Integrated geophysical and geological study of the tectonic framework of the 38th parallel lineament in the vicinity of its intersection with the extension of the New Madrid fault zone. Annual progress report, fiscal year 1979
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An integrated gravity, magnetic, crustal seismic refraction, and basement geology study is being conducted of the northeastern extension of the New Madrid Fault Zone in the vicinity of the 38th Parallel Lineament. Gravity and magnetic anomaly maps prepared of this area plus regional seismicity suggest that the basement structural feature associated with the New Madrid seismicity extends northeasterly into southern Indiana to at least 39/sup 0/N latitude. Gravity and subsurface data indicate that the Rough Creek Fault Zone, a major element of the 38th Parallel Lineament, is the northern boundary of a complex graben which formed in late Precambrian-early Paleozoic time and since has been reactivated. Surface wave studies indicate that the crustal thickness of the northern Mississippi Embayment is probably in the range of 50 to 55 km, and the structure of the crust obtained from these studies is highly suggestive of a failed rift. 40 figures, 3 tables.Keywords:
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Digital free air and Bouguer gravity anomaly images have been constructed from approximately 287,000 station readings for the region bordered by 25°–49°N latitude and 80°–110°W longitude. The technique used to interpolate between station locations was based on a two‐dimensional spatial filter, where the average of the anomaly values located within the filter area was computed. The images contain as many as 256 contours (values in byte variable), so that subtle anomaly patterns can be identified and traced with much greater certainty than on most contour maps. A newly discovered feature in the midcontinent is a gravity low that begins at a break in the midcontinent gravity high in SE Nebraska, extends across Missouri in a NW‐SE direction, and intersects the Mississippi Valley graben to form the Pascola arch. The anomaly varies from 120 to 160 km in width, extends about 700 km, and is best expressed in southern Missouri, where it has a Bouguer amplitude of approximately −34 mGal. The magnitude of the anomaly cannot be explained on the basis of a thickened section of Paleozoic sedimentary rock. The gravity data and the sparse seismic refraction data for the region are consistent with an increased crustal thickness beneath the gravity low. Some of the discrete positive magnetic anomalies in Missouri are located along the borders of the gravity low. Digitally enhanced thermal infrared images from the Heat Capacity Mapping Mission show a distinct alignment of linear structures with the gravity feature. The linear features in some cases correspond to mapped high‐angle normal faults, to drape folds over relief within the Precambrian basement, and in some cases to extensions of mapped structures. The gravity anomaly also cuts across the major Precambrian boundary in SE Missouri, marking the change from older, sheared granites and metasedimentary rocks to younger granites and rhyolites. Given the cumulative evidence, the gravity anomaly is probably the present expression of a failed arm of a rifting event, perhaps one associated with the spreading that led to or preceded formation of the granite and rhyolite terrain of southern Missouri.
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A gravity data base from more than 35,000 stations was used to generate a series of regional gravity maps of the Ouachita Mountains area including adjacent parts of the craton and the Gulf coastal plain. These maps were used in conjunction with information from 96 wells, data from pre-existing geophysical and geological investigations, and computer models to interpret four gravity profiles that transect the study area (approximately lat. 30-37°N, long. 91.5-99°W). These models, gravity maps, and previous investigations were then used to analyzed various regional gravity anomalies and to interpret the gross crustal structure of the region and its tectonic implications. These data suggest that variably attenuated continental crust lies beneath the Gulf coastal plain, south of the Ouachita system gravity gradient, as opposed to typical continental crust of the craton north of this gradient. This variation in crustal structure probably reflects the complexity of Eocambrian and early Mesozoic rifting in the area. The Arkoma basin gravity minima may result from the combined effect of a late Paleozoic foreland basin and an Eocambrian northwest-trending, rift-related basin. The Ouachita system interior zone gravity maximum varies along strike of this orogenic belt. This anomaly appears to be a good indicator of the position of the Eocambrian continental margin and associated rift zone. Gravity anomalies in the Gulf coastal plain appear to be a combined e fect of variable crustal attenuation, basins and uplifts, and mafic intrusions. Gravity maxima in the southern Oklahoma aulacogen result from uplifts and deep-seated mafic intrusions; gravity minima result from deep sedimentary basins.
