3D full tensor gradiometry and Falcon Systems data analysis for iron ore exploration: Baú Mine, Quadrilátero Ferrífero, Minas Gerais, Brazil

Braga, Marco Antônio; Endo, Issamu; Galbiatti, Henry Francisco; Carlos, Dionı́sio Uendro

doi:10.1190/geo2014-0104.1

Cited by 15 publications

(7 citation statements)

References 4 publications

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“…In recent years, gravity gradiometry surveys have been widely conducted to obtain detailed subsurface structure data (e.g., Jekeli 1988;Dransfield 2010;Chowdhury and Cevallos 2013;Braga et al 2014). Data collected by these surveys is the gravity gradient tensor defined by second derivatives of the gravity potential, and its response to subsurface structures is more sensitive than the gravity anomaly.…”

Section: Introductionmentioning

confidence: 99%

Eigenvector of gravity gradient tensor for estimating fault dips considering fault type

Kusumoto

2017

Prog. in Earth and Planet. Sci.

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The dips of boundaries in faults and caldera walls play an important role in understanding their formation mechanisms. The fault dip is a particularly important parameter in numerical simulations for hazard map creation as the fault dip affects estimations of the area of disaster occurrence. In this study, I introduce a technique for estimating the fault dip using the eigenvector of the observed or calculated gravity gradient tensor on a profile and investigating its properties through numerical simulations. From numerical simulations, it was found that the maximum eigenvector of the tensor points to the high-density causative body, and the dip of the maximum eigenvector closely follows the dip of the normal fault. It was also found that the minimum eigenvector of the tensor points to the low-density causative body and that the dip of the minimum eigenvector closely follows the dip of the reverse fault. It was shown that the eigenvector of the gravity gradient tensor for estimating fault dips is determined by fault type. As an application of this technique, I estimated the dip of the Kurehayama Fault located in Toyama, Japan, and obtained a result that corresponded to conventional fault dip estimations by geology and geomorphology. Because the gravity gradient tensor is required for this analysis, I present a technique that estimates the gravity gradient tensor from the gravity anomaly on a profile.

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Section: Introductionmentioning

confidence: 99%

Eigenvector of gravity gradient tensor for estimating fault dips considering fault type

Kusumoto

2017

Prog. in Earth and Planet. Sci.

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“…반면 중력 변화율 텐서의 측정은 여러 개의 가속도계를 복합적으로 이용하는 중력 변화율 측정 시스템이 개발되어 활발히 이용되 고 있다 (Dransfield, 2010;Lee, 2001). 중력 변화율 텐서는 기본적으로 서로 독립인 5개의 성분이 존재 하므로 중력이나 벡터 중력에 비해 정보의 양이 비 약적으로 증가하므로 이를 응용하려는 다양한 연구들 이 수행되고 있다 (Zhdanov et al, 2004;Beike, 2010;Beike and Pedersen, 2010;Rim and Li, 2012;Martinez et al, 2013;Braga et al, 2014).…”

Section: 서 론unclassified

Determination of the Strike and the Dip of a Line Source Using Gravity Gradient Tensor

Rim¹,

Jung²

2014

Journal of the Korean earth science society

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In this paper, the automatic determination algorithm of strike and dip of a line source using gravity gradient on a single profile is proposed. In general, the gravity gradient tensor due to a line source has only two independent components because of its 2-Dimensional (2-D) characteristics. However, if the line source has the strike and dip regarding the observation profile, it comes to have five independent components. The proposed algorithm of the determination both strike and dip is based on the rotational transform that converts full gravity gradient tensor to reduced 2-D gravity gradient tensor. The least-square method is applied in order to find optimum rotational angles that make one of the row components minimalized simultaneously. The two synthetic cases of a line source are represented; one has strike only and the other has both strike and dip. This study finds that the automatic determination method using gravity gradient tensor can find directions of a line source in each case.

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“…Gravity gradient signals can provide the small-scale features of sources, such as oil, gas and mineral resources buried in the ground [ 2 ]. As a high-accuracy, high-resolution signal of the gravity field, the gravity gradient has an important role in hydrocarbon or mineral exploration, geophysics and inertial navigation [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. With the Euler deconvolution as an example, more detailed information and more accurate results could be obtained through gravity gradient data [ 6 ].…”

Section: Introductionmentioning

confidence: 99%

“…Among these gradiometers, FTG and FALCON are the only two measuring instruments that have passed the flight test and achieved acceptable sensitivity in the field surveys with high-resolution [ 25 ]. FTG and FALCON airborne gravity gradiometer survey systems have been used in iron ore exploration in the Bau Mine Site, Quadrilatero Ferrifero, State of Minas Gerais, Brazil [ 5 ]. Thus, unless explicitly stated in the rest of this article, “gravity gradiometer” refers to rotating accelerometer-based gradiometers, such as FTG and FALCON.…”

Section: Introductionmentioning

confidence: 99%

New Matching Method for Accelerometers in Gravity Gradiometer

Wei

Cao

2017

Sensors

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The gravity gradiometer is widely used in mineral prospecting, including in the exploration of mineral, oil and gas deposits. The mismatch of accelerometers adversely affects the measuring precision of rotating accelerometer-based gravity gradiometers. Several strategies have been investigated to address the imbalance of accelerometers in gradiometers. These strategies, however, complicate gradiometer structures because feedback loops and re-designed accelerometers are needed in these strategies. In this paper, we present a novel matching method, which is based on a new configuration of accelerometers in a gravity gradiometer. In the new configuration, an angle was introduced between the measurement direction of the accelerometer and the spin direction. With the introduced angle, accelerometers could measure the centrifugal acceleration generated by the rotating disc. Matching was realized by updating the scale factors of the accelerometers with the help of centrifugal acceleration. Further simulation computations showed that after adopting the new matching method, signal-to-noise ratio improved from −41 dB to 22 dB. Compared with other matching methods, our method is more flexible and costs less. The matching accuracy of this new method is similar to that of other methods. Our method provides a new idea for matching methods in gravity gradiometer measurement.

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3D full tensor gradiometry and Falcon Systems data analysis for iron ore exploration: Baú Mine, Quadrilátero Ferrífero, Minas Gerais, Brazil

Cited by 15 publications

References 4 publications

Eigenvector of gravity gradient tensor for estimating fault dips considering fault type

Eigenvector of gravity gradient tensor for estimating fault dips considering fault type

Determination of the Strike and the Dip of a Line Source Using Gravity Gradient Tensor

New Matching Method for Accelerometers in Gravity Gradiometer

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