Definitions Flashcards
Mineral
Naturally occurring chemical substance having a definite composition and crystalline structure.
Rock
An aggregate or mixture of one or more minerals.
Sublimation
Solid to gas
Lusture
Surface appearance of a mineral as light interacts with it
Crystal
Solid with plane faces formed when atoms are arranged in a structurally ordered pattern.
Glass
An amorphous solid with no crystalline structure.
Grain boundary
Line of contact between mineral crystals in a rock.
Igneous rock
Those that have cooled from magma
Phenocrysts
Large or clearly visible crystals on an igneous rock, much marger than groundmass
Essential mineral
This minerals used to classify igneous rock.
Accessory/secondary mineral
May be present but not used for classification
Felsic
Light coloured and silica rich
Mafic
Dark coloured, silica poor and rich in mg and fe
Magma
Molten rock below earth’s surface
Flow banding
Formed by friction as magma slows down near interfaces, aligning minerals.
Conchoidal
A fracture which results in a curved surface
Vesicular
Rock containing vesicles. Gas comes out of solution as a result of pressure release.
Porphyritic
Large phenocrysts are surrounded by groundmass
Equigranular
Crystals are approximately the same size
Amygdaloidal
Large vesicles fille din by secondary mineral
Lava
Molten rock cooled at surface
Ophiolites
Sections of earth’s oceanic crust that have been tectonically moved onto continental crust.
Isochemical
No elements added or removed
Granoblastic
He texture found in met rocks with interlocking equidimensional crystals
Foliation
Preferred alignment of flat minerals in met rocks
Slaty cleavage
The texture in fine grained, low grade, regional metamorphic rock. Perpendicular to pressure
Cataclasis
The brittle fracturing and grinding down of existing rock in fault zones
Porohyroblasts
Large crystals grown during recrystalisation in a met rock and surrounded by a finer grained ground mass.
Schistosity
Med and coarse grained met rocks formed by preffered alignment of flat/tabular minerals. Perpendicular to stress. No traces of original bedding remain
Gneissose banding
Segregation of light and dark minerals into bands. Light band is granoblastic and dark band shows schistosity.
Metamorphic grade
A measure of the intensity of metamorphism.
Country rock
Rock into which igneous rock is intruded
Metamorphic aureole
Region surround an igneous intrusion in which the country rocks have been recrystalised and changed by heat from the intrusion
Spotted rock
Formed by low grade metamorphism on the outer part of an aureole.
Index minerals
Metamorphic minerals which are stable under specific. Temp and pressures. They indicate grade.
Weathering
In situ chemical alteration, mechanical and biological breakdown of rocks by exposure to the atmosphere, water or organic matter
Carbonation
Reaction between carbon via acid and minerals
Hydrolysis
The reaction between minerals and water, causing the minerals to decompose.
Exfoliation
Occurs when sheets of rock split off due to differential expansion and contraction of minerals during diurnal heating and cooling.
Frost shattering
Caused by the expansion of freezing water in fractures by 9%.
Pressure release
Expansion and fracturing of rock due to removal of overlying rock.
Root action
Causes mechanical and chemical weathering by wedging open rojc by roots.
Burrowing
Animals bring rock and soil to the surface. Allows weathering at a greater depth.
Erosion
The wearing away of the land surface and removal of sediment by transport.
Abrasion
Wearing away of earth by wind, water ice dragging sediment over a surface
Attrition
Wearing down of sediment due to collisions with other grains.
Mineralogical maturity
Extent to which minerals have been destroyed by weathering and attrition
Solution
Transport of ions dissolved I. Water
Traction
The transport of material by rolling and sliding on a surface
Saltation
Bouncing
Suspensuon
Transport in water or air without touching earth’s surface
Roundness
How similar the outline of a grain is to a circle
Shape
Hwo similar it is to a sphere, rod, disc or blade
Phi scale
Grain size on a logarithmic scale
Textual maturity
Extent to which sediment is well sorted and well rounded.
Fossil
Any trace of past life. Parts or whole organisms as well as traces of them.
Organism
Individual life form.
Body fossil
Hard parts of an organism
Replacement
Atom by atom substitution of one mineral for another
Dissolution
Minerals that make up fossils are dissolved away and removed in solution.
Taphonomy
Study of fossilisation
Mould
Impression of the outside/inside of a fossil
Cast
An infilled fossil void, usually with another mineral.
Extant
Still alive
Extinct
No longer alive
Death assemblage
Collection of organisms found in a different place to where they lived
Disarticulated
Fragments of organisms
Life assemblage
Organisms fiund found within sediments in the same position as they they would’ve lived
Geopetal structures
Way up indicators
Derived fossils
Weathered out of one rock and deposited in another
Ornament
Surface features such as ribs, spines growth lines etc
Robustness
Ability to resist abrasion
Articulated
Whole or connected organisms
Luttoral zone
Area between high and low tide
Anoxic
Lack oxygen
Species
Group of organisms that can interbreed to poruce fertile offspring
Trace fossils
Formed by benthonic infaunal and benthonic epifaunal organisms.
Tracks
Footprints of an organism made when it moved along sediment e.g. Cruziana
Trails
Impressions of animals which were travelling.
