3D inversion of airborne gravity gradiometry data in mineral exploration: A case study in the Quadrilátero Ferrífero, Brazil

Geophysics ◽  
2013 ◽  
Vol 78 (1) ◽  
pp. B1-B11 ◽  
Author(s):  
Cericia Martinez ◽  
Yaoguo Li ◽  
Richard Krahenbuhl ◽  
Marco Antonio Braga
Keyword(s):  
Iron Ore ◽  
Mineral Exploration ◽  
Density Contrast ◽  
Airborne Gravity ◽  
Gravity Gradiometry ◽  
Inversion Algorithm ◽  
3D Inversion ◽  
Ore Bodies ◽  
Airborne Gravity Gradiometry

We present a case study of applying 3D inversion of gravity gradiometry data to iron ore exploration in Minas Gerais, Brazil. The ore bodies have a distinctly high-density contrast and produce well-defined anomalies in airborne gravity gradiometry data. We have carried out a study to apply 3D inversion to a [Formula: see text] subarea of data from a larger survey to demonstrate the utility of such data and associated inversion algorithm in characterizing the deposit. We examine multiple density contrast models obtained by first inverting [Formula: see text]; then [Formula: see text], [Formula: see text], and [Formula: see text] jointly; and finally all five independent components to understand the information content in different data components. The commonly discussed [Formula: see text] component is sufficient to produce geologically reasonable and interpretable results, while including additional components involving horizontal derivatives increases the resolution of the recovered density model and improves the ore delineation. We show that gravity gradiometry data can be used to delineate the iron ore formation within this study area.

Fast 3D inversion of airborne gravity-gradiometry data using Lanczos bidiagonalization method

2016 ◽  
Vol 132 ◽  
pp. 211-228 ◽  
Author(s):  
Zhaohai Meng ◽  
Fengting Li ◽  
Dailei Zhang ◽  
Xuechun Xu ◽  
Danian Huang
Keyword(s):  
Airborne Gravity ◽  
Gravity Gradiometry ◽  
3D Inversion ◽  
Lanczos Bidiagonalization ◽  
Airborne Gravity Gradiometry

3D inversion of airborne gravity gradiometry data for the Budgell Harbour Stock, Newfoundland: A case history using a probabilistic approach

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. B269-B284 ◽  
Author(s):  
Meixia Geng ◽  
J. Kim Welford ◽  
Colin G. Farquharson ◽  
Alexander L. Peace
Keyword(s):  
Joint Inversion ◽  
Probabilistic Approach ◽  
Stable Solution ◽  
Airborne Gravity ◽  
Inversion Method ◽  
Gravity Gradiometry ◽  
3D Inversion ◽  
Long Wavelength ◽  
Text Model ◽  
Airborne Gravity Gradiometry

We have studied the Mesozoic Budgell Harbour Stock, a gabbroic intrusion in north-central Newfoundland, Canada, using 3D inversion of airborne gravity gradiometry data based on a probabilistic inversion method. Significantly, differences were observed between the results when inverting the single [Formula: see text] component and when inverting the 5C combination. We also found that the [Formula: see text] model failed to reproduce the long-wavelength signals from other components, whereas the model recovered from five components accommodated all of the signals from all of the components. To estimate the influence of long-wavelength signals from targets other than the intrusion, such as deeper bodies or large-scale terrain variations, inversion tests are performed on a synthetic model. The inversion results for the synthetic example indicate that the joint inversion of five components is more sensitive to long-wavelength signals, which can generate spurious structures to fit all of the signals from the five components. In contrast, the [Formula: see text] model is less affected by the long-wavelength signals and thus tends to produce a stable solution, despite failing to incorporate all of the long-wavelength signals from the tensor data. We found that gravity gradiometry data could be used to delineate the intrusion within this study area, which is also consistent with the susceptibility model recovered from inversion of aeromagnetic data and with results from a previous geophysical study. Moreover, the differences between the [Formula: see text] model and the 5C model may reflect the long-wavelength signals in the gravity gradiometry data.

scholarly journals AIRBORNE GRAVITY GRADIOMETRY – DATA PROCESSING AND INTERPRETATION

