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The geology of Mississippi includes some deep igneous and metamorphic crystalline basement rocks from the Precambrian known only from boreholes in the north, as well as sedimentary sequences from the Paleozoic. The region long experienced shallow marine conditions during the tectonic evolutions of the Mesozoic and Cenozoic, as coastal plain sediments accumulated up to 45,000 feet thick, including limestone, dolomite, marl, anhydrite and sandstone layers, with some oil and gas occurrences and the remnants of Cretaceous volcanic activity in some locations. [1]
The Black Warrior Basin was the southern margin of the proto-North American continent Laurentia. Precambrian rocks have only been found in a few boreholes in the north of the state, including microperthite granite and a syenite sample dated to 785 million years ago in the Proterozoic. The oldest documented basement granites are 790 million years old while researchers Thomas and Osborne, in 1987 found gneiss up to 1.12 billion years old. [2]
During the Ordovician, the 650 foot thick Knox Dolomite, Stones River Group and Nashville Group sediments formed in the shallow marine platform environment of the Black Warrior Basin. Shale, limestone and undifferentiated sediments comprise the Wayne Group and Brownsport Formation from the Silurian, overlain by Devonian chert and the Chattanooga shale. Some Devonian rocks contain trilobite fossils. A number of different formations took shape during the Carboniferous, including the Floyd Shale, intermixed with several different sandstone layers and overlain by the Pottsville Formation. [3]
Shallow seas dropped between the Mississippian and Pennsylvanian around 330 million years ago. During the formation of the supercontinent Pangea, sediments in the Black Warrior Basin were uplifted and faulted as the region experienced dry, continental conditions.
The Mississippi Interior Salt Basin underlies southern and west-central Mississippi with up to 3000 feet of Late Jurassic salt and 50 shallow salt domes. It formed during the beginnings of the Gulf of Mexico during the breakup of Pangea. Triassic igneous sills injected into shales in the Black Warrior Basin during the rifting process.
Salt deposition ended by 150 million years ago. Mantle upwelling thinned the crust in the Jurassic. In Mississippi, the Smackover Limestone covered over earlier evaporite deposits.
A complex stratigraphic sequence formed during the Cretaceous, with the reef limestones, anhydrite and sandstones of the Rodessa Formation, Mooringsport Formation, Paluxy Formation, Gordo Formation and Coker Formation, overlain by the Eutaw Group, Austin Chalk, Selma Chalk and numerous thin marl, chalk and sandstone layers. [4]
The Richton Salt Dome was briefly famous in the early 1980s as a proposed site for US nuclear waste disposal. A volcano built the Jackson Dome, uplifting the Eutaw Formation on a 184 square mile island. Magma and thermal gas created halos in the Smackover Limestone, Norphlet Sandstone and Cotton Valley Group rich in hydrogen sulfide and carbon dioxide and over-pressurized gas is a risk in the poor quality gas fields on the southeastern side of Jackson Dome. The Midnight Volcano in southern Humphreys County is another buried volcanic feature from 75 million years ago in the Cretaceous. [5]
During the Cenozoic, the Mississippi Embayment was filled by large river and delta systems, depositing sediments reaching up to 45,000 feet thick beneath the Gulf Coastal Plain and 35,000 feet in the Terrebonne Trench, west of the Mississippi River. In the Paleocene, the Midway Group limestone, marl and sand lenses formed, followed by the Wilcox Group into the Eocene. Shale, sandstone and limestone typified the Eocene Claiborne Group and Jackson Group, with a greater presence of limestone in the Oligocene Vicksburg Group. Thicker units such as the Catahoula and Hattiesburg Formations formed in the Miocene, followed by the Pascagoula Formation, Graham Ferry Formation and Citronelle Formation into the Pliocene. Alluvium, sand, gravel, barrier islands and loess define most of the Quaternary deposition from the past 2.5 million years. [6]
Soils in Mississippi result from the weathering of bedrock, fine grained alluvial fill and loess (windblown glacial rock flour from the Mississippi River Alluvial Plain). The high fertility soils of the Loess Belt attracted many people to pursue plantation agriculture in the 1800s. Hardwood trees dominate in loess deposits north of Vicksburg, particularly sweet gum, basswood, water oak, cherrybark, poplar and bitternut. A few small prairies developed atop Cretaceous and Eocene chalk.
