Three-dimensional Gravity Inversion Research Articles

Three-Dimensional Gravity Inversion Based on Attention Feature Fusion.

Three-dimensional gravity inversion is a process of obtaining the location, shape, and physical property parameters of underground anomaly sources using gravity anomaly data observed on the surface. In recent years, with the rapid development of data-driven methods, the application of deep learning (DL) to 3D gravity inversion has also attracted wide attention and achieved certain results. In this paper, based on the U-Net network, a three-dimensional gravity inversion method using an attention feature fusion mechanism is proposed. Using U-Net as the basic framework, the coarse-grained semantic features and fine-grained semantic features in the encoder and decoder are connected by long hops, and the global and local semantic features are aggregated through the attention feature fusion module, which avoids feature loss in the network training process. Compared with the inversion results of the U-Net network, the proposed method has a higher vertical resolution and effectively alleviates the influence of the skin effect on three-dimensional gravity inversion. Ablation experiments show that the attention feature fusion module is the key to improving the vertical resolution and prediction accuracy of inversion results. Noise experiments show that the inversion network in this study has a strong anti-noise ability and good generalization performance. The experimental results of the inversion network used in the prediction of the SAN Nicolas deposit in Mexico show that the inversion network can clearly predict the basic location and general shape of the sulfur deposit, and the results are in good agreement with the known geological data.

Delineating subbasins of sedimentary rock structure beneath eastern Central Sumatra Basin based on gravity model, seismic profiles, and well-log data: A case study

The Central Sumatra Basin is a vast sedimentary basin that has been proven to produce hydrocarbon. The basin comprises several subbasins that are not sufficiently imaged by conventional seismic reflection profiles and limited well-log data, particularly in the nearshore area to the east. This research aims to delineate sedimentary subbasins, interpret the subsurface geologic model, and identify geologic structures beneath the eastern part of the Central Sumatra Basin using integrated geophysical gravity, seismic profiles, and well-log data. Three-dimensional gravity inversion modeling results indicate that the pre-Tertiary granitic basement is a continental crust with a mass density value of 2.67 gr/cc. The modeling results indicate that the sedimentary rock is composed of Early Oligocene–Middle Miocene sedimentary rock, with a mass density of 2.35 gr/cc, arranged from bottom to top. The residual gravity anomaly model identifies 13 sedimentary subbasins with structural features such as basement height, graben, and fault mapped in a relatively northwest–southeast direction. Moreover, based on the graben pattern and the basement high beneath the eastern Central Sumatra Basin, many structural patterns support the development of petroleum systems similar to that of the western part of the basin, which has already produced hydrocarbon. Our research also revealed the thickness of the Sihapas Formation in the eastern part of the basin, which shows great potential as a hydrocarbon reservoir. The results show that integrated analysis of many geophysical data sets can substantially decrease the uncertainty associated with individual data sets and produce more reliable imaging of subsurface geology.

A constrained 3D gravity inversion for complex density distributions: Application to Brazil rifted continental margin

Gravity inversion is a highly effective method for investigating regional geological structures, and this paper proposes an optimization scheme for constrained three-dimensional (3D) gravity inversion to obtain a 3D density model, utilizing prior geological and geophysics information. Specifically, the proposed method enhances deep structural imaging resolution and minimizes false structures by progressively inverting deep and shallow-density structures using long and short-wavelength signals of gravity anomaly with prior information. The scheme is applied in the southeast passive continental margin of Brazil, and the results show that the density model is consistent with the previous reflection and refraction seismic data. Moreover, the 3D density model reveals several insights: (i) The Abimael Ridge (AR) and the São Paulo Plateau (SPP) exhibit thin crustal thickness (∼5–7 km) indicative of proto-oceanic crust. The SPP and AR area crustal thinning may be related to an aborted opposing rift propagator pair. (ii) The rifting modes of Santos and Campos Basins differ significantly. Campos Basin exhibits a depth-dependent lithospheric stretching model with a relatively intact upper crust. In contrast, Santos Basin shows a highly brittle upper crust that is partially thinned and, in some regions, even absent under the far-field effect of spreading failed rifts, while the lower crust remains relatively intact. Moreover, the upper crustal stretching factor is about five to ten higher than the lower crustal. Thus, the constrained 3D gravity inversion scheme provides a new avenue for continental rifted margin geological structure studies.

