sediment grain size analysis

8/2/2019 Sediment Grain Size Analysis

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QAB 2023

CLASTIC SEDIMENTOLOGY & PETROGRAPHY

SAND GRAIN ANALYSIS

NUR AFIQAH ISMAIL

14581

PETROLEUM GEOSCIENCES


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INTRODUCTIONDespite being removed and transported from time to time, the sand grain size analysis could

tell us a lot regarding the source of the rock and the depositional environment. Sediment can

come from both physical and chemical weathering of the source rock that had been brokeninto smaller fragment. Different kind of weathering and different type of depositional

environment leads to different type of the sediment grain size.

After being transported, the sediment will deposit and undergo lithification and diagenesis

to form sedimentary rock. Sedimentary rock that formed in clastic group could be identified

by its grain size. Generally, conglomerate consists of fragment greater than 2mm in

diameter. Sandstone were mainly originated from the sand particle range from 0.006mm to

2mm. Mudstone or shale is then composed by smaller particle which is less than 0.006mm.

Besides the particle size, other physical property of the sediment itself could be studied suchas shape, roundness, sorting, or in simple term, texture. The shape of the particle refers to

the sphericity of a grain. Most of the grain is spherical, but could be elongated or flattened.

The roundness of the grain is then referring to the smoothness of the grain edges. The

distribution of the grain size in the certain location could tell the sorting of the sediment.

Well sorted sediment is defined as the grains are about the same size. If the size of the grains

are varies, then it could be considered as poorly sorted.

Figure 1: The sorting of sediment

This experiment is focusing on unconsolidated sediment that being taken from several

locations. We are going to study the sample and run it through several sieve of certain size

and using statistical methods to describe the population and other properties of the

sediment.


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METHODOLOGY1. 5 different samples are taken from different locations with different type of sediment.

The locations selected are as below :

Sample 1 : Sg Perak Sample 5 : Beach sand

Sample 2 : Sg Kelantan

Sample 3 : Mining sand

Sample 4 : Construction sand

2. Estimate 250g of the sample is weight on the balance and recorded. Before that thesamples were dried for three days in order to make sure that there is no accumulated

sand.3. A set of sieves are prepared and stacked on top of each other. The smallest sieve is at

the base and the largest at the top. Pan is placed at the very base of the stack. Sieve

size is recorded. The 250g of the sample is then is dumped on top of the first sieve

and covered.

4. By using the shaker machine, the sieve is shook with circular motion for 5 minutes.5. When the shaker is stopped, the top cover of the cover is taken off. First sieve is

removed and the sieve is turned over and the content is dumped on the paper. The

sieve is slammed a bit on the paper to lose any stuck sediment. The grains are

transferred to the weighing pan and the weight is recorded.

6. The previous step is repeated for each sieve and pan.7. From the data recorded, all the weight from the each sieve is sum up and compared

with the initial weight. The percentage error is calculated and discussed.

Percentage error % = weight of size fraction x 100

Total weight of sample

8. Step 2 until 8 is repeated for remaining sample.9. The overall data is tabulate in table 1 (Sungai Perak), table 2(Sungai Kelantan), table

3(Beach), table 4(Construction), and table 5(Mining). Various diagrams are drawn for

the further presentation and discussion.

10.A histogram for respective sample is drawn. Phi size is used for x-axis and individualweight percent is used for y-axis. Mode of the grain size distribution is taken from the

range of phi that has the tallest column.

11.A graph of phi size versus cumulative weight percent is plotted using a lineararithmetic scale. The points on the graph of plotted using French Curve. By using

cumulative weight percent, the phi size for each of the following percentage: 5%,

16%, 25%, 50%, 75%, 84%, and 95%. The results are recorded in the table 2.


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12.By using values from previous table, other statistical calculation is done. The resultsof the calculation are also recorded in the table 6.

13.The retained sediment is taken for manual observation for its texture and later willbeen compared with the mathematical result.

