Correcting airborne gravity data for overburden thickness: a case study from the Nechako interior plateau, British Columbia

Large areas of bedrock in Canada, such as in the interior plateau of British Columbia, are covered by a thick glacial overburden. Lateral variations in overburden thickness can create spurious anomalies in gravity data. These anomalies can be of a size and amplitude similar to those associated with mineral bodies and can be mistaken for them. A methodology is introduced that corrects gravity data for changes in overburden thickness through the use of a bedrock topography map created by integrating information from a helicopter transient electromagnetic survey with geological survey data, well water data, and gravel pit locations. The approach is tested for a 68 km × 38 km area in the prospective Nechako interior plateau of British Columbia, Canada. The methodology extends the traditional Bouguer corrections by taking into account the gravitational contribution of the overburden. Results show that the capability of an airborne survey to detect a change in overburden thickness depends primarily on survey line spacing and to a lesser extent on the level of random noise in the gravity data. The bedrock topography correction has the capability of removing the gravitational attraction of overburden for the purpose of revealing, through interpretation, geological structures in the gravity data that originate from the bedrock and are otherwise concealed.

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Correcting airborne gravity data for overburden thickness using airborne transient electromagnetic data

10.22215/etd/2017-11801 ◽

2017 ◽

Author(s):

Raymond Caron

Keyword(s):

Gravity Data ◽

Airborne Gravity ◽

Electromagnetic Data ◽

Transient Electromagnetic ◽

Overburden Thickness

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Sedimentary basin analysis using airborne gravity data: a case study from the Bohai Bay Basin, China

International Journal of Earth Sciences ◽

10.1007/s00531-015-1284-x ◽

2015 ◽

Vol 105 (8) ◽

pp. 2241-2252 ◽

Cited By ~ 1

Author(s):

Wenyong Li ◽

Yanxu Liu ◽

Jianxin Zhou ◽

Xihua Zhou ◽

Bing Li

Keyword(s):

Sedimentary Basin ◽

Gravity Data ◽

Basin Analysis ◽

Airborne Gravity ◽

Bohai Bay ◽

Bohai Bay Basin

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Quasi Geoid and Geoid Modeling with the Use of Terrestrial and Airborne Gravity Data by the GGI Method—A Case Study in the Mountainous Area of Colorado

Remote Sensing ◽

10.3390/rs13214217 ◽

2021 ◽

Vol 13 (21) ◽

pp. 4217

Author(s):

Marek Trojanowicz ◽

Magdalena Owczarek-Wesołowska ◽

Yan Ming Wang ◽

Olgierd Jamroz

Keyword(s):

Gravity Data ◽

Research Work ◽

Airborne Gravity ◽

Mountainous Area ◽

Geoid Model ◽

Data Inversion ◽

Gravimetric Quasigeoid ◽

The Mean ◽

Grid Points

This article concerns the development of gravimetric quasigeoid and geoid models using the geophysical gravity data inversion technique (the GGI method). This research work was carried out on the basis of the data used in the Colorado geoid experiment, and the mean quasigeoid (ζm) and mean geoid (Nm) heights, determined by the approaches used in the Colorado geoid experiment, were used as a reference. Three versions of the quasigeoid GGI models depending on gravity data were analyzed: terrestrial-only, airborne-only, and combined (using airborne and terrestrial datasets). For the combined version, which was the most accurate, a model in the form of a 1′×1′ grid was calculated in the same area as the models determined in the Colorado geoid experiment. For the same grid, the geoid–quasigeoid separation was determined, which was used to build the geoid model. The agreement (in terms of the standard deviation of the differences) of the determined models, with ζm and Nm values for the GSVS17 profile points, was ±0.9 cm for the quasigeoid and ±1.2 cm for the geoid model. The analogous values, determined on the basis of all 1′×1′ grid points, were ±2.3 cm and ±2.6 cm for the quasigeoid and geoid models, respectively.

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On Downward Continuing Airborne Gravity Data for Local Geoid Modeling

10.5194/egusphere-egu21-2706 ◽

2021 ◽

Author(s):

Xiaopeng Li ◽

Jianliang Huang ◽

Martin Willberg ◽

Roland Pail ◽

Cornelis Slobbe ◽

...

Keyword(s):

Gravity Data ◽

Simulated Data ◽

Real Data ◽

Airborne Gravity ◽

Test Bed ◽

Collective Wisdom ◽

Resource Limitations ◽

Work Done ◽

Local Geoid

<p>The theories of downward continuation (DC) have been extensively studied for many decades, during which many different approaches were developed. In real applications, however, researchers often just use one method, probably due to resource limitations or to finish their work, without a rigorous head-to-head comparison with other alternatives. Considering that different methods perform quite differently under various conditions, comparing results from different methods can help a lot for identifying potential problems when dramatic differences occur, and for confirming the correctness of the solutions when results converge together, which is extremely important for real applications such as building official national vertical datums. This paper gives exactly such a case study by recording the collective wisdom recently developed within &#160;the IAG&#8217;s study group SC2.4.1. A total of six normally used DC methods, which are SHA (NGS), LSC (DTU Space), Poisson and ADC (NRCan), RBF (DU Delft), and RLSC (TUM), are applied to both simulated data (in the combination of two sampling strategies with three noise levels) and real data in a Colorado-area test bed. The data are downward continued to both surface points and to the reference ellipsoid surface. The surface points are directly evaluated with the observed gravity data on the topography. The ellipsoid points are then transformed into geoid heights according to NRCan&#8217;s Stokes-Helmert&#8217;s scheme and eventually evaluated at the GNSS/Leveling benchmarks. In this presentation, we will summarize the work done and results obtained by the aforementioned workgroup.</p>

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Airborne geoid mapping of land and sea areas of East Malaysia

Journal of Geodetic Science ◽

10.1515/jogs-2017-0010 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 3

Author(s):

H. Jamil ◽

M. Kadir ◽

R. Forsberg ◽

A. Olesen ◽

M. N. Isa ◽

...

Keyword(s):

Spherical Harmonic ◽

Tide Gauge ◽

Gravity Data ◽

Airborne Gravity ◽

Gravimetric Geoid ◽

Spherical Harmonic Degree ◽

Vertical Datum ◽

East Malaysia ◽

Marine Areas ◽

Airborne Survey

AbstractThis paper describes the development of a new geoid-based vertical datum from airborne gravity data, by the Department of Survey and Mapping Malaysia, on land and in the South China Sea out of the coast of East Malaysia region, covering an area of about 610,000 square kilometres. More than 107,000 km flight line of airborne gravity data over land and marine areas of East Malaysia has been combined to provide a seamless land-to-sea gravity field coverage; with an estimated accuracy of better than 2.0 mGal. The iMAR-IMU processed gravity anomaly data has been used during a 2014-2016 airborne survey to extend a composite gravity solution across a number of minor gaps on selected lines, using a draping technique. The geoid computations were all done with the GRAVSOFT suite of programs from DTU-Space. EGM2008 augmented with GOCE spherical harmonic model has been used to spherical harmonic degree N = 720. The gravimetric geoid first was tied at one tide-gauge (in Kota Kinabalu, KK2019) to produce a fitted geoid, my_geoid2017_fit_kk. The fitted geoid was offset from the gravimetric geoid by +0.852 m, based on the comparison at the tide-gauge benchmark KK2019. Consequently, orthometric height at the six other tide gauge stations was computed from H

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