The state has up to 125,000 water wells, with the most significant pumping from the Mississippi River alluvial aquifer for agriculture. Analysis of 1369 water wells from 1989 to 2007 found only three wells with unsafe levels of pesticides and agricultural chemicals. The Miocene, Wilcox, Sparta, Lower Cretaceous and Tuscaloosa are the next most important aquifers after the Mississippi River aquifer. Historically, the thick Yazoo Clay made groundwater difficult to extract on the Jackson Prairie. [7]
The discovery of the Amory Gas Field in Monroe County in 1926 and Jackson Gas Field in 1929 propelled the state to become an oil and gas producer. Oil was first produced from the Tinsley Field from the Late Cretaceous and the state had already produced over one billion barrels by 1970. A few wells were drilled as much as 20,000 feet deep.
Aside from amateur collecting Mississippi does not have mineable mineral resources. [8]
The Perth Basin is a thick, elongated sedimentary basin in Western Australia. It lies beneath the Swan Coastal Plain west of the Darling Scarp, representing the western limit of the much older Yilgarn Craton, and extends further west offshore. Cities and towns including Perth, Busselton, Bunbury, Mandurah and Geraldton are built over the Perth Basin.
The Dallas–Fort Worth Metroplex sits above Cretaceous-age strata ranging from ≈145-66 Ma. These Cretaceous-aged sediments lie above the eroded Ouachita Mountains and the Fort Worth Basin, which was formed by the Ouachita Orogeny. Going from west to east in the DFW Metroplex and down towards the Gulf of Mexico, the strata get progressively younger. The Cretaceous sediments dip very gently to the east.
The geology of Kansas encompasses the geologic history and the presently exposed rock and soil. Rock that crops out in the US state of Kansas was formed during the Phanerozoic eon, which consists of three geologic eras: the Paleozoic, Mesozoic and Cenozoic. Paleozoic rocks at the surface in Kansas are primarily from the Mississippian, Pennsylvanian, and Permian periods.
The Santos Basin is an approximately 352,000 square kilometres (136,000 sq mi) large mostly offshore sedimentary basin. It is located in the south Atlantic Ocean, some 300 kilometres (190 mi) southeast of Santos, Brazil. The basin is one of the Brazilian basins to have resulted from the break-up of Gondwana since the Early Cretaceous, where a sequence of rift basins formed on both sides of the South Atlantic; the Pelotas, Santos, Campos and Espírito Santo Basins in Brazil, and the Namibia, Kwanza and Congo Basins in southwestern Africa.
The Aquitaine Basin is the second largest Mesozoic and Cenozoic sedimentary basin in France after the Paris Basin, occupying a large part of the country's southwestern quadrant. Its surface area covers 66,000 km2 onshore. It formed on Variscan basement which was peneplained during the Permian and then started subsiding in the early Triassic. The basement is covered in the Parentis Basin and in the Subpyrenean Basin—both sub-basins of the main Aquitaine Basin—by 11,000 m of sediment.
The Pyrenees are a 430-kilometre-long, roughly east–west striking, intracontinental mountain chain that divide France, Spain, and Andorra. The belt has an extended, polycyclic geological evolution dating back to the Precambrian. The chain's present configuration is due to the collision between the microcontinent Iberia and the southwestern promontory of the European Plate. The two continents were approaching each other since the onset of the Upper Cretaceous (Albian/Cenomanian) about 100 million years ago and were consequently colliding during the Paleogene (Eocene/Oligocene) 55 to 25 million years ago. After its uplift, the chain experienced intense erosion and isostatic readjustments. A cross-section through the chain shows an asymmetric flower-like structure with steeper dips on the French side. The Pyrenees are not solely the result of compressional forces, but also show an important sinistral shearing.
The geology of Lebanon remains poorly studied prior to the Jurassic. The country is heavily dominated by limestone, sandstone, other sedimentary rocks, and basalt, defined by its tectonic history. In Lebanon, 70% of exposed rocks are limestone karst.
The geology of Western Sahara includes rock units dating back to the Archean more than two billion years old, although deposits of phosphorus formed in the Mesozoic and Cenozoic have helped to prompt the current Moroccan occupation of most of the country.
The geology of Somalia is built on more than 700 million year old igneous and metamorphic crystalline basement rock, which outcrops at some places in northern Somalia. These ancient units are covered in thick layers of sedimentary rock formed in the last 200 million years and influenced by the rifting apart of the Somali Plate and the Arabian Plate. The geology of Somaliland, the de facto independent country recognized as part of Somalia, is to some degree better studied than that of Somalia as a whole. Instability related to the Somali Civil War and previous political upheaval has limited geologic research in places while heightening the importance of groundwater resources for vulnerable populations.
