Geological model and development of the Cenozoic Wiang Pa Pao Basin, Chiang Rai Province, Northern Thailand, based on gravity data modelling and surface structural interpretation

Gravity gradient profiles across subsurface structures that are approximately 2-D contain diagnostic information regarding depth, size, and structure (geometry). Gradient space plots, i.e., plots of horizontal gradient versus vertical gradient, present the complete magnitude and phase information in the gradient profiles simultaneously. Considerable previous work demonstrates the possibility for complete structural interpretation of a truncated plate model from the gradient space plot. The qualitative and quantitative diagnostic information contained in gradient space plots is general, however. Examination of the characteristics of gradient space plots reveals that 2-D structures are readily classified as extended or localized. For example, the truncated plate model is an extended model, while the faulted plate model is a localized model. Comparison of measured or calculated gradient space plots to a model gradient space plot catalog allows a rapid, qualitative determination of structure or geometry. “Corners” of a polygonal cross‐section model are then determined as profile points corresponding to maxima on the vertical gradient profile. A generalized approach to structural interpretation from gravity data consists of (1) determining vertical and horizontal gradient profiles perpendicular to the strike of a 2-D gravity anomaly, (2) determining the structural geometry from the gradient space plot, and (3) locating profile positions of structural corners from the vertical gradient profile. This generalized inversion procedure requires no quantitative information or assumption regarding density contrasts. Iterative forward modeling then predicts the density contrasts. Application of this generalized gravity gradient inversion procedure to high quality gravity data results in an effective density prediction consistent with measured near‐surface densities and the known increase in density with depth in deep sedimentary basins.

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The structural/stratigraphic development of the Sishen South (Welgevonden) iron ore deposit, South Africa, as deduced from ground gravity data modelling

Applied Earth Science ◽

10.1179/174327506x138940 ◽

2006 ◽

Vol 115 (4) ◽

pp. 174-186

Author(s):

D. J. Alchin ◽

W. J. Botha

Keyword(s):

South Africa ◽

Iron Ore ◽

Gravity Data ◽

Data Modelling ◽

Ore Deposit ◽

Iron Ore Deposit

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SIMULATION MODELLING IN THE STRUCTURAL GRAVITY PROSPECTING

Prospecting and Development of Oil and Gas Fields ◽

10.31471/1993-9973-2019-2(71)-38-48 ◽

2019 ◽

pp. 38-48

Author(s):

S. H. Anikeyev ◽

S. M. Bahriy ◽

B. B. Hablovskiy

Keyword(s):

Cross Sections ◽

Gravity Data ◽

A Priori ◽

Structural Type ◽

Simulation Modelling ◽

Gravity Modeling ◽

Gravity Inversion ◽

Density Structure ◽

Data Modelling ◽

Computer Technologies

In accordance with the purpose of geophysical exploration, the gravity data interpretation is aimed at prospecting mineral resources which is based on the study of the geological cross-section structure. The task of quantitative interpretation, which uses methods of gravity modeling and gravity inversion, is the modelling of a gravity field (gravity modeling) and of a density structure of geological environments (gravity inversion). The article presents the definition and steps of the gravity data modelling technique. This technique is based on the construction of an informal sequence of equivalent solutions. The technological and geological features of methods for modelling the density structure of complex geological environments are given; among them geological content, consistency with a priori data and the subordination of modelling to geological hypotheses are important. The topicality and methods of simulation modelling are outlined. The purpose of simulation modelling is to study the properties of gravity inversion in the general formulation, as well as to evaluate the degree of detail and reliability of the methods and technologies of gravity modelling, which claim to be an effective solution to geological problems. The example of structural simulation testing of the methods of informal sequence of equivalent solutions and its computer technologies shows that a complex interpretation of seismic and gravity measurements data enables the creation of detailed density models of structural cross-sections. The ways of increasing the veracity of gravity data modelling of structural cross-sections have been studied. It is revealed that the best approximation of the regional background is an inclined plane which approximates the observed field of gravity according to characteristic pickets over the research areas that are better studied. The increase in the veracity of modeling can also be achieved by rebuilding the near side zones in the structural type models in an interactive process of solving structural gravity inversion problems. Substantive modeling depends primarily on the experience of the interpreter since computer technologies for gravity modeling and gravity inversion are merely an interpretation tool.

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