type to the others and that describes rocks as continuously forming from preexisting rocks.
rock cycle
is a continuous process through which rocks transform from one type to another over geological time scalts. Molten rock called magma is the source material for rocks.
rock cycle
_________ rocks form both under the surface and above it when magma becomes lava. Heat and pressure changes igneous and sedimentary rocks into __________rocks. Erosion and weathering break igneous and sedimentary rocks up, which compact into sedimentary rocks.
Sediments from organic sources also contribute to sedimentary rocks. ___________ forces drive some rocks back below the surface, where they can change forms or melt and become magma once again.
igneous
metamorphic
tectonic
Importance of Rocks and Minerals in Reservoir Studies
______________________. Understanding the different types of rocks and their properties aids in finding probable reservoir rocks that have the suitable porosity and permeability for oil and gas accumulation.
_________________. Detailed rock classification helps develop accurate geological maps and models, which are crucial for exploration and production planning.
_________________. Accurate categorization and analysis of rock types and qualities is critical when estimating the size and potential output of hydrocarbon reserves.
______________________. Knowledge of rock types aids in the selection of optimal extraction and enhanced oil recovery techniques, which are suited to the reservoir rocks’ individual features.
______________________. Understanding the geology and mineralogy of a location assists in appraising the environment.
Identification of Reservoir Rocks
Geological mapping.
Resource estimation
Production techniques
Environmental considerations