Resting traces
A trail as the whole body of the organism has stopped
Bioturbation
Burrowing or working the sediment in a way that disrupts bedding caused by organisms
Substrate
Sediment or rock on sea floor.
Continental drift
Theory that the position of continents has changed. Convection currents moved continents like rafts.
Passive plate tectonics
Global seismic network set up and shows that lateral displacement of hundreds of kilometers had occurred.
Active plate tectonics
Evidence mounted that the passive model was neither machanically or thermodynamucally robust.
Tillites
Ancient glacial deposits preserved in a rock sequence
Evaporates
Formed by evaporation of hypersaline water, for example halite, gypsum and anhydrite.
Apparent polar wandering curve
A line on a map which joins up the apparent positions of the magnetic north pole over time.
Orogeny
A period of mountain building.
Geosycncline model
Continents fixed through time, lateral compression caused orogeny. Contraction theory - cooling of earth caused it to shrink
Random synclines.
Fossils found in SA and Aftrica
Mesosaurus and Glossopteris
Solar system
Consists of the sun, planets, moons comets and asteroids.
Sun
A star composed of hydrogen an helium. 98.8% of mass of solar system
Planets
Sizeable object orbiting star has its own grvaity
Moon
Natural satellite that orbits a planet
Asteroids
Rocky objects which failed to form planets
Meteorites
Rock fragments which fall to earth from space
Cmet
Composed of ice and dust. Outer layers metlt when closer to the sun.
Protoplanetory disc
Rotating disc of dense gas and dust surrounding newly formed star.
Planetessimala
Solid objects in protoplanetory discs
Protoplanet
Moon sized object that formed in protoplanetory disc.
Bed
A unit of sedimentation, which can vary considerably in thickness
Bedding plane
Mark a break between beds. They represent a break in sedimentation, a change in composition or grain size or change in colour.
Dip
The maximum inclination of a bed measured from horizontal
True dip
Angle measured at 90° to strike
Apparent dip
Dip that is measured to be less than the maximum inclination.
Strike
The horizontal line along a bedding plane. Measured as a bearing from north at 90° to dip.
Fault
A fracture in a rock along which there has been an observable amount of displacement.
Fault plane
A plane of fracture along which the rock has been displaced
Upthrow
The side of the fault where the movement is upwards, in relation to the other side.
Downthrow
The side of the fault where the movement is downwards in relation to the other side
Throw
The vertical displacement of rocks along the fault plane.
Footwall
Lies below the fault plane if it isn’t vertical
Hanging wall
Lies above the maximum inclination of the fault plane.
Normal fault
Crustal extension. Tensional forces.
Reverse fault
Crustal shortening. Comprwssional forces.
Thrust fault
Low angle reverse fault (<45°)
Grab and horst
Two normal faults which dip away from each other. Crustal extension.
Porosity
% volume of pore space
Permeability
Rate of flow of fluids through rock
Capillary pressure
The pressure between two immiscible fluids in narrow pore spaces. Resulting from interaction of forces between the fluids and grains.
Connate water
Trapped din pore spaces of a rock as it formed. It includes water trapped in the original sediment and water released during diagenesis.
Groundwater
Water occupying pores and other spaces in rocks and sediments which is derived mostly from rainfall percolating into underlying rock.
Water table
The surface separating unsaturated rock above from saturated rock below.
Hydrostatic pressure
The pressure at a point in a body of water due to overlying column of water.
Hydraulic gradient
The difference in hydrostatic pressure between two points divided by the distance between them.
Aquifer
A body of porus and permeable rock capable of storing and yielding significant amounts of water.
Recharge zone
The area of an aquifrr open to the atmosphere, allowing replenishment of water.
Artesian basin
A large synclinal confined aquifer under hydrostatic pressure.
Artesian well
Hold water under pressure which rises to a piezometeic surface.
Piezometeic surface
Imaginary level to which groundwater would rise to if under hydrostatic pressure.
Abstraction
The removal of water from any source.
Amplitude
Maximum displacement of an oscillation, measured from equilibrium.
Attenutation
The loss of energy experienced by a wave as it propigates through a material. Loss of amplitude
Moment
Turning force around a pivot
Geohazard
Geological condition that is dangerous or potentially dangerous to the environment and people who live within it.
Liquefaction
Saturated or partially saturated unconsolidated material losing strength and rigidity In response to applied stress eg earthquake.
Resonant frequency
Frequency at which amplitude of oscillation is at maximum
Intensity
Measure of surface shaking and damage caused by an earthquake. The mercalli scale measures intensity. Based on local accelerations.
Cratons
Stable portions of continental crust no longer tectonically active, mostly thick basement rock, thicker parts of the crust.
GOE
Great oxygenation event. Appearance of oxygen in atmosphere 2.3 BA
Snowball earth
Planet is frozen or frozen to very low latitudes.
Albedo
The fraction of solar energy reflected from earth back into space. Reflectivity of earth’s surface. Ice has high albedo.
Pannotia
A short lived super continent that formed at end of precambrian
Gondwanaland
Fomed 570-510ma. Includes most southern land masses.
Laurasia
Laurentia and Eurasia. North hemisphere continents
Variscan orogeny
Mountain building event caused by collision between gondwanaland and laurasia to form pangea.
