It's a lot of rock types and rock telahdikenal are arranged by the minerals of the primary minerals minerals to secondary minerals accompaniment. These minerals can be classified into two major categories namely:
1. Felsik minerals, minerals that have a bright mineral colors.
2. Mefik Minerals, a mineral that has the color of dark minerals.
Mineral Felsik as an example is quartz, feldspar group, class feidspatoid and others. While the mineral olivine is mefik example, piroksin, hornblende, and much more.
In the process of cooling of magma in which the magma was not immediately froze everything, but decreasing the temperature or the temperature is slowly perhaps even sooner. This decrease in temperature accompanied the start of the formation and precipitation of certain minerals in accordance with the temperature. formation of minerals in the magma by a decrease in temperature, have been prepared by Bowen. Bowen has made tables and tables of mineral formation is very useful in interpreting these minerals.
Sudah banyak sekali jenis batuan yang telahdikenal dan batuan tersebut disusun oleh mineral-mineral dari mineral utama mineral pengiring sampai ke mineral sekunder. Mineral-mineral tersebut dapat digolongkan dalam dua golongan besar yaitu :
1. Mineral Felsik, mineral yang mempunyai warna mineral yang terang.
2. Mineral Mefik, mineral yang mempunyai warna mineral yang gelap.
Mineral Felsik sebagai contoh adalah kuarsa, golongan felspar, golongan feidspatoid dan lain-lainnya. Sedangkan mineral mefik contohnnya ialah olivin, piroksin, hornblende dan banyak lagi.
Dalam proses pendinginan magma dimana magma itu tidak langsung semuanya membeku, tetapi mengalami penurunan suhu atau temperatur secara perlahan bahkan mungkin cepat. Penurunan temperatur ini disertai mulainya pembentukan dan pengendapan mineral-mineral tertentu yang sesuai dengan temperaturnya. pembentukan mineral dalam magma berdasarkan penurunan temperatur, telah disusun oleh BOWEN. Bowen telah membuat tabel pembentukan mineral dan tabel tersebut sangat berguna sekali dalam menginterprestasikan mineral-mineral tersebut.
Definition CrystalsCrystals according to their language comes from the Greek meaning krustallos ice or something resembling ice. Crystal
is a homogeneous solid bounded by planes (face area) and having a
regular arrangement of atoms and molecules in a disordered state as
well. Apart from this definition there are various definitions of crystals from several experts. 1. WikipediaCrystal is a solid atom, molecule, or its constituent ions packed regularly and repeatedly widened pattern in three dimensions. 2. SnechalCrystals are solids that are essentially having a specific diffraction pattern. 3. Djauhari NoorIs defined as a mineral crystal that has a specific shape in nature and
density of state as the embodiment of an orderly arrangement in it. From
some of the definitions above we can see that the crystal is a solid
object which has a specific shape and geometrically regular basis this
is because the synchronization between atoms and molecules that make up
the crystal.
CRYSTAL SYSTEM Crystal form contained in the earth so much variety, from its most simple to the very complex. Crystalline forms contained in the earth can be grouped into several basic groups. This
division is based on the number of crystal axis, the location or
position of the axis to the axis krisatal other, the magnitude of the
parameters of each axis and the symmetry axis "c" of the crystal axis. Below are seven crystal systems are known, namely:
1. Isometric system This system is also called a system of regular crystals, or also known as a cube or cubic crystal system. The number of crystal axis and there are three mutually perpendicular to each other. By
comparison the same length for each axis so that the axes are often
given the name of a1, a2, a3, and also has a crystallographic angle α = β
= γ = 90 ˚. This shows that the system is all crystal angles (α, β and γ) perpendicular to each other (90 ˚).
Isometric system is divided into five classes, namely:· Tetaoidal §Class: all-28 § Symmetry: 2 3 § Elements of Symmetry: there are 4 axis rotary three and three rotary axes two·
Gyroida § Class: all-30 § Symmetry: 4 3 2 § Elements of Symmetry: there are 3-axis swivel four, three swivel axis 4, and 6 axis rotary two·
Diploida § Class: all-29 § Symmetry: 2 / m 3bar § Symmetry Elements: There are three rotary 4th axis, 3 axis swivel two, three areas of glass and one center·
Hextetrahedral § Class: all-31 § Symmetry: 4bar 3 m § Symmetry Elements: There are three rotary 4th axis, 3 axis putaempat, and 6 areas of glass.·
Hexoctahedral § Class: all-32 § Symmetry: 4 / m 3bar 2 / m § Elements of Symmetry: is the most symmetry classes for three-dimensional field with 4 axis rotary three, 3two rotary axes and two rotary axes. With 9 fieldsand a major center Some examples of minerals with an isometric crystal system is gold, pyrite, galena, halite, Fluorite (Pellant, Chris: 1992).
2. Tetragonal system Tetragonal
system with isometric system, because in this crystal system has three
axes of each crystal are perpendicular to each other. Axes a and b have the same unit length, so the naming of the axes is often the b axis as the axis a2 and a1 as the axis a. While the different c-axis, can be longer or shorter. But generally longer. Tetragonal system also has a crystallographic angle α = β = γ = 90 ˚.
Tetragonal system is divided into 7 classes:
Pyramid § Class: all-21 § Symmetry: 4 § Symmetry Elements: There is a rotary axis four
Bipiramid§ Class: all-23 § Symmetry: 4 / m § Symmetry Elements: There is a rotary axis and a plane of symmetry of four
Bisfenoid § Class: all-22 § Symmetry: 4bar § Symmetry Elements: There is a rotary axis four
Trapezohedral § Class: all-26 § Symmetry: 4 2 2 § Symmetry Elements: There is a four-axis swivel, 2 swivel axis two, all intersecting the spin axis perpendicular to the other.
