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Clastic Sedimentary Rocks

Clastic rocks are made up of particles of pre-existing rocks and minerals. Clastic

rocks are made up of particles of a pre-existing rocks and minerals. These particles may have

originally been from igneous rocks, metamorphic rocks, or even other sedimentary rocks.

These particles Originally May have been from Igneous rocks, metamorphic rocks, or even

other sedimentary rocks. Clastic rocks are deposited under the influence of some type of

current (flowing water, waves, winds, or moving ice), therefore particle size is a reflection of

the amount of energy that transported the sediments to the place of deposition and tells us

something about how the rock was formed. Clastic rocks are deposited under the influence of

Some type of current (flowing water, waves, Winds, or moving ice), particle size is therefore

a reflection of the amount of energy That Transported the sediments to the place of

deposition, and tells us something about how the rock was formed.

Particle size is described in three major categories, gravel (all particles larger than 2

mm in diameter), sand (particles smaller than 2 mm, but larger than 0.0625 mm), and mud

(particles smaller than 0.0625 mm). Particle size is described in three major categories, gravel

(all particles larger than 2 mm in diameter), sand (particles Smaller than 2 mm, but larger

Than 0.0625 mm), and mud (particles Smaller Than 0.0625 mm). The first step in any

identification of a clastic rock is to determine the grain size of the particles. The first step in

any identification of a clastic rock is to determine the grain size of the particles. If more than

30% of a rock is composed of gravel sized clasts, then it is either a conglomerate or a breccia.

If More Than 30% of a rock is composed of gravel sized clasts, then it is Either a

conglomerate or a breccia. A conglomerate has clasts which have rounded corners, a breccia

has clasts with angular corners. A conglomerate clasts has the which have rounded Corners, a

breccia with angular clasts has Corners. Remember, the shape of the grains in the rock is the

important feature, not the shape of the hand specimen. Remember, the shape of the grains in

the rock is the Important features, not the shape of the hand specimens.

All clastic rocks which are made up of sand sized particles are called sandstones, but

not all sandstones are alike. All the which clastic rocks are made up of sand sized particles

are Called sandstones, but not all sandstones are alike sessions. The three common types of

sand particles are quartz, feldspars and rock fragments. The three common types of sand

particles are quartz, feldspars and rock fragments. If the sandstone is made up mostly of

quartz, it is called a quartz sandstone . If the sandstone is made up of quartz Mostly, it is

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Called a quartz sandstone . If the sandstone have a significant amount of feldspar grains, it is

called an arkosic sandstone . If the sandstone have a significant amount of feldspar grains, it

is Called an arkosic sandstone . In order to differentiate between a quartz sandstone and an

arkosic sandstone, you must be able to tell the difference between quartz and feldspar. In

order to differentiate Between a quartz sandstone and an arkosic sandstone, you must be Able

to tell the difference Between quartz and feldspar. Arkosic sandstones have a high percentage

of quartz, but also contain identifiable feldspar grains. Arkosic sandstones have a high

percentage of quartz, but contain identifiable Also feldspar grains. The final type of

sandstone is made up of rock fragments. The final type of sandstone is made up of rock

fragments. These may be pieces of basalt, shale, limestone, rhyolite or even other sandstone,

and the rock is called a lithic sandstone or litharenite . May These few pieces of basalt, shale,

limestone, rhyolite sandstone or other events, and the rock is Called a lithic sandstone or

litharenite.

Clastic rocks made up of mud sized particles have particles too small to see either

shape of composition, so classification is based on the properties of the rock as a whole

(rather than the grains), or by particle size. Clastic rocks made up of mud sized particles have

particles too small to see Either shape of composition, so classification is based on the

properties of the rock as a whole (rather Than the grains), or by particle size. Mud includes

two subgroups, the coarser grains are silt (0.0625 mm to 0.0039 mm) and the finer grains are

called clay (smaller than 0.0039 mm in diameter). Mud includes two subgroups, the coarser

grains are silt (0.0625 mm to 0.0039 mm) and the finer grains are Called clay (Smaller Than

0.0039 mm in diameter). A rock dominated by silt particles is called a siltstone . A rock

dominated by silt particles is Called a siltstone . A rock dominated by clay particles is called

a claystone. A rock dominated by clay particles is Called a claystone. By now you are asking

yourself, if the particles are too small to identify, how can I tell them apart. By now you are

Asking yourself, if the particles are too small to identify, how can i tell Them apart. Your

eyes are less sensitive than your touch. Your eyes are less sensitive Than your touch. Sand

will feel gritty between your fingers, but silt will feel smooth. Sand Between Gritty earnest

feel your fingers, but silt earnest feel smooth. Clay particles are so small that the particles

even feel smooth on your teeth (a test which must be performed to be believed). Clay

particles are so small That even the particles feel smooth on your teeth (a test the which must

be performed to be believed). Most rocks in the mud family are made up a mixture of silt and

clay sized particles. Most rocks in the mud family are made up a mixture of silt and clay

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sized particles. In these cases, if the rock shows some degree of bedding (layering caused by

gravity) then the rock is called a shale . In these cases, if the rock shows Some degree of

bedding (layering the caused by gravity), then the rock is Called a shale . If the rock shows no

evidence of bedding (described as massive) it is called a mudstone. If the rock shows no

evidence of bedding (described as massive) it is Called a mudstone.

