Age of the source of the Jarrafa gravity and magnetic anomalies offshore Libya and its geodynamic implications

Reeh, Giuma; Aı̈fa, Tahar

doi:10.1016/j.jog.2008.01.001

Cited by 8 publications

(2 citation statements)

References 23 publications

(25 reference statements)

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“…The transform essentially consists of a Reduction to Pole operation to centre the magnetic anomaly over its causative body and a vertical integration to simplify the anomaly such that the pseudogravity anomaly due to a uniformly, induced magnetised body has the same shape as the gravity anomaly due to the same uniform density body. Pseudo-gravity has been used to map contacts (Pilkington, 2007), as an alternative domain for comparing observed and modelled magnetic fields (Kimbell et al, 2010) or for direct comparison of gravity and magnetic anomalies (Reeh and Aïfa, 2008). The pseudo-gravity can be analysed and modelled in the same manner as gravity data, but it remains a magnetic anomaly and can only be interpreted in terms of magnetisation (or susceptibility as induced magnetisation is effectively assumed).…”

Section: Introductionmentioning

confidence: 99%

Mapping basement relief of Abu Gharadig Basin, Western Desert of Egypt using 3D inversion of pseudo-gravity data

Salem

Green

Fairhead

et al. 2012

ASEG Extended Abstracts

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Section: Introductionmentioning

confidence: 99%

Mapping basement relief of Abu Gharadig Basin, Western Desert of Egypt using 3D inversion of pseudo-gravity data

Salem

Green

Fairhead

et al. 2012

ASEG Extended Abstracts

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“…The pseudogravity is thus essentially the same as the magnetic potential for a vertical magnetic field. Pseudogravity has been used to map contacts (Fairhead et al, 2004;Pilkington, 2007), as an alternative domain for comparing observed and modeled magnetic fields (Kimbell et al, 2010) or for direct comparison of gravity and magnetic anomalies (Reeh and Aifa, 2008). The pseudogravity can be analyzed and modeled in the same manner as gravity data, but it remains a magnetic anomaly and can only be interpreted in terms of magnetization distribution.…”

Section: Introductionmentioning

confidence: 99%

Mapping the depth to magnetic basement using inversion of pseudogravity: Application to the Bishop model and the Stord Basin, northern North Sea

et al. 2014

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Magnetic depth estimation methods are routinely used to map the depth of sedimentary basins by assuming that the sediments are nonmagnetic and underlain by magnetic basement rocks. Most of these methods generate basement depth estimates at discrete points. Converting these depth estimates into a grid or map form often requires the application of qualitative methods. The reason for this is twofold: first, in deeper parts of basins, there is generally a scarcity of depth estimates and those that have been determined tend to be biased toward the shallower basement structures close to the basin edge; and second, depth estimates intrinsically relate to magnetic anomalies that emanate from the top edges of basement faults/contacts resulting in a shallow depth bias. Thus, simple grid interpolation of these depth estimates often forms a shallower and structurally unrepresentative map when evaluated in detail. To overcome these problems of qualitative and/or simple grid interpolation of these point-depth estimates into a regular grid, we use the pseudogravity field transform response of the magnetic field to constrain this interpolation using inversion methods together with the relationship between the point-depth estimates and their pseudogravity values. The pseudogravity transformation converts a grid of magnetic data such that the resulting grid has the same simple relationship to magnetic susceptibility that a gravity grid has to density. The pseudogravity map is thus straightforward to visualize in terms of basement structure, but it only maps the magnetic properties of the subsurface and is not related to the gravity anomaly or the density. We describe a practical approach to invert pseudogravity grids using gravity inversion software to produce a 3D basin model assuming a constant susceptibility basement. The approach is initially tested on the Bishop 3D model and then applied to an example from the northern North Sea. This approach can be considered complementary to 3D gravity inversion and has the advantage that the pseudogravity response is not affected by structure within the sediments or effects such as sediment compaction, inversion, or isostatic compensation, all of which often complicate the gravity response of sedimentary basins.

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Facies, depositional environments and drowning of Tethyan isolated carbonate platforms: the Paleogene carbonates of Malta

Gatt

2022

Facies

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Age of the source of the Jarrafa gravity and magnetic anomalies offshore Libya and its geodynamic implications

Cited by 8 publications

References 23 publications

Mapping basement relief of Abu Gharadig Basin, Western Desert of Egypt using 3D inversion of pseudo-gravity data

Mapping basement relief of Abu Gharadig Basin, Western Desert of Egypt using 3D inversion of pseudo-gravity data

Mapping the depth to magnetic basement using inversion of pseudogravity: Application to the Bishop model and the Stord Basin, northern North Sea

Facies, depositional environments and drowning of Tethyan isolated carbonate platforms: the Paleogene carbonates of Malta

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