The Study of Geology

Comprehensive Summary of Geology and Its Importance

• Geology studies the Earth's materials, processes, and history
• Physical geology examines Earth's materials and processes like earthquakes and volcanism
• Historical geology studies Earth's origin, evolution, and past environments
• Geology is an important element of economic development, environmental management, and hazard mitigation
• Geologists locate and manage energy resources which is important for the transition to renewable resources
• Geology is essential for understanding aquifers, water supply, and contamination prevention
• Mineral resource management supports modern industry and technology through mineral exploration
• Ground condition assessment ensures safe construction, a component of infrastructure and engineering
• Pollution and industrial impact management contributes to environmental health
• Geology provides insights into geohazards like earthquakes, volcanic eruptions, landslides, and tsunamis
• Analysis of geological records helps predict future climate trends
• Geological knowledge is used for sustainable resource use and land management
• Natural hazard management includes landslides and floods
• Natural resource management focuses on minerals, water, and soil
• Anthropogenic hazards include waste disposal and pollution
• Sustainable development shifts to renewable energy, slows population growth, and reduces overconsumption
• Geology is essential in engineering projects for safety, stability, and cost-effectiveness
• Material selection identifies suitable construction materials based on durability and composition
• Site assessment determines ground stability for dams, bridges, tunnels, and buildings
• Water management locates groundwater sources and assesses its impact on infrastructure
• Risks from earthquakes, erosion, and land subsidence are evaluated
• Geological surveys prevent costly failures and unexpected ground conditions

