Sedimentary Rocks (Part 2 - Textures and Maturity) Flashcards
Parameters for Textures
Grain Size
Grain Shape
Grain Orientation
Porosity
Permeability
A classification scheme that describes sedimentsβ particle sizes in epiclastic rocks. It also classifies particles sizes based on a logarithmic phi scale using the diameter (d).
Grain Size
expressed as: π· = βπππ2d
The component of detrital sedimentary rocks that have particles sizes from sand to gravel.
Clasts
also called as Coarse Fraction
Clasts
Mud sized particles component of detrital sedimentary rocks.
Matrix
Also called Fine Fraction
Matrix
A measure of particle population in an attempt to represent the typical particle size in the population.
Central measure
A bar graph that shows the weight percentage vs. phi values of clasts.
Histogram
A line graph that shows the weight percentage vs. phi
values of clasts.
Frequency curve
A line graph that shows the cumulative weight percent of all size coarser than, including the phi size fraction under consideration, are plotted against phi size classes.
Cumulative curve
The most abundant particle size.
Mode
The average size of the particles
Mean
The average diameter of the particles
Graphic geometric mean (GM)
A method of passing soil and sediment samples through a series of stacked mesh to determine the distribution of grain sizes.
Sieving
Determines or gives information regarding the nature or maturity of a grain.
Grain Shape
2 Factors that affect shape
Lithology
Hardness
Spheroid particles that have similar dimensions in all directions.
Equant
Rod-shaped particles that have an elongate cylindrical that have on axis much longer than the other two.
Prolate
Disk-shaped particles that have a flattened cylindrical or disk-like shape where two axes are shorter than the other.
Oblate
Particles that have a flattened shape where the three axes have three different lengths.
Bladed
The distribution of grain sizes present within a sedimentary rock.
Sorting
A quick method of determining the phi size value for any percentile
Sorting coefficient
A more complicated measure of sorting that involves finding values that are one standard deviation and two standard deviations above and below the mean.
Inclusive graphic standard deviation
The volume of void space in a sedimentary rock.
Porosity
The arrangement of grains in a rock.
Packing density
The degree of how much fluids can pass through the materials.
Permeability
The extent of how much sedimentary rock has undergone change starting from its parent material(s).
Maturity
2 Ways to measure maturity
Textural and Compositional
The degree of maturity that can indicate a sedimentary rockβs transportation history.
Textural Maturity
The degree of maturity that measures the amount of components present.
Compositional Maturity
Toblerone Sandstone Classification (for Detrital Seds)
Pettijohn Sandstone Classification (memorize boss)
pic: https://imgur.com/a/FS4ucTg