Ditetragonal Pyramids § Class: all-25 § Symmetry: 4 m m § Symmetry Elements: There is a four-and 4-axis rotary plane of symmetry
Skalenohedral § Class: all-24§ Symmetry: 4bar 2 m § Symmetry Elements: There is a four-axis swivel, 2 swivel axis two, and the second plane of symmetry
Ditetragonal Bipiramid § Class: all-27§ Symmetry: 4 / m 2 / m 2 / m § Symmetry Elements: There is a fourth rotary axis, 4 axis rotary two-, five-axis symmetry
Some
examples of minerals with a tetragonal crystal system is rutile,
autunite, pyrolusite, leucite, scapolite (Pellant, Chris: 1992)
3. Hexagonal System The system has four hexagonal crystal axis, where the c axis perpendicular to the three other axes. Axes a, b, and d each forming an angle of 120 ˚ to each other. Axes a, b, and d have the same length. The length of c is different, can be longer or shorter (generally longer). System has a hexagonal crystallographic angle α = β = 90 ˚; γ = 120 ˚. This means that, on this system, α and β angles perpendicular to each other and form a 120 ˚ angle to the axis of γ.
The system is divided into 7:
Hexagonal Pyramids § Class: all-14§ Symmetry: 6 § Symmetry Elements: There is only one of six rotary axis.
Hexagonal Bipramid § Class: all-16§ Symmetry: 6 / m § Symmetry Elements: There is a six rotary axis, a plane of symmetry
Dihexagonal Pyramids § Class: all-18§ Symmetry: 6 m m § Symmetry Elements: There is a six-axis swivel, 6 plane of symmetry
Dihexagonal Bipiramid § Class: all-20§ Symmetry: 6 / m 2 / m 2 / m §
Symmetry Elements: There is a six rotary axis, rotary axis 6 two, 7
plane of symmetry intersecting each perpendicular to one axis of
rotation and a central
Trigonal Bipiramid § Class: to-1§ Symmetry: 6bar (equivalent to 6 / m) § Symmetry Elements: There is a six rotary axis, a plane of symmetry
Ditrigonal Bipiramid § Class: all-17 § Symmetry: 6bar 2m § Symmetry Elements: There is a six rotary axis, 3 axes turn two, and the fourth plane of symmetry
Hexagonal Trapezohedral § Class: all-19 § Symmetry: 6 2 2 § Symmetry Elements: There is a six rotary axis, 6 axis rotary two
Some examples of minerals with the Hexagonal crystal system is quartz, corundum, hematite, calcite, dolomite, apatite. (Mondadori, Arlondo. 1977).
4. Trigonal system If
we read some external reference, this system has another name, namely
rhombohedral, other than that some experts put this system into the
Hexagonal crystal system. Similarly, his description is the same way. The
difference, if the trigonal system once it has formed the base plane,
which is formed hexagons, then the triangle formed by connecting two
vertex that passes through one vertex.Trigonal
system has axial ratio (ratio of axes) a = b = d ≠ c, which means a
long axis equal to the same axis with the axis b and d, but not the same
as the axis c. And also has a crystallographic angle α = β = 90 ˚; γ = 120 ˚.
The system is divided into five classes:
Trigonal pyramid Trigonal Trapezohedral § Class: all-12 § Symmetry: 3 2 § Symmetry element: there is a third rotary axis, 3 axes turn two.
Ditrigonal Pyramids § Class: all-11 § Symmetry: 3m § Symmetry Elements: There are three rotary axes 1 and 3 plane of symmetry
Ditrigonal Skalenohedral § Class: all-13§ Symmetry: 3bar 2 / m § Symmetry element: there is a rotary field of three, three play areas two, three plane of symmetry Rhombohedral Some examples of minerals with trigonal crystal system is tourmaline and cinabar (Mondadori, Arlondo. 1977)
5. Orthorhombik System This system is also called Rhombis system and has 3 crystal symmetry axis perpendicular to one another. All three axes have different lengths.In
actual conditions, the system has axial crystal Orthorhombik ratio
(ratio of axes) a ≠ b ≠ c, so long axes do not have the same length or
different from each other. And also has a crystallographic angle α = β = γ = 90 ˚. This means that, on this system, the three mutually perpendicular angle (90 ˚).
Orthorombik symmetry of the system has 3 symmetry elements such as: · 3 plane of symmetry: axis fields · 3 diagonal symmetry axis: axis-axis crystallographic center of symmetry
The system is divided into three classes:
Bisfenoid § Class: to-7 § Symmetry: 2 2 2 § Symmetry Elements: There are 3 rotary axes
Pyramid § Class: to-6 § Symmetry: 2 m § Symmetry Elements: There are two rotary axes 1 and 2 areas
Bipiramid § Class: to-8 § Symmetry: 2 / m 2 / m 2 / m §
Symmetry Elements: There are two 3-axis swivel with a plane of symmetry
which perpendicularly intersects with the third axis and a center.The third axis and a center
Some
examples of mineral crystals Orthorhombik premises of this system is
stibnite, chrysoberyl, aragonite and witherite (Pellant, Chris. 1992)
6. Monoclinic system Monoclinic meaning has only one axis is tilted from its three axes. A-axis perpendicular to the axis n, n perpendicular to the c axis, but not c-axis perpendicular to the axis a. The third axis has a length that is not the same, generally the longest c axis and b the shortest axis. Monoclinic system has axial ratio (ratio of axes) a ≠ b ≠ c and a crystallographic angle α = β = 90 ˚ ≠ γ. This means, in this ancer, angles α and β are perpendicular (90 ˚), while γ is not perpendicular (oblique).
Monoclinic system is divided into three classes:·
Sphenoid § Class: all-4 § Symmetry: 2 § Elements of Symmetry: 1 rotary axis·
Doma § Class: 3rd § Symmetry: m § Symmetry elements: a plane of symmetry·
Prism § Class: to-5 § Symmetry: 2 / m § Elements of Symmetry: a rotary axis with a plane of symmetry of two intersecting perpendicular
Some
examples of minerals with ancer monoclinic crystals are azurite,
malachite, colemanite, gypsum, and epidote (Pellant, Chris. 1992)
7. Triklin System This system has three axes of symmetry with each other are not mutually perpendicular. Likewise the length of each axis is not the same. System
Triklin crystals have axial ratio (ratio of axes) a ≠ b ≠ c, which
means long axes do not have the same length or different from each
other. And also has a crystallographic angle α = β ≠ γ ≠ 90 ˚. This means, in this system, the angle α, β and γ are not mutually perpendicular to each other.
