Classification of sedimentary rocks
This secondary rocks deposited under conditions that vary greatly, resulting in genesis variety. Similarly, texture, composition and appearance of the resulting sedimentary rocks. So there is classification base manifold.
The ideal classification of sedimentary rocks, based on grain size and shape, and composition of its constituent materials.
Simple grouping in sedimentary rocks are the two major groups:
1. Clastic sedimentary rocks, formed from rock fragments, or the remains of shells of marine or freshwater animals, either still intact or debris.
2. Non-clastic sedimentary rocks, or organic chemistry and is formed by chemical processes or biological processes.
Clastic sedimentary rocks
Loose fragments or dust destruction or rombakan results mechanically from pre-existing rocks are called detritus (from the Latin word became obsolete). Sedimentary detritus also called clastic sediments (derived from the Greek meaning klastos rupture). Clastic sediments transported in various ways, can be rolled down the slope due to gravity, or carried away gletsyer, by wind or by water flow.
When transportation stops, mechanically deposited sediment with a typical system in accordance with the mechanism of transport. Precipitation occurs because the energy carrier down.
Sediment sliding, rolling or flowing down the slopes either by gravity or gletsyer in general is a mixture of random particles of various sizes. While the sediment particles carried by wind or water deposited when wind speed or water flow is reduced. Deposited particle size relates to the speed of the carrier. The greater the speed the greater-borne particles. The big difference between the fine grain and the rough is very extreme.
Because it takes a great reference point, and was created by Wentworth, known as the Wentworth classification or scale, Table 1.1.
Nama Ukuran
Boulder ³256 mm
Cobble 64 - 256 mm
Pebble 4 - 64 mm
Granule 2 - 4 mm
Sand 1/16 - 2 mm
Silt 1/256 - 1/16 mm
Clay £ 1/256 mm
 |
| Table 1.1 Scale Wentwoth; boulder and Cobble can be interpreted as a lump, pebble with gravel, granule size of gravel, sand with sand, while silt and clay with silt is clay. |
Clastic sedimentary rocks or sedimentary rocks also called detritus, consists of fragments of various sizes. Large granules called fragments and "bound" by the mass of the grains are more subtle, which is called the matrix. And grouped according to grain size material components, becomes:
Rudaceous
Sedimentary rocks consisting of coarse grained fragments or fragments of rock. Rocks including conglomerates and breccias are.
Conglomerates is the result of a mixture of gravel lithification, sand, silt and mud fragment size from pebbles to boulders of rock which is a fraction of existing (old),
and rounded shape (rounded). While the matrix which are among the fragments are generally composed of mineral fragments.
Breccia is similar to conglomerate but fragments form an angle (angular not rounded) (Figure 1.1 A and B).
Similar breccia generated by a volcanic eruption activity called volcanic breccia.
FIGURE 1.1. Conglomerate, rounded fragments of (A) and Breccia, fragmen angled (B).
Conglomerates or breccias are fragment consisting of a wide range of materials called conglomerate or breccia polimik. While consisting of only one kind of framen just called conglomerate or breccia monomik. For example, only fragments of andesite.
Arenaseous (arenaceous)
Rocks are dominated by sand-sized material, consisting of sandstone, arkose and graywacke.
Sand-stone consists of material which is mainly sand-sized grains (1 / 16 to 2 mm), although there are particles larger or smaller (eg sandstone or sandstone gravel silt). Distinction of different types of sandstones are usually based on the composition. The most resistant mineral quartz, is a common mineral in sandstones. When the grains are mainly quartz, quartz sandstone called.
Arkose sandstone or arkose. Arenaceous rocks generally consist of a mixture of sand quartz and feldspar fragments. May also contain rock fragments and small-grained minerals and angled.
Arkose appearance similar to granite, so that there are interpreting as a result of decomposition of granite. Arkose often colored red or pink caused by a mineral containing iron oxide.
Greywacke term is generally used for the sandstone composition of quartz, feldspar and large amounts of rock fragments (frozen, sedimentary and metamorphic) are smooth (lithic particles). A common association is volcanic ash and dust with quartz and feldspar fragments. Generally gray to black due to the matrix that resembles slate. The composition of the matrix is composed of a mixture of mica, and quartz chlorit. Graywacke interesting because its existence is widespread in the active pathway (tectonic) in the entire world. Percentage of total volume of sediment.
Argillaceous
Entirely composed of clay or the percentage of high clay content. Argillaceous The term is also used as an adjective to name rocks containing clay. Examples are shale.
Shale, silt, mudstone and marl, including the rock group claystone (argilaceous rock) and is also called pelitik rocks. Relatively uniform large egg, smaller than sand (1 / 16 to 1 / 256 mm), including mudstone, consisting of fragments of minerals, especially quartz and feldspar, precipitated in water, fresh, brackish or marine. Shale when weathered broken into squares or small blocks. While the silt fractions of fragments forming thin sheets (eg cleavage).
Stone clay (claystone) very fine grained, less than 1 / 16 mm. In general can not be used to examine an ordinary microscope, but it must be with an electron microscope that mempunuai very high magnification power. Although the grains are not visible, but is included in the clastic sediments
