Classification Of Rocks PDF

CLASSIFICATION OF ROCKS EARTH SCIENCE CLASS https://www.learner.org/wp-content/interactive/roc kcycle/completecycle/  ROCKS a natural, solid, nonliving material made of one or more minerals.  MINERALS Minerals combine to form Rocks THREE TYPES OF ROCKS IGNEOUS ROCK THE...

CLASSIFICATION OF ROCKS EARTH SCIENCE CLASS https://www.learner.org/wp-content/interactive/roc kcycle/completecycle/  ROCKS a natural, solid, nonliving material made of one or more minerals.  MINERALS Minerals combine to form Rocks THREE TYPES OF ROCKS IGNEOUS ROCK THE WORD IGNEOUS IS DERIVED FROM A LATIN WORD THAT MEANS “FIRE” IGNEOUS ROCKS ARE FORMED WHEN MAGMA COOLS AND SOLIDIFIES THROUGH THE PROCESS OF Crystallization The size of the mineral crystals in the rock is affected by the time the magma or lava cools. MAIN CATEGORIES OF IGNEOUS ROCKS - Extrusive & Intrusive Extrusive rocks ( volcanic rock) are formed on the surface of the Earth from lava, which is magma that has emerged from underground The faster it cools the smaller the minerals are  Crystals inside solid volcanic rocks are small because they do not have much time to form until the rock cools all the way, which stops the crystal growth These fine-grained rocks are known as aphanitic —from a Greek word meaning “invisible.” Intrusive rocks(plutonic) are formed from magma that cools and solidifies within the crust of the planet  They have large crystals that are usually visible without a microscope. This surface is known as a phaneritic texture. Igneous rocks may be characterized by their texture and composition. Texture describes the overall appearance of the igneous rocks based on the size, shape, and arrangement of the interlocking crystals The rate of COOLING strongly influences CRYSTAL size. SLOW cooling of magma results in the formation of LARGE crystals. RAPID cooling results in the formation of SMALL crystals TYPES OF IGNEOUS ROCKS BASED ON TEXTURE  COARSE GRAINED OR PHANERITIC TEXTURE - Consists of large crystals that are clearly visible to the eye, with or without hand lens or microscope GRANITE GABBRO GRANITE DIORITE ORTT FINE – GRAINED or APHENITIC texture consists of SMALL crystals that cannot be seen by the eye, even with the aid of a hand lens BASALT  PORPHYRITIC rocks consists of two minerals having a large difference in grain size. The larger is called PHENOCRYST and the finer grain is called groundmass or matrix FELDSPAR WITH Porphyritic phonolite with large GRANITE DOLERITE phenocrysts of anorthoclase (pale colors) in a very fine-grained ENCLOSURES groundmass of sanidine and nepheline GLASSY- TEXTURED ( vitreous) rocks are noncrystalline and contain NO mineral grains OBSIDIAN Vesicular Texture -As magma rises up to the surface, it is subjected to decreasing pressure, allowing dissolved gases to come out of the solution forming gas bubbles. Types of Igneous Rocks Based on Chemical Composition  FELSIC - This term used to describe rocks with light color is a connotation of “fel”, which refers to feldspar of the potassium-rich variety , and “ sic”, which indicates a high percentage of Quartz: Quartz is another common mineral found in granite, accounting for up to 30% of the rock’s composition Feldspar: This is the most common mineral found in granite, accounting for up to 60% of the rock’s composition.  MAFIC iron - This term used to describe rocks that are usually dark in color is derived from “ma”, referring to magnesium , and “fic”, which is the Latin word for iron Basalt's overall composition is classified as mafic, meaning it's rich in magnesium (Mg) and iron (Fe)  ANDESITIC or Intermediate rocks - Contain a mixture of both light- dark-colored minerals, such as amphibole and plagioclase feldspar  ULTRAMAFIC - Rocks contain mostly dark-colored minerals such as olivine and pyroxene Peridotite, a type of ultramafic rock  Norman Bowen( 1887- 1956) - Investigated the crystallization of magma - - As magma cools, certain minerals crystallize first at a relatively high temperature, followed by BOWEN’S REACTION SERIES  Discontinuous Reaction Series - Series consists of olivine, pyroxene, amphibole, and biotite - - As you down the series, there is an increase in the proportion of SILICA - - the minerals on TOP contain HIGH amounts During the process of