The system is divided into 2 classes:
Pedial § Class: to-1 § Symmetry: 1 § Elements of Symmetry: only a central
Pinakoidal § Class: to-2 § Symmetry: 1bar § Elements of Symmetry: only a central
Some
examples of minerals with crystal Triklin ancer is albite, anorthite,
labradorite, kaolinite, microcline and anortoclase (Pellant, Chris.
1992).
Plate tectonics theory (English: Plate tectonics) is a theory in the field of geology developed to provide an explanation for the existence of evidence of large-scale movements undertaken by the lithosphere of the earth. This theory has been included and also replaced the theory of continental drift which first put forward in the first half of the 20th century and the concept of seafloor spreading developed in the 1960s.
Outermost part of Earth's interior is formed of two layers. At the top there lithosphere comprising the crust and upper mantle is rigid and solid. Under the layers of the lithosphere asthenosphere there is a solid but can flow like a liquid with a very slow and in a geological time scale is very long because the viscosity and shear strength (shear strength) is low. Deeper, the mantle below the asthenosphere is more rigid nature become again. The cause is not the cooler temperatures, but high pressure.
Layers of the lithosphere is divided into tectonic plates (Tectonic plates). On earth, there are seven major plates and many plates are smaller. These lithospheric plates ride on the asthenosphere. They move relative to each other at plate boundaries, both divergent (away), convergent (colliding), or transform (sideways). Earthquakes, volcanic activity, mountain formation, and formation of oceanic trenches are all generally occurs in areas along plate boundaries. Lateral movement of the plates is typically speed 50-100 mm / a.
A. Development of Theory
At the end of the 19th century and early 20th century, geologists assumed that the appearance of the main appearance of the earth-fixed domicile. Most geological appearance as mountains can be explained by vertical crustal movement as described in the theory geosinklin. Since 1596, it has been observed that the Atlantic coast that face to face between the continents of Africa and Europe with North America and South America have similar shapes and seem to never become one. This accuracy will be more obvious if we look at the edges of the continental shelf in there. Since then many theories have been advanced to explain this, but all of a stalemate because of the assumption that the earth is fully dense complicate the discovery of an appropriate explanation.
The discovery of radium and heating properties in 1896 encouraged the review of the age of the earth, because previous estimates obtained from the cooling rate and assuming the earth's surface radiating like a black body. From these calculations it can be concluded that even if at first the earth was a red-glowing object, the temperature will fall to Earth as it is now within a few tens of millions of years. With the newly discovered source of heat is then the scientists think it makes sense that the Earth is actually much older and the core is still hot enough to be in the liquid state.
Theory of Plate Tectonics Hypothesis The shift comes from the Continent (continental drift) Alfred Wegener proposed in 1912. and developed again in his book The Origin of Continents and Oceans, published in 1915. He suggested that the continents that now there was once a landscape front that is moving away thus releasing the continents from the Earth's core as 'iceberg' of granite that low-mass type that floats on a sea of more dense basalt. However, in the absence of detailed evidence and calculation of the forces involved, this theory was marginalized. Perhaps the earth has a solid crust and liquid core, but still it does not seem possible that parts of the crust can be moving. Later, the theory put forward dibuktikanlah British geologist Arthur Holmes in 1920 that links parts of the crust is likely to exist under the sea. Also proved his theory that convection currents within the Earth's mantle is the driving force.
The first evidence that the plates do experience gained from the discovery of differences in the movement direction of the magnetic field in rocks of different age. This discovery was first expressed at a symposium in Tasmania in 1956. At first, the invention is incorporated into the theory of Earth expansion, but later more precisely leads to the development of plate tectonic theory which explains the expansion (spreading) as a consequence of vertical movement (upwelling) rocks, but avoids the necessity of the earth whose size continues to grow or expand ( expanding earth) by entering the subduction zone / hunjaman (subduction zone), and fault translation (translation fault). At that time the theory of plate tectonics changed from a radical theory into theories which are commonly used and widely accepted among scientists. Further studies on the relationship between seafloor spreading and the reversal of the earth's magnetic field (geomagnetic reversal) by geologist Harry Hammond Hess and Ron G. oseanograf Mason pinpointing the mechanisms that explain the vertical movement of the new rock.
Along with the receipt of the earth's magnetic anomaly indicated by the lane-lane parallel to the symmetry with the same magnetization on the seafloor on either side of mid-oceanic ridge, plate tectonics became widely accepted. Rapid advances in seismic imaging techniques initially in and around Wadati-Benioff zones and various other geologic observations soon confirmed as the theory of plate tectonics that has a remarkable ability in terms of explanation and prediction.
Research on the seafloor, a branch of the rapidly growing marine geology in the 1960s played an important role in the development of this theory. Correspondingly, plate tectonic theory was also developed in the late 1960's and has been pretty universally accepted in all disciplines, as well as renew the earth sciences by giving an explanation for the wide range of geological phenomena and their implications in other fields such as paleogeografi and paleobiology .
B. Key Principles
Parts of the outer layer, the Earth's interior is divided into layers of the lithosphere and asthenosphere layer based on differences in the occurrence of mechanical and heat transfer. Llitosfer more cold and rigid, whereas the asthenosphere is hotter and mechanically weaker. In addition, the lithosphere loses heat through conduction process, whereas the asthenosphere also transfers heat by convection and has a nearly adiabatic temperature gradient. This division is very different from the chemical division of earth into core, mantle, and crust. Lithosphere includes the crust and also own a portion of the mantle.
A part of the coat could have been part of the lithosphere or the asthenosphere at different times, depending on the temperature, pressure, and power sliding. Key principle of plate tectonics is that the lithospheric plates separated into different tectonic. These plates move a ride on the asthenosphere which has viskoelastisitas so it behaves like a fluid. The movement of the slab can reach 10-40 mm / a (growing as fast as your fingernails) as in the Mid-Atlantic Ridge, or can reach 160 mm / a (as fast hair growth) as the Nazca Plate.
These plates about 100 km thick and consists of a coat litosferik upon which is coated with a stretch of one of two types of crustal material.
The first is the oceanic crust or often called "sima", a combination of silicon and magnesium.