Isostatic
Sea level change due to local events such has uplift or subsidence of crust.
Eustatic
Worldwide change. Volume of water oceans changes.
Which O isotope is more readily taken up by glaciers
O16 is more easily taken up. Leaving more O18 in oceans.
Which C isotope is more readily taken up by plants
C12 so during icehouse, it has higher % in ocean.
Marginal marine environment
Not marine or terrestrial, both due to tides.
Land mass
Continent/large body of land
Graptolites
Extinct marine organisms that lived in colonies, most of which floated freely in the sea, some may have been attached to the sea bed.
Avalonia
Microcontinent during the paleaozoic which contained Wales, Ireland, England and southern Scotland in the southern hemisphere.
Baltica
Microcontinent during paleaozoic containing baltic coutries (east of avalonia)
Laurentia
Microcontinent during paleaozoic which contained Scotland and Ireland, and north American continent
Iapetus
Ocean which existed in the lower paleaozoic wfhich closed due to collision between avalonia, baltic a and laurentia.
Caledonian orogeny
Mountain building era for scotland
Terranes
Fragments of crustal material broken from one tectonic plate and acreted onto another. The boundary is usually a fault.
Cations
Positively charged atoms
Anions
Negatively charged
Covalent bond
Sharing of a pair of electrons
Tetrahedron
4 sided object
Solid solution
One or more type of atoms may be substituted for the original atoms whilst in solid state, no change to strucutr as atomic radii are similar.
Bridging oxygen
An oxygen shared by two tetrahedra
Polymers
Repeating chains of small molecules
Twinning
Feature of feldspar where two or more crystals grow with different orientations from a common plane. One is a mirror of the other
Magma accumulation
Magma collecting in a magma chamber
Intrusion
Composed of igneous rock formed below earth’s surface. Forced into pre existing rock
Extrusion
Emission of magma onto surface where it forms a flow
Deposition
Laying down of sediment that occurs when transporting agent loses energy.
Transport
The means by which weathered material is moved from one place to another.
Uplift
The return of bhried rocks to earth’s surface by tectonic forces and erosion.
Single tetrahedra
Eg olivine
4- charge
1:4
Chains
E.g. Augite
2- charge
1:3
Double chains
E.g amphibole/hornblende
6- charge
4:11 charge
Sheets
E.g. Mica
-4 charge
2:5
Frameworks
E.g. Quartz
0 charge
1:2
Hypabyssal
Igneous rock intruded at relatively shallow depth ~1km - 10km
Plutonic
Rock intruded at >10km
Euhedral
Well formed with good crystal faces
Equant
All axis of crystals the same.
Prismatic
Four or more sides but elongated in one direction
Anhedral
Poorly formed crystal faces
Subhedral
Some well formed faces some poorly formed faces.
Pegmatite
Exceptionally large crystals of igneous rock.
Glassy
No crystals. Conchoidal fracture
Equicrystalline
All crystals the same size
Vesicular and amygdaloidal
Gas bubbles trapped in lava as it cools rapidly. Elongated in direction of flow. Vesicles filled in by minerals deposited by groundwater e. G. Calcite/quartz. Making an amygdale.
Flow banding
Separation of minerals in a lava flow by friction / viscosity
Porphyritic
Two stages of cooling. Two sizes of crystal. Groundmass and phenocrysts.
Ophitic
One mineral enclosed by another
Cumulated texture
Crystals settle out of magma on the floor of a magma chamber and accumulate in mutual contact.
Mechanically formed. (siliclastic)
Sedimentary rocks result from processes of erosion transport and deposition.
Siliclastic roxk
Formed from sediment compose dof silica ye material and rock fragments.
Matrix
The background material of small grans in which larger grains occur
Clay minerals
A group of sub-microscopic platy aluminium silicates called mica.
Plasticity
The ability of a material to permanently change shape without fracture
Fissile
Tendency of rock to split into thin layers
Rudaceous
Coarse >2mm
Arenaceous
2mm-0.0625mm medium
Argillacous
<0.0625mm fine
Ooliths
Spherical grains showing concentric banding of carbonate material. These are less than 2mm diameter
Pisolite
Very large ooliths in rock
Micrite
Microcrystaline calcite. Depositional matrix of lime mud
Sparite
Coarse grained crystalline calcite cement
Cement
Minerals precipitated between grains
Pellets
Carbonate material excreted by animals
Diagenesis
The changes that take place in sediments close to earth’s surface
Lithification
The process of changing u consolidated sediment into rock
Pressure dissolution
Minerals dissolve due to applied pressure between grains, resulting in reduced rock volume
Porosity
5he volume occupied by spaces in between grains
Peat
Partly decomposed plant remains with high water content
Coal
Carbon rich rock formed from fossil remains
Relict structures
E. G. Bedding partially preserved in metamorphic rock
Dalradian
Regionally metamorphised group of rocks deposited in precambrian found in Scotland and ireland
Inclusion
Early formed mineral enclosed by one which grew later
Unfoliated
Random orientation of minerals in metamorphic rock
Hornfels
Fine grained, hard, splintery, granoblastic metamorphic rock formed when shale is completely recrystallised close to contact with an intrusion. Index minerals are silimanite.