Comprehensive Summary of Minerals

• A mineral is a naturally occurring substance formed through geological processes
• A mineral is an inorganic solid
• A mineral is a solid with a fixed structure at standard conditions
• Minerals have a definite chemical composition with slight variations
• Atoms are arranged in a repeating pattern in minerals with a crystalline structure
• Minerals are amorphous if atoms are not arranged in a definite crystal structure
• Opal (SiO2) is the amorphous equivalent of the mineral quartz (SiO2)
• Polymorphs are minerals that share the same chemical make-up, but have different crystal structures, created by changes in temperature and pressure
• Diamond and graphite are carbon polymorphs
• Diamond forms under high pressure
• Graphite forms under low pressure
• Calcite and aragonite are both CaCO3, but with different crystal lattices
• Solid solution series occur when one ion substitutes for another in a crystal lattice without changing the mineral’s structure
• Minerals with the same basic chemical formula that experience substitution of elements in one or more atomic sites share a compositional range
• Iron and magnesium replacement of one another exemplifies this
• A complete substitution of elements can result in end-member mineral compositions
• Olivine, (Mg2SiO4) forsterite to (Fe2SiO4) fayalite, is a complete solid solution end-member mineral composition
• Magnesium and iron freely substitute in Olivine (Mg,Fe)2SiO4
• Plagioclase feldspar ranges from albite(NaAlSi3O8) to anorthite (CaAl2Si2O8)
• Crystals are naturally occurring solids with an order atomic arrangement
• The terms crystal and crystalline refer to any natural solid with an ordered, repetitive, atomic structure
• Crystals are single, continuous pieces of a crystalline solid bounded by flat surfaces called crystal faces
• Crystal formation methods:
• Atoms accumulate as a melt solidifies and cools from magma/lava: ice
• Minerals form as water evaporates from a solution: salt deposits
• Atoms rearrange in solid rock: garnet
• Organisms create minerals either within or on their bodies: shell creation
• Volcanic gasses or steam cools abruptly: sulfur deposits
• Crystal habit is the external shape of a mineral, for example needle-like, cubic, fibrous
• Geodes are hollow, rounded rocks lined with crystals that form as mineral-rich water fills a cavity and minerals like quartz and calcite precipitate inside over time
• Have a well-defined geometric patter of atoms:crystalline minerals, for example quartz
• Lack A regular structure, typically forming from rapid cooling:amorphous minerals, for example obsidian
• Some minerals have consistent colour, for example olivine (green), but others vary, for example quartz
• Streak is the colour of powdered mineral on unglazed porcelain
• Very diagnostic
• Luster is how light reflects off a mineral’s surface
• Can be described as metallic versus non-metallic, and non-metallic varieties include glassy, silky, pearly, earthy, or dull
• Hardness refers to a mineral's resistance to scratching
• Measured by the Mohs Scale, where 1 = talc and 10 = diamond
• Depends on the strength of the chemical bonds
• Cleavage is the tendency to break along weak planes
• For example, mica has one perfect cleavage plane
• Break occurs along preferred directions along reflective planar surfaces
• Fracture occurs when minerals break irregularly
• For example, quartz with conchoidal fracture
• Descriptive terms for fracture are splintery (talc), fibrous (asbestos), irregular (bornite), hackly (native metals)
• Specific gravity, or density, is ratio of a mineral's weight to water
• Special properties include:
• Reaction to acid
• Magnetism
• Fluorescence
• Radioactivity
• Double refraction
• Minerals are classified by their dominant anion
• The silicon-oxygen tetrahedron (SiO44−) is the fundamental building block of silicate minerals.
• It is abundant because of the large amounts of silicon (Si) and oxygen (O2) in Earth's crust
• A silicon atom surrounded by four oxygen atoms forms the building block
• Tetrahedra can link together in various ways to form different mineral structures
• Silicate minerals without substantial Fe and Mg in their crystalline structure are considered Non-ferromagnesian Silicates
• They are generally lighter-colored compared to the ferromagnesian silicates
• Silicates with Fe and/or Mg in their structure are Ferromagnesian Silicates
• Most ferromagnesium minerals are dark-colored and denser than the non-ferromagnesian silicates
• Examples of ferromagnesian silicates:
• Olivine
• Pyroxene
• Amphibole (Hornblende)
• Biotite
• Silicate minerals are categorized based on how their silicon-oxygen tetrahedra are arranged
• The arrangements determine the minerals properties and appearance
• Seven total groups: nesosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, and tectosilicates
• Nesosilicates share no oxygens byut are linked by cations and contain isolated tetrahedra
• Sorosilicates consist of pairs of tetrahedra sharing one oxygen atom and contain double tetrahedra
• Cyclosilicates comprise tetrahedra forming rings of three, four, or six tetrahedrons and contain ring silicates
• Each Si atom is bound by two O2 atoms that are part of another tetrahedron
• Inosilicates are chain silicates as follows:
• Single chains containing tetrahedrons sharing two O2 atoms with two other tetrahedrons and form a seemingly endless chain
• Double chains contain alternating tetrahedra that share tow or three oxygen atoms. Two single chains lie side by side , so that all the right sided tetrahedrons of the left chain are linked by an oxygen to the the left sided tetrahedrons of the right chain
• Phyllosilicates comprise sheet silicates
• Tetrahedra form continuous sheets bonded by layers of cations
• Rings of tetrahedrons are linked by shared oxygens to other rings in a two-dimensional plane that produces a sheet-like structure
• Tectosilicates are framework silicates
• Every oxygen atom is shared, creating a three-dimensional framework
• Composed of interconnected tetrahedrons going outward in all directions forming an intricate framework