The second is the continental crust is commonly called "unfortunate", a combination of silicon and aluminum.
Both types of crust thickness is different in terms of where the continental crust has a thickness that is much higher than the oceanic crust. Continental crust thickness reaches 30-50 km whereas oceanic crust is only 5-10 km.
Two plates will meet along the plate boundary (plate boundary), ie areas where geological activity like earthquakes generally occur and the formation of topographical appearance such as mountains, volcanoes and oceanic trenches. Most active volcanoes in the world is above the plate boundaries, such as the Pacific Ring of Fire (Pacific Ring of Fire) on the Pacific Plate is the most active and widely known.
Plate tectonics can be continental or oceanic crust, but usually one plate consists of both. For example, the African Plate includes the continent itself and in part the basis of the Atlantic and Indian Ocean.
The difference between the continental crust by oceanic crust is based on the density of its constituent materials.
• Oceanic crust is denser than continental crust due to differences in the comparison of various elements, especially silicon.
• Continental crust is more dense because the composition contains less silicon and more material by weight. In this case, said the oceanic crust is more mafic than felsik. Thus, oceanic crust generally lies below sea level like most of the Pacific Plate, while the continental crust occur over the sea surface, follow a principle known as isostasi
Types ofPlateBoundaries
Threetypes ofplate boundaries
There are three types of plate boundaries are different from the way the plates are moving relative to one another. These three types are each associated with different phenomena on the surface. Three types of plate boundaries are:
1. Boundary transform (transform boundaries) occurs when plates move and experiencing friction with each other laterally along the transform fault (transform fault). The second plate relative motion can be sinistral (left on the side opposite the observer) or dekstral (to the right on the side opposite the observer). Examples of this type of fault is the San Andreas Fault in California.
2. Limit divergent / constructive (divergent / constructive boundaries) occurs when two plates move away from each other. Mid-oceanic ridge and fracture zones (rifting) is an example of active divergent boundary
3. Limit convergent / destructive (convergent / destructive boundaries) occurs when two plates rub against each other so close to form a subduction zone if one plate moves under another, or continent collision (continental collision) if the two plates contain continental crust. Deep ocean trench usually located in a subduction zone, where the pieces of plate which contains many are terhunjam hydrate (containing water), so that the water content is released when heating occurs mixed with the mantle and cause melting, causing volcanic activity. Examples of these cases we can see in the Andes Mountains in South America and the island arc of Japan (Japanese island arc). Strength Activator Plate Movement
The movement of tectonic plates can occur because of the relative density of oceanic lithosphere and asthenosphere is relatively weak character. The release of heat from the mantle has been found as the original source of energy that drives plate tectonics. The view is approved now, although still quite debatable, is that the excess density of oceanic lithosphere that makes infiltrate downward in subduction zones is the strongest source of the movement of the slab.
At the time of its formation in mid-ocean ridge, oceanic lithosphere initially have a lower density than the surrounding asthenosphere, but this density increases with aging due to cooling and thickening. Magnitude of the density of the old lithosphere relative to the underlying asthenosphere allows the infiltration into the deep mantle at subduction zones so that the source of most of the driving forces-the movement of plates. Weaknesses asthenosphere allows the plates to move easily towards a subduction zone. Although subduction is believed to be the strongest driving forces-the movement of plates, there are other driving forces as evidenced by the presence of the slab as the North American plate, Eurasian plate is also moving but did not experience anywhere subduction. Driving source is still a topic of intensive research and discussion among scientists of earth sciences.
Two-and three-dimensional imaging of the Earth's interior (seismic tomography) shows a heterogeneous density distribution throughout the mantle laterally. Variations in density may be material (from rock chemistry), mineral (from variations in the mineral structure), or thermal (through thermal expansion and contraction from heat energy). Manifestation of lateral density heterogeneity is mantle convection from buoyancy (buoyancy forces). How mantle convection relate directly and not by movement of the planet is still a field that is being studied and dealt in geodinamika. With one way or another, this energy must be transferred to the lithosphere to tectonic plate movement. There are two main types of styles in its influence to the movement of planets, ie friction and gravity.
Earth is the third planet from the eight planets in the Solar System. Estimated to reach 4.6 billion years old. The distance between the Earth to the sun is 149.6 million kilometers, or 1 AU (ing: astronomical units). earth has a layer of ozone, as high as 50 kilometers, are in the stratosphere and mesosphere and protect the earth from ultraviolet rays.
Earth has a mass weighing 59,760 billion tons, with a surface area of 510 million square kilometers. The density of the Earth (about 5,500 kilograms per cubic meter) is used as the unit of weight ratio of other types of planets, the gravity of Earth is set as 1. Earth has a diameter of over 12 756 kilometers. Earth's gravity was measured as 10 N kg-1 used as a unit the size of the gravity of other planets, the Earth's gravity is set as 1.
The structure of planet Earth consists of 3 (three) main layers, namely Barysphere or centrosphere (core), Mesosphere, or mantle (sheath) or Chalkosphere, and lithosphere.
A. Barysphere or Centrosphere (The Earth)
Barysphere or Centrosphere (The Earth) has a radius of ± 3475 km and consists of the elements iron (Fe) and nickel (Ni), so it is often called the Ni-Fe layers. The core is divided into 2 (two), namely:
a) in the dense core, composed of crystalline iron or iron-nickel crystals, fingers ± ± 1,200 km with a temperature of 4800 ° C.
b) the outer core in the form of highly-viscous liquids, the thickness ± ± 2250 km with a temperature of 3900 ° C.
B. MESOSPHERE or Mantel
Mesosphere or mantle is the layer that envelops the earth's core, because it's called the mantle, which means sheath. This layer is a layer between the lithosphere and the core, because it is also called Mesosphere. Thickness ± ± 2900 km with a temperature of 1500 ° C - 3000 ° C, composed of rocks containing oxide and sulfide scales. Because the content of this chemical, called Chalkosphere. The coat consists of inner and outer coat coat. On the outer sheath bordering the lithosphere there is a layer called the asthenosphere liquid.