Figure 2: Weighing process with electronic balance

Figure 3: Electric sieving shaker


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Table 3: Beach Sand Grain Size Distribution

Original weight: 250g

Error: 0.192%

Sieve size

(mm)

Phi () Individual

weight

retained (g)

Individual weight

%

Cumulative

weight

Cumulative

weight %

2.00 -1 49.82 19.97 49.82 19.97

1.0 0 66.54 26.67 116.36 46.64

0.5 1 91.23 36.56 207.59 83.20

0.250 2 30.73 12.32 238.32 95.52

0.125 3 9.44 3.78 247.76 99.300.0625 4 1.40 0.56 249.16 99.86

Pan 5 0.36 0.14 249.52 100

TOTAL 249.52 xxx xxx xxx

Table 4: Construction Grain Size Distribution

Original weight: 250.02g

Error: 0.016%

Sieve size

(mm)

Phi () Individual

weight

retained (g)

Individual weight

%

Cumulative

weight

Cumulative

weight %

2.00 -1 20.95 8.38 20.95 8.38

1.0 0 40.00 16.00 60.95 24.38

0.5 1 70.13 28.05 131.08 52.43

0.250 2 68.32 27.33 199.40 79.76

0.125 3 37.64 15.06 237.04 94.82

0.0625 4 11.38 4.55 248.42 99.37

Pan 5 1.56 0.62 249.98 100



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Table 5: Mining Grain Size Distribution

Original weight: 250.02g

Error: 0.124%

Sieve size

(mm)

Phi () Individual

weight

retained (g)

Individual weight

%

Cumulative

weight

Cumulative

weight %

2.00 -1 2.38 0.95 2.38 0.95

1.0 0 4.77 1.91 7.15 2.86

0.5 1 31.34 12.57 38.49 15.43

0.250 2 125.08 50.18 163.57 65.61

0.125 3 72.76 29.19 236.33 94.800.0625 4 10.40 4.17 246.73 98.97

Pan 5 2.53 1.02 249.26 100


TABLE 6: MEASURES FOR STATISTICAL CALCULATIONS

By referring to the respective graph of the sample, phi value for certain percent of

cumulative weight were taken in order to calculate their particular median, mean, standard

deviation, skewness and kurtosis.

% Sg Kelantan Sg Perak Mining Construction Beach Sand

5 -3.1 -3.1 -0.2 -0.8 -3.0

16 -2.0 -1.9 0.1 -0.1 -1.3

25 -1.2 -1.1 1.7 0.4 -0.7

50 -0.6 0 2.0 1.2 0.1

75 -0.2 0.8 2.1 2.2 0.7

84 0.5 1.2 2.3 2.7 1.095 0.7 2.0 3.0 3.6 2.0


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TABLE 7 : STATICTICAL CALCULATIONS

Grain Size Mode: Tallest column in the respective histogram.

Median Grain Size : Phi value at 50% of cumulative weight.

Mean Grain Size : Calculated by the formula;

Standard Deviation : Calculated by the formula;

Skewness : Calculated by the formula;

Kurtosis : Calculated by the formula;

Sample Sg Kelantan Sg Perak Mining Construction Beach Sand

Grain Size Mode 0.5

(coarse grain)

0.45

(coarse grain)

0.5

(coarse grain)

0.5

(coarse grain)

0.5

(coarse grain)

Median Grain

Size

0.6 0 2.0 1.2 0.1

Mean Grain Size -0.70 -0.23 1.47 1.27 -0.07

StandardDeviation

0.63

Moderately

well sorted

0.78

Moderately

sorted

0.55

Moderately

well sorted

0.58

Moderately

well sorted

0.58

Moderately

well sorted

Skewness -0.22

Symmetrical

0.01

Symmetrical

-0.55

Coarse skewed

0.08

Symmetrical

-0.23

Symmetrical

Kurtosis 1.56

Very

platykurtic

1.10

Very

platykurtic

3.28

Mesokurtic

1.00

Very

platykurtic

1.46

Very

platykurtic


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Discussion1) River (Sungai Kelantan and Sungai Perak)

River flow is unidirectional flow means one way direction of flow. River transports two types of

sediments which are wash load and bed material load. Wash load consist of light sediment for

examples silt and clay. This wash load suspended in the river and being transported by the

suspension of the current flow. While the bed material loads sediments are sediments that have

heavier weight. They transported by creeping or salting.

