FORMATION sedimentary rocks

FORMATION sedimentary rocksSedimentary rocks are rocks that occur as the result of erosion or deposition of material dissolution. So the origin of the existing rocks, both igneous rocks, metamorphic rocks undergo weathering, eroding, caught then deposited elsewhere, so it had to be litifikasi cementation process and sedimentary rocks that hard. Sediment would be a sedimentary rock through the process of hardening or pembatuan involving:a. Compression (Compaction)b. Penyimenan (Cementation)c. Original crystallization (Recrystallization) primarily carbonate sediments)2.1.1 compression (compaction)Compression causing sediment grain will be depressed during tertimbus. The composition will be composed of the original grains with denser. If many partikal soft like scarves, sediments more susceptible to compression. As a result instead of compression, the layer becomes more juice, porositi berkurangan, especially in sediment mud terrigenus.Porositi reduction and water loss reached 60-80%. The water will flow to a region of high berketelapan such as sand, and will play an important peranakans in dissolution and chemical pemendapan in the sand. Having composed the original, which terterusan compression causes grain touching each other. Place a touch of high pressure and changes fizikal apply, such as the solution of the pressure (pressure solution). Dissolved silica that will fit in the cavity between the granules and may form Simen.2.1.2 Penyimenan (cementation)Penyimenan is the process by which new minerals derived rather than fluid cavity (pore fluids) will be formed / termendap on grain surfaces or validity grown-added or growth-past or pertumbesaran (overgrowths) minerals available there. The main types are kuarza Simen and calcite.Simen will bind sediment grains lead to stone. Penyimenan usually applies rated mid diagenesis. If applicable rated early, he may deduct the impression of compression, which must withstand harsh Simen pressure.Simen kuarza than water from burrows tepu with silica, namely bersilika results than the dissolving organisms, kuarza pressure solution, chemical diagenesis clay minerals and others. Simen calcite sediments may be formed during terendap, namely in the area surrounding carbonates.2.1.3 Initially crystallization (recrystallization)Original crystallization process is saiz changes and / or changes in the shape, without any chemical or mineralogical changes. Usually saiz will increase, but the diminution saiz may apply. Original crystallization is important in the limestone, which saiz calcite becomes larger, the texture and structure may be destroyed.
2.2 TYPES sedimentary rocksIn general, sediment or sedimentary rocks are formed in two ways, namely:1) formed in lembangan deposition or in other words it is not experiencing the transport process. Sediment sebegini recognized as autochthonous sediments. Between sediments are included in this collection is evaporit, limestone, laterite.2) undergo a process of transport, or in other words, rather than the outer regions lembangan puncanya and luluhawa process, hakisan and sediment transport is to take the deposition of the new lembangan. These sediments are called allochthonous sediments. Reuters is included in this collection is a conglomerate, volkanoklastik.In addition to the above welding, sedimentary rocks may be classified to several types, depending on the manner and process of formation. Among the major classes of sedimentary rocks is;1 - terrigenous (detrital or classless / clastic - clastic). Clastic rocks are rocks that originated puncanya than somewhere else, and have been deposited in a new lembangan after experiencing the process of transportation. Among the major rock names contained in this collection is; conglomerate or breksia, Sandstone, Stone lodak, & Shawls.2 - Sediment deposition chemistry / biochemistry (Chemical / biochemical). Chemical endapat rock is a rock formed pemendapan results than the chemical rather than the solution, or composed than life shelled carbonate minerals precipitate or bersilika or berfosfat etc. .. Between the rocks belonging to this collection is; Evaporit, carbonate sedimentary rocks (limestone and dolomite), bersilika Sedimentary rocks (chert), and organic deposition (coking).3 - Rock volkanoklastik (Volcanoclastic rocks). Rocks derived volkanoklastik than aktiviti volcano. Dust than aktiviti volcanic sediment would terendap like the others. Between the rocks in this collection is; bertuf Sandstone and agglomerates.