Three-dimensional constrained gravity inversion of Moho depth and crustal structural characteristics at Mozambique continental margin

Three-dimensional constrained gravity inversion of Moho depth and crustal structural characteristics at Mozambique continental margin

3D gravity inversion based on mixed-norm regularization in spherical coordinates with application to the lunar Moscoviense Basin

Three-dimensional gravity inversion has been widely used to infer density structures and tectonic movements of the earth and Moon. However, two problems (the nonuniqueness and low depth resolution) of current gravity inversion methods still exist and are not completely resolved, which affect the reliability of the inversion results and the corresponding geologic interpretation. To improve the depth resolution of the 3D gravity inversion, we propose an efficient inversion method in spherical coordinates based on a mixed smooth and focused regularization with depth-weighting functions. In the inversion, we also use the kernel matrix equivalence strategy and the fast kernel-vector multiplication method based on a fast Fourier transform in each iteration to increase computational efficiency. Two synthetic inversion examples indicate that the proposed method can recover more complex density structures compared with the often used smooth-constraint inversion approach. Finally, the proposed inversion approach is applied to the latest lunar gravitational field model GL1500E to study the 3D density structures of the Moscoviense Basin. The inverted results indicate that the density structure with high-positive anomalies is principally distributed at depths ranging from 5 to 70 km, forming a giant asymmetrical high-density structure inclining from the southwest to the northeast. We may conclude that the Moscoviense Basin was formed by the double impact, where the second collision occurred in the southwest of the basin center of the first collision.

Study on Geothermal Genesis Mechanism and Model in the Western Margin of Ordos Basin

Among so many fault basins around Ordos presenting good geothermal background, Yinchuan Plain is the key development and protection area of the Ecological and Economic Belt along the Yellow River in Ningxia and Yinchuan Metropolitan Area. The study of geothermal resources in this region is of great significance to the sustainable economic development of Yinchuan Plain. Most scholars suggested that Yinchuan Plain geothermal resources are low-to-medium temperature geothermal resources and have high value in terms of development and utilization due to their large reserves, good water quality conditions, and wide distribution. However, there is much controversy over the geothermal mechanism of this region. As an effective means to study geothermal mechanism, geophysical methods can be used to study regional basement uplift and structural distribution characteristics. Based on the discussion of regional geothermal geology background, this paper studies the distribution rules of Moho and Curie depths in the region by applying different geophysical data. The results show that the western margin of Yinchuan Plain is obviously uplifted. As inferred from the epicentral distribution of Yinchuan Plain section, there is a significant difference of the seismic bottom interface on the east and west sides of the Yellow River fault in Yinchuan Plain. The three-dimensional gravity inversion confirms basement uplift in this region. By referring to results obtained by the inversion of gravity and magnetic data and deep seismic exploration, the paper presents a comprehensive analysis of the regional geothermal geology conditions and proposes a geothermal conceptual model of Yinchuan Plain. The heat source comes from the earth heat flow and migrates to the thermal reservoir through the fault or fissure convection. The deep-large active faults provide a channel for deep heat flow to the shallow part, and the thermal fluid accumulates in the uplift area to form the high geothermal anomaly area. There should be two large-scale geological activities in the geotropics around Ordos. One is the basement uplift of the basins around Ordos platform, which provide the heat source. The other is the uplift of Ordos, which places the surrounding basin in an extensional environment and provides a channel for the heat source upwelling.

Three-dimensional direct gravity inversion for Moho and basement depths of the Tuchinh-Vungmay basin, offshore southeast Vietnam, incorporating a lithosphere thermal gravity anomaly correction

This paper presents the determination of the Moho and basement depths of Tuchinh-Vungmay basin (TCVMB) offshore southeastern Vietnam by the three dimension direct gravity inversion. The Moho depth was predicted from the mantle residual gravity anomaly with the lithosphere thermal gravity correction. The downward continuation of the basement residual gravity anomaly is also applied to enhance the basement topography’s resolution. The mean depths of the basement and Moho surfaces were constrained by the power density spectrum (PDS) of the residual gravity anomalies and the oceanic bottom seismic (OBS) data. The predicted Moho depth varies from 13.5 km to 23 km and the basement depth is from some hundred meters to 8.5 km. The gravity basement topography has higher resolution and detail than the National Oceanic and Atmospheric Administration (NOAA) seismic basement.

