Gravity characterization of the La Rioja Valley Basin, Argentina

Geophysics ◽  
2009 ◽  
Vol 74 (3) ◽  
pp. B83-B94 ◽  
Author(s):  
Mario Ernesto Gimenez ◽  
Myriam Patricia Martinez ◽  
Teresa Jordan ◽  
F. Ruíz ◽  
Federico Lince Klinger
Keyword(s):  
3D Model ◽  
Bouguer Anomaly ◽  
First Order ◽  
3D Gravity ◽  
Anomaly Map ◽  
Bouguer Anomaly Map ◽  
Basement High ◽  
La Rioja ◽  
Deconvolution Techniques

The La Rioja Valley is a sedimentary basin in the Pampean Ranges, a region of basement uplifts and broad valleys in the Andean foreland. The present study advances understanding of the genesis of the basin by providing subsurface data on its geometry and characteristics. Gravity and topographic data, including a newly completed gravity survey, were integrated to create a complete Bouguer anomaly map. Euler and Werner deconvolution techniques sum with traditional potential-fields methods and sparse independent data from seismic and magnetotelluric methods to test and constrain the subsurface geophysical characterization of the La Rioja Valley Basin. The residual anomaly, obtained through upward continuation, was inverted to obtain the best 3D gravity model of the La Rioja Valley Basin, which shows the first-order geometry of the basin. This reveals that the basin is asymmetric, with up to [Formula: see text] of low-density basin fill in a depocenter located in the west-central sector of the valley. Second-order features of the basin include a southeast-trending basement high, likely a fault zone that subdivides the basin, which has been revealed by a suite of analytical methods (3D model of depth to basement, a 2D inverse model, and Werner deconvolution solutions).

3D Gravity modeling of the volcanic island of Surtsey, Iceland

2021 ◽  
Author(s):  
sara sayyadi ◽  
Magnús T. Gudmundsson ◽  
Thórdís Högnadóttir ◽  
James White ◽  
Joaquín M.C. Belart ◽  
...  
Keyword(s):  
Sea Level ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Gravity Modeling ◽  
Gravity Station ◽  
Effusive Activity ◽  
3D Gravity ◽  
Anomaly Map ◽  
Bouguer Anomaly Map ◽  
Drill Cores

<p>The formation of the oceanic island Surtsey in the shallow ocean off the south coast of Iceland in 1963-1967 remains one of the best-studied examples of basaltic emergent volcanism to date. The island was built by both explosive, phreatomagmatic phases and by effusive activity forming lava shields covering parts of the explosively formed tuff cones.  Constraints on the subsurface structure of Surtsey achieved mainly based on the documented evolution during eruption and from drill cores in 1979 and in the ICDP-supported SUSTAIN drilling expedition in 2017(an inclined hole, directed 35° from the vertical). The 2017 drilling confirmed the existence of a diatreme, cut into the sedimentary pre-eruption seafloor (Jackson et al., 2019). </p><p>We use 3D-gravity modeling, constrained by the stratigraphy from the drillholes to study the structure of the island and the underlying diatreme.  Detailed gravity data were obtained on Surtsey in July 2014 with a gravity station spacing of ~100 m. Density measurements for the seafloor sedimentary and tephra samples of the surface were carried out using the ASTM1 protocol. By comparing the results with specific gravity measurements of cores from drillhole in 2017, a density contrast of about 200 kg m<sup>-3</sup> was found between the lapilli tuffs of the diatreme and the seafloor sediments.  Our approach is to divide the island into four main units of distinct density: (1) tuffs above sea level, (2) tuffs below sea level, (3) lavas above sea level, and (4) a lava delta below sea level, composed of breccias over which the lava advanced during the effusive eruption.  The boundaries between the bodies are defined from the eruption history and mapping done during the eruption, aided by the drill cores. </p><p>A complete Bouguer anomaly map is obtained by calculating a total terrain correction by applying the Nagy formula to dense DEMs (5 m spacing out to 1.2 km from station, 200 m spacing between 1.2 km and 50 km) of both island topography and ocean bathymetry.  Through the application of both forward and inverse modeling, using the GM-SYS 3D software, the results provide a 3-D model of the island itself, as well as constraints on diatreme shape and depth.</p>

scholarly journals Caracterização Estrutural da Região Central do Graben do Cupe, Bacia Sedimentar de Pernambuco: Implicações para o Padrão Atual da Rede de Drenagem

2020 ◽  
Vol 13 (5) ◽  
pp. 2355
Author(s):  
João Carlos Morais de Araújo Júnior ◽  
Willian Alexandre De Lima Moura ◽  
Isis Mayara Gomes da Silva ◽  
Osvaldo José Correia Filho ◽  
João Adauto De Souza Neto
Keyword(s):  
Central Region ◽  
Structural Characterization ◽  
Bouguer Anomaly ◽  
Border Region ◽  
Normal Faults ◽  
Structural Framework ◽  
Gravimetric Data ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