For the sediment from the Sungai Kelantan case, the modal distribution is in very coarse grain

region by 38% of the total weight of the sample. Actually the site of the sample taken is at the

sand suction activity and its activity still actively conducted. Result from the sieving shows that

the sorting for this site is moderately well sorted and has symmetrical skewness, therefore it can

be said that there are no excess of coarse or fine sediments which would be good for commercial

value. Closely examine the grains in each size fraction with hand lens the grains tend to be

bladed shape and it has angular grain. Therefore it might be said that the source of the sediment

is quite near since it has angular grain.

Figure 4: The arrangement maturity and distance of sediment

While for the Sungai Perak, the modal distribution is in range coarse grain region by 25% of the

total weight of the sample. From the result it shows that Peraks river has bimodal distribution.

Its coarse grain is higher than fine grain. It can be said that the Peraks river has high velocity

current that can washed away the silt and leave the coarse grain to settle down on the river bed.

Result from the sieving shows that the sorting for this site is moderately sorted and has

symmetrical skewness. The textures of the Peraks river grains are quite same with the

Kelantans river which is bladed shape and it has angular grain.


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The analysis of these four straight lines in the cumulative frequency curve, tells us the transport

history. The fine and very fine grain which constitutes the lowest weight percentage is

transported by suspension in the river and as the river has high current velocity, the suspended

material not being settled on the river bed. The medium to coarse grains is probably transported

by saltation where the individual grains would jump in a projectile motion.

2) MiningThe cumulative frequency curve plotted on the probability scale has four straight line segments

which consist of very coarse, coarse, medium and fine and lastly very fine grains. The modal

sediment is coarse grained accounting for 37% of total weight. The mean value of 1.47 is the

highest than the other samples thus the mining sand is the most dispersed in grains compared to

the other samples. The sorting and skew values indicate that it is moderately well sorted and

coarse skew respectively. There is no obvious transportation of sand (because it is a still lake,

therefore no water movement). The sorting value again might be impaired due to the

continuous mixing during the accumulation of the sediments in the mining site. The skewness

value indicates that the mining area coarse skew. Closely examine the grains in each size fraction

with hand lens the grains tend to be aquent and it has almost rounded grain. Therefore it might

be said that the source of the sediment is being reworked once time ago by the mining process,

but because of the weathering and transportation from the other sources of sediment, the

sediment being mixed of coarse and angular grains.

The colour of the sand is blackish. Since it is ex-mining area therefore it contains high

concentration of tin ore minerals.

3) ConstructionThe sample was taken from the construction site at Sri Iskandar. From the frequency distribution

curve, it shows a bimodal distribution of grains with one peak being of coarse grain size and the

other being of very fine grains. This occurrence also agrees with the cumulative frequency curve

plotted on the probability scale which has two straight line segments. The coarse grains are its

modal grain size accounting for 26% of its total weight. Its sorting value tells that it is moderately

well sorted while its skewness value is symmetrical. The grain is almost well sorted since the

grain already being processes for the construction purposed. The sand might also be obtained

both in the middle (coarse grains) and also the side (finer grains) of the river. The variation of the

grain size may help the construction be more stable and be better.

4) BeachBeach sediments typically travelled some distance from a sediment source to their present

location on the beach. The sediment source could be quite distance. As wind, rivers, and ocean

currents carry sediment grains, abrasion and collisions tend to break and smooth the grains.

Grains are further smoothed on the beach as they are washed back and forth by waves.


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Closely examine the grains in each size fraction with hand lens the grains tend to be equant

shape and it had mixed rounded and angular grain. Angular grains have sharp corners and

projections. Rounded grains have no corners or projections

The sample was taken from the residential area that very closed to the beach, therefore the

supposedly it should be well sorting, but the beach was being causeway by the sandbag since it

experience very serious erosion. The sand from the sandbag being mixed with the original

depositional sand when there is high tide. That the reason why the sorting for our beach sand is

moderately well sorted.