Gravity inversion for crustal thickness investigation of the continental and oceanic crusts of Brazil incorporating a lithosphere thermal gravity anomaly correction

The application of potential field methods in regional geophysical studies with orbital data has proven helpful in identifying, modeling, and dimensioning structural features and geophysical signatures in regions of interest. Potential field data, particularly those from gravity satellites, are robust and have a high resolution for regional studies. Therefore, gravity data enable in-depth identification of information from low-frequency sources, interpreted as features with relevant geotectonic significance. Furthermore, by containing wavelengths from low-frequency sources, these data allow investigation of lithospheric depths. However, it is necessary to apply thermal correction because gravity data are affected by thermal anomalies present in the lithosphere. Thus, the greater precision/robustness is attributed to these extensive and heterogeneous areas onshore. In this context, data from the compilation World Gravity Map – 2012 were applied to evaluate the density variation of features in depth and obtain the crust-mantle limit. The three-dimensional (3D) gravity inversion with seismic and seismological constraints was applied to obtain the crust-mantle limit for the onshore and offshore regions of Brazil. Furthermore, our objective was to apply and evaluate a gravity inversion methodology with seismic data constraints for the onshore portion of Brazil, which has an exotic and rich geological setting. The onshore portion is covered by seismographic stations, but has sparse coverage areas, mainly in the Amazonian Craton. In addition, the scarcity of seismic refraction data in the national territory makes it impossible to detail the structure of the base of the crust or lithosphere in a spatialized manner. To obtain the crust-mantle limit, the inversion permits corrections, such as topographic effects, the gravity effect of sediments, and the thermal gravity anomaly correction, which interferes with the investigation of crustal thickness using gravity data. Thus, it was possible to observe shallow Moho depths (∼10 km) in the offshore portion and deep (∼50 km) in the cratonic regions onshore, equivalent to the depths provided by the deep refraction seismic and receiver function data. Therefore, from the gravity inversion, it was possible to obtain the 3D depth of the Moho, adding information to the seismic interpretations, with the possibility of observing 3D features and profiles that present a resolution compatible with the seismic data. Moreover, we interpreted areas with obliterated signatures owing to thermal anomalies in the heterogeneous continental lithosphere.

Three-dimensional gravity inversion based on optimization processing from edge detection

Gravity inversion requires much computation, and inversion results are often non-unique. The first problem is often due to the large number of grid cells. Edge detection method, i.e., tilt angle method of analytical signal amplitude (TAS), helps to identify the boundaries of underground geological anomalies at different depths, which can be used to optimize the grid and reduce the number of grid cells. The requirement of smooth inversion is that the boundaries of the meshing area should be continuous rather than jagged. In this paper, the optimized meshing strategy is improved, and the optimized meshing region obtained by the TAS is changed to a regular region to facilitate the smooth inversion. For the second problem, certain constraints can be used to improve the accuracy of inversion. The results of analytic signal amplitude (ASA) are used to delineate the central distribution of geological bodies. We propose a new method using the results of ASA to perform local constraints to reduce the non-uniqueness of inversion. The guided fuzzy c-means (FCM) clustering algorithm combined with priori petrophysical information is also used to reduce the non-uniqueness of gravity inversion. The OpenAcc technology is carried out to speed up the computation for parallelizing the serial program on GPU. In general, the TAS is used to reduce the number of grid cells. The local weighting and priori petrophysical constraint are used in conjunction with the FCM algorithm during the inversion, which improves the accuracy of inversion. The inversion is accelerated by the OpenAcc technology on GPU. The proposed method is validated using synthetic data, and the results show that the efficiency and accuracy of gravity inversion are greatly improved by using the proposed method.

Three-Dimensional Gravity Inversion in the Presence of the Sediment-Basement Interface: A Case Study in Utah, USA

We introduce a novel approach to three-dimensional gravity inversion in the presence of the sediment-basement interface with a strong density contrast. This approach makes it possible to incorporate the known information about the basement depth in the inversion. It also allows the user to determine the depth-to-basement in the initial inversion phase. One can then use this interface to constrain the final inversion phase. First, the inversion generates the depth-to-basement model based on the 3D Cauchy-type integral representation of the gravity field. Then, in the second phase, full 3D voxel-type inversion applies the depth-to-basement model determined in the first phase as an a priori constraint. We use this approach to the 3D inversion of the Bouguer gravity anomaly data observed in Utah, USA. The results of inversion generated a 3D density model of the top layers of the earth’s crust, including unconsolidated sediments and the top of the crystalline basement.