2013 ◽  
Vol 31 (3) ◽  
pp. 427 ◽  
Author(s):  
Dionisio Uendro Carlos ◽  
Marco Antonio Braga ◽  
Henry F. Galbiatti ◽  
Wanderson Roberto Pereira
Keyword(s):  
Iron Ore ◽  
A Priori ◽  
Synthetic Data ◽  
Real Data ◽  
Geological Mapping ◽  
Airborne Gravity ◽  
Gravity Gradient ◽  
Gravity Gradiometry ◽  
Quadrilátero Ferrífero ◽  
Airborne Gravity Gradiometry

ABSTRACT. This paper discusses some processing techniques (all codes were implemented with open source software) developed for airborne gravity gradient systems, aiming at outlining geological features by applying mathematical formulations based on the potential field properties and its breakdown into gradiometric tensors. These techniques were applied to both synthetic and real data. These techniques applied to synthetic data allow working in a controlled environment, under- standing the different processing results and establishing a comparative parameter. These methodologies were applied to a survey area of the Quadrilátero Ferrífero to map iron ore targets, resulting in a set of very helpful and important information for geological mapping activities and a priori information for inversion geophysical models.Keywords: processing, airborne gravity gradiometry, iron ore exploration, FTG system, FALCON system. RESUMO. Neste trabalho apresentamos algumas técnicas de processamento (todos os códigos foram implementados em softwares livres) desenvolvidas para aplicação aos dados de aerogradiometria gravimétrica. Os processamentos foram aplicados tanto a dados sintéticos como a dados reais. A aplicação a dados sintéticos permite atuar em um ambiente controlado e entender o padrão resultante de cada processamento. Esses mesmos processamentos foram aplicados em uma área do Quadrilátero Ferrífero para o mapeamento de minério de ferro. Todos os resultados desses processamentos são muito úteis e importantes para o mapeamento geológicoe como informação a priori para modelos de inversão geofísica.Palavras-chave: processamento, dados de aerogradiometria gravimétrica, exploração de minério de ferro, sistema FTG, sistema FALCON.

Lithologic characterization using airborne gravity gradient and aeromagnetic data for mineral exploration: A case study in the Quadrilátero Ferrífero, Brazil

2015 ◽  
Vol 3 (2) ◽  
pp. SL1-SL13 ◽  
Author(s):  
Cericia Martinez ◽  
Yaoguo Li
Keyword(s):  
Iron Ore ◽  
Physical Property ◽  
Density Contrast ◽  
Iron Formation ◽  
Magnetic Data ◽  
Airborne Gravity ◽  
Gravity Gradient ◽  
Contrast Model ◽  
Ore Bodies ◽  
Quadrilátero Ferrífero

We present a study on utilizing airborne gravity gradient and magnetic data to characterize an iron ore formation in Minas Gerais, Brazil. The target iron ore bodies have a distinctly high density contrast and produce well-defined anomalies in airborne gravity gradiometry data. The high-grade hematite iron ores are associated with low and moderate susceptibility, making magnetic data useful in distinguishing potential ore bodies from the host iron formation. The airborne gravity gradient and magnetic data over part of the Gandarela Syncline iron formation in the Quadrilátero Ferrífero are independently inverted to obtain a 3D susceptibility and density contrast model. These detailed 3D physical property distributions of subsurface features are then used for geologic characterization and interpretation purposes through lithologic associations. We outline two approaches to link the two physical property distributions and identify representative geologic units in the study area. The geologic units are then organized into a 3D lithology model to help characterize subsurface geologic structure and ore distribution. The lithologic models provide an intuitive representation of the geology and can assist in future exploration plans or in assessment of resource distribution and quality. Our study demonstrates that such approaches are feasible on the deposit scale.

scholarly journals Interpretation of airborne gravity gradiometry and magnetic data using cross-gradients

2012 ◽  
Vol 2012 (1) ◽  
pp. 1-4
Author(s):  
Carlos Cevallos ◽  
Mark Dransfield ◽  
Jacqueline Hope ◽  
Heather Carey
Keyword(s):  
Magnetic Data ◽  
Airborne Gravity ◽  
Gravity Gradiometry ◽  
Airborne Gravity Gradiometry
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