Among those layers are not continuous with the layers (discontinu), namely:
• Mohorovivic Discontinuity (or Moho layer also called M-Discontinuity). This layer is to limit the Earth's crust (crust) with the upper mantle at depths of 35-60 km +. Was first put forward by A. Andrija Mohorovivic (1857-1936) in 1909. Seismic wave velocity increases after passing through this layer.
• Gutenberg Discontinuity. This layer was found by Beno Gutenberg, limits to the outer core and mantle lies at a depth of 2900 + km.
C. Lithosphere
Lithosphere is derived from the Lithos (= rock) and the sphere or sphaira (= layer), is wrapped around the outside of the Earth. Lithosphere consists of a relatively lighter rock (light rock) than the asthenosphere and the mesosphere. Most of the chemical elements are Silicate (SiO2) which is a mixture of oxygen and silicon. Unsusr other chemical elements are oxygen (46.6%), silicon (27.7%), aluminum (8.1%), iron (5%), calcium (3.6%), sodium (2.8% ), potassium (2.6%), and magnesium (2.1%).
Lithosphere layer is a layer of very thin, dense, hard, strong, and the most rigid, yet elastic (springy) among all layers of the Earth, because it is called the crust (crust). This crust forms occur because of differences in temperature (temperature amplitude) are great between asthenosphere layer which can reach> 10000 C with a face of the Earth. About 100 km thick lithosphere, including the earth's crust and upper mantle layer. other than as a place to stand, move, and plant growth media, the lithosphere is a vehicle mines and mineral materials.
According to the theory of plate tectonics (Tectonic plate theory), the lithosphere consists of plates of each pair, so it resembles Earth-tide loading games (puzzles). The plates continuously move away from each other or each slide or grind each other, resulting in an uneven shape Earth. Lithospheric plates are divided into two kinds, namely the continental shelf and oceanic plates.
Continental plate is a plate that is not submerged sea water and on it stood the continents with an average thickness of ± 30 km and in mountainous areas ± 70 km. These plates are subdivided into 3 (three) layers:
The top layer with a thickness of + 15 km (type granite magma), the main chemical elements silicium and aluminum;
• The thick middle layer + 25 km (type basaltic magma), the main chemical elements silicium and aluminum; and
• The bottom layer thickness + 20 km (type peridotite magma and eklogit), the main chemical elements silicium and magnesium.
Plates meet the oceanic lithosphere ± 65%. The main chemical elements are silicium and magnesium, so-called Ma-Si layer, its thickness at the bottom of the ocean reaching ± 6 km.
continental crust
oceanic crust
layer called the si-al (aluminum silisium)
called ma si-layer (silisium magnesium)
contains elements of aluminum in large quantities
contains elements of magnesium in large quantities
composed of very old rocks that are granitis
consisting of rock basaltis younger are more dense than continental crust
the main elements forming the aluminum-rich silicate minerals, potassium, and sodium
its main constituent elements of silicate minerals which are rich in magnesium, iron, calcium, and a little aluminu
The process of formation of earth from several theories:
• Big Bang Theory
This theory is the most famous. Based on Big Bang Theory, the process of formation of the earth originated from tens of billions of years ago. At first there were wisps of fog giant spinning on its axis. Round it does allow small parts and light was thrown out and gathered a large part in the center, forming a giant disc. At one point, the giant mist exploded with a vengeance in outer space which later formed the galaxies and nebula, nebula. Over a period of approximately 4.6 billion years old, the nebula nebula-freeze and form a galaxy called the Milky Way's name, then formed the solar system. Meanwhile, the light which had been thrown off condenses to form clots that cools and solidifies. Then, the clumps that formed the planets, including planet Earth.
During its development, planet earth continues to experience a gradual process and to form it is today. There are three stages in the process of formation of the earth, namely:
1. Initially, the planet earth is still a homogeneous and has not experienced bedding or difference element.
2. Establishment of bedding structure of the earth that begins with the occurrence of differentiation. Iron material is its density is greater will sink, while the lighter weight species will move to the surface.
3. the Earth is divided into five layers, namely inner core, outer core, the mantle, outer mantle, and crust. Changes in the earth caused by weather and climate change.
• Kant-Laplace theory Fog
Since the time before Christ, the experts have a lot of thinking and doing an analysis of natural phenomena. Starting the 18th century scholars had thought process of the Earth. Do you remember about the theory of fog (nebula) proposed by Immanuel Kant (1755) and Pierre de Laplace (1796). They are famous for fog Kant-Laplace theory. In this theory proposed that in the universe there is a gas which is then assembled into mists (nebulae). Force of attraction between these gases form a very large collection of fog and spinning faster and faster. In the process very quick turnaround, the material parts of the equatorial haze thrown apart and solidified (for cooling). The part is then thrown into the planets in the solar system.
• Planetesimal theory
A century after the theory of the mist, appeared planetesimal theory advanced by Chamberlin and Moulton. This theory has revealed that in the beginning there is the sun's origin. At one point, the sun's origin is approached by a large star, which led to the withdrawal on the part of the sun. Solar energy due to the withdrawal of earlier origin, there was a great explosions. The gas exploded out of the solar atmosphere, then condenses and freezes as solid objects, and called planetesimals. These planetesimals in its development into the planets, and one of them is our planet Earth.
Basically, the theoretical processes of the planets and the earth, starting daribenda gaseous temperature is very hot. Then due process and turnaround time (centrifugal) quickly, then the cooling occurs that causes compaction (on the outside). Adapaun Earth's inner body temperature remains high.
• Tidal Theory of Gases
This theory was put forward leh jeans and Jeffreys, namely, that a massive star near the sun in a short distance, thus causing the ebb and flow in the body of the sun, when the sun was still in a gaseous state. The occurrence of the tides on Earth as we know, size, very small. The reason is the small mass of the moon and the distance of the moon to the Earth (60 times the radius of Earth's orbit). However, if a star's mass is almost as large as the sun approaches the sun, it will form a kind of giant mountains of waves on the body of the sun, caused by an earlier star attraction. Mountain-high guung will achieve remarkable and form a kind of immense incandescent tongue, protruding from the mass of the sun before and stretch toward the big star.
