The New Gravity System: Changes in International Gravity Base Values and Anomaly Values

Woollard, George P.; Godley, Valerie M.

doi:10.21236/ada095615

Cited by 5 publications

(4 citation statements)

References 5 publications

(13 reference statements)

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“…This included on July 30, 2015 gsabulletin.gsapubs.org Downloaded from making latitude, free-air, vertical acceleration, and Eötvös corrections (Harlan, 1968;Woollard, 1979) based on differential, carrier-phase, kinematic global positioning system (GPS) positional data (Mader, 1992). In addition to the standard processing steps, mentioned previously, a correction was made for gravimeter reading errors caused by the platform tilting, when it was subjected to horizontal accelerations (Swain, 1996).…”

Section: Survey Design and Data Reductionmentioning

confidence: 99%

Aerogravity evidence for major crustal thinning under the Pine Island Glacier region (West Antarctica)

Jordan

Ferraccioli

Vaughan

et al. 2009

Geological Society of America Bulletin

133

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Section: Survey Design and Data Reductionmentioning

confidence: 99%

Aerogravity evidence for major crustal thinning under the Pine Island Glacier region (West Antarctica)

Jordan

Ferraccioli

Vaughan

et al. 2009

Geological Society of America Bulletin

133

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“…Latitude, Eotvos and free air corrections were taken to obtain the free air gravity anomalies (Fig. 3b) (Harlan, 1968; Woollard, 1979). Differential, carrier phase, kinematic, GPS methods provided all the navigational information used in these corrections (Mader, 1992).…”

Section: Aerogravity Survey and Data Processingmentioning

confidence: 99%

Subglacial imprints of early Gondwana break‐up as identified from high resolution aerogeophysical data over western Dronning Maud Land, East Antarctica

et al. 2005

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Determining the location and geometry of possible subglacial rifts in western Dronning Maud Land is a key element to address processes leading to early Gondwana break‐up. However, previous geophysical investigations did not lead to unambiguous delineation of rift structures over this region. We interpret high‐resolution airborne radar and aerogravity data to image subglacial rift structures. Subglacial topography, free‐air and Bouguer gravity maps, coupled with 3D inverse gravity models, image a rift–rift–rift triple junction at the intersection of the Jutulstraumen ice stream and the Pencksökket glacier. These continental rifts were associated with alkaline and tholeiitic intrusions, minor dyke swarms and flood basalts of Jurassic age, but not with huge volumes of Karoo magmatism, such as that which characterizes the southern Africa conjugate margin. The western Dronning Maud Land triple junction may be linked to the Karoo mantle plume and represents an early stage of magmatism and rifting during Gondwana break‐up.

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“…Originally, these data were tied to the Postdam gravity reference. Following Woollard & Godley (1980), we converted them to IGSN 71. Van de Meulebrouck (1983) estimates their accuracy to be between 3 and 7 mgal.…”

Section: Datamentioning

confidence: 99%

Gravity anomalies, crustal structure and thermo-mechanical support of the Himalaya of Central Nepal

Cattin¹,

Martelet

Henry³

et al. 2001

Geophysical Journal International

111

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Summary We use two gravity profiles that we measured across Central Nepal, in conjunction with existing data, to constrain the mechanical behaviour and the petrological structure of the lithosphere in the Himalayan collision zone. The data show (1) overcompensation of the foreland and undercompensation of the Higher Himalaya, as expected from the flexural support of the range; (2) a steep gravity gradient of the order of 1.3 mgal km−1 beneath the Higher Himalaya, suggesting a locally steeper Moho; and (3) a 10 km wide hinge in southern Tibet. We compare these data with a 2‐D mechanical model in which the Indian lithosphere is flexed down by the advancing front of the range and sedimentation in the foreland. The model assumes brittle Coulomb failure and non‐linear ductile flow that depends on local temperature, which is computed from a steady‐state thermal model. The computed Moho fits seismological constraints and is consistent with the main trends in the observed Bouguer anomaly. It predicts an equivalent elastic thickness of 40–50 km in the foreland. The flexural rigidity decreases northwards due to thermal and flexural weakening, resulting in a steeper Moho dip beneath the high range. Residuals at short wavelengths (over distances of 20–30 km) are interpreted in terms of (1) sediment compaction in the foreland (Δρ = 150 kg m−3 between the Lower and Middle Siwaliks); (2) the contact between the Tertiary molasse and the meta‐sediments of the Lesser Himalaya at the MBT (Δρ = 220 kg m−3); and (3) the Palung granite intrusion in the Lesser Himalaya (Δρ = 80 kg m−3). Finally, if petrological transformations expected from the local (P, T) are assumed, a gravity signature of the order of 250 mgal is predicted north of the Lesser Himalaya, essentially due to eclogitization of the lower crust, which is inconsistent with the gravity data. We conclude that eclogitization of the Indian crust does not take place as expected from a steady‐state local equilibrium assumption. We show, however, that eclogitization might actually occur beneath southern Tibet, where it could explain the hinge observed in the gravity data. We suspect that these eclogites are subducted with the Indian lithosphere.

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The New Gravity System: Changes in International Gravity Base Values and Anomaly Values

Cited by 5 publications

References 5 publications

Aerogravity evidence for major crustal thinning under the Pine Island Glacier region (West Antarctica)

Aerogravity evidence for major crustal thinning under the Pine Island Glacier region (West Antarctica)

Subglacial imprints of early Gondwana break‐up as identified from high resolution aerogeophysical data over western Dronning Maud Land, East Antarctica

Gravity anomalies, crustal structure and thermo-mechanical support of the Himalaya of Central Nepal

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