Slaty cleavage
Splits into thin sheets along cleavage planes. Formed from platy minerals, chlorite and mica.
Schistosity
In phyllites and schists. Aligned flat minerals at 90° to pressure. Granite porphyroblastoften present.
Gneissose banding
Light leucocratic minerals and dark melanocratic minerals separate into bands roughly 90° to pressure
Porphyroblastic fabric
Large crystals that grow and are surrounded by finer groundmass. Pyrite cubes found in slate, garnet found in schist
Granoblastic
Contact met only. Unfoliated. Randomly orientated equidimensional crystals
Crenulation cleavage
When there are two directions of max stress, creating a wavy pattern.
Catastrophism
The theory that changes in the earths crust have resulted from sudden, violent, short lived events.
Gradualism
Changes come gradually. E.g. Evolution
Uniformitariansim
Slow incremental changes created earth’s features. Processes observable now we’re acting in the same way in the past.
Absolute dating
Specific dates for rock in ma
Relative dating
Putting units into a sequential order
Half life
The time taken for half the unstable parent nuclei to decay into stable daughter products.
Closure temperature
The temperature at which a system has cooled so there is no diffusion of isotopes into or out of this system
Closed system
When a mineral neither gains nor loses atoms. The higher the temperature, the more likely exchange of atoms or ions will be.
Quaternary
- 6ma to present
Neogene
2.6 to 23 ma
Palaeogene
23-66 ma
Cretaceous
66-145 ma
Jurassic
145-201ma
Triassic
201ma-252ma
Permian
252-299ma
Carbiniferous
299-359ma
Devonian
359-419ma
Silurian
419-444ma
Ordovician
444-485ma
Cambrian
485-541ma
Stress
Force pr unit area
Strain
Change in shape of an object due to stress
Seismometer
Device which monitors seismic vibrations
Seismogram
Paper or electronic record made by a seismometer
Seismograph
A device which both writes and records seismic vibrations
Focus
The point within tne earth at which the earthquake originates as movement occurs along a fault plane. Waves radiate in all directions from this point
Epucentre
The point directly above the focus on earth’s surface
Shadow zone
Area where earthquake waves are not recorded. 103-142°
Intensity
Measure of surface damage caused by an earthquake
Moho
Crust/mantle discontinuity.
Rock type change
U mantle
35km-700km
L mantle
700km-2900km
Gutenberg
2900km
Phase and rock type change
Outer core
2900km-5100km
Liwuid iron-nickel alloy
Lehman discontinuity
5100km
Phase change
Inner core
5100km-6371km
Solid nickel iron alloy
Transform fault
A strike sli fplt whihh ends at the junction of another plate boundary or fault.
Tear fault
A strike slip fault fail which dies out without a junction
Transform plate boundary
A fault where no crust is created or destroyed.
Sheeted dykes
For magma which usually does not reach the surface and usually composed of dolerite
Pillow lava
Forms when lava erupts underwater. Made of basalt
Island arc
Curved line of andesitic volcanic islands.
Deep ocean trench
A long narrow linear submarine depression with relatively steep sides. Alongside island arcs into a subduction zone.
Benioff zone
A zone of earthquake foci sloping down at 45° from the ocean trench
Slickensides
The striations and polishing found on a fault plane indicating the direction of relative movement.
Fault breccia
Composed of fragments produced by rocks fracturing during faulting. Found on fault planes.
Fault gouge
Very finely groups particles, produced by grinding of rock during faulting. Often fused due to heat of friction.
Mylonite
Rock produced by dynamic met on a fault plane.
Antiform
Upward closing fold
Synform
Downward closing fold :)
Fold Hinge
Along the length of it. Measures the dip of the fold itself. Not the limbs.
Overfold
Both fold limbs dipping in same direction by different amounts.
Recent folds
Recumbent folds have axial planes which are close to horizontal
Nappe
Recumbent fold whihh are broken along thrust planes
Isoclinal fold
Parallel limbs whi b are nearly vertical.
Gentle fold
180-120
Open fold
120-70
Closed
70-30
Cone of depression
Lowering of water table around a well. Due to abstraction.
Acid mine drainage
Water flows over sulfur bearing materials e.g. Iron pyrite. This causes acidification of the water by it reacting with water to form sulfuric acid.
Ore
Rock containing valuable metals that is economic to mine
Resource
Useful and valuable natural material
Mineral resources
Can be metallic or non metallic industrial minerals
Reserves
The amount of a resource which can be extracted at a profit using existing technology.
Ore deposit
An accumulation of metal that may be economic to mine
Average crustal abundance
The amount of metal in average crustal rock
Concentration factor
The number of times a metal is concentrated above average crustal abundance.
Ore mineral
A mineral containing valuable metals
Gangue mineral
Low value waste mineral
Grade
Concentration of valuable minerals within an ore
Cut off grade
Grade below which an ore becomes uneconomical to mine.
Secondary enrichment
Metals are leached from surface rocks and precipitated below the water table.
Leaching
Where ions are dissolved from rocks and carried downwards in solution
Gossan
A cap of iron oxides at the surface of a mineral vein
Oxidising
Oxygen rich conditions, allowing elements to combine with oxygen to form oxides.