Feldspar Group Classification & Common Silicate Minerals

• Feldspar minerals are the most abundant silicates
• Two subgroups of classification exist: alkali feldspar and plagioclase feldspar
• Alkali feldspar contains potassium and sodium
• Alkali feldspars are solid solutions of K-feldspar and albite, like orthoclase (KAlSi3O8)
• Plagioclase feldspar contains varying amounts of calcium and sodium, forming a solid solution series, and are solid solutions of albite and anorthite
• Examples of plagioclase feldspar are albite (NaAlSi3O8) and anorthite (CaAl2Si2O8).
• Feldspars show diagnostic striations (parallel lines on cleavage surfaces) and unique twinning properties
• Common silicate minerals include:
• Olivine (Mg,Fe)2SiO4 (Nesosilicate)
• Zircon ZrSiO4 (Nesosilicate)
• Garnet (Nesosilicate)
• Epidote (Sorosilicate)
• Pyroxene (Inosilicate, Single Chain)
• Amphibole (Hornblende) (Inosilicate, Double Chain)
• Muscovite and Biotite (Phyllosilicates)
• Talc and Chlorite (Phyllosilicates)
• Kaolinite (Clay Mineral, Phyllosilicate)
• Quartz SiO2 (Tectosilicate)
• Non-silicate minerals are classified based on their dominant anions, like oxides, sulfides, and carbonates
• They make up about 8% of Earth’s crust
• Economic importance derived from use as ores and industrial materials
• Oxide minerals contain metal cations bonded to oxygen (O2-)
• Often are valuable for metal extraction
• Hematite (Fe2O3) is a major iron ore and may be red or brown
• Rutile (TiO2) is an important source of titanium
• Corundum (Al2O3) is known for varieties like ruby and sapphire
• Magnetite (Fe3O4) is magnetic and often used as an iron ore
• Hydroxides are formed when metals combine with water or hydroxyl ions (OH-) and often result from weathering
• Goethite (FeO.OH) is a yellow-brown iron ore
• Limonite (FeO.OH·nH2O) typically forms from hydrated iron oxides
• Sulphides are composed of sulfur (S2-) and metal cations
• Many are important metal ores
• Pyrite (FeS2) is often mistaken for gold and is known as "Fool's gold"
• Chalcopyrite (CuFeS2) is a major copper ore
• Galena (PbS) is a primary lead ore with a metallic luster
• Sulphates form from metal cations bonded to sulfate ions (SO42-) and often occur in evaporite deposits
• Gypsum (CaSO4·2H2O) is used in plaster and drywall
• Anhydrite (CaSO4) is similar to gypsum, but without water
• Carbonates are characterized by the carbonate ion (CO32-) bonded to metal cations
• they form in marine environments and are used in construction/manufacturing
• Calcite (CaCO3) is the main component of limestone and marble, and reacts with acid
• Dolomite (CaMg(CO3)2) is similar to calcite, but includes magnesium
• Halides are composed of metal cations and halogen ions (Cl-, F-, Br-, I-) and often form in evaporite deposits
• Halite (NaCl) is common table salt, and forms from evaporated seawater
• Fluorspar (CaF2) is industrially used in metallurgy and ceramics
• Phosphates consist of phosphate ions (PO43-) bonded to metal cations
• Typically used as fertilizers
• Apatite (Ca5(PO4)3(F,Cl,OH)) is a primary source of phosphorus for fertilizers