In the heat of the tongue is the case sealing gases and finally the columns will be broken, and then split into separate objects, ie planets. Massive star that causes the withdrawal on the body parts the sun was, move on in the universe, so it will gradually lose its effect on earlier-shaped planet. The planets will revolve around the sun and cools. This cooling process was slow on large planets like Jupiter and Saturn, while on a small rocky planets like our Earth, runs relatively faster cooling.
While the cooling takes place, the planets around the sun was still in an elliptical orbit, so most likely at some point meraka will approach the sun within a short distance. As a result of the withdrawal force of the sun, there will be ups and downs on planetary bodies of the new born. The sun will draw material from the columns of the planets, so was born the months (satellites) that revolve around the planets. role in shaping the sun held this month in principle the same as the big star role in shaping the planets, as discussed above.
• Twin Stars Theory
This theory was put forward by an expert Astronomy RA Lyttleton. According to this theory, galaxies comes from a combination of twin stars. One of the exploded star, so much material that was thrown. Since the star that exploded not have the force of gravity is still strong, then the fractional distribution of stars surrounding the star explosion which did not explode. The star that exploded was not the sun, while another fraction of stars that are the planets that surround it
Conclusion
There are two conclusions that can be taken from the explanation of the formation process of the earth, namely:
1. Earth from a giant blob that exploded terrible fog, then forming galaxies and nebulae. After that, nebulae freezes to form the Milky Way, and system of surya.Bumi formed from the small light that was thrown out when a giant exploding mist that cools and solidifies, forming the earth.
2. Three stages of the process of formation of the earth, ie starting from the beginning the earth was formed, differentiation until the earth began to split into several zones or layers, namely the core, outer core, mantle deep, outer mantle, and crust.
Geology (from Greek: γη-[-ge, "earth"] and λογος [logos, "word", "reason"]) is a science (science that studies the Earth, its composition, structure, physical properties, history, and formation process.
The word "geology" was first used by Jean-André Deluc in 1778 and introduced as a standard term by Horace-Benedict de Saussure in 1779.
GEOLOGICAL SCIENCE BRANCH
• mineralogy
The study of minerals in mineral megaskopis and specify the name of the description (physical properties, parts, scratches, color, gloss, etc.)
• petrology
The study of rocks, the origin of its formation, classification, where the formation and deposition, and its spreading both inside and outside the bowels of the earth.
• Geological Structure (King of Geology)
The study of changes in the earth's crust bentuk2 resultant by force so as to produce the geological structure in the form of folds, faults, stocky, and so on.
• Geomorphology
The study of landscape and Proses2 who influenced him.
• Stratigraphy (Queen of Geology)
studies of rock bedding, distribution, composition, thickness, age and correlation of rock layers.
• geochemistry
is basically the study of the chemical composition of the earth. study the existence of unsur2 isotopes in the earth, etc..
• paleontology
The study of all aspects of past life in the form of either macro-or micro-fossils found in rocks reply.
• Applied geology
Application of Geology to the interests manusiapada particular field. eg: Mining Geology, Coal Geology, Oil and Gas Geology, Hydrogeology, and so on.
Geology is part of the various aspects of the human environment. Various aspects of society formation process and requires knowledge of geology dasarr. Examples of natural resources and energy, development environment and natural disasters.
Geology is a word derived from the word "geo" meaning earth and logos meaning science. So it literally means the science of geology of the earth or the study of nature. Earth here does not mean just physical material of the earth that is only a constituent of the earth and the shape of the earth itself, but also the processes that occur on earth and tebentuknya earth until now. These processes occurring both within and on the earth's surface. Scram is also life ever existed on this earth and its evolution is studied in geological objects.
So learn all asoek geology associated with the earth. To understand the earth is actually not an easy task, because the planet is not a period of silence or rock that has not changed, but it is a time of silence or rock that has not changed, but it is a very dynamic period which has a complex history of the wedding and . of Geological Sciences is traditionally divided into two large sections of Physical Geology and History.
Physical Geology is the science of geology that studies about amterial-material making up the earth and try to understand and comprehend the processes that occur on the inside and on its surface. While the history of geology is the science of geology that studies about the origin of the earth and its development over time. So, this section attempts to explain relationships in the chronology of changes in physical and biological behavior that appears in the geological past. The study of physical geology logically prior to the study of geological history, because we must first understand how the Earth works before we dismantle or study the events of the past.
Menurut bahasanya Kristal berasal dari bahasa Yunani
yaitu krustallos yang berarti es atau
sesuatu yang menyerupai es. Kristal
merupakan padatan homogeny yang dibatasi oleh bidang-bidang datar(bidang muka)
yang teratur dan mempunyai susunan atom dan molekul dalam keadaan teratur pula.
Selain dari definisi ini terdapat pula berbagai definisi Kristal dari beberapa
ahli.
1.Wikipedia
Kristal adalah suatu padatan yang
atom, molekul, atau ion penyusunnya terkemas secara teratur dan polanya
berulang melebar secara tiga dimensi.
2.Snechal
Kristal merupakan padatan yang
secara esensial mempunyai pola difraksi tertentu.
3.Djauhari
Noor
Kristal di definisikan sebagai mineral yang memiliki sifat
dan bentuk tertentu dalam keadaan padatnya sebagai perwujudan dari susunan yang
teratur di dalamnya.
Dari
beberapa definisi diatas dapat kita pahami bahwa Kristal merupakan benda padat
yang memiliki bentuk tertentu dan teratur secara geometris hal ini dikarenakan
sinkronisasi antar atom dan molekul yang membentuk Kristal tersebut.
SISTEM
KRISTAL
Bentuk kristal yang terdapat di bumi
sangat banyak sekali ragamnya, dari bentuk yang paling sederhana sampai yang
sangat rumit. Bentuk-bentuk Kristal yang terdapat di bumi dapat dikelompokkan
menjadi beberapa kelompok dasar. Pembagian ini berdasarkan jumlah sumbu
Kristal, letak atau posisi sumbu krisatal terhadap sumbu lain, besarnya
parameter masing-masing sumbu dan simetri sumbu “c” dari sumbu Kristal. Dibawah
ini 7 sistem Kristal yang dikenal, yaitu :
1.Sistem Isometrik
Sistem ini juga disebut sistem
kristal regular, atau dikenal pula dengan sistem kristal kubus atau
kubik. Jumlah sumbu kristalnya ada 3 dan saling tegak lurus satu dengan yang
lainnya.
