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	Aulacogen - Wikipedia, the free encyclopedia
		In geology, an aulacogen is a failed arm of a triple junction of a plate tectonics rift system.
		The resulting failed rift is called an aulacogen and becomes a filled graben within the continent and is a zone of structural weakness.
		The Mississippi embayment with the associated New Madrid Seismic Zone is an example of an ancient aulacogen that dates back to the breakup of the ancient continent Rodinia.
	en.wikipedia.org /wiki/Aulacogen (199 words)

	THE SOUTHERN OKLAHOMA AND DNIEPR-DONETS AULACOGENS: A COMPARATIVE ANALYSIS
		The classic failed continental rift or aulacogen is one that intersects a rifted continental margin at a high angle.
		Based on recent geological and geophysical studies, we have revisited a classic analogy that was drawn between two major intracratonic rifts, the Southern Oklahoma aulacogen in the southern portion of Laurentia and the Dniepr-Donets basin in the southern portion of Baltica.
		The Southern Oklahoma aulacogen (SOA), also known as the Wichita aulacogen, consists of a linear alignment of extensively inverted rift structures that begins at the rifted margin of Laurentia in northeast Texas and extends northwestward to New Mexico.
	gsa.confex.com /gsa/2004AM/finalprogram/abstract_77093.htm (537 words)

	CRSQ Abstracts, Volume 41, Number 2 (Site not responding. Last check: 2007-10-14)
		The basement in Oklahoma consists of igneous rocks, mostly granitic, whose surface is a profound erosional discontinuity overlain by marine sediments.
		Basement deforming tectonism was active in the southern part of the state forming the Southern Oklahoma Aulacogen, which is commonly interpreted as a Cambrian rift.
		The lithologic and erosional discontinuities that mark the transition from the igneous crust to overlying Paleozoic marine sediments probably represents the pre-Flood boundary, and the tectonism of the Southern Oklahoma Aulacogen may reject activity at the onset of the Flood in the southern midcontinent.
	www.creationresearch.org /crsq/abstracts/Abstracts41-2.htm (659 words)

	[No title]
		Wright and I have generated several new high precision U-Pb age dates of igneous activity associated with this rift that indicate large volumes (10,000's of km3) of felsic magmas invaded the crust in a relatively short time interval (Hogan et al., 1996; Deggeller et al., 1996).
		In addition, Dr. Willis E. Hames and I determined crystallization ages for gabbro from 40Ar/39Ar laser probe investigations of primary amphibole and biotite that demonstrate a close temporal relationship for mafic and felsic magmas (Hames et al., 1995).
		A Nd and Sr isotopic study (47 samples) of these rocks revealed that A-type rhyolites and granites of the Southern Oklahoma Aulacogen were derived from primitive mantle sources with little to no involvement of ancient continental crust.
	www.ou.edu /faculty/H/hogan/jhvita.htm (4408 words)

	Oilfield Glossary: Term 'aulacogen'
		At the junctions of tectonic plates, three intersecting lithospheric plates typically are separated by "arms." Arms might be areas of rifting, convergence or transform faults (similar to strike-slip faults).
		The arm along which the motion that spreads the plates apart ceases is termed the failed arm, or aulacogen.
		Spreading or rifting along the other arms of the triple junction can form new oceanic basins, whereas the aulacogen can become a sediment-filled graben.
	www.glossary.oilfield.slb.com /Display.cfm?Term=aulacogen (95 words)

	UNIT 4 THE LIVING MACHINE: (Site not responding. Last check: 2007-10-14)
		The rift zones show evidence of extension and crustal thinning, and with the introduction of plate tectonics, it was assumed that the Horn of Africa was in the early stages of splitting away from the rest of the continent, a continuation of the breakup of Gondwana.
		The rivers often flow down the failed rifts, the course of the Mississippi river flows down an aulacogen of the North America plate.
		This appears to have happened in the case of the Benue Trough, at the mouth of the Niger River in Nigeria.
	mac01.eps.pitt.edu /harbbook/c_iv/chapter_4b.htm (9193 words)