Reducing
Anoxic, oxygen poor conditions.
Enriched deposit
A zone of high grade ore just below the water table formed by secondary enrichment.
Porphyry
Large igneous intrusion with porphyritic texture. Ores form from a wet magma at the top of the intrusion from hydrothermal fluid precipitating incompatible metals e.g. Copper.
Resonance
The tendency to oscillate with greater amplitude at a buildings natural frequency.
Geological hazard
A geological condition that is dangerous or potentially dangerous to the environment and people in it.
Seismic risk
The possibility of suffering harm because of a seismic event in a particular time
Probability
A measure of the likely hood an event occurs.
Return period
The average time an earthquake of a given magnitude to occur again.
Problems of abstraction
Lowered water table
Subsidence
Salt water encroachment
Copper ore
Chalcopyrite
Tin ore
Cassiterite
Zinc ore
Sphalerite
Anthropocene
Suggested name for current geological epoch. Human activity has been dominant.
Holocene
Present epoch. 11700 years. Warm interglacial.
Phyletic gradualism
Model of evolution which states speciation is slow, uniform and gradual.
Genes
Sections of DNA that code for a protein.
Adaptive radiation
Organisms diversify rapidly into many different forms, usually as a response to change in the environment or exploit a new niche.
Morphology
Shape of orfanism
Benthonic
Bottom of sea/river may have sediment on top of it
Epifaunal
Living on top of sediment
Substrate
Sedent or rock at sea floor
Pelagic
Floating in water column
Nektonic
Swimming in water column.
Infaunal
Living in sediment maybe burrower.
Anthropocene markers
Chicken bones as fossils
Radionuclides distributed 3T plutonium
Farming markers e.g. Fertiliser or plough marks
Plastics in oceans
Nema
Extension of the sicula. Possibly to attach a floatation device
Theca
Individual cup where a zooid lived
Virgella
Spine at end of the sicula
Sicula
Conical tube excreted by first zooid.
Stipe
The stack of thecae built up to form a colony
Viviparous
Producing live young instead of eggs
Pycnofibres
Hair filaments
Adiabatic
Thermodynamic process in which no heat enters or leaves the system during expansion or compression.
Divergent plate bohndary
Two plates moving apart magma rising up between them.
Hot spots
Formed by a fixed mantle plume bringing magma to the surface
Convergent plate margin
Two plates colliding. Magma formed above a subduction zone or deep in the crust.
Batholith
Very large igneous intrusion, plutonic in depth.
Decompression metling
Decompression of peridot ite causes partial melting and produces mafic magma by decompression melting.
Concordant
Parallel to the existing beds
Discordant
Cut across existing beds
Dyke
Discordant sheet like intrusion
Minor intrusions
Cool at hypabyssal depth below earth’s crust, including sills and dykes.
Sill
Concordant sheet like intrusion.
Facies
Characteristics of a sedimentary rock that are produced by it’s environment.
Lithofacies
Physical /chemical characteristics
Biofacies
Paelaeontological characteristics of a rock.
Varves
Annual lake clays and silts in thin layers
Polymictic conglom
Many different rock types
Monomictic conglom
One rock type
Till fabric analysis
Tracking former movement direction of ic eby taking compass bearings of large clasts
Fluvio glacial deposits
Melt water deposits
Polymorphs
Same composition but different crystal forms
Isograd
Line on map joining points of equal metamorphic grade.
Metamorphic zone
Area between two isograds. Zone is named after the lower isograds. E.g. Silimanite.
Barrovian zones
Regional Metamorphic zones in scotland
Prograde
Recrystallisation in response to increase of metamorphism. Retrograde is as rocks are returned to surface.
Dalradiam supergroup
Regionally metamorphised rock in Scottish Highlands. Due to close of Iapetus ocean. Caledonian orogeny.
Relative dating methods lithologiaclly (4 principles)
Original horizontality
Cross cutting relationships
Principle of superposition
Included fragments.
Lateral variation
Changes in thickness or lithology in beds laid down at the same time.
Marker horizon
Bedding plane with a change of lithology easily distinguished from othe beds.
Varve deposit
Alternating layers of light and dark layers in glacial deposit due to summer winter variations. Each pair =1 year
Zone fossils
Fossils with ideal properties to identify a biozone
Stratigraphic range
The time the fossil existed for
Assemblage
The collection of fossils identified in a rock used to find its stratigraphic range
Biozones
Intervals of strata which are defined by their characteristic fossils
Coral phylum
Cndearia
Trilobites phylum
Arthropoda
Bivavle phylum
Molusca
Brachiopod phylum
Brachiopoda
Graptolite phylum
Hemi-chordata
Dinosaur phylum and class
Cordata, dinosauria
Ammonoid phylum. Examples
Cephalopod. Goniotite. Nautiloid. Ceratites. Belemnites. Ammonites.
Transform fault
Strike slip fault which ends at junction with another plate boundary.
Tear fault
Strike slip fault which stops when it reaches another fault. not plate boundary
Transform plate boundary
A fault where no crust is created or destroyed.
Sheeted dykes
At a mor magma that doesn’t reach the surface and cools as dykes.
Pillow lava
When lava erupts under water cools rapidly in seawater. Basalt
Island arc
Line of andesitic volcanoes which erupt due to partial melting of subducting oc plate.
