PENGELOMPOKAN BATUAN MENURUT PROSES PEMBENTUKANNYA (GROUPING ROCKS ACCORDING TO THEIR FORMATION PROCESS)


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(ENGLISH VERSION)



 

Tahukah kalian, Proses pembentukan batuan memerlukan waktu hingga jutaan tahun dan siklus batuan berawal dari terbentuknya batuan beku, pelapukan batuan beku, pergerakan batuan, sedimentasi, metamorfosis, dan pencairan magma kembali. Jenis- jenis batuan menurut proses pembentukannya meliputi batuan beku, batuan sedimen, dan batuan metamorf. Diantara ketiga jenis batuan tersebut batuan sedimen merupakan batuan yang paling banyak tersingkap di permukaan bumi, dengan jumlah kurang lebih 75% dari luas permukaan bumi.

Ketiga batuan tersebut dibagi lagi ke dalam beberapa sub jenis. Mulai dari batuan beku yang dibagi menjadi dua yaitu  batuan beku intrusif dan batuan beku ekstrusif. Batuan beku intrusif terbentuk dari pembekuan magma di dalam kerak bumi dan memerlukan waktu yang lama untuk mendingin dan mengeras. Contoh batuan beku intrusif antara lain granit dan diorit. Lalu, Batuan beku ekstrusif terbentuk dari pembekuan lava di atas permukaan bumi dan memerlukan waktu yang lebih singkat untuk mendingin dan mengeras. Contoh batuan beku ekstrusif antara lain basal dan andesit.

Lanjut, ke batuan sedimen. Batuan sedimen dibagi menjadi tiga jenis yaitu batuan sedimen klastik, batuan sedimen kimia, dan batuan sedimen organik. Batuan sedimen klastik terbentuk dari endapan bahan-bahan anorganik seperti pasir, lempung, dan kerikil. Bahan-bahan tersebut terendapkan dan mengalami proses pengendapan sehingga membentuk batuan sedimen klastik. Contoh batuan sedimen klastik antara lain breksi, konglomerat, batu pasir, lempung, serpih, dan kaolin. Sementara, batuan sedimen kimia terbentuk dari endapan bahan-bahan anorganik yang terbentuk melalui proses kimia seperti presipitasi, evaporasi, dan konsentrasi. Contoh batuan sedimen kimia antara lain batu kapur (gamping), gipsum, dan batu garam. Lalu, Batuan sedimen organik terbentuk dari sisa-sisa organisme seperti tumbuhan dan hewan yang mati. Sisa-sisa organisme tersebut terendapkan dan mengalami proses pengendapan sehingga membentuk batuan sedimen organik. Contoh batuan sedimen organik hanya satu jenis yaitu batu bara.

Terakhir, batuan metamorf atau batuan malihan dibagi menjadi tiga jenis yaitu batuan metamorf regional, batuan metamorf kontak, dan batuan metamorf dinamik. Batuan metamorf regional terbentuk akibat tekanan dan suhu yang tinggi akibat pergerakan lempeng tektonik. Batuan metamorf regional umumnya terbentuk di daerah pegunungan dan dapat membentuk lapisan batuan yang luas. Contoh batuan metamorf regional antara lain gneiss, schist, dan slate. 

Di sisi lain, Batuan metamorf kontak terbentuk akibat adanya suhu yang sangat tinggi akibat kontak dengan magma. Batuan metamorf kontak umumnya terbentuk di sekitar tubuh intrusi magma seperti batolit dan lakolit. Contoh batuan metamorf kontak antara lain marmer, hornfels, dan skarn. Kemudian, Batuan metamorf dinamik terbentuk akibat tekanan dan gesekan yang tinggi akibat pergerakan lempeng tektonik. Batuan metamorf dinamik umumnya terbentuk di daerah yang mengalami deformasi tektonik seperti zona sesar. Contoh batuan metamorf dinamik antara lain mylonite dan kataklasit.


(English Version)

GROUPING ROCKS ACCORDING TO THEIR FORMATION PROCESS

Did you know, the process of rock formation takes up to millions of years and the rock cycle starts from the formation of igneous rocks, igneous weathering, rock movement, sedimentation, metamorphosis, and magma melting again. types of rocks according to the formation process include igneous rocks, sedimentary rocks, and metamorphic rocks. Among the three types of rocks, sedimentary rocks are the most exposed rocks on the Earth's surface, with approximately 75% of the Earth's surface area.

The three rocks are further divided into several sub-types. Starting from igneous rocks which are divided into two, namely intrusive igneous rocks and extrusive igneous rocks. Intrusive igneous rocks are formed from the freezing of magma in the Earth's crust and take a long time to cool and solidify. Examples of intrusive igneous rocks include granite and diorite. Then, extrusive igneous rocks are formed from lava freezing above the Earth's surface and require a shorter time to cool and solidify. Examples of extrusive igneous rocks include basalt and andesite.

Next, to the sedimentary rocks. Sedimentary rocks are divided into three types, namely clastic sedimentary rocks, chemical sedimentary rocks, and organic sedimentary rocks. Clastic sedimentary rocks are formed from deposits of inorganic materials such as sand, clay, and gravel. The materials are deposited and undergo a deposition process to form clastic sedimentary rocks. Examples of clastic sedimentary rocks include breccia, conglomerate, sandstone, clay, shale, and kaolin. Meanwhile, chemical sedimentary rocks are formed from deposits of inorganic materials that are formed through chemical processes such as precipitation, evaporation, and concentration. Examples of chemical sedimentary rocks include limestone (limestone), gypsum, and salt rock. Then, organic sedimentary rocks are formed from the remains of organisms such as dead plants and animals. The remains of these organisms are deposited and undergo a deposition process to form organic sedimentary rocks. Examples of organic sedimentary rocks are only one type, namely coal.

Finally, metamorphic rocks or malihan rocks are divided into three types, namely regional metamorphic rocks, contact metamorphic rocks, and dynamic metamorphic rocks. Regional metamorphic rocks are formed as a result of high pressure and temperature due to the movement of tectonic plates. Regional metamorphic rocks generally form in mountainous areas and can form extensive rock layers. Contoh batuan metamorf regional antara lain gneiss, schist, dan slate.

On the other hand, contact metamorphic rocks are formed due to the presence of very high temperatures due to contact with magma. Contact metamorphic rocks generally form around magma intrusion bodies such as batolith and laccolite. Examples of contact metamorphic rocks include marble, hornfels, and skarn. Later, dynamic metamorphic rocks are formed as a result of high pressure and friction due to the movement of tectonic plates. Dynamic metamorphic rocks generally form in areas subject to tectonic deformation such as fault zones. Examples of dynamic metamorphic rocks include mylonite and cataclysmite. 


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