Relation of regional crustal structures and the distribution of ore deposits in western USA based on magnetic and gravity data

1999 ◽  
Vol 7 (2) ◽  
pp. 105-111
Author(s):  
T.G. Hildenbrand ◽  
R.C. Jachens ◽  
S. Ludington ◽  
B. Berger
Keyword(s):  
Gravity Data ◽  
Ore Deposits ◽  
Western Usa ◽  
Crustal Structures

A Hybrid PCG- Bat Algorithm for 2D Gravity Inversion: Applications for Ore Deposits Exploration and Interpretation of Sedimentary Basins

2020 ◽  
Author(s):  
Mohamed Abdrabou ◽  
Maha Abdelazeem ◽  
Mohamed Gobashy
Keyword(s):  
Conjugate Gradient ◽  
Hybrid Algorithm ◽  
2D Gravity ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Sedimentary Basins ◽  
Bat Algorithm ◽  
Ore Deposits ◽  
Preconditioned Conjugate Gradient ◽  
Residual Gravity

<p>Geophysical data such as gravity data can be inverted to get a subsurface image, which depicts the subsurface distribution of physical property. Consequently, inversion of geophysical data has an effective role for interpreting measured geophysical anomalies in hydrocarbons and mineral applications. Interest about ore deposits exploration and sedimentary basins interpretation is associated with their economic importance. The presence of sedimentary basins gives lower amplitude of gravity anomalies with negative signals, due to the negative density contrast as these sedimentary basins have lower density than that of the neighboring basement rocks. In prospecting ore deposits, studying the spatial distributions of densities in the subsurface is essential of significance.Two dimensional forward modelling strategy can be done via locating the rectangular cells with fixed size directly underneath the location of the observed data points using regular grid discretization. Density vector of the subsurface rectangular cells are obtained via solving the 2D gravity inverse problem by optimizing an objective function (i.e., the differences between observed and inverted residual gravity data sets). In this work, a hybrid algorithm merging a bat (BAT) algorithm with the preconditioned conjugate gradient (PCG) method is suggested as a mean for inverting surface gravity anomalies to obtain the density distribution in the subsurface. Like the hybrid, minimization algorithm has the capability to make use of the advantages of both two techniques. In this hybrid algorithm, the BAT algorithm was utilized to construct an initial solution for the PCG technique. The BAT optimizer acts as a rapid build-up of the model, whereas the second modifies the finer model approximated solution. This modern algorithm was firstly applied on a free-noise synthetic data and to a noisy data with three different levels of random noise, and good results obtained through the inversion. The validity and applicability of our algorithm are applied to real residual gravity anomalies across the San Jacinto graben in southern California, USA, and Sierra Mayor - Sierra Pinta graben, USA and prospecting of the Poshi Cu-Ni deposits, Xinjiang, northwest China. The obtained results are in excellent accordance with those produced by researchers in the published literature.</p><p> </p><p><strong>Keywords: </strong>Gravity data, 2D Inversion, BAT algorithm, Preconditioned Conjugate Gradient, Sedimentary Basins.</p>

scholarly journals Two-dimensional crustal structures of Taiwan from gravity data

Tectonics ◽  
1998 ◽  
Vol 17 (1) ◽  
pp. 104-111 ◽  
Author(s):  
Horng-Yuan Yen ◽  
Yih-Hsiung Yeh ◽  
Francis T. Wu
Keyword(s):  
Gravity Data ◽  
Two Dimensional ◽  
Crustal Structures

DEEP CRUSTAL REFLECTIONS IN EUROPE

Geophysics ◽  
1975 ◽  
Vol 40 (1) ◽  
pp. 25-39 ◽  
Author(s):  
Gerhard P. Dohr ◽  
Rolf Meissner
Keyword(s):  
Cross Sections ◽  
Digital Processing ◽  
Ore Deposits ◽  
Wide Angle ◽  
Seismic Velocities ◽  
Low Velocity ◽  
Seismic Sounding ◽  
Crustal Structures ◽  
Multiple Coverage ◽  
Reconnaissance Surveys

Deep crustal reflected arrivals in the near‐vertical and the wide‐angle range have been recorded in various parts of Europe. A high resolution of deep crustal structures can be obtained by special seismic investigations. Reconnaissance surveys may be performed during routine prospecting work by using recording lengths up to 15 sec. Several profiles with multiple coverage and digital processing of the data demonstrate the possibility of obtaining seismic cross‐sections down to the Moho. In addition to near‐vertical reflection work, studies of wide‐angle arrivals at distances up to 150 km and more are most favorable for a calculation of seismic velocities in the deeper crust. Ray‐tracing programs have revealed low‐velocity zones at depths below 10 km in many continental crusts. From comparison of reflected amplitudes in the near‐angle and the wide‐angle ranges and from other observations, a lamellar structure in the deeper crust is often detected. Regional differences of various traveltime branches show characteristic crustal structures. It is shown that deep seismic sounding is useful for estimating the shape and development of sedimentary troughs and their connection to oil‐bearing structures, heat energy, and possible ore deposits.

scholarly journals Geological structure of central Vietnam by interpretation processing of gravitational survey data using the “COSCAD 3D” computer technology

