Natural Processes Of Geomaterials Flashcards
Bowen’s reaction series describes
The susceptibility of common rock-forming minerals is to chemical weathering
In the bowen’s series, the higher a minerals melting point . . .
The higher it’s susceptibility to chemical weathering
Minerals in the bowen’s series have melting points ranging from
1200-700°C
The most to the least reactive of the bowen’s series is
Olivine
Ca-plagioclase
Pyroxene
Hornblende - yo wtf
Biotite - BOY YOU TIGHT
Na-plagioclase
Orthoclase feldspar
Muscovite
Quartz
Sedimentary rocks can be divided into two principal groups
Clastic (exogenic)
Non-clastic (endogenic)
What is meant by clastic/exogenic rock?
Exo- originate externally to the earth’s surface
What is mean by a non-clastic/ endogenic rock?
Endo- originates from within the earth- volcanoes etc.
What are the six deposition’s environments from top to bottom
River bed
Lake
Beach
Tidal flats
Shallow Marine
Deep marine
In engineering terms what is a well graded, poor sorted aggregate mix?
Many sizes of grains, a good mix for engineering applications
In engineering terms what is a well sorted, poorly graded aggregate mix?
An aggregate mix of similar size grains
Which kind of rock has a <0.004mm grain size?
Clay
Which kind of rock has a <0.004-0.06mm grain size?
Silt
Which kind of rock has a 0.06 - 0.25mm grain size
Fine sand
Which kind of rock has a 0.25-0.5mm grain size?
Medium sand
Which kind of rock has a 0.5-2mm grain size?
Coarse sand
Which kind of rock has a 2-4mm grain size?
Granules
Which kind of rock has a 4-64mm grain size?
Pebbles
Planes of weakness in sedimentary rocks correspond to
Direction of mineral deposit
What is meant by a rock sample that exhibits anisotropic behaviour?
Does not behave the same in every direction
What are three clastic sedimentary rocks?
Conglomerate (with gravels)
Sandstone
Shale (mudstone)
What are three non-clastic sedimentary rocks?
Carbonate rocks (limestone)
Evaporites (salt rocks)
Carbonaceous (peat,lignite,coal)
What does metamorphism mean?
Solid-state transformation of pre-existing rock into texturally or mineralogically distinct new rock.
Accomplished through high temperature, high pressure or both
What are the technical names for the three types of metamorphosed rocks?
Thermal/contact metamorphism (temperature)
Dynamic/dislocation metamorphism (stress)
Regional (temp + stress)
In the recrystallisation of metamorphic rocks, what happens to voids?
They are filled by intergrown crystals
What are folliations?
Layers in rock formation induced by directional pressure
From low grade to high grade, what are three foliated rocks?
slate, schist, gneiss
Slate is late, gneiss is nicely at the top
Metamorphic rocks are not defined by their appearance or rock content but rather by their grade of metamorphism.
What does this grading involve?
Crystal size, coarseness of foliation, band size
The bigger the better
How are non foliated metamorphic rocks formed?
Metamorphosed through temperature alone (thermal/contact)
What is the name of minerals formed through metamorphism?
Garnite
What are the rock strength tests?
Brazilian tensile test
Point load test
Unconfined compression test
Why does the Brazilian tensile test involve?
Cut a puck of the rock sample
Place the puck between two presses
Apply pressure on both sides
Break the rock
What the does the point load test involve? (Is 50)
Cut out a cylinder of rock
Place between two conical points
Apply pressure through the points
Measure resistance
Rock breaks
What does the unconfined compression test involve?
Cylinder of rock is cut out
Placed between two presses
Pressure applied until rock breaks
(Essentially Brazilian tensile test with a cut cylinder as used in the point load test)
The direct shear of rocks in done using what apparatus ?
Triaxial cell
How is the Is50 point load strength index calculated?
IS50=P/De^2
P is failure load
De is the equivalent core diameter
What is the most common way to describe the strength of a material?
List it’s UCS
What features are important when classifying sandstone specimen?
Dott’s classification chart.
The main clast constituent
matrix percentage
Grain shape
Olivine and pyroxene are the first to be removed by weather from an igneous rock sample, why? (exclude Bowen’s reaction series as an explanation)
They are the simplest silicate based minerals
form weak connections between minerals, thus easy to break
first to come out of solution from magma pool