2.3 Classification of sedimentary rocksBased on the results of the energy mengangakut weathering / erosion, can be classified into:a. Sediment Aquatis, the sediments were deposited by water power. Example: sandbank, flood plain, natural levee, alluvial fan, delta, and so on.b. Sediment Aeolis / Aeris, the sediments were deposited by wind power. Example: sand dunes, soil loss, and so on.c. Glacial sediments, the sediments transported by glaciers labor Example: morena, drumline.Coarse particles of matter there is nothing subtle two carriage ways variety, there are compelled (trection), borne by jumping (saltion, carried in duspensi, there is also a (solution). According formation (depositional environment), sedimentary rocks divided into divided into three, namely:a. Marine sediments (marine), deposited in the sea eg limestone, dolomite, marl, and so on.b. Sediment land (teristris / continent), the process occurs on land, for example: stream sediment (alluvium), lake sediment, talus, koluvium, sediment desert (Aeolis), and so on.c. Sediment transition pembentukanya location situated between land and sea, such as silt and sediment delta marshes (limnis).Various classification and naming of sedimentary rock have been put forward by experts, both genetic and descriptive berdarkan. Genetically summed up in two groups (Pettijohn, 1975 ddan WT Huang, 1962):a. Clastic sedimentary rocksClastic sedimentary rocks are sedimentary rocks formed by the deposition process is mechanically or litifikasi rocks that have been there before. Clastic sedimentary rocks contain a lot of allogenic Minerals (minerals that formed in the sedimenasi or when sedimenasi lasts). Allogenic minerals have high durability. These minerals are derived from existing bataun which has undergone phase transport and then deposited on the environment sedimenasi. Some examples of these minerals, among others kwarasa, hornblende, biotite, plagioclase, kaolinite, montmorillonite, hydromuscovite, gypsum, chalcedony, hematite, siderite, limonite, and garnet.b. Non-clastic sedimentary rocksNon-clastic sedimentary rocks are sedimentary rocks formed by chemical processes either from solution or organic activity. In the non-clastic sedimentary rocks to get to meet a lot of Authigenic minerals (minerals that formed in the basin or the environment sedimenasi). Some examples Authigenic minerals are gypsum, anhydrite, calcite, and halite. Besides composed of minerals, sedimentary rocks are also composed of rock fragments and fossils. The crystals in sedimentary rocks also have contributed to the classification of sedimentary rocks. Classification of sedimentary rocks based on the size of crystals made by Howell and Hirschwald. Classification as follows: Makrokristalin, rock the constituent mineral crystals larger than 0.75 mm. Mesokristalin, rock the constituent mineral crystals measuring 0.2 mm to 0.75 mm. microcrystalline, rock the constituent mineral crystals measuring 0.01 mm to 0.2 mm. Kriptokristalin, rocks the size of its constituent mineral crystals lebihkecil of 0.01 mm
2.4 TEXTURE sedimentary rocksThe texture of sedimentary rocks is any appearance related to sediment grains, ranging from grain size, grain shape, up to orientation. The process of forming sedimentary rocks can be seen in the structure. Of texture, we can also interpret the sedimenasi a sedimentary rock.
2.4.1 Texture rocks clastic sedimentThe elements of the texture of clastic sedimentary rocks, is as follows: fragments, grains are larger than sand. matrix, grain size is smaller than the fragments, and filled the sidelines between the fragments, and deposited with the fragments. Cement, fine material which acts as a binder. Semen is deposited after the fragments and matrix. Semen is generally in the form of silica, calcite, sulfate, or iron oxide.To measure the size of the grains in the clastic sedimentary rocks used scale Wentworth (1922).Grain Size (mm) Item Name> 256 Blocks64-256 Brangkal4-64 gravel2-4 Gravel1-2 Sand Very Rough-1 ½ Coarse Sand¼ - ½ Sand MediumFine sand 1/8-1/41/16-1/8 Sand Very Fine1/16-1/256 siltClayWentworth ScaleThere are several factors that affect the size of the grains. These factors are as follows:a. Type of Weatheringb. Type of Transportc. Time / distance Transportd. ResistanceGrain shapeShape of the main grain sedimentary rocks are of two kinds. First, rounded (conglomerates). And both are tapered (Breccia). Level of grain roundness clastic sedimentary rocks is influenced by several factors. These factors are as follows:- The composition of the grain- Grain size- Type the transprtasi- The distance transportThe grains of minerals that are resistant will be shaped less round than the less resistant rocks. Grain size above 64 mm will be more rounded than the smaller. Distance transport effect on the level of roundness. The farther distance transport, the more round.Sorting or sortingConsists of sorting good and bad sorting.- Sorting is good, if uneven grain size or as large.- Sorting is bad, if the grain size is uneven, there are fragments and matrix.BoxedPack in clastic sedimentary rocks consist of:- Pack open, biila granules are not touching.