No pain, no grain
Sedimentary Structures
Clastic or Non-clastic?
Conglos and Breccias
Sandstone and Mudstone
Limestones
Other Non-clastics
100
What is the relationship between grain size and distance?
Inversely proportional
100
Sedimentary structure?
Depositional environment/s?
Normal graded bedding
Deep marine (turbidity currents), Lacustrine, Alluvial
100
B < C < A
100
Which is more texturally mature, polymictic orthobreccia or monomictic orthoconglomerate?
Monomictic orthoconglomerate
100
A rock has 75% quartz grains and 25% matrix. What would you name this rock?
Quartz wacke
100
Identify the allochem. (scale = 0.5mm)
Bryozoan
100
Provide the rock name and possible depositional environment/s?
Banded Iron Formation
Deep/Shallow Marine
100
What is wrong with the sieving procedure given below?
1. Weigh the dry mixed-grain sample.
2. Arrange sieve in increasing mesh size, from top to bottom.
3. Pour mixture in the topmost sieve, cover and shake in the sieve shaker equipment.
Sieves should be in decreasing mesh size, from top to bottom.
100
Sedimentary structure?
Depositional environment/s?
Varves
Lacustrine
100
a. Nonclastic
b. Shell fragments
c. Calcirudite, Fossiliferous Limestone, Coquina
100
Based on the roundness of the framework grains and fabric support, what will you name this rock?
Polymictic Parabreccia
100
If a rock is composed of 76% mud matrix, what would you name it based on the Pettijohn diagram?
Mudstone :)
100
Identify the allochem and determine the section shown in the photomicrograph.
Echinoid spine
Cross section
100
Provide the rock name and possible depositional environment/s?
Bituminous coal or Coal
Paludal/Deltaic/Lacustrine/Alluvial
200
Is it recommendable to separate silt and clay using sieving method? If yes, would you apply dry sieving or wet sieving? If no, what is a better method for this?
No, it's not recommendable. Pipette analysis :)
200
Sedimentary structure?
Paleocurrent direction?
Part of the bed depicted in the photo (top or bottom)?
Flute cast
East
Bottom
200
a. Clastic
b. Quartzite clasts, sandy matrix
c. Monomictic orthoconglomerate
200
Average roundness of clasts?
Descriptive term for the rock name based on roundness and fabric support?
Rounded to well-rounded
Polymictic orthoconglomerate
200
Provide the rock name and possible depositional environment/s?
Shale
Deep marine/Lacustrine
200
What is the fabric of the calcite cement?
Drusy :)
200
Differentiate centrales and pennales diatoms in terms of shape and occurrence.
Centrales: centric-shaped; marine
Pennales: pennate-shaped; freshwater
200
Complete the analogy below:
Prolate (rod) : S=I<L ; Oblate (disc) : ______
S < I = L
200
Sedimentary structure?
Paleocurrent direction?
Cross lamination
West
200
Differentiate black shale and bituminous coal in terms of diagnostic features in hand samples.
Shale - fissile
Coal - low specific gravity, shiny
200
How would you distinguish a conglomeratic sandstone from sandy conglomerate based from the diagram below?
more than 30% gravel - conglomerate
200
What kind of contact between grains is shown (longitudinal, concavo-convex, sutured)? Which diagenetic process are grain contacts associated with?
Sutured contact between quartz grains, pressure solution - compaction
200
True or False.
Chalk and crystalline limestone are considered calcilutites.
False - no grabau name for crystalline limestone
200
True or False
Nodular cherts are older than the host rock.
False - they are younger
300
Given the axes ratios, what is the corresponding Zingg Shape of the following samples?
A: Oblate
B: Prolate/Rod
C: Equant
D: Bladed
300
What do you call this structure? Where is the top of the bed in this picture? (indicate direction: up, down, into the page, out of the page)
ripple marks, out of the page
300
A. Clastic or non-clastic?
B. If clastic, what is dominant detrital grain? Is the sample calcareous?
If non-clastic, give the Folk classification.
A. Clastic
B. Qm; yes it is calcareous
300
A: Organic-rich environment/anoxic condition; organic matter/carbon
B: Oxidizing environment; ferric iron
300
Identify the allochem and give one diagnostic feature useful in identifying it.
Pelecypod shell
Smoothly curved shell thickening towards the hinge
300
Provide the rock name and one possible depositional environment from the sample description given below.
Fine-grained siliceous rock dominantly composed of micro- to cryptocrystalline quartz, chalcedony, opal and preserved radiolarians.
Chert
Deep marine/Lacustrine
300
What is the skewness (fine/positive, coarse/negative) and best possible environment of deposition (desert, meandering river, beach) of
A.
B.
A. negative/coarse skew, beach
B. positive/fine skew, meandering river
300
What is the term for the cut off load cast shown in the picture?
Ball and pillow structure
300
a. Quartz, calcite cement
b. Medium sand
c. Quartz arenite
d. No.
300
a. Pelsparite
b. Grainstone
c. 16
d. 7 (Shelf lagoon open circulation)
400
Which cumulative weight percentages will you use to determine the mean, median, standard deviation and skewness of the sample?
cumulative wt:
mean - phi at 16%, 50%, 84%
median - phi at 50%
standard deviation - 5%, 16%, 84%, 95%
skewness - 5%, 16%, 50%, 84%, 95%
400
Name the structure. Which organism produced this kind of structure?
Stromatolites
Cyanobacteria
400
a. Very coarse sand
b. Q: 12.90; F: 62.58; L: 24.52
c. Lithic arkose
d. Arkosic arenite