crystallization, the composition of the minerals CHANGES because of the depletion of some elements - In the discontinuous reaction series, the earlier-formed cyrstals react with the remaining magma in a series of discrete steps to produce a NEW mineral  CONTINUOUS REACTION SERIES - They are the plagioclase minerals - - at the highest temperature, the plagioclase minerals contain only CALCIUM - -at the lowest temperature, they contain only SODIUM  SEDIMENTARY ROCKS - are formed from pre-existing rocks or pieces of once-living organisms - -these are rocks that are formed at or near the surface SEDIMENTARY PROCESSES:  Weathering - The first step is transforming solid rock into smaller fragments  Erosion -begins the transportation process by moving the weathered products from their original location. Transportation - Sediment can be transported by sliding down slopes, being picked up by the wind, or by being carried by running water in streams, rivers, or ocean currents. Deposition - Sediment is deposited when the energy of the transporting medium becomes too low to continue the transport process  Lithification (Diagenesis) - Lithification is the process that turns sediment into rock. The first stage of the process is compaction. Compaction occurs as the weight of the overlying material increases. Compaction forces the grains closer together, reducing pore space and eliminating some of the contained water Compaction occurs as the weight of the overlying material increases. Compaction forces the grains closer together, reducing pore space and eliminating some of the contained water Compaction occurs as the weight of the overlying material increases. Compaction forces the grains closer together, reducing pore space and eliminating some of the contained water Compaction occurs as the weight of the overlying material increases. Compaction forces the grains closer together, reducing pore space and eliminating some of the contained water COMMON SEDIMENTARY FEATURES Stratification and Bedding 1. Cross Bedding - Sets of beds that are inclined relative to one another. The beds are inclined in the direction that the wind or water was moving at the time of deposition.  2.Graded Bedding - As current velocity decreases, first the larger or more dense particles are deposited followed by smaller particles. This results in bedding showing a decrease in grain size from the bottom of the bed to the top of the bed 3.Ripple Marks - Water flowing over loose sediment creates bedforms by moving sediment with the flow.  4.Mudcracks - result from the drying out of wet sediment at the surface of the Earth.  5.Fossils - Remains of once living organisms. Probably the most important indicator of the environment of deposition.  TYPES OF SEDIMENTARY NONCLASTI CLASTICROCKS C  CLASTIC - SEDIMENTARY grains, matrix and cement are - ROCKS the components of clastic clastic rocks are commonly rocks classified based on particle size  Non-clastic sedimentary rocks - evaporation and precipitation from solution or lithification of organic matter  -classified as evaporites (halite, gypsum and dolostone), precipitates (limestone) and bioclastics (coal, coquina. Evaporites: rocks formed from the evaporation of water leaving the dissolved minerals to crystallize Precipitates: rocks formed when minerals from a mineralsupersaturated waters start to crystallize at the bottom of the solution Bioclastic: r o c k forrmed from compacted organic matter conglomerate breccia claystone sandstone limestone coquina  METAMORPHIC ROCKS - formed below the surface of the earth through the process of metamorphism with the recrystallization of minerals in rocks due to changes in pressure and temperature conditions  CONTACT METAMORPHISM - heat and reactive fluids as main factors: occurs when a pre-existing rock gets in contact with magma which is the source of heat and magmatic fluids where metamorphic alterations and transformations occur around the contact ❑ creates non-foliated metamorphic rocks  REGIONAL METAMORPHISM - pressure as main factor - occurs in areas that have undergone considerable amount of mechanical deformation and chemical recrystallization during orogenic event which are commonly associated with mountain belts THANK YOU! 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