A área de estudo está inserida no contexto geológico do Graben do Cupe, região de borda da Bacia Sedimentar de Pernambuco (BPE) com o embasamento cristalino adjacente. O Graben do Cupe é considerado um importante depocentro da região onshore dessa bacia e sua origem está ligada à abertura do Oceano Atlântico Sul. A partir da integração de dados gravimétricos, dados altimétricos obtidos por LIDAR e dados de campo, foi possível realizar uma caracterização estrutural dos principais lineamentos gravimétricos e topográficos que cortam a região central do Graben do Cupe. O mapa de anomalia bouguer residual revelou que o arcabouço estrutural mais profundo da BPE é representado por falhas normais de direção NE-SW, bem como falhas transcorrentes sinistrais, de direção NW-SE e dextrais ENE-WSW. A mesma orientação de lineamentos topográficos foi obtida através da interpretação dos dados altimétricos. Os rios inseridos na área de estudo seguem a mesma orientação dos lineamentos topográficos e gravimétricos, NW-SE e NE-SW. O mapeamento estrutural revelou que os lineamentos gravimétricos e topográficos estão associados à direção da foliação NE-SW, presente no embasamento adjacente a bacia, e às falhas originadas durante a fase rifte da BPE; A) NE-SW e NNE-SSW caracterizadas como falhas normais e B) NW-SE que corresponde a falhas oblíquas. As estruturas mais profundas tanto do embasamento, quanto as estruturas rifte que compartimentam o Graben do Cupe foram responsáveis por controlar a evolução quaternária da paisagem, o que provocou a captura da drenagem de alguns cursos fluviais, e o significante condicionamento tectônico dos vales fluviais.  Structural Characterization of the Central Region of the Graben Cupe, Pernambuco Sedimentary Basin: Implications for the Current Pattern of the Drainage Network A B S T R A C TThe study area is inserted in the geological settings of the Cupe Graben, which is located in the border region of the Pernambuco Basin with the adjacent crystalline basement. The Cupe Graben is considered an important depocenter in the onshore region of this basin and its origin is linked to the opening of the South Atlantic Ocean. From the integration of gravimetric data, altimetric data obtained by LIDAR and field data, it was possible to carry out a structural characterization of the main gravimetric and topographic lineaments that cut the central region of Cupe Graben. The residual bouguer anomaly map revealed that the deep structural framework of the BPE is represented by normal faults NE-SW and NNE-SSW and sinistral strike slip faults NW-SE. The same orientation of topographic lineaments was obtained through the interpretation of the topographic lineaments. The rivers inserted in the study area have the same orientation as the topographic and gravimetric lineaments, NW-SE and NE-SW. The structural mapping revealed that the gravimetric and topographic lineaments are related to foliation in the adjacent basement NE-SW, and the faults originated during the BPE rift phase; A) NE-SW and NNE-SSW characterized as normal faults and B) NW-SE which corresponds to oblique faults. The deeper structures of both the basement and the rift structures that constraint the Cupe Graben were responsible for controlling the quaternary evolution of the landscape, which caused the capture of the drainage of some rivers, and the strong conditioning of the drainage network.Keywords: Cupe Graben, Pernambuco Basin, structural geology, river capture.

Tectonic insight and 3-D modelling of the Lusi (Java, Indonesia) mud edifice through gravity analyses

2021 ◽  
Vol 225 (2) ◽  
pp. 984-997
Author(s):  
Álvaro Osorio Riffo ◽  
Guillaume Mauri ◽  
Adriano Mazzini ◽  
Stephen A Miller
Keyword(s):  
Risk Mitigation ◽  
Bouguer Anomaly ◽  
Geological Model ◽  
Resource Exploitation ◽  
Subsurface Structures ◽  
Central Java ◽  
Geostatistical Interpolation ◽  
Gravity Response ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

SUMMARY Lusi is a sediment-hosted hydrothermal system located near Sidoarjo in Central Java, Indonesia, and has erupted continuously since May 2006. This mud eruption extends over a surface of ∼7 km2, and is framed by high containment dams. The present study investigates the geometry of the subsurface structures using a detailed gravimetric model to visualize in 3-D the Lusi system and surrounding lithologies. The obtained residual Bouguer anomaly map, simulated through geostatistical interpolation methods, supports the results of previous deformation studies. The negative gravity anomaly zones identified at Lusi are interpreted as fractured areas through which fluids can ascend towards the surface. A 3-D detailed geological model of the area was constructed with Geomodeller™ to highlight the main features. This model relies on the structures’ density contrasts, the interpreted residual Bouguer anomaly map, and geological data from previous authors. 3-D algorithms were used to calculate the gravity response of the model and validate it by inverse methods. The final output is a gravity constrained 3-D geological model of the Lusi mud edifice. These results provide essential details on the Lusi subsurface and may be useful for possible future geothermal resource exploitation and for the risk mitigation plans related to the maintenance of the man-made framing embankment.