Dengan perbandingan panjang yang
sama untuk masing-masing sumbunya sehingga sumbu-sumbu tersebut sering diberi
nama a1, a2, a3 dan juga memiliki sudut
kristalografi α = β = γ = 90˚. Hal ini menunjukkan bahwa system ini semua sudut
kristalnya ( α , β dan γ ) tegak lurus satu sama lain (90˚).
gambar sistem isometri
Sistem
isometrik dibagi menjadi 5 Kelas, yaitu :
·Tetaoidal
§Kelas : ke-28
§Simetri : 2
3
§Elemen
Simetri : terdapat 4 sumbu putar tiga dan tiga sumbu putar dua
·Gyroida
§Kelas : ke-30
§Simetri : 4 3
2
§Elemen
Simetri : terdapat 3 sumbu putar empat, 4 sumbu putar tiga, dan 6 sumbu putar
dua
·Diploida
§Kelas : ke-29
§Simetri :
2/m 3bar
§Elemen
Simetri : ada 4 sumbu putar tiga, 3 sumbu putardua, 3 bidang kaca dan satu pusat
·Hextetrahedral
§Kelas :
ke-31
§ Simetri : 4bar 3 m
§Elemen
Simetri : ada 4 sumbu putar tiga, 3 sumbu putaempat, dan 6 bidang kaca.
·Hexoctahedral
§Kelas : ke-32
§Simetri :
4/m 3bar 2/m
§Elemen
Simetri : merupakan klas yang paling simetri untuk bidang tiga dimensi dengan 4
sumbu putar tiga, 3
sumbu putar dua, dan sumbu putar dua. Dengan 9 bidang
utama dan 1 pusat
Beberapa contoh mineral dengan
system kristal Isometrik ini adalah gold, pyrite, galena, halite, Fluorite (Pellant,
chris: 1992).
2.Sistem Tetragonal
Sistem tetragonal sama dengan system
Isometrik, karena pada system kristal ini mempunyai 3 sumbu kristal yang
masing-masing saling tegak lurus. Sumbu a dan b mempunyai satuan panjang sama,
sehingga penamaan sumbu-sumbu tersebut sering menjadi sumbu a2 sebagai
sumbu b dan a1 sebagai sumbu a. Sedangkan sumbu c berlainan, dapat
lebih panjang atau lebih pendek. Tapi pada umumnya lebih panjang. System
tetragonal juga memiliki sudut kristalografi α = β = γ = 90˚.
gambar sistem tetragonal
Sistem tetragonal dibagi menjadi 7 kelas:
Piramid
§Kelas :
ke-21
§Simetri : 4
§Elemen
Simetri : terdapat 1 sumbu putar empat
Bipiramid
§Kelas :
ke-23
§Simetri :
4/m
§Elemen
Simetri : terdapat 1 sumbu putar empat dan 1 bidang simetri
Bisfenoid
§Kelas :
ke-22
§ Simetri : 4bar
§ Elemen Simetri : terdapat 1 sumbu putar empat
Trapezohedral
§Kelas :
ke-26
§Simetri : 4
2 2
§Elemen
Simetri : terdapat 1 sumbu putar empat, 2 sumbu putar dua, semuanya berpotongan
tegak lurus ke sumbu putar lain.
Ditetragonal Piramid
§Kelas :
ke-25
§Simetri : 4
m m
§Elemen
Simetri : terdapat 1 sumbu putar empat dan 4 bidang simetri
Skalenohedral
§Kelas :
ke-24
§Simetri :
4bar 2 m
§Elemen
Simetri : terdapat 1 sumbu putar empat, 2 sumbu putar dua, dan 2 bidang simetri
Beberapa contoh mineral dengan sistem kristal Tetragonal ini
adalah rutil, autunite, pyrolusite, Leucite, scapolite (Pellant, Chris:
1992)
3.Sistem Hexagonal
Sistem hexagonal ini mempunyai 4 sumbu kristal, dimana sumbu c
tegak lurus terhadap ketiga sumbu lainnya. Sumbu a, b, dan d masing-masing
membentuk sudut 120˚ terhadap satu sama lain. Sumbu a, b, dan d memiliki
panjang sama. Sedangkan panjang c berbeda, dapat lebih panjang atau lebih
pendek (umumnya lebih panjang). System hexagonal memiliki sudut kristalografi α
= β = 90˚ ; γ = 120˚. Hal ini berarti, pada sistem ini, sudut α dan β saling
tegak lurus dan membentuk sudut 120˚ terhadap sumbu γ.
gambar sistem hexagonal
Sistem
ini dibagi menjadi 7:
Hexagonal Piramid
§Kelas :
ke-14
§Simetri : 6
§Elemen
Simetri : hanya terdapat 1 sumbu putar enam.
Hexagonal Bipramid
§Kelas : ke-16
§Simetri :
6/m
§Elemen
Simetri : terdapat 1 sumbu putar enam, 1 bidang simetri
Dihexagonal Piramid
§Kelas : ke-18
§Simetri : 6
m m
§Elemen
Simetri : terdapat 1 sumbu putar enam, 6 bidang simetri
Dihexagonal Bipiramid
§Kelas : ke-20
§Simetri :
6/m 2/m 2/m
§Elemen
Simetri : terdapat 1 sumbu putar enam, 6 sumbu putar dua, 7 bidang simetri
masing-masing berpotongan tegak lurus terhadap salah satu sumbu rotasi dan satu
pusat
Trigonal Bipiramid
§Kelas : ke-1
§Simetri :
6bar (ekuivalen dengan 6/m)
§Elemen
Simetri : terdapat 1 sumbu putar enam, 1 bidang simetri
Ditrigonal Bipiramid
§Kelas :
ke-17
§Simetri :
6bar 2m
§Elemen
Simetri : terdapat 1 sumbu putar enam, 3 sumbuputar dua, dan 4 bidang simetri
Hexagonal Trapezohedral
§Kelas : ke-19
§Simetri : 6
2 2
§Elemen
Simetri : terdapat 1 sumbu putar enam, 6 sumbu putar dua
Beberapa contoh mineral dengan sistem kristal Hexagonal ini
adalah quartz, corundum, hematite, calcite, dolomite, apatite. (Mondadori,
Arlondo. 1977).