	[No title]
		The intrusive style of granites is determined by both mechanical and compositional effects (Hogan and Gilbert, in press).
		For example, in the Southern Oklahoma Aulacogen the unconformity between the underlying mafic layered complex and overlying rhyolite pile was activated as a CMT when the magma driving pressure exceeded the lithostatic load at the level of this crustal anisotropy.
		Under such conditions successive rising batches of magmas were stopped by this CMT and spread out to crystallize as sheet granites at the base of the volcanic pile rather than continuing to the surface to erupt as rhyolite.
	www.ou.edu /faculty/H/hogan/research.htm (2129 words)

	USGS Open File Report 99-50G Timan-Pechora Basin - Reservoir Properties
		Upper Devonian reservoirs are all sandstone on the westernmost edge of the province, mostly carbonate in the eastern region, and mixed carbonate and siliciclastic across most of the Izhma-Pechora Depression and Pechora-Kolva Aulacogen.
		Youngest Upper Permian and Triassic reservoirs (all sandstone and averaging 7 to 9 meters net thickness) are located on anticlines of the northern Pechora-Kolva Aulacogen, the northern Sorokin Swell and offshore on Kolguyev Island (Figure 1).
		Timan-Pechora siliciclastic reservoirs average 16% porosity and 154 md permeability, and carbonate reservoirs average 13% porosity and 208 md permeability (Petroconsultants, 1996) (Table 2).
	geology.cr.usgs.gov /energy/WorldEnergy/OF99-50G/rpropert.html (768 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		Rifting processes in the Pripyat-Donets aulacogen were significantly influenced by tangential stresses from the mobile frame of the platform.
		At the early stage of the Hercynian these caused the initial break of the Earth▓s crust along an old transcontinental fault zone and the subsequent rise of an asthenolith and, at the final stage, influenced markedly the duration and number of stages of rifting processes in the Pripyat and Dnieper parts of the aulacogen.
		In accordance with the ideas of deep dynamics of continental rifting, the late rifting stage genetically associated with the mantle diapir degradation has been distinguished and substantiated, besides the early and main phases of the rifting basin evolution.
	www.igs.ac.by /lithosphere/2003.no19/l19-e1.html (180 words)

	Vilyuy maps (Site not responding. Last check: 2007-10-14)
		The map shows the edges of the Vilyuy Aulacogen in the high-frequency anomalies in the southeast corner of the map and along the north-central edge.
		Southwest of the area of this map, the magnetic data clearly show the Devonian dike swarms associated with the opening of the aulacogen.
		The low-intensity, high-frequency anomalies in the northeast corner are probably thrusted volcaniclastics in the Cretaceous Verkhoyansk Fold Belt, which impinges on the east side of the East Siberian Craton.
	www.gravmag.com /vilyugif.html (97 words)

	Aulacogen (Site not responding. Last check: 2007-10-14)
		, an aulacogen is a failed arm of a triple junction
		A triple junction is the point where the boundaries between three tectonic plates, and three plate margins, meet.
		Two of these evolve to the point of seafloor spreading, while the third ultimately fails, becoming an aulacogen.
	ba08216f13dd1742157412386eee1225.yo.ogarnij.pl /en/aulacogen (10925 words)

	Litasfera (Lithosphere), 2002, No.1(16) (Site not responding. Last check: 2007-10-14)
		The fragments of this formation are preserved in the Orsha depression, Moscow graben and Pachelma aulacogen.
		In the Pachelma aulacogen the Lower-Baikalian structural complex is divided into two formations which vertically replace one another.
		There is some similarity in the structure and rock composition of the Lower-Baikalian deposits of the Pachelma aulacogen and Volyn-Centralrussian depression system.
	www.ac.by /publications/litho/litho16.html (3176 words)

	USGS Open File Report 99-50G Timan-Pechora Basin - Thermal Maturity
		The primary Domanik source rock is thermally mature in most of the Timan-Pechora Basin Province (Figure 5 and Figure 6), but there is considerable disagreement as to exactly when thermal maturity was first reached in different parts of the province.
		Structural inversion on the margins of the Pechora-Kolva and Varandey-Adzva Aulacogens began by middle Carboniferous time and continued intermittently throughout the Hercynian and Early Cimmerian orogenies.
		The Pechora-Kolva Aulacogen is also prospective where it projects southeastward under the Uralian foredeep.
	geology.cr.usgs.gov /energy/WorldEnergy/OF99-50G/thermal.html (745 words)