scholarly journals Geophysical perspective on the structural interference zone along the Neoproterozoic Brasília and Ribeira fold belts in West Gondwana

2017 ◽  
Vol 47 (1) ◽  
pp. 3-19
Author(s):  
João Gabriel Motta ◽  
Norberto Morales ◽  
Walter Malagutti Filho
Keyword(s):  
Bouguer Anomaly ◽  
Shear Zones ◽  
Magnetic Data ◽  
Gravity Modeling ◽  
West Gondwana ◽  
Fold And Thrust Belt ◽  
Fold Belts ◽  
Thrust Sheets ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

ABSTRACT: The Brasília and Ribeira fold belts have been established in south-southwestern São Francisco Craton during the Brasiliano-Pan African orogeny (0.9-0.5 Ga - Tonian to Cambrian), and played an important role in West Gondwana continent assembly. The region is given by a complex regional fold and thrust belt superposed by shearing during the orogeny late times, with superposing stress fields forming a structural interference zone. These thrust sheets encompasses assemblies from lower- to upper-crust from different major tectonic blocks (Paranapanema, São Francisco), and newly created metamorphic rocks. Re-evaluation of ground gravity datasets in a geologically constrained approach including seismology (CRUST1 model) and magnetic data (EMAG2 model) unveiled details on the deep- crust settings, and the overall geometry of the structural interference zone. The Simple Bouguer Anomaly map shows heterogeneous density distribution in the area, highlighting the presence of high-density, high metamorphic grade rocks along the Alterosa suture zone in the Socorro-Guaxupé Nappe, lying amid a series of metasedimentary thrust scales in a regional nappe system with important verticalization along regional shear zones. Forward gravity modeling favors interpretations of structural interference up North into Guaxupé Nappe. Comparison to geotectonic models shows similarities with modern accretionary belts, renewing the discussion.

scholarly journals Geometrical Characterisation of the Mamfe Basin, Cameroon, from the Earth, Gravitational Model (EGM 2008)

2018 ◽  
Vol 7 (1) ◽  
pp. 94
Author(s):  
Anatole Eugene Djieto Lordon ◽  
Mbohlieu YOSSA ◽  
Christopher M Agyingi ◽  
Yves Shandini ◽  
Thierry Stephane Kuisseu
Keyword(s):  
Average Length ◽  
Gravity Data ◽  
Bouguer Anomaly ◽  
Igneous Rocks ◽  
Average Depth ◽  
The Earth ◽  
Gravitational Model ◽  
Petroleum Generation ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

Gravimetric studies using the ETOPO1-corrected high resolution satellite-based EGM2008 gravity data was used to define the surface extent, depth to basement and shape of the Mamfe basin. The Bouguer anomaly map was produced in Surfer 11.0. The Fast Fourier Transformed data was analyzed by spectral analysis to remove the effect of the regional bodies in the study area. The residual anomaly map obtained was compared with the known geology of the study area, and this showed that the gravity highs correspond to the metamorphic and igneous rocks while the gravity lows match with Cretaceous sediments. Three profiles were drawn on the residual anomaly map along which 2D models of the Mamfe basin were drawn. The modeling was completed in Grav2dc v2.06 software which uses the Talwini’s algorithm and the resulting models gave the depth to basement and the shape of the basement along the profiles. After processing and interpretation, it was deduced that the Mamfe basin has an average length and width of 77.6 km and 29.2 km respectively, an average depth to basement of 5 km and an overall U-shape basement. These dimensions (especially the depth) theoretically create the depth and temperature conditions for petroleum generation. 

scholarly journals New Bouguer Anomaly Map for the Territory of the Slovenia

2021 ◽  
Vol 13 (22) ◽  
pp. 4510
Author(s):  
Klemen Medved ◽  
Oleg Odalović ◽  
Božo Koler
Keyword(s):  
Gravity Anomaly ◽  
Significant Influence ◽  
Bouguer Anomaly ◽  
High Quality ◽  
Digital Terrain ◽  
Terrain Models ◽  
Gravimetric Data ◽  
The Republic ◽  
Anomaly Map ◽  
Bouguer Anomaly Map

The existing Bouguer anomaly map, which covers the territory of the Republic of Slovenia is a few decades old. Since then, quite a few new gravimetric measurements (data) for the territory of Slovenia as well as high quality digital terrain models that are needed for creating such a map have been made available. The methodology and standards for creating gravity anomaly maps are also changing. Thus, the national Bouguer anomaly map was updated. There were some gross errors detected in the set of old gravimetric data. Additionally, the influence of new updated gravimetric data was analyzed. The comparison of the various maps and the analysis of the influence of input gravimetric data indicates that the new gravimetric data of Slovenia has a significant influence on the creation of the gravimetric anomaly maps for Slovenia (even over 30 mGals at some points).

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