4.Sistem Trigonal
Jika kita membaca beberapa referensi
luar, sistem ini mempunyai nama lain yaitu Rhombohedral, selain itu beberapa
ahli memasukkan sistem ini kedalam sistem kristal Hexagonal. Demikian pula cara
penggambarannya juga sama. Perbedaannya, bila pada sistem Trigonal setelah
terbentuk bidang dasar, yang terbentuk segienam, kemudian dibentuk segitiga
dengan menghubungkan dua titik sudut yang melewati satu titik sudutnya.
System Trigonal memiliki axial ratio
(perbandingan sumbu) a = b = d ≠ c , yang artinya panjang sumbu a sama dengan
sumbu b dan sama dengan sumbu d, tapi tidak sama dengan sumbu c. Dan juga
memiliki sudut kristalografi α = β = 90˚ ; γ = 120˚.
§Elemen
Simetri : ada 1 sumbu putar tiga dan 3 bidang simetri
Ditrigonal Skalenohedral
§Kelas : ke-13
§Simetri :
3bar 2/m
§Elemen
Simetri : ada 1 bidang putar tiga, 3 bidang putar dua, 3 bidang simetri
Rombohedral
Beberapa contoh mineral dengan
sistem kristal Trigonal ini adalah tourmaline dan cinabar
(Mondadori, Arlondo. 1977)
5.Sistem
Orthorhombik
Sistem ini disebut juga sistem
Rhombis dan mempunyai 3 sumbu simetri kristal yang saling tegak lurus satu
dengan yang lainnya. Ketiga sumbu tersebut mempunyai panjang yang berbeda.
Pada kondisi sebenarnya, sistem
kristal Orthorhombik memiliki axial ratio (perbandingan sumbu) a ≠ b ≠ c , sehingga
panjang sumbu-sumbunya tidak ada yang sama panjang atau berbeda satu sama lain.
Dan juga memiliki sudut kristalografi α = β = γ = 90˚. Hal ini berarti, pada
sistem ini, ketiga sudutnya saling tegak lurus (90˚).
Kesimetrisan dari sitem orthorombik
memiliki 3 elemen simetri seperti :
·3
bidang simetri : bidang-bidang sumbu
·3
sumbu simetri diagonal : sumbu-sumbu kristalografi pusat simetri
gambar sistem orthorombik
Sistem
ini dibagi menjadi 3 kelas:
Bisfenoid
§Kelas :
ke-7
§Simetri : 2
2 2
§Elemen
Simetri : ada 3 sumbu putar
Piramid
§Kelas : ke-6
§Simetri : 2 m
§Elemen Simetri : ada 1 sumbu putar dua dan 2 bidang
Bipiramid
§Kelas :
ke-8
§Simetri :
2/m 2/m 2/m
§Elemen
Simetri : ada 3 sumbu putar dua dengan sebuah bidang simetri yang berpotongan
tegak lurus dengan ketiga sumbu dan sebuah pusat.
ketiga sumbu dan sebuah pusat
Beberapa contoh mineral denga sistem
kristal Orthorhombik ini adalah stibnite, chrysoberyl, aragonite dan
witherite (Pellant, chris. 1992)
6.Sistem
Monoklin
Monoklin artinya hanya mempunyai
satu sumbu yang miring dari tiga sumbu yang dimilikinya. Sumbu a tegak lurus
terhadap sumbu n; n tegak lurus terhadap sumbu c, tetapi sumbu c tidak tegak
lurus terhadap sumbu a. Ketiga sumbu tersebut mempunyai panjang yang tidak
sama, umumnya sumbu c yang paling panjang dan sumbu b paling pendek. System
Monoklin memiliki axial ratio (perbandingan sumbu) a ≠ b ≠ cdan memiliki sudut kristalografi α = β = 90˚
≠ γ. Hal ini berarti, pada ancer ini, sudut α dan β saling tegak lurus (90˚),
sedangkan γ tidak tegak lurus (miring).
gmabar sistem monoklin
Sistem Monoklin dibagi menjadi 3
kelas:
·Sfenoid
§Kelas :
ke-4
§Simetri
: 2
§Elemen
Simetri : 1 sumbu putar
·Doma
§Kelas :
ke-3
§Simetri
: m
§Elemen
Simetri : 1 bidang simetri
·Prisma
§Kelas :
ke-5
§Simetri
: 2/m
§Elemen
Simetri : 1 sumbu putar dua dengan sebuah bidang simetri
yang berpotongan tegak lurus
Beberapa contoh mineral dengan ancer
kristal Monoklin ini adalah azurite, malachite, colemanite, gypsum,
dan epidot (Pellant, chris. 1992)
7.Sistem
Triklin
Sistem ini mempunyai 3 sumbu simetri
yang satu dengan yang lainnya tidak saling tegak lurus. Demikian juga panjang
masing-masing sumbu tidak sama. System kristal
Triklin memiliki axial ratio (perbandingan sumbu) a ≠ b ≠ c , yang artinya
panjang sumbu-sumbunya tidak ada yang sama panjang atau berbeda satu sama lain.
Dan juga memiliki sudut kristalografi α = β ≠ γ ≠ 90˚. Hal ini berarti, pada
system ini, sudut α, β dan γ tidak saling tegak lurus satu dengan yang lainnya.
gambar sistem triklin
Sistem
ini dibagi menjadi 2 kelas:
Pedial
§Kelas :
ke-1
§Simetri
: 1
§Elemen
Simetri : hanya sebuah pusat
Pinakoidal
§Kelas :
ke-2
§Simetri
: 1bar
§Elemen
Simetri : hanya sebuah pusat
Beberapa contoh mineral dengan ancer
kristal Triklin ini adalah albite, anorthite, labradorite, kaolinite,
microcline dan anortoclase (Pellant, chris. 1992).