Imaging crustal features and Moho depths through enhancements and inversion of gravity data from the Philippine island arc system

The Philippine archipelago is a complex island arc system, where many regions still lack geopotential field studies. The high-resolution isostatic anomaly and free-air anomaly digital grids from the World Gravity Map (WGM) were processed and analyzed to present a general discussion of the Philippines’ gravity signatures and contribute to understanding its regional geology and tectonics. The isostatic anomaly map was continued upward to investigate the high-density ophiolitic basement rocks and low-gravity sedimentary basins at depth. The first vertical derivative (1VD) filter was applied to the free-air anomaly grid map to locate regional structures represented by density contrast boundaries. The depth to the top of the Moho and basement rock over the Sulu Sea was computed using the two-dimensional (2-D) radially averaged power spectrum analysis. Three-dimensional (3-D) gravity inversion was applied to some major sedimentary basins in the Philippines to present 3-D subsurface density contrast models. The interpreted gravity maps highlighted prominent geologic features (e.g., trench manifestation, ophiolite distribution, basin thickness). The negative isostatic anomalies (< 0 mGal) represent the thick sedimentary basins, while the moderate signatures (0 to 80 mGal) correspond to the metamorphic belts. The distinct very high-gravity anomalies (> 80 mGal) typify the ophiolitic basement rocks. The gravity data’s upward continuation revealed contrasting deep gravity signatures; the central Philippines with continental affinity (with 20–35 mGal) was distinguished from the regions with oceanic affinity (with 45–200 mGal). The 1VD map over the Sulu Sea showed anomalies associated with shallow features dominantly related to the Cagayan Ridge. The 2-D radially averaged power spectrum analysis exposed gravity anomalies with tectonic significance (e.g., basement characterization, Moho depth estimation). The estimated average Moho depth in the Sulu Sea is from 12 to 22 km, while the average basement depth is within the range of 5 to 11 km. Lastly, the 3-D subsurface density contrast models characterized the very low-density zones representing the deep (> 7 km) sedimentary basins in the northern Cagayan Valley and southern Central Luzon basins. Furthermore, thin (~ 3.5 km) sedimentary formations are inferred for the low-density areas in northern Agusan-Davao and eastern Cotabato basins.

Deep Learning for 3-D Inversion of Gravity Data

Three-dimensional (3-D) gravity inversion obtains the density distribution of subsurface geological bodies through observed gravity anomalies. Recently, data-driven methods based on deep neural networks (DNNs) have received considerable attention for geophysical inverse problems. They proved to be superior to physics-driven methods that suffer from nonuniqueness issues and high computational costs. Several deep-learning inversion strategies have been developed for geophysical modeling and are mainly applicable for two-dimensional (2-D) subsurface imaging. Despite their effectiveness, deep-learning inversions suffer from appropriate generalization to new case scenarios. In this study, a novel 3-D gravity inversion method based on encoder–decoder neural networks is proposed. The network has a gravity field encoder for 2-D gravity field feature extraction, a dimension transformation module for feature space transformation, and a density structure decoder for 3-D density structure reconstruction. A highly random dataset is constructed to enlarge the feature distribution space of the samples and perform hyper-parameter experiments to improve the accuracy and generalisability of the network. Numerical examples using synthetic gravity data show that the accuracy of the network can reach 97% in the entire area and 81.5% in the area of density structures while reducing the computational time by 20 times. In the experiments on real data of the Vinton salt dome, the results are in good agreement with the known geological information. Our method significantly improves the inversion accuracy and generalisability of 3-D gravity inversion and can be applied in real case scenarios with less computational time.

Three-dimensional gravity inversion based on 3D U-Net++

Three-dimensional gravity inversion based on 3D U-Net++

Subsurface structure investigation of the United Arab Emirates using gravity data

AbstractThe crustal structure beneath the United Arab Emirates (UAE) is still relatively unknown. Here, we use regional gravity data to constrain the subsurface density distribution and structure of the crust of the UAE by applying diverse gravity derivatives methods such as horizontal derivative (HDR), analytic signal (AS), and tilt angle (TA) to analyze the subsurface structure and perform three-dimensional (3D) gravity inversion for imaging crustal structure from the surface down to 35 km depth. The results are compared with known geological regional structures and the location of the petroleum fields.The Bouguer anomalies range from −100.8 to 113.5 mGal. The 3D gravity inversion results and the maximum Bouguer values coincide with the ophiolitic Hajar mountains in the east and the successive anticlines (uplifted basement rocks) and synclines in different parts of UAE, which could be promising sites for future mining and petroleum exploration. Also, the 3D density model results and the minimum Bouguer anomalies are located over the Aruma Basin, eastern UAE Platform, and Low Central UAE Platform, which can be the places for deep groundwater aquifers. These new results from HDR, AS, and TA successfully identify known geological structures, especially in the eastern part of UAE.