2021 ◽  
Vol 63 (5) ◽  
pp. 77-90
Author(s):  
T. H. Phan ◽  
A. V. Petrov ◽  
M. Ph. Do ◽  
M. G. Lai ◽  
T. L. Nguyen
Keyword(s):  
Gravitational Field ◽  
Computer Technology ◽  
Gravity Data ◽  
Mineral Resources ◽  
Geological Structure ◽  
Ore Deposits ◽  
Spectral Correlation ◽  
Fault Systems ◽  
Central Vietnam ◽  
Tectonic Dislocations

Background. The central regions of Vietnam are of strategic importance for the Republic, being, in fact, the gateway to the ASEAN countries. Investing in the exploration and evaluation of mineral resources, in particular ore minerals hidden at great depths, is a specific and necessary task for the country.Aim. To clarify the structural-tectonic scheme of the analysed area and to identify the main fault systems and zoning of the Central Vietnam area by the gravitational field based on classification algorithms.Materials and methods. The objectives were achieved by assessing the total gradient of the gravitational field, analysing the distribution of the field variance and the results of tracing the axes of the gravitational field anomaly. Interpretation processing of gravity data was carried out using the “COSCAD 3D” computer technology of statistical and spectral correlation data analysis.Results. The defined fault systems, which play an important role in the processes of mineral formation, have a northwestern, northeastern and latitudinal strike. The zoning of the study area according to the gravitational field, its characteristics and available geological information made it possible to identify 13 homogeneous areas. Each area is characterised by a certain level of gravitational field, the values of dispersion and total field gradient, as well as correlations between attributes. The classification results confirms the complexity of the geological structure of the area under study and the presence of three main strikes of the systems of tectonic dislocations – northwestern, northeastern and latitudinal.Conclusions. A large number of tectonic dislocations of various strikes and intensities, revealed using the methods of the probabilistic-statistical approach, implemented in the “COSCAD 3D” computer technology, indicates that the area under study is promising in terms of ore deposits.

Introducing the Sylvester Graben, a ?Neoproterozoic depocenter on the eastern flank of the Toko Syncline, southern Georgina Basin, Queensland

2016 ◽  
Vol 56 (2) ◽  
pp. 534
Author(s):  
Robbert J. Willink ◽  
Nathan C. Palmer ◽  
Mathew Davies ◽  
Chris Woodfull ◽  
Peter Stuart-Smith ◽  
...  
Keyword(s):  
Lower Cambrian ◽  
Gravity Data ◽  
Ore Deposits ◽  
Glacial Origin ◽  
Eastern Flank ◽  
Eastern Edge ◽  
Seismic Lines

Regional 2D seismic lines acquired in 2013 along the eastern edge of the Toko Syncline in Queensland have imaged a complexly faulted, northwest–southeast trending graben below subcropping Cambrian carbonates. At its deepest, this depocenter contains some 3,500 m of sediments that are inferred to be of Neoproterozoic age, if not older at depth. Surface outcrops of this succession are mapped as the Sylvester Sandstone. Shallow core holes confirm that the uppermost ~1,000 m of sediments are of fluvioglacial, glacio lacustrine and glacial origin, overlain by a thin carbonate of Lower Cambrian age based on the occurrence of archaeocyathids. Unconformably underlying this succession is an internally reflective sedimentary section that is up to 2,500 m which has not been drilled to date. Although the localised development of Neoproterozoic depocenters below Cambrian carbonates in the Toko Syncline has been inferred previously based on vintage seismic and gravity data, such features were not imaged as clearly as on the newly acquired seismic. Inferred sediments in this faulted graben may be correlatives of the Neoproterozoic succession in the Amadeus Basin and could be prospective for hydrocarbons as well as ore deposits.

Deep crustal structures interpreted from potential field data along deep seismic sounding transects in Australia

2015 ◽  
Vol 55 (2) ◽  
pp. 450
Author(s):  
Irena Kivior ◽  
David Boyd ◽  
David Tucker ◽  
Stephen Markham ◽  
Francis Vaughan ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Potential Field ◽  
Field Data ◽  
Gravity Data ◽  
Sedimentary Basins ◽  
Deep Seismic Sounding ◽  
Magnetic Data ◽  
Potential Field Data ◽  
Seismic Sounding ◽  
Crustal Structures

Energy spectral analysis techniques have been applied to magnetic and gravity data acquired across the Olympic Dam cratonic area in Australia and sedimentary basins along the Equatorial Margin of Brazil. Analysis has been conducted along two Deep Seismic Sounding lines (DSS) acquired by Geoscience Australia. There is a good correlation between interfaces found in this analysis and structures interpreted from the seismic data. Interpretation of gravity data using energy spectral analysis along the DSS survey lines show a number of deep crustal structures are evident, including the Moho which was detected using gravity data, while similar analysis of the magnetic data show indications of the Curie isotherm. In addition, the analysis was extended away from the seismic lines to detect many deep crustal horizons and structures at considerable distances from the DSS lines. The results obtained from energy spectral analysis across this area in Australia encouraged the application of this technique on the Equatorial Margin of Brazil, where the potential field data is of much lower resolution. This suggests that a much wider application of this approach could be highly valuable to investigate the deep structure under other sedimentary basins and to assist heat flow studies.

Sign in / Sign up

Export Citation Format

Share Document