Lithological redirects here.
Petrology (from Greek: πέτρα, petra, rock; and λόγος, logos, knowledge) is a field of geology that focuses on the study of rocks and the conditions on which they form. Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere The word lithology once was approximately synonymous with petrography, but today lithology is essentially a subdivision of petrology focusing on macroscopic hand-sample or outcrop-scale description of rocks. Petrography is that branch of Petrology which focuses on detailed descriptions of rocks.
Lithology as it is called in the oil industry, more specifically mud logging, is the graphic representation of geological formations being drilled through, and drawn on a log called a mud log. The petroleum industry includes the global processes of exploration, extraction, refining, transporting (often by Oil tankers and pipelines Mud logging, also known as hydrocarbon well logging is a type of borehole logging performed by the Mud logger, that provides well owners with information about the Lithology A Mud log is a graphical representation of the ROP ( R ate O f P enetration Lithology, Hydrocarbons and other drilling parameters As the cuttings are circulated out of the hole they are sampled, examined (normally under a 10x microscope) and tested chemically when needed.
There are three branches of petrology, corresponding to the three types of rocks: igneous, metamorphic, and sedimentary. Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock)
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Methodology
Petrology utilizes the classical fields of mineralogy, petrography, optical mineralogy, and chemical analyses to describe the composition and texture of rocks. Mineralogy is an Earth Science focused around the Chemistry, Crystal structure, and physical (including optical) properties of Minerals Petrography is that branch of Petrology which focuses on detailed descriptions of rocks. Optical mineralogy is the study of Minerals by measuring their optical properties Modern petrologists also include the principles of geochemistry and geophysics through the studies of geochemical trends and cycles and the use of thermodynamic data and experiments to better understand the origins of rocks. The field of geochemistry involves study of the chemical composition of the Earth and other Planets chemical processes and reactions that govern the composition Geophysics, a major discipline of Earth sciences, is the study of the Earth by quantitative physical methods especially by seismic, electromagnetic In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning "
Branches of petrology
- Igneous petrology focuses on the composition and texture of igneous rocks (rocks such as granite or basalt which have crystallized from molten rock or magma). Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet Igneous rocks include volcanic and plutonic rocks. Plate tectonics and hotspots Divergent plate boundaries At the In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth.
- Sedimentary petrology focuses on the composition and texture of sedimentary rocks (rocks such as sandstone, shale, or limestone which consist of pieces or particles derived from other rocks or biological or chemical deposits, and are usually bound together in a matrix of finer material). Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Sandstone is a Sedimentary rock composed mainly of Sand -size Mineral or rock grains. Shale (also called mudstone) is a fine-grained Sedimentary rock whose original constituents were Clay minerals or Muds It is characterized by Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 The matrix or groundmass of rock is the fine-grained mass of material in which larger grains or Crystals are embedded
- Metamorphic petrology focuses on the composition and texture of metamorphic rocks (rocks such as slate, marble, gneiss, or schist which started out as sedimentary or igneous rocks but which have undergone chemical, mineralogical or textural changes due to extremes of pressure, temperature or both)
- Experimental petrology employs high-pressure, high-temperature apparatus to investigate the geochemistry and phase relations of natural or synthetic materials at elevated pressures and temperatures. Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change Slate is a fine-grained foliated homogeneous, Metamorphic rock derived from an original Shale -type Sedimentary rock composed of Clay Marble is a nonfoliated Metamorphic rock resulting from the Metamorphism of Limestone, composed mostly of Calcite (a crystalline form of Gneiss (ˈnaɪs is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally The schists form a group of medium-grade Metamorphic rocks chiefly notable for the preponderance of lamellar Minerals such as Micas chlorite In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties Experiments are particularly useful for investigating rocks of the lower crust and upper mantle that rarely survive the journey to the surface in pristine condition. In Geology, a crust is the outermost solid shell of a planet or moon The mantle is a part of an Astronomical object. The interior of the Earth, similar to the other Terrestrial planets, is Chemically divided The work of experimental petrologists has laid a foundation on which modern understanding of igneous and metamorphic processes has been built.
Terminology
- Acid test - using acid to test rock or soil for carbonates
- Suite - a collection of rock specimens from a given area, or it can refer to the succession of closely associated sedimentary strata or layers, especially a repeated sequence of layers.
References
- Bayly, M. Brian (1968) Introduction to petrology Prentice-Hall, Englewood Cliffs, NJ;
- Blatt, Harvey and Tracy, Robert J. (1996) Petrology: igneous, sedimentary, and metamorphic W. H. Freeman, New York, ISBN 0716724383 ;
- Dietrich, Richard Vincent and Skinner, Brian J. (1979) Rocks and rock minerals Wiley, New York, ISBN 0471029343 ;
- Fei, Yingwei; Bertka, Constance M. and Mysen, Bjorn O. (eds. ) (1999) Mantle petrology: field observations and high-pressure experimentation The Geochemical Society, Houston, TX, ISBN 0941809056 ;
- Stanton, R. L. (1972) Ore petrology McGraw-Hill, New York, ISBN 0070608431 ;
See also
External links
- Atlas of Igneous and metamorphic rocks, minerals, and textures Geology Department, University of North Carolina;
- Metamorphic Petrology Database (MetPetDB) Department of Geology and Geophysics, Louisiana State University;
- Petrological Database of the Ocean Floor (PETDB) Center for International Earth Science Information Network (CIESIN), Columbia University;
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