Crustal Density Inversion and Its Tectonic Structure in Badong-Zigui Area

Objectives The Badong-Zigui Basin is located in the west of the Three Gorges area, and it is surrounded by four different tectonic units: With the Xuefengshan thick-soil tectonic belt on the south, the Qinling orogenic belt on the north, the Huangling anticline on the east, and the eastern extension of the Sichuan Basin in the west. The Badong-Zigui basin is a north-south syncline structure, the sediments in the basin are dominated by Late Triassic-Late Turassic argillaceous rocks, and the special tectonic setting causes strong tectonic activities in the basin. Methods Using a three-dimensional gravity inversion algorithm based on Lagrangian multiplier constraints, the local Bouguer gravity anomaly in Badong-Zigui area is inverted, and the underground three-dimensional density structure of Badong-Zigui and adjacent areas is obtained. Results The inversion results show that the Zigui Basin is a low-density area compared with the surrounding area. The sedimentation thickness in the east is deeper than that in the west, and the sediment density is lower than that in the west. The small and medium earthquakes in the area are basically 4-12 km underground. Conclusions The north-south and north-east ancient water flows in the northern edge of the Zigui Basin successively provide sources for the sedimentation and filling of the basin, forming a structure with lower material density and deeper deposits in the eastern part of the basin; low-density materials in the east are transported and accumulated to the west in the basin. At the same time, it is squeezed by the eastward extension of the Sichuan Basin, and it is speculated that there is a tendency of east-west movement and compression in the basin.

Sedimentary basement structure of the Southwest Sub-basin of the East Vietnam Sea by 3D direct gravity inversion

In this paper, we present a procedure based on Parker’s three-dimensional direct gravity inversion to determine the sedimentary basement depth rapidly and objectively. In the foregoing procedure, the Bouguer gravity anomaly is continued downward near the seabed before inversion, and the mean depth of the basement is constrained by the power density spectrum of the gravity anomaly. The bulk density of sediment and basalt rocks are also constrained by the logging data obtained from Expedition 349 Scientists (Expedition 349 Scientists, in: International Ocean Discovery Program Preliminary Report, 349, (2014). doi:10.14379/iodp.pr.349.2014). The sedimentary basement depth of the Southwest Sub-basin (SWSB) of the East Vietnam Sea (South China Sea) derived from the inversion of the downward continued Bouguer anomalies has more detail and accuracy than the sediment basement depth inverted from Bouguer anomaly at the sea level. The calculated basement depth and the sedimentary thickness in the SWSB vary from 4.0 to 6.5 km and from 0.5 to 2.0 km, respectively. The crustal thickness beneath the SWSB ranges from 4.0 to 7.5 km. Our model is consistent with sedimentary basin structure where spreading ridge valley is presented as the deepest points in the sedimentary basement and the terrain along the two banks of the valley is elevated. In addition, the SWSB is divided into four structure domains that are useful for the geodynamic and tectonic implications of the SWSB and surrounding area.

Three-dimensional gravity inversion based on sparse recovery iteration using approximate zero norm

This research proposes a novel three-dimensional gravity inversion based on sparse recovery in compress sensing. Zero norm is selected as the objective function, which is then iteratively solved by the approximate zero norm solution. The inversion approach mainly employs forward modeling; a depth weight function is introduced into the objective function of the zero norms. Sparse inversion results are obtained by the corresponding optimal mathematical method. To achieve the practical geophysical and geological significance of the results, penalty function is applied to constrain the density values. Results obtained by proposed provide clear boundary depth and density contrast distribution information. The method’s accuracy, validity, and reliability are verified by comparing its results with those of synthetic models. To further explain its reliability, a practical gravity data is obtained for a region in Texas, USA is applied. Inversion results for this region are compared with those of previous studies, including a research of logging data in the same area. The depth of salt dome obtained by the inversion method is 4.2 km, which is in good agreement with the 4.4 km value from the logging data. From this, the practicality of the inversion method is also validated.