Ocean trench
Linear submarine depression, perpendicular to subducting plate.
Benioff zone
Zone of earthquake foci sloping down 45 from ocean trench.
Stress
Force over area applied to a rock
Strain
Deformation in response to stress
Competent
Strong and brittle. Joint and fault
Incompetent
Weak and plastic. Tend to fold and develop cleavge
Tension
Pulling force. Crustal extension. E. G. Normal fault
Compression
Force trying to push rocks together
Shear
Act along a plane and promote sliding along that plane
Joint
A fracture in competent rocks along which no observable movement occurred.
Tension joints
Form as a result of Folding and cause tension joints parallel to axial plane. Cross joints on limbs
Cooling joints
Form as a result of contraction on cooling of igneous rocks.
Unloading joints
Horizontal as well as vertical and form as a result of lower pressure near to the surface
Dredging
Material scraped of river/sea bed
Hydraulic mining
Using high pressure water to dislodge material.
Geo chemical anomaly
A concentration of a metal above its normal background value
Dispersion
Where small amounts of metal are spread out around it’s ore deposited by erosion and transport.
Catastrophic dilution
Where tributaries meet and water and sediment from other sources are added.
Forecast
A statement of the probable occurrence of an event based on information and data. Probability of an event occurring.
Prediction
A statement about what you think will happen in the future. Includes more qualitative information such as when and where.
Polyp
Soft body part of coral
Mural pores
Connect multiple adjacent corralites together.
Symbiotic relationship
Two organisms live together for mutual benefit.
Zoozanthellae
The algea which live within a coral polyp
Bleaching
Changes in temperature or pollution cause corals to expel their algae and they die.
Strophic
Straight hinge line in a brachiopod
Astrophic
Hinge line is not straight in a brachiopod.
Commisure
Margin between two valves. Shape depending on environment
Spatfall
Settling and attachment of juvenile brachiopods.
Lobe finned fish
Have both lungs and gills. Four fleshy limbs supported by bones.
Swim bladder
Filled with gas or fluid to control buoyancy of a fish.
Lophophore
Gathers food and digests it and excretes it. Also respiration. Yuck.
The 3 pyroclastic materials and sizes
Bombs >64mm
Lapilli 2-64mm
Ash <2mm
Aa
Rough blocky jagged lava flows
Pahoehoe
Smooth or ropy lava flow
Nuée ardente
Pyroclastic cloud of magma droplets and ash.
Pyroclastic flow
Mix of pyroclastic material and gas. E. G. Nuée ardente.
Isostacy
The theoretical state of equilibrium between earth’s litho sphere and aesthenosphere such that the lithospher floats at an elevation that depends on its thickness and density.
Subduction
One section of the lithospher is forced down beneath another.
Slab pull
A process where cold dense section of lithosphere sinks intoantle.
Hot spot
Area of high heat flow above mantle
Thermal flux
Watts per square meter. Rate of energy transfer through a given surface per unit time.
Advenction
Thermal energy transfered through a fluid
Convection
Thermal energy is transfered by a substance due to buoyancy differences within the substances
Conduction
Thermal energy transferred with no movement. Atom to atom
Migmatite
Metamorphic rock e.g. Gneiss that melts to form an igneous rock
Guyot
Flat topped seamount, usually eroded by wave action
Seamount
A submarine mountain, often extinct volcano
Diapir
A low density botany material rising upwards in the same way as a lava lamp
Ridge push
A process where two sections of lithosphere are pushed apart by rising magma at the MOR
Slab pull
A process where cold dense sections O lithosphere descend into mantle at subduction zone
Cleavage
Planes of weakness in incompetent rock(e.g. Shale, made of clay minerals) and low grade metamorphic rocks along which these rocks will split forms perpendicular to maximum stress. At an angle to bedding planes.
Sustainability
Using a resource so that it is not depleted or harmful to the environment. Supporting a long term balence in ecological and other systems.
Non renewable resources
Do not renew themselves at a sufficient rate for sustainable economic extraction within a human lifetime.
Open cast mining
Extracting ore from a surface quarry
Shafts
Vertical openings to an underground mine
Stope (mine)
Void where ore was once extracted form in underground mine
Froth floatation
Aerate and agitate slurry to separate froth from tailings. Froth contains hydroponic minerals.
Leachate
Liquid that drains from a landfill site. Containing dissolved chemicals and microbial contaminants.
Pollution plumes
A zone of contamination produced by the flow of leachate through permeable rock into aquifers
Transuranic elements
Elements with a higher atomic number than uranium, 92.
Carbon sequestration
Co2 removed from atmosphere and held in alternative form, either solid or liquid.
Placisity
The property of a substance has when deformed continuously under a finite force.
Tilt
Change in elevation between two points divided by the distance between those points.
Inflection point
A point in a curve where the curve changes from concave to convex
Sinkholes
Hollows or holes in the ground caused by collapse of a surface layer, usually by dissolution of limestone.
Dinosr
Mesozoic reptile with upright walking position
Amniotic egg
Eggs with shells produced by birds and reptiles
Pubis
Public bone
Ornithischia
Bird hopped dinosaurs. Both hip bones point backwards.