Plate Tectonics

• According to the theory of plate tectonics, Earth's lithosphere comprises rigid plates moving over the asthenosphere
• Plate movement explains the formation of continents, ocean basins, mountain ranges, earthquakes, and volcanoes
• Plate movement rates are around 1.15 cm/year
• Continental drift(Wegener, 1912) is a key concept regarding how continents were once part of a supercontinent, Pangaea, and drifting into current positions
• Seafloor spreading(Hess, 1950s) is a key concept describing how new oceanic crust forms at mid-ocean ridges and spreads outward
• Subduction is a key concept stating old oceanic crust sinks into the mantle at deep-ocean trenches
• Divergent boundaries(constructive) exist as plates move apart
• New oceanic crust forms at mid-ocean ridges, or the Mid-Atlantic Ridge
• Pillow lava forms as lava cools underwater rapidly
• Transform faults occur between ridge segments
• Convergent Boundaries(destructive) exist when plates collide
• Oceanic-Continental boundaries: Oceanic crust subducts beneath continental crust, which forms a continental volcanic arc, like the Andes and Cascades
• Oceanic-Oceanic boundaries: One plate subducts, forming an island arc, like Japan and the Philippines
• Continental-Continental boundaries: Neither plate subducts, so mountains are formed, like the Himalayas Features found at boundaries: Subduction zones, Wadaiti-Benioff zones(deep earthquakes), accretionary prisms ( scraped sediments)
• Transform boundaries involve plates sliding past each other
• Characterized by transform faults, like the San Andreas Falult
• Triple Junctions are points where three plate boundaries meet, like the Mendocino Triple Junction or the afar triangle in East Africa
• Hotspots are volcanic regions caused by mantle plumes, like Hawaii Yellowstone or Iceland.
• Pillow lava is lava that spills from the mid-ocean ridge axis and cools quickly to form a layer of basalt blobs
• Formation occurs when basaltic lava erupts underwater at mid-ocena ridges
• Pillow lava resembles rounded, pillow-like shapes due to rapid cooling in seawater
• Typically found at divergent boundaries where the seafloor spreading occurs
• Subduction Zones are where one tectonic plate sinks beneath another into the mantel
• formation occurs at convergent boundaries between a continental plate and oceanic plate
• characterized by deep ocean trenches and volcanic activity
• The Wadati-Benioff zone is a sloping zone of earthquake activity along a subducting plate, that indicates the presence of a descending tectonic plate
• Extends from the surface to depths of 660km
• Accretionary prism - composed of sediments scraped off the subducting plate and piled up agasint the overriding plate
• Accretionary prisms have a wedge-like cross-section
• Typically found at convergent boundaries near oceanic trenches
• Continental Volcanic Arc involves a volcano chain formed by magma rising from a subducting plate
• Magma formation created by the partial melting of the mantle
• Example: The andes in South America
• Island Arc are chains of volcanic islands formed above a subducting oceanic plate
• Formation is similar to continental arcs
• Example: The Japanese Archipelago
• Transform faults at mid-ocean ridges are large fractures that accumulate the horizontal movements of tectonic plates
• they exist between segments of mid-ocean ridges at divergent boundaries
• Often the the sites of frequent earthquakes
• Seamount chains are a chain of isolated submarine mountains, which are volcanoes that have been previously active
• Hot spots are places where hot mantle rock rises from the core-mantle boundary and causes anomalous volcanism at an isolated volcano
• The plate moves over the mantel plume
• The volcano moves off the hot spot and dies
• The end result, hot spots spawn seamount chairs and some hot sports are located above continents

Magma Formation

• Intermediate rock partial melting produces felsic magma
• Type, density, temperature and viscosity of Magma:
• Felsic type is a very low density whose temperature is very low (600-850C). Its viscosity is very high with explosive eruptions
• Intermediate density has a temperature that is low and its viscosity is High with explosive eruptions
• Mafic is a High Density With a High Temperature Their viscosity is low and thin hot runny eruptions
• Ultramafic has a very high density,Very High Temperature,and viscosity
• Magma forms through these means.
• Pressure decrease allows mantle rock to melt from Decompression melting
• Water and CO2 lower the melting point in the Addition of volatiles of Magma.
• There are Dry Magma( No volatiles) and Wet Magma(Volatiles)
• Heat melts surrounding rock through Heat transfer from rising magma .
• Magma composition can be altered through:
• Different minerals melt at different temperatures, producing silica-rich magmas by Partial melting
• Magma incorporates surrounding rock, changing its composition in Assimilation
• Early-forming minerals crystallize first, leaving a more silica-rich melt through Fractional crystallization
• Magmas of different compositions blend during Magma mixing
• Bowen's Reaction Series explains the crystallization order of minerals from a cooling magma
• Branch 1: Olivine -> Pyroxene > Amphibole -> Biotite Branch 2: Calcium-rich plagioclase-> Sodium-rich plagioclase Final crystallization: Orthoclase, Muscovite, Quartz
• Intrusive Igneous rocks have characteristics that is thermally altered in the Baked Zone