	Charles Gilbert (Site not responding. Last check: 2007-10-14)
		Combining information on mineral chemistry with order of crystallization leads to models of low pressure (shallow depth) crystallization at high temperatures under relatively dry conditions for many granite bodies emplaced in extensional terranes.
		The granite bodies of some rift zones, such as the Southern Oklahoma Aulacogen (SOA), appear to have the shape of sheets rather than the bulbous forms associated with compressional orogenic belts such as the Sierra Nevada.
		Applying the concepts of crustal magma traps to the geometry of the crustal column and of magma driving pressure rationalizes the geometries of the intrusive bodies in extension setings.
	geology.ou.edu /gilbert.html (766 words)

	Triple junction - Wikipedia, the free encyclopedia
		These three divergent boundaries ideally meet at near 120° angles.
		In plate tectonics theory during the breakup of a continent, one of the divergent plate boundaries would fail (see aulacogen) and the other two would continue spreading to form an ocean.
		The opening of the south Atlantic Ocean began with a triple junction in the present Gulf of Guinea.
	en.wikipedia.org /wiki/Triple_junction (644 words)

	Integrated geophysical studies of continental rifts in West Texas and New Mexico.
		The Rio Grande rift study focused on the structure of the rift in south-central New Mexico.
		The Pecos mafic intrusive suite is represented by a series of layered mafic intrusions in the basement under the Central basin platform and Roosevelt uplift in the Permian basin.
		Paired gravity and magnetic maxima indicate that the intrusion may be composed of four large intrusive centers which extend north under the rest of the Central basin platform and Roosevelt uplift covering a minimum area of 9200 km$\sp2$.
	digitalcommons.utep.edu /dissertations/AAI9536831 (523 words)

	THE CLASSIC SOUTHERN OKLAHOMA AND DNIEPR-DONETS AULACOGEN ANALOGY REVISITED
		Long before the advent of plate tectonics, rift structures in the Wichita uplift region of southern Oklahoma and the Dniepr-Donets basin in Ukraine were interpreted as being analogous.
		In a plate tectonics framework, the southern Oklahoma aulacogen is a classic failed continental rift or aulacogen.
		Based on recent geological and geophysical studies, we have revisited a classic analogy that was drawn between these two major intracratonic rifts.
	gsa.confex.com /gsa/2005SC/finalprogram/abstract_84032.htm (560 words)

	Crystalline basement hydrocarbons - Dniper-Donets Depression
		Actually the Dniper-Donets Aulacogen (Oil-And-Gas-Bearing Province) consists of Central Trough (Dniper-Donets Paleorift), Southern and Northern Shoulders.
		Block Tectonics of the crystalline basement of the Dnieper-Donets Aulacogen (in relation to oil and gas prospecting).
		Anyway, the natural records available exactly suggest for the existence of two type of the fissures in the crystalline basement rocks, and the subhorizontal cracks in the drill cores are always more open and permeable than the subvertical, commonly sealed to veins, fractures.
	www.geofuel.lviv.net /PETGF/MATLAS/polta.htm (2636 words)

	Dr. Nowell Donovan
		1988 Donovan, R.N., The Southern Oklahoma Aulacogen: a study in inheritance.
		1989 Donovan, R.N., A view of the Arbuckle Mountains as the northeastern margin of the Southern Oklahoma Aulacogen.
		1986 Donovan, R.N., Lower Paleozoic sedimentation in the southern Oklahoma aulacogen; Geological Society America, National Meeting, San Antonio, Texas (Invited paper for symposium on the southern margin of the North American Craton).
	geowww.geo.tcu.edu /faculty/donovan/publications.html (7245 words)

	Volcanoes Threaten To Divide Africa (Site not responding. Last check: 2007-10-14)
		"aulacogene: A tectonic trough on a craton, bounded by convergent normal faults.
		Aulacogenes have a radial orentation relative to craton and are open.
		Cf: graben, rift." Generally considered to be the failed third arm of a triple junction.
	www.freerepublic.com /focus/f-news/630340/posts (1783 words)