Saurischia
Reptile hipped. One bone points forward.
Gastroliths
Stones swallowed by animals to help digestion.
Olfactory lobes
The part of the brain which processes smell.
Dinobird
Dinosaur with feathers
Sternum
The breast bone
Furcula/wishbone
Forked bone which strengthens the skeleton
Sexual dimorphism
Means difference in size/appearance between sexes in animals
Volcanoes
Vents at the surface of earth though which magma is erupted
Fissure erpution
Where magma reaches the surface along long linear cracks or fissures
Composite/strato volcanoes
Tall, conical shaped and composed of alternating layers of ash and lava
Caldera
Volcanic crater that ha undergone collapse, following an eruption
Effusive
Non explosive magma
Vei
Volcanic explosivity index
Hawaiian eruptions
Large amounts of low viscosity, basaltic lava
Strombolian eruption
More explosive with less fluid basalt and andesite lava. Explosive and produce has and pryoclasts
Plinian eruptions
Extremely explosive with andesitic and rhyolitic lava
Isopachyte
Lines joining points of equal thickness of deposits such as ash on a pyroclastic distribution map.
Flash floods
Brief but very high energy flows of water over a surface or down a river channel usually caused by heavy rainfall.
Wadis
River channels in hot desert regions in whi h flow occurs very occasionaly
Playa lakes
Temporary lakes formed by storm run off in deserts having inland drainage.
Evaporites
Sedimentary rocks resulting from the evaporation of saline water
Spring tides
Tides with greatest range. Happen every two weeks
Longshore drift
Drift of sediment along a beach.
Glauconite
Green coloured mineral. Formed on continental shelves
Transgression
Sea spreads over land
Regression
Sea retreats from land
Macrofossils
Large fossils visible to the eye
Microfossils
Can only be seen by microscope or hand lens
Detrital mud
Fragments derived from mechanical weathering of rock
Cryptocrystalline
Material is too fine grained to be distinguished with a microscope
Radiolaria
Plankton ic animals with a silicic shell that form chert
Calcerous ooze
Clay containing >30% skeletal material made of caco3
Evaporite sequence
First
Calcite
Gypsum
Anhydrite
Halite
K minerals
Last
CCD
Carbonate compensation depth.
Depth above which the supply of carbonate fossils is more than what dissolves in the water.
Seismic tomography
A technique for 3D imaging of the subsurface of earth using seismic waves
Mantle plume
Stationary area of high heat flow in the mantle. Rises from great depths and produces magma which feeds hot spot volcanoes such as hawaiian or iceland
Curie point
Temperature above which magnetic minerals lose their permanent magnetism. 585 for magnetite.
Remanent magnetism
Recorded in rocks due to the alignment of their magnetic minerals according to the earth’s magnetic field at the time of their formation
Palaeomagnetism
Ancient magnetism preserved in rock.
Magnometer
Instrument which detects field strength and direction of the magnetic field.
Magnetic inclination
The angle of dip of the lines of a magnetic field it is the dip angle made with horizontal and the earth’s magnetic field. Can be used to find latitude
Obduction
A process by which the edge of oceanic crust is scraped onto continental crust. Forming ophiolites
Multi beam echo sounder
Sends out beams of sound in a fan from below a ship to make a transect.
Side scan sonar
Towed at depths, a side view profile is made of the ocean floor.
Adibiatic melting
Melting due to change in melting point due to a release in pressure
Mush
A mixture of crystals and melt
Continuous magma chamber
Continuous produces lava
Discontinuous magma chamber
Produces lava periodically, with long periods of inactivity
Black smoker
Hydrothermal vent ascociated with volcanic activity at Mor it emits dark clouds of sulfide particles
Metasomatism
The hydrothermal alteration of rock
Serpentine
A mineral formed by the hydration of olivine
Serpentinite
A rock made of serpentine
White smokers
Cooler hydrothermal vents which emit more silicic minerals
Talus
Debris accumulating at the foot of a slope due to erosion of the rock face above.
Translational slide
Several beds sliding down a slope together
Isotropic clay
Equal properties in all driections
E.g. No particular cleavage
Tsunamite
A tsunami deposit. Deposited onshore.
Fabric
Spatial and geometric configuration of all the components of a rock.
Confining pressure
The combined lithostatic and hydrostatic pressure
Ductile deformation
Rock sufferers large strain without large scale fracturing.
Brittle deformation
Causes the rock to fracture.
Principle stresses
The direction of each stresses 01 02 and 03. Show the direction of maximum stress and median and minimum where they are all perpendicular.
Lithostatic pressure
Vertical pressure due to the mass of the rock only.
Asperity
The term mostly used to describe the roughness of the surface of a discontinuity
Residual strength
The remaining resistance to movement after the rock has failed and been displaced
Joint sets
Are fractures across which there is little displacement. They are mostly to dissapate the remaining stress left after Folding. As they are the result of regional stress they tend to form sub parallel sets.
Traps
Large scale volcanism resulting in the formation of mafic igneous rock. (kinda shield volcanoes but massive)
Shocked quartz
Grains showing deformation under high pressure. First descovered at nuclear testing sites.