Three-dimensional gravity inversion using automatic regional-residual components separation with application to the Iwaki area in Fukushima Prefecture, Japan

We have developed a simple method for analysing gravity data to define 3D subsurface structures consistent with geological maps and reflection seismic survey results. This new method makes it possible to automatically separate gravity anomalies caused by structures that are the target of analysis (residual gravity) and not subject to gravity anomaly analysis (trend surfaces or regional gravity variations). This separation is achieved by assuming that the gravity anomaly trend surface is extremely smooth prior to analysis. In addition, this analysis can be carried out automatically, so it is possible to use a boot-strap simulation to evaluate the effect that gravity data accuracy and survey point distribution have on the analysis results. Using this newly developed method, we conducted a 3D subsurface structural analysis based on newly obtained gravity survey data in an area around Iwaki City, Fukushima Prefecture. The results of the 3D structural analysis revealed sharp depressions in the basement rock and basin-shaped underground structures along the Yunodake and Yamada faults. Finally, we were able to estimate the influence of survey point distribution and abrupt changes in the structure on the analysis results using a boot-strap simulation of the 3D analysis.

Gravity compression forward modeling and multiscale inversion based on wavelet transform

The main problems in three-dimensional gravity inversion are the non-uniqueness of the solutions and the high computational cost of large data sets. To minimize the high computational cost, we propose a new sorting method to reduce fluctuations and the high frequency of the sensitivity matrix prior to applying the wavelet transform. Consequently, the sparsity and compression ratio of the sensitivity matrix are improved as well as the accuracy of the forward modeling. Furthermore, memory storage requirements are reduced and the forward modeling is accelerated compared with uncompressed forward modeling. The forward modeling results suggest that the compression ratio of the sensitivity matrix can be more than 300. Furthermore, multiscale inversion based on the wavelet transform is applied to gravity inversion. By decomposing the gravity inversion into subproblems of different scales, the non-uniqueness and stability of the gravity inversion are improved as multiscale data are considered. Finally, we applied conventional focusing inversion and multiscale inversion on simulated and measured data to demonstrate the effectiveness of the proposed gravity inversion method.

Crustal structure of Baffin Bay from constrained three-dimensional gravity inversion and deformable plate tectonic models

Mesozoic to Cenozoic continental rifting, breakup and spreading between North America and Greenland led to the opening, from south to north, of the Labrador Sea and eventually Baffin Bay between Baffin Island, northeast Canada and northwest Greenland. Baffin Bay lies at the northern limit of this extinct rift, transform and spreading system and remains largely underexplored. With the sparsity of existing crustal-scale geophysical investigations of Baffin Bay, regional potential field methods and quantitative deformation assessments based on plate reconstructions provide two means of examining Baffin Bay at the regional scale and drawing conclusions about its crustal structure, its rifting history and the role of pre-existing structures in its evolution. Despite the identification of extinct spreading axes and fracture zones based on gravity data, insights into the nature and structure of the underlying crust have only been gleaned from limited deep seismic experiments, mostly concentrated in the north and east where the continental shelf is shallower and wider. Baffin Bay is partially underlain by oceanic crust with zones of variable width of extended continental crust along its margins. 3-D gravity inversions, constrained by bathymetric and depth to basement constraints, have generated a range of 3-D crustal density models that collectively reveal an asymmetric distribution of extended continental crust, approximately 25–30 km thick, along the margins of Baffin Bay, with a wider zone on the Greenland margin. A zone of 5–13 km thick crust lies at the centre of Baffin Bay, with the thinnest crust (5 km thick) clearly aligning with Eocene spreading centres. The resolved crustal thicknesses are generally in agreement with available seismic constraints, with discrepancies mostly corresponding to zones of higher density lower crust along the Greenland margin and Nares Strait. Deformation modelling from independent plate reconstructions using GPlates of the rifted margins of Baffin Bay was performed to gauge the influence of original crustal thickness and the width of the deformation zone on the crustal thicknesses obtained from the gravity inversions. These results show the best match with the results from the gravity inversions for an original unstretched crustal thickness of 34–36 km, consistent with present-day crustal thicknesses derived from teleseismic studies beyond the likely continentward limits of rifting around the margins of Baffin Bay. The width of the deformation zone has only a minimal influence on the modelled crustal thicknesses if the zone is of sufficient width that edge effects do not interfere with the main modelled domain.