Terrigenous clastic sediments: Gravel, Sand and Mud

Four main groups of rocks can be recognized based on their composition; terrigenous clastic

sediments, carbonate sediments, evaporation deposition, and volcaniclastic. General and

specific composition to determine the nature of sediments and sedimentary rocks that formed

character. Classification scheme, naming, and descriptions have been developed to categorize

sediments and sedimentary rocks through the characteristics of a particular material.

Description of sediments and sedimentary rocks including estimates of origin of mineral and

biogenic constituent. Quantitative analysis of grain size, shape, and particle distribution.

Description of lithology can be made of loose material or hand specimen and petrographic

analysis completed by using a microscope. Some information about the process and

deposition conditions can be obtained through the study of sediment and rock as well as with

additional data from field and subsurface data. This chapter discusses the terrigenous clastic

sediments (gravel, sand, and mud) and litifikasinya; composed of minerals and rock

fragments derived from the weathering and erosion of older rocks.

2.1 Components of Sediments and Sedimentary Rocks

Sediments and sedimentary rocks can be classified based on the constituent or the origin of

the formation, or a combination of both. Distribution of sedimentary rocks is shown below

(Figure 2.1).

TERRIGENOUS MATERIAL clastic

Materials derived from clastic rock particles or older. This is the erosion of clastic detritus

from source rocks and are generally composed of silicate minerals; term detrital sediments

and sedimentary siliciklastik also be used for this material. Clastic sizes ranging from clay

particles (micrometer) to boulders (meters). Sandstones and conglomerates prepare as much

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as 20% - 25% of sedimentary rocks in the stratigraphic record and mudstone arrange 60% of

the total.

2.2 Classification and Naming of Sediments and Sedimentary Rocks Terrigenous clastic

Terrigenous clastic sediments is a collection of (aggregate) which separated from the clastic

material into terrigenous clastic sedimentary rocks when the material is terlitifikasi (litifikasi

is the process of rock formation) (7.21). Mud, silt, and sand is a loose aggregate; additional

affixes 'rocks' (mudstone, siltstone, sandstone) indicating that the material has been

terlitifikasi and has become rock solid. Loose gravel material named according to their size,

such as grain (granule), gravel (pebble), berangkal (cobble), and boulders (boulder) that can

terlitifikasi into conglomerates (sometimes added size, sample conglomerate gravel / 'pebble

conglomerate').

2.2.1 Sediment and Rock Terrigenous clastic sediments

Division based on grain size is used as a starting point for classifying and naming of

sediment and terrigenous clastic sedimentary rocks, pebbles and conglomerates composed of

clastic more than 2 mm in diameter, sand-sized grains between 2 mm to 1 / 16 mm (63 m);

mud (including clay and silt) consists of particles less than 63 μm in diameter. There are

several types of schemes and the division of categories, but sedimentologist tend to use the

Wentworth scale (Figure 2.2) to determine and name terrigenous clastic sediment.

2.2.2 Grain Size Scale Udden – Wentworth

Commonly known by the name of Wentworth Scale, this scheme is used for classification of

aggregate particles of matter (Udden, 1914, Wentworth 1922). Scale division are based on a

factor of 2; examples are grains of sand diameter 0.25 mm - 0.5 mm, very coarse sand of 1

mm - 2 mm, and so on. This scale was chosen because the distribution of reflections showing

the natural distribution of sediment particle; simple, large blocks of broken into two parts,

and so on.

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Four basic division is introduced:

- clay (<4 m)

- silt (4 μm - 63 m)

- sand (63 μm - 2 mm)

- gravel / aggregate (> 2 mm)

Phi scale is the number of representatives on the Wentworth scale. Greek letter 'Ф' (phi) is

often used as a unit of this scale. By using the logarithm of 2, the grain size can be shown on

a scale of phi as follows: Ф = - log 2 (grain diameter in mm) By using this formula, grain

diameter 1 mm is 0Ф; is-1Ф 2mm, 4 mm is-2Ф, and so forth; a decreasing grain size, 0.5 mm

is +1 Ф, 0.25 mm is 2Ф, and so on . The negative sign is used because it is used to represent

the grain size of the chart, that the grain size decreases from right to left.

2.2 Classification of grain size Udden-Wentworth scale