It has a modal class of coarse grains accounting for 29% of total weight. The sorting value and

skewness tells that it is moderately well sorted and symmetrical skewed respectively. The

analysis of these four straight lines in the cumulative frequency curve, tells us the transport

history. The very fine grain which constitutes the lowest weight percentage is transported by

suspension in the sea where they are desposited on the beach when the tide resides. The

medium to coarse grains is probably transported by saltation where the individual grains would

jump in a projectile motion. Lastly, the very coarse grains are probably creeping along the sea

floor, rolling in a circular motion. Turbulent waves mix the coarser and finer grain sediments in

suspension and deposit them on the beach.

While the colour of our beach sand sample slightly gray. This may indicate the presence of

organic carbon which is come from remain of plant and animal matter.

Precaution and ModificationIn order to get the better result, there are some precautions to take care of.

- The sand must be making sure that completely dry so that the sieving process can be wellconducted.

- Shield the electronic balance in order to get the accurate reading of the grain weight.- The Sand Shaker must be clean from any grain stucking on it. This is in order to make sure

all the grains are well separated.

- Place a large paper or large plastic during removing the sieved grain from the SandShaker, and make sure does it gently so that the weight loss can be reduce.

- The experiment should be repeated 3 times to reduce the percentage error.


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ConclusionFrom this experiment, students can learn better properties and texture of the clastic

sedimentary. As the sediment move further from the source, the grain size became rounded and

spherical. The sediment being transported by suspension, saltation, creeping and even dissolvesin the river. But to know the mineral of the sand, mineral analysis under microscope should be

done. From the bivariate plot it shows that the samples that taken mainly come from river

provenance. To have a thorough understanding of grain size distribution in the research area,

several samples need to be collected at an interval distance, covering the entire research site. So

that the behaviour of the specific site can be interpreted through the calculation of statistical

distribution. A collective study can then be done.


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APPENDIXAppendix A: Sungai Kelantan

Graph 1: Frequency curve of Sungai Kelantan

Histogram 1: Texture and percentage of grain size distribution for Sungai Kelantan.

0

10

20

30

40

50

60

granules very

coarse

sand

coarse

sand

medium

sand

fine sand very fine

sand

coarse silt

individualweightpercent

Curve frequency of Sungai Kelantan

31.29

48.94

19.6

0.09 0.02 0.01 0.050

10

20

30

40

50

60

granules very

coarse

sand

coarse

sand

medium

sand

fine sand very fine

sand

coarse silt


Grain Size Distribution Frequency %


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Appendix B: Sungai Perak

Graph 2: Frequency curve of Sungai Perak

Histogram 2: Texture and percentage of grain size distribution for Sungai Perak.

0

5

10

15

20

25

30

35

granules very

coarse

sand

coarse

sand

medium

sand

fine sand very fine

sand

coarse silt


Curve Frequency of Sungai Perak

27.89

21.51

30.22

17.55

1.55 0.9 0.38

0

5

10

15

20

25

30

35

granules very

coarse

sand

coarse

sand

medium

sand

fine sand very fine

sand

coarse silt




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Appendix C: Construction

Graph 3: Frequency curve of construction sand

Histogram 3: Texture and percentage of grain size distribution for construction sand.

0

5

10

15

20

25

30

granules very

coarsesand

coarse

sand

medium

sand

fine sand very fine

sand

coarse silt


Curve Frequency of Construction

sand

19.97

26.67

36.56

12.32

3.780.56 0.14

0

5

10

15

20

25

30

35

40

granules very

coarse

sand

coarse

sand

medium

sand

fine sand very fine

sand

coarse silt




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Appendix D: Mining

Graph 4: Frequency curve of Mining sand

Histogram 4: Texture and percentage of grain size distribution for Mining sand.

0

10

20

30

40

50

60

granules very

coarse

sand

coarse

sand

medium

sand

fine sand very fine

sand

coarse silt


Curve Frequency of Mining sand

8.38

16

28.05 27.33

15.06

4.55

0.62

0

5

10

15

20

25

30

granules very

coarse

sand

coarse

sand

medium

sand

fine sand very fine

sand

coarse silt

individualweightperc

ent



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Appendix F: Grain size classification

Figure 5: The Udden-Wentworth Grade Scale for classification of siliciclastic sediment.


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Appendix G

Figure 6: The Logarithmic Folk and Ward (1957) graphical measures

sediment grain size analysis

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