The geology of Somaliland is very closely related to the geology of Somalia. Somaliland is a de facto independent country within the boundaries that the international community recognizes as Somalia. Because it encompasses the former territory of British Somaliland, the region is historically better researched than former Italian Somaliland. Somaliland is built on more than 700 million year old igneous and metamorphic crystalline basement rock.. These ancient units are covered in thick layers of sedimentary rock formed in the last 200 million years and influenced by the rifting apart of the Somali Plate and the Arabian Plate.
The geology of Morocco formed beginning up to two billion years ago, in the Paleoproterozoic and potentially even earlier. It was affected by the Pan-African orogeny, although the later Hercynian orogeny produced fewer changes and left the Maseta Domain, a large area of remnant Paleozoic massifs. During the Paleozoic, extensive sedimentary deposits preserved marine fossils. Throughout the Mesozoic, the rifting apart of Pangaea to form the Atlantic Ocean created basins and fault blocks, which were blanketed in terrestrial and marine sediments—particularly as a major marine transgression flooded much of the region. In the Cenozoic, a microcontinent covered in sedimentary rocks from the Triassic and Cretaceous collided with northern Morocco, forming the Rif region. Morocco has extensive phosphate and salt reserves, as well as resources such as lead, zinc, copper and silver.
The geology of Nigeria formed beginning in the Archean and Proterozoic eons of the Precambrian. The country forms the Nigerian Province and more than half of its surface is igneous and metamorphic crystalline basement rock from the Precambrian. Between 2.9 billion and 500 million years ago, Nigeria was affected by three major orogeny mountain-building events and related igneous intrusions. Following the Pan-African orogeny, in the Cambrian at the time that multi-cellular life proliferated, Nigeria began to experience regional sedimentation and witnessed new igneous intrusions. By the Cretaceous period of the late Mesozoic, massive sedimentation was underway in different basins, due to a large marine transgression. By the Eocene, in the Cenozoic, the region returned to terrestrial conditions.
The geology of South Dakota began to form more than 2.5 billion years ago in the Archean eon of the Precambrian. Igneous crystalline basement rock continued to emplace through the Proterozoic, interspersed with sediments and volcanic materials. Large limestone and shale deposits formed during the Paleozoic, during prevalent shallow marine conditions, followed by red beds during terrestrial conditions in the Triassic. The Western Interior Seaway flooded the region, creating vast shale, chalk and coal beds in the Cretaceous as the Laramide orogeny began to form the Rocky Mountains. The Black Hills were uplifted in the early Cenozoic, followed by long-running periods of erosion, sediment deposition and volcanic ash fall, forming the Badlands and storing marine and mammal fossils. Much of the state's landscape was reworked during several phases of glaciation in the Pleistocene. South Dakota has extensive mineral resources in the Black Hills and some oil and gas extraction in the Williston Basin. The Homestake Mine, active until 2002, was a major gold mine that reached up to 8000 feet underground and is now used for dark matter and neutrino research.
The geology of Bosnia & Herzegovina is the study of rocks, minerals, water, landforms and geologic history in the country. The oldest rocks exposed at or near the surface date to the Paleozoic and the Precambrian geologic history of the region remains poorly understood. Complex assemblages of flysch, ophiolite, mélange and igneous plutons together with thick sedimentary units are a defining characteristic of the Dinaric Alps, also known as the Dinaride Mountains, which dominate much of the country's landscape.
The geology of Bahrain is poorly studied before the Cenozoic. Extensive sedimentary formations from the Eocene through recent times cover much of the island.
The geology of Utah, in the western United States, includes rocks formed at the edge of the proto-North American continent during the Precambrian. A shallow marine sedimentary environment covered the region for much of the Paleozoic and Mesozoic, followed by dryland conditions, volcanism, and the formation of the basin and range terrain in the Cenozoic.
The geology of North Dakota includes thick sequences oil and coal bearing sedimentary rocks formed in shallow seas in the Paleozoic and Mesozoic, as well as terrestrial deposits from the Cenozoic on top of ancient Precambrian crystalline basement rocks. The state has extensive oil and gas, sand and gravel, coal, groundwater and other natural resources.
The geology of Afghanistan includes nearly one billion year old rocks from the Precambrian. The region experienced widespread marine transgressions and deposition during the Paleozoic and Mesozoic, that continued into the Cenozoic with the uplift of the Hindu Kush mountains.
The geology of Israel includes igneous and metamorphic crystalline basement rocks from the Precambrian overlain by a lengthy sequence of sedimentary rocks extending up to the Pleistocene and overlain with alluvium, sand dunes and playa deposits.
The geology of Saudi Arabia includes Precambrian igneous and metamorphic basement rocks, exposed across much of the country. Thick sedimentary sequences from the Phanerozoic dominate much of the country's surface and host oil.