	SEMP -
		The theory of plate tectonics initially stemmed from observations of the shapes of the continents, particularly South America and Africa, which fit together like pieces in a jigsaw puzzle and have similar rocks and fossils despite being separated by a modern ocean.
		Rifting of tectonic plates may result in the formation of “triple junctions” and “aulacogens”.
		Rather it was a “failed arm” or aulacogen that filled with sediment whenever it was in a sinking phase.
	www.semp.us /biots/biot_328.html (2189 words)

	August 1998 BAGS Seminar (Site not responding. Last check: 2007-10-14)
		In the southeast, the Precambrian continental crust (the Yangtze-Cathaysian craton) did not grow considerably during Paleozoic.
		The so-called Huanan Caledonides between Yangtze and Cathaysian massives is nothing but an early Paleozoic aulacogen.
		The northeastern extension of this aulacogen in Korean peninsula is the Ogchean belt between Gyeonggi massif in the northwest and Ryeongnam massif in the southeast.
	sepwww.stanford.edu /bags/Talks/1998/9808chang.html (642 words)

	MMRI Remote Sensing - Geospatial Projects (Site not responding. Last check: 2007-10-14)
		Projects continue to focus primarily on north Mississippi and have yielded a better understanding of the surface geology, regional structural architecture, tectonics, and earthquake hazard potential.
		In turn, petroleum exploration has benefited from a refined model of the fault systems associated with the Black Warrior Basin and Reelfoot Aulacogen.
		Tectonic Model for the Structural Architecture of North Mississippi - The regional composite structural architecture for north Mississippi, as interpolated using existing public and private geologic data, provides a cursory basis for understanding regional structure and fault systems, tectonics, and seismicity associated with the evolution of the Reelfoot Aulacogen and Black Warrior Basin.
	www.olemiss.edu /depts/mmri/programs/gis_rs.html (181 words)

	Cordillera Ibérica
		A geotectonic model for the alpine evolution of the Iberian Chain was proposed by Alvaro, Capote and Vegas (1978) and modified by Salas and Casas (1993).
		Its particular location between the Pyrenean and Betic active margins determined that the aulacogen was compressed in two main directions (SE-NW to ESE-WSW and NNE-SSW, parallel and orthogonal to the aulacogen, respectively).
		During the Neogene the situation of the southeastern Iberian Chain changes as a consequence of the opening of the Valencia Trough.
	wzar.unizar.es /acad/fac/geoestruc/research/iber.html (458 words)

	Field Trip itinerary:
		The Timbered Hills, having the highest relief in the Arbuckles, are held up by basement rocks of the Colbert Rhyolite (Cambrian).
		Examine Rhyolite, and diabase dikes (bimodal syn-rift volcanism), Examine Reagan Sandstone (Cambrian) representing initial transgression of seas into Southern Oklahoma Aulacogen.
		Examination of Tishomingo Granite; Precambrian basement of craton (outside of Oklahoma Aulacogen).
	www.uwosh.edu /faculty_staff/lehrmann/OKitinerary.htm (933 words)

	37
		The Southern Oklahoma Aulacogen: an Example of Rapid Crustal Growth During Extension
		The Cambrian Southern Oklahoma Aulacogen (SOA) is one of several rifts that formed along eastern North America during breakup of the Laurentian supercontinent.
		Associated igneous rocks include: 1) an extensive layered anorthositic gabbro complex, 2) voluminous A-type rhyolite, 3) A-type sheet granites, 4) biotite-bearing gabbro plutons, and 5) late diabase dikes.
	www.the-conference.com /JConfAbs/2/37.html (565 words)

	Petro97 field trip (Site not responding. Last check: 2007-10-14)
		Rifting of that continent to form an ocean basin occurred in the latest Precambrian through middle Cambrian.
		Part of the rifting system included an aulacogen (a failed rift arm) called the Southern Oklahoma Aulacogen.
		In that aulacogen the rifting process included intrusion of a series of mafic igneous rocks including the Glen Mountains layered complex (GMLC).
	www.atu.edu /acad/mining/people/misk/petro97.htm (3818 words)

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