Iridium
Rare transition metal, but common in meteorites
Tektites
Spheres or irregular shaped lumps of solidified molten rock, a few cm in diameter. Thought to have formed as a result of extremely high pressures and temperatures caused by meteorite impact.
Biota
The plants or animals living in an area or environment.
Low energy
Water not moving or moving very slowly. E.g. Lakes, deep sea.
Anaerobic
Without oxygen. Conditions within a sediment.
Anoxic
Water without oxygen. Bacteria and scavengers cannot live in these conditions.
Reaction rim
One mineral surrounding another. As cooling of a melt occurs reactions between high temp minerals and the melt substitute the minerals and change the crystals composition. This is often incomplete as the magma may be erupted before it is complete.
Liquidus
The phase boundary showing 5he temperature at which the last solid crystal melts
Solidus
The phase boundary showing the temperature at which the first crystal melts when heated.
Flocculation
When clay particles stick together. Therefore decreasing there depositional velocity. Clay are charged so this only happens in electrolitic sea water.
Turbidity current
High velocity current that flows down gentle gradients because the sediment dispersed within it is more dense than sea water. Triggered by instability or earthquakes.
Tirbidites
Upward fining deposit of greywacke deposited from turbidity current
Bouma seauence
Sequence of deposits in a turbidite
Climbing ripples
Form when deposition exceeds the migration of ripples.
Tool marks
Pretty similar to flute casts
Rip up clasts
Pieces of shale or mudsrone eroded by the turbidity current and included in the turbidite deoosit
Silacous ooze
Containing biogenic skeletal material made of silica
Plankton
Minute organisms living in the surface layers of the ocean. They die and sink to ocean floor forming calcerous and silicaous oozes.
Diatoms
Plankton ic algae that secrete silicaous material.
Pelagic fallout
The planktonic tests that fall from shallow water to the abyssal plane after they die.
Inert
Chemically inactive. Unreactive
Bioavailability
The proportion of metals that are available for incorporation into biota. E. G how badly metal pollution affects the environment.
Ion exchange
Exchange of ions between two electrolytes. Used to describe the process of purification or decontamination of ion containing solutions.
Adsorption
The process where clay removes heavy metals from ground water as a filter.
Isomorphus subsitution
Replacement of one atom by another similarly sized during Crystal growth without changing the structure.
North north Sea example and description
Piper oil field. Kimmerage clay is source, sandstone reservoir, clay caprock. Fault traps
South North Sea basin example
Ekofisk gas field. Anticline trap. Kimmerage clay is source. Chalk reservoir. Mudsrone caprock.
Fossil fuel
Hydrocarbon made from the remains of a once living organism.
Source rock
Organic rich mudsrone or shale which contained plankton which died in anoxic marine conditions
Reservoir rock
Porus and permeable rock capable of storing significant amounts of hydrocarbons.
Caprock
I permeable rock preventing further migration of hudrocarbons
Sapropel
Organic rich deposit which becomes source rock.
Maturation
Converts plankton to hydrocarbons by the effect of temperature
Oil/gas window
The narrow pressure and temperature conditions which allow oil/gas to be formed.
Migration
The movement of hydrocarbons from source to reservoir rock
Trap
Geological situations that concentrate hydrocarbons
Frazctional crystalisation
Higher melting point crystals fork first. They are metal rich. This leaves the magma relatively depleted in metals and becomes more silicic.
Gravity settling
Crystals are more dense than magma so sink to the bottom of the chamber. Combined with fractional crystalisatuon you get cumulate layers where the layers are more silicic upwards due to the depletion of metals in the magma over time.
Filter pressing
When enough crystalisatuon has occurred and the magma is more of a mush, the combined weight of the crystals in the magma squeezes the liquid magma out where it forms a layer above the crystals.
Contamination of magma
Stopping and assimilation of xenoliths changes the bulk composition of the magma.
Cumulate
Igneous rocks formed by the accumulation of crystals due to gravity settling and are typical of layered intrusions.
Drift
The superficial deposits of glacial or fluvio glacial material. Basically sediments above mapped rock that aren’t really considered important as they only formed very recently. Alluvium refers to river deposits.
Seismic refraction surveys
Drop something heavy or blow something up and see how the seismic waves travel through the rock. Slow = low density, fast = high density
Unknown affinity
Unrelated to any know organism. Living or extinct.
Disarticulation
Separation of body parts such as shells after death.
Arthropods
Invertibrate organisms with jointed apendages, segmented body and an exoskeleton.
Necrolytic features
Features associated with dramatic cause of death. Death throes in a dying animal. Can show destruction of tissue and cells in the organism.
Synsedimentaru faults
Show displacement over an extended time period usually within sediments during deposition.
Distributary
A stream channel that takes water away from the main channel.
Cyclotherms
Layers repeated due to cyclic sedimentation
Topsets
Uppermost layers of delta containing coarse sandstone, coal, seat earth
Foresets
The inclined layers formed on the delta front. Cross bedded sandstones
Seat earth
A sandy or clay rich fossil soil found beneath the coal seam. Soil in which coal forming plants formed. Trace roots.
Bottom sets
The lowest horizontal layers of a delta commonly made of marine shapes or limestone.
Banded iron formations
Units of sedimentary rock of precambrian age consisting of alternating layers of iron oxides and chert