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This paper presents a joint interpretation of aerial survey data from gravimetry and magnetometry, 2D seismic data and terrestrial gravity data in order to examine the stratigraphic framework and configuration of the basement in the central-eastern Parnaiba Basin in region of Transbrasiliano Lineament north-northeast of Brazil. The main objective of this study is to map the architecture and composition of the basement, the structural, stratigraphic and volcanic rocks, in order to characterize the hydrocarbon prospectivity. The Transbrasiliano Lineament (LTB) is a suture zone of NNE-SSW direction, which reaches 100 km wide, featuring behind the geophysical constrain Parnaiba Basin resulting on zones of crustal weakness reactivated since the Precambrian. The tectonic movement in LTB reflects the evolution of Paleozoic and Mesozoic sedimentary basins along its length. Fairhead et al., 2007, based on aeromagnetic data from Brazil and Northern Africa, considers the LTB as part of the crustal lineament Argentina - Brazil - Algeria (ABA). The workflow includes integrated interpretation of 2D seismic, gravity data and detailed land-scale aerial survey data covering gravimetric and magnetometric methods with imaging and filtering; solutions depth of magnetic basement using Werner deconvolution, Euler technique and half slope of Peters; 2D seismic time and sections depth in the initial links with gravity and magnetic modeling.
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The boundary zone between the Churchill and Superior geological provinces was investigated by a 35-km-long seismic survey in an area where this zone is covered with 1.4 km of phanerozoic sedimentary rocks. The seismic reflection profile revealed a fault zone, which indicates that the boundary zone was tectonically active as late as Cretaceous time. Such late activity was not observed in areas where the boundary is exposed in the Precambrian shield. The present investigation shows that the central portion of this zone is associated with salt solution features in the sedimentary section and with topographic anomalies on the crystalline basement surface. The seismic section revealed that major intrusions and fracture zones formed the upper 13 km of the crystalline crust. A simple model study of the related gravity anomalies also exhibited anomalous bodies in the same zone.
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Research Article| September 01, 2002 Near-surface Faulting and Deformation Overlying the Commerce Geophysical Lineament in Southern Illinois J. K. Odum; J. K. Odum U.S. Geological Survey, Box 25046, MS-966 Denver Federal Center Denver, CO 80225 (J.K.O., W.J.S., R.A.W.) Search for other works by this author on: GSW Google Scholar W. J. Stephenson; W. J. Stephenson U.S. Geological Survey, Box 25046, MS-966 Denver Federal Center Denver, CO 80225 (J.K.O., W.J.S., R.A.W.) Search for other works by this author on: GSW Google Scholar R. A. Williams; R. A. Williams U.S. Geological Survey, Box 25046, MS-966 Denver Federal Center Denver, CO 80225 (J.K.O., W.J.S., R.A.W.) Search for other works by this author on: GSW Google Scholar J. A. Devera; J. A. Devera Illinois State Geological Survey Natural Resources Building 615 East Peabody Drive Champaign, IL 61820-6964 (J.A.D.) Search for other works by this author on: GSW Google Scholar J. R. Staub J. R. Staub Department of Geology Southern Illinois University Carbondale, IL 62901-4324 (J.R.S.) Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2002) 73 (5): 687–697. https://doi.org/10.1785/gssrl.73.5.687 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation J. K. Odum, W. J. Stephenson, R. A. Williams, J. A. Devera, J. R. Staub; Near-surface Faulting and Deformation Overlying the Commerce Geophysical Lineament in Southern Illinois. Seismological Research Letters 2002;; 73 (5): 687–697. doi: https://doi.org/10.1785/gssrl.73.5.687 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search nav search search input Search input auto suggest search filter All ContentBy SocietySeismological Research Letters Search Advanced Search Abstract Over the last decade, several investigations have demonstrated a plausible link between surface and near-surface tectonic features and the vertical projection of the Commerce geophysical lineament (CGL), a 5- to 10-km-wide basement magnetic anomaly longer than 600+ km that extends from Arkansas through southeast Missouri and southern Illinois and into Indiana. Structural features interpreted from the Tamms, Illinois high-resolution seismic-reflection survey and supporting microgravity data correlate with anomalous changes in drainage patterns, strikingly linear topographic bluff-front scarps, and the complex faulting and folding of Paleozoic rock.Post-Devonian displacement associated with the CGL is clearly identified in the Tamms area of southern Illinois. Several imaged faults are traceable to the Paleozoic/Quaternary interface, and, at one site, deformed Quaternary strata may have been faulted upward 5 to 10 m. Based upon the seismic-reflection and microgravity data provided within this paper, we believe that faults associated with the CGL need to be investigated further to determine their potential as hazardous seismic sources outside of the main zones of New Madrid seismicity. You do not currently have access to this article.
