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Geophysical characterization of bottom simulating reflectors in the Fairway Basin (off New Caledonia, Southwest Pacific), based on high resolution seismic profiles and heat flow data ArchiMer
Nouze, Herve; Cosquer, Emmanuel; Collot, Julien; Foucher, Jean-paul; Klingelhoefer, Frauke; Lafoy, Yves; Geli, Louis.
High-resolution reflection and refraction seismic data were collected in 2004 to investigate, in further detail than allowed by pre-existing low resolution seismic data, the nature of a Bottom Simulating Reflector (BSR) that extends over a broad area of the Fairway Basin, a rifted, continental structure located on the eastern flank of the Lord Howe Rise, to the southwest of New Caledonia. Two main reflectors are documented: the shallower (RN) mimics the seafloor and has a negative polarity while the deeper (RP) does not always mimic the seafloor and has a positive polarity. Using the existing regional seismic lines, we can show that reflector RN can be continuously followed up to DSDP 208 drill hole site. Reflector RP is discontinuous and cannot be traced...
Tipo: Text Palavras-chave: Stratigraphy; Gas hydrates; Geophysics; Southwest Pacific; Fairway Basin; BSR.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-7321.pdf
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Ground penetrating radar non-invasively positions an underground dam and estimates its water reservoir shape and volume. Repositório Alice
VASQUES, G. de M.; RODRIGUES, H. M.; HUBER, E.; TAVARES, S. R. de L.; MARQUES, F. A.; SILVA, M. S. L. da.
The objectives are to use ground penetrating radar (GPR) to: (a) find a suitable length and location for a future underground dam; and (b) model the shape and estimate the volume of its water reservoir. Radargrams were obtained in a 0.85-ha area in northeastern Brazil along five survey lines parallel to, and eight lines transverse to the slope, starting from the proposed location of the dam. The 13 radargrams were pre-processed and migrated. The terrain surface and the top of the regolith delineated in the radargrams were interpolated, plotted in 3D showing the shape of the water reservoir, and used to estimate its volume. From the radargrams, the future dam should be 45 m longer and centered 22 m south of the proposed location, increasing the water...
Tipo: Anais e Proceedings de eventos Palavras-chave: GPR; Brazilian semiarid region; Barragem Subterrânea; Radar; Solo; Geophysics; Soil depth; Regolith.
Ano: 2022 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1140030
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Management zones from proximal soil sensors capture within-field soil property and terrain variations. Repositório Alice
VASQUES, G. de M.; RODRIGUES, H. M.; OLIVEIRA, R. P. de; HERNANI, L. C.; TAVARES, S. R. de L..
The objectives are to delineate soil management zones from soil proximal sensor data, and compare soil property values among zones in a 72-ha crop field in southeastern Brazil. Apparent electrical conductivity (aEC) and magnetic susceptibility (aMS), and equivalent Th (eTh) and U (eU) were measured across the field by a Geonics EM38-MK2 and a Medusa MS1200 sensors, respectively. These properties were kriged and used as input for delineating three management zones by fuzzy k-means clustering. Soil properties were measured at 0-10 cm at 72 sites, and their means were compared among the zones. Soil clay, organic C and exchangeable Ca and Mg vary significantly among the zones, according to Brown-Forsythe and Games-Howell tests (p=0.05), while pH, available P...
Tipo: Anais e Proceedings de eventos Palavras-chave: Gamma radiometrics; Geophysics; Electrical conductivity; Precision agriculture; Geostatistics.
Ano: 2022 URL: http://www.alice.cnptia.embrapa.br/alice/handle/doc/1140033
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New evidence of perfect overlapping of Haploops and pockmarks field: Is it a coincidence? ArchiMer
Champilou, Jean-baptiste; Baltzer, Agnes; Murat, Anne; Reynaud, Marine; Maillet, Grégoire M.; Nardelli, Maria Pia; Metzger, Édouard.
In the shallow waters of the Bay of Concarneau (South Brittany, France), previous studies reported a dense settlement of the species Haploops (tube-dwelling bioengineer amphipod) that perfectly overlaps a field of pockmarks. A possible mechanistic link may therefore exist between the Haploops colonies and the shallow pockmarks. To test this hypothesis, interferometry sonar and sub-bottom profiler chirp data were acquired in two new areas located in the marine estuary of the Loire River, “La Lambarde” and “Le Croisic”. The new sites share the same sedimentary and geological characteristics as those found in the Bay of Concarneau. The three sites are similarly located in shallow and muddy environments above a faulted Middle Eocene formation that is incised...
Tipo: Text Palavras-chave: Shallow waters; South Brittany (France); Geophysics; Pockmarks; Haploops.
Ano: 2019 URL: https://archimer.ifremer.fr/doc/00502/61324/64896.pdf
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Space-time evolution of a large field of pockmarks in the Bay of Concarneau (NW Brittany) ArchiMer
Baltzer, Agnes; Reynaud, Marine; Ehrhold, Axel; Fournier, Jerome; Cordier, Celine; Clouet, Helene.
About a decade ago, a large field of pockmarks, covering an overall area of 36 km(2) was discovered in water depths of < 30m in the central part of the Bay of Concarneau (Southern Brittany, France). This field, composed of features from 5 m to 35 m in diameter and < 1 m in depth, is characterized by unusual high densities of pockmarks, up to 5840 per square kilometre. Geophysical data correlated with sedimentary samples acquired in 2005 and 2009 show that pockmarks and their immediate surroundings are associated with dense tubes benches cover, built by a filter-feeding amphipod: Haploops nirae, forming original benthic communities. Two complementary surveys were carried out in April 2011 (Pock and Ploops) and April 2014 (Pock and Tide), on the...
Tipo: Text Palavras-chave: Géophysique; Marée; Failles; Gaz; Geophysics; Pockmarks; Tide; Turbidity; Gas; Chimneys pipes; Concarneau.
Ano: 2017 URL: http://archimer.ifremer.fr/doc/00410/52107/52938.pdf
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USE OF GROUND PENETRATING RADAR TO STUDY SPATIAL VARIABILITY AND SOIL STRATIGRAPHY REA
Campos,José R. da R.; Vidal-Torrado,Pablo; Modolo,Alcir J..
ABSTRACT Ground Penetrating Radar (GPR) is a geophysical method that uses electromagnetic waves to study subsurface structure in different fields such as geology, agriculture and civil engineering. The wave penetration in the soil is strongly controlled by the electrical conductivity of soil components such as clay, organic matter, and water. In this study, tests were conducted in a floodplain in the Elizabeth Creek watershed (New Jersey – USA). We established one transect where measurements were completed using two techniques, common mid point (CMP) and constant offset profile (COP), both with 100- MHz frequency antennas. Measurements were also completed using 250 and 500 MHz shielded antennas. GPR showed good accuracy to study soil spatial variability...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Geophysics; Soil stratigraphy; Agricultural engineering.
Ano: 2019 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-69162019000300358
Registros recuperados: 6
Primeira ... 1 ... Última
 

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