- Pack closed, if the grains are touching.2.4.2 Texture Non-clastic sedimentary rocksIn general, non-clastic sedimentary rock composed of the mineral or commonly called monomineralik. The division of the types of textures on non-clastic sedimentary rocks usually by observing the appearance of the constituent crystals. Various textures non-clastic sedimentary rocks are as follows: Amorphous, generally sized particles such as clay or colloidal, non-crystalline Oolitik, composed of crystals that are round or ellipsoid. Colonize or gathering, grain size ranges from 0.25 mm - 2mm Pisolitik, have characteristics such oolitik, but has a larger grain size, more than 2mm Sakaroidal, consists of items that are very smooth with the same size Crystalline, composed of crystals that are largeCrystal grain size of non-clastic sedimentary rock distinguished by:- Coarse grained, with a size> 5mm- Medium grained, with a size of 1-5mm- Fine grained, with a size of <1mm br="br">
2.5 STRUCTURE sedimentary rocksIn general, the structure of sedimentary rocks are divided into 2 types• Structure Syngenetik, these structures are formed simultaneously with the formation of sedimentary rocks, often referred to as the primary structure of the rock.• Epiginetik structure, this structure is formed after the formation of thick, faults, and folds.The structure of sedimentary rocks Sygenetik classifiable into two parts, because the physical process and therefore biological processes.Due to Physical Processes1. External structure, appearance sedimentary rock structures that look as a whole in the ground. Examples of external structures, such as sheet, lens, wedge, and tabular prisms.2. Internal structure, the appearance of these structures are located on the inside of the sedimentary rocks. Various kinds of internal structure is as follows: perlapisan and LaminatesPerlapisan and laminates formed due to changes in physical, chemical, and biological. If more than 1 cm thick, it is called perlapisan. If the thickness is less than 1 cm, it is called lamination. Various kinds of laminated and perlapisan:a. Perlapisan / parallel lamination, coating / laminating arranged horizontally and are parallel to one another.b. Perlapisan / confusing cross lamination, coating / laminating intersect with each other.c. Gradaed Bedding, where the grains changed gradually. Massive, When in the sediment structure there is no appearance of the structure of the sediment.3. The appearance of the Surface Layer- Ripple Mark, wavy surface shape, because of the currents.- Flute Cast, scouring the surface layer forms due to the current activity.- Mud Cracks, cracks form in the soil layer, generally has a polygonal shape.- Rain Marks, the appearance on the surface of the sediment due to rain.4. Happens Because Deformation Structures- Load Cast, resulting indentation on the surface layers due to the existing load on it.- Convolute Structure, canting in sedimentary rocks due to the deformation process.- Sandstone Dike and Siil, arises because the sand can be injected in the sedimentary layers above it.Because biological processes- Traces (Track and Trail)Track, a trail tread in the form of the organism. While Trail is a trail in the form of dragging the body of organisms.- Excavation (Burrow)Hole is a result of akitivitas organisms.- Mold (Cast and Mold)Mold is an organism of the body mold. While the cast is a mold from Mold.
STRUCTURE 2.6 SedimentStudy of Sediment structure is best done in the field (Pettijohn, 1975), can be grouped into three types of structures, namely:
1. Primary Sedimentary StructuresThis structure is a structure formed by sedimentary processes may reflect mechanization sedimenasi deposition. Examples like perlapisan, gelembur wave, perlapisan cross maze, konvolut, perlapisan composite, and others. (Suhartono, 1996: 47)The primary structure is a structure that is formed when the deposition process and when the flow or igneous rock cools and no visible outcrops. The primary structure is important as a determinant of the position or orientation of the origin of the rocks are exposed, especially in sedimentary rocks.Structure formed during the deposition process is underway, including a layer of horizontal (flat bedding), cross-layer, laminated and cross laminated micro (micro-crosslamination), is the appearance of ripples. (Mohamed, 2007).2. Sediment Secondary StructureStructure formed after the sedimenasi, before or at the time diagenesa. Also reflect the state of the environment of deposition as the ground state, the slope and the environment organisnya. Among other things: weight, wrinkle fracturing, animal tracks.3. Sediment Organic StructureStructure formed by the activity of organisms, such as mollusk, worm or other animals. Among other things: skeletons, laminated growth.
2.7 INSTRUCTIONS sedimentary rocks1 - The presence perlapisan or Stratification2 - The structure of the sediments above satah or in perlapisan3 - Terjumpanya fossil4 - The presence of grains that have undergone the process of transport (class)5 - The presence of a random mineral sediments (glaukonit, chamosite)