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Integrated Geophysical and Geologic Study of Deep Structure and Tectonics of Permian Basin: ABSTRACT
An integrated geophysical and geological study of the deep basement structure and tectonics of the Permian basin of west Texas and southeastern New Mexico was made using gravity, magnetic, and subsurface data. Over 6,000 gravity and 13,000 magnetic readings from different sources were used to construct gravity and magnetic maps of the area. The Central Basin platform is reflected by prominent positive Bouguer gravity and magnetic anomalies. However, both the gravity and magnetic maps show an east-west trending saddle in the Central Basin platform region which must be due to a deep-seated intrabasement structure. The West Platform fault zone which separates the Central Basin platform from the Delaware basin is reflected by a steep gravity gradient. By combining gravity and abundant well data in two-dimensional computer modeling, earth models were derived for two profiles crossing the area. These earth models show that the gravity relief between the Central Basin platform and the Delaware basin is far too large (±40 mgal) to be explained simply by the thickness of the sedimentary section of the Delaware basin. These models indicate a deficiency of mass in the basement underlying End_Page 763------------------------------ the Delaware basin or an excess of mass under the Central Basin platform. The West Platform fault zone is basement controlled. The seismic activity recently recorded in the area may be related to these deep-seated basement structures. The geophysical and geologic similarities between the southern Oklahoma aulacogen and the Permian basin suggest that the latter may be related to a late Precambrian aulacogen. End_of_Article - Last_Page 764------------
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The Jemez lineament (N52/sup 0/E) is one of several northeast-trending lineaments that traverse the southwestern United States. It is defined by a 500-km-long alignment of late Cenozoic volcanic fields extending southwest from at least the Jemez Mountains in the north-central New Mexico to the San Carlos-Peridot volcanic field in east-central Arizona. Geochronologic data from Precambrian basement rocks indicate that the lineament is approximately coincident with a boundary between Precambrian crustal provinces. Characteristics of the lineament are high heat flow (>104.5 mW/m/sup 2/), an attenuated seismic velocity zone from 25 to 140 km depth, and an upwarp of the crustal electrical conductor inferred from magnetotelluric studies. The high electrical conductivity is probably caused by the presence of interstitial magma in the rocks of the mid-to-upper crust. The average electical strike within the Precambrian basement is N60/sup 0/E, supporting a relationship between the Precambrian structural grain and the Jemez lineament. The geological and geophysical data suggest that the lineament is a structural zone that extends deep into the lithosphere and that its location was controlled by an ancient zone of weakness in the Precambrian basement. Ages of late Cenozoic volcanic rocks along the lineament show no systematic geographic progression, thus indicating thatmore » a mantle plume was not responsible for the alignment of the volcanic fields.Most of the faults, dikes, and cinder cone alignments along the lineament trend approximately N25/sup 0/E and N5/sup 0/W. These trends may represent Riedel shears formed by left-lateral transcurrent movement along the structure. Less common trends of cinder cone alignments and dikes are approximately N65/sup 0/W and N85/sup 0/W. The diversity in orientation indicates that the magnitudes of the two horizontal principal stresses within the lineament have been approximately equal for at least the last 5 m.y.« less
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