textures and maturity Flashcards
parameters of textures
- grain size
- grain shape
- grain orientation
- porosity
- permeability
a system used by geologists to classify the grain size of sediments.
udden wentworth scale
a classification scheme that describes sediments particle sizes in epiclastic rocks. it also classifies particles sizes based on a logarithmic phi scale using the diameter expresses as
(basta 0 =-log2d)
grain size
also known as “coarse fraction”, is the components of detrital sedimentary rocks that have particle sizes from sand to gravel
clast
also known as the “fine fraction” is the mud sized partuicles component of detrital sedimentary rocks
matrix
a measure of particle population in an attempt to represent the typical size 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
a method of passing soil and sediment samples through a series of stacked mesh to determine the distribution of grain sizes
sieving
determines or give information regarding the nature or maturity of a grain
grain shape
factors affecting 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 exes 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