Rock Body &Igneous Rocs

• Chill margin refers to rapid cooling at intrusion edges
• Xenoliths describe fragments of older country rock within intrusion
• Magma is cooler then assimilated
• Thermal metamorphism describes heat that alter surrounding
• There is Fractured inflation by expanding magma pushing rock aside in Earth's country rock
• Hydrothermal alteration describes Hot water that circulates to altering minerals in earth's country rock
• Tabular (sheet-like) are classified as:
• Sill (parrallel to existing layers)
• Dike that cuts across layers (discordant)
• There are large, irregular bodies of Plutonic (large, irregular bodies) to rock that are called
• Batholith
• Stock
• Laccolith
• Lopolith
• Factors that contribute to magma cooling have all to do with (1)Depth, (2)Size (3) presence of ground water
• Depth has slower cooling the deeper you get
• The size effects the cooling with the larger cooling more slowly
• The presence of ground water is quicker at transferring
• Slow ( crystals ) is Fewer but larger
• Fast ( Crystal) there are (Many crystals ) Very Fast (crystals ) creates (Glass)
• Igneous Rock Textures
• Glassy texture has (No crystals, rapid cooling that is obsidian)
• There are Inter- grown mineral crystals texture
• Aphanitic is fine-grained at surface
• Phaneritic is coarse-ground
• Porphyritic, large crystals in finer grind
• Pegnatitic Exceptionally large crystals
• Fragmental (Pyclosatic) Made of a volcanic debris
• Classification of Igneous Rocks is made up of mineral textures
• Granitic of Quartz, K-feldspar & Sodium-plagioclase
• Dioritic of Amphile
• Gabbroic of Naplagioclase pyroxene
• Ultramafic rocks has to do with pyroxene, olivine
• Pumice is frothy, felsic, vesicular which it floats.
• There is Crystalline rock with Grainistic of Rhyolite, Granodiorite Gabbrotic is with Basalt

Sedimentary Rocks

• Consists of precipitated material that's in a solution
• InOrganic of Chemical sedimentary that are from precipitation of rock that has from in organic water
• Organic has sediment from life, Microscopic that are from Calium
• Clastic sediment can be derived after the e physically weathered parts of original rock. Such as Quartz
• Chemical sediment dissolves eventually with in its solid
• Organic-rich which has shale from the ocean that can derive shale for oil
• Chert (silica-based) forms with calcium that can derive and is made to have formation with caluim
• Sandstone which is made of sand with great amounts or quartz
• Arkose > 25% feldspars grain Siltstone is a combination with shale along with a small amount of clay Shales splits into a thin layer Angularity & Sphericity Rounded grains that is from a longer distance Sharper grains which a shorter distance There are many of sedimentary Environ with 4 Different Types Continental Environment's can form from all sorts, Rivers, Lakes Shoreline has Beach and much more. Bedding-Stratifications Layerings which helps determine when the the sedimentation and environment began.
• In order to study Metamorphism what is looked at is transformation which is studied through changes of pressure(P),
• Temperature (T) and composition (X)
• If high grades then the rocks that have been made is in a increase environment
• Then we observe the agents with look though the rock with the help of Heat (T), Pressure (P), & Chemical fluids
• Isotropic fabric will form in environments that do not have a lot movement or low deformation Granoolistic texture. Which has a mosaic of equigranular crystals Porphyroblatic texture: with is a rock crystals
• Anisotropic fabric (Forms with more stress
• Slate is Very fine with clear cleavage of rock and is from shale
• Shistocity rock crystals that is highgrade band with high grade in them rock There are some rocks that might be non Foliated is has its reason being
• The rocks not subjected have different stress. The degree of Metamorphism Then the rock has to of not equal size mineral and has to dominate minerals.

Geological Rock Formation

• Principles of superposition helps determine the layered igneous rocks and when they where formed Original horizontality and Continuty, are the sediments with in the ground at which they tilted or made them
• Is why they are tilted
• cross-Cutting which helps cut across rocks and which way is that it's cut to and which it is cut trough Inclusion will be known as fragment of other rocks that is young are form the rock from the inclusions originated from. Bake of contacated where heats things to the extreme

Fossils are in a different sequence of the rock

• A particular the rock of fossil successions.
• Uncomfty is one of the largest record through the erosion. There are three types which are
• Angular Uncomformity of all the layers that or tilt.