Holleford gravity

Description

Gravity data from surveys of Holleford impact structures. Provided on the Geosoft database of Gravity data and the gravity grid from which modelling was derived for paper Armour, M.-H., Boyce, J.I., Shulman, Z. and Zilkey, D.R. (2024), 3-D geophysical modeling of a buried, simple impact crater: Holleford impact structure, Ontario, Canada. Meteorit Planet Sci, 59: 171-192. https://doi.org/10.1111/maps.14113

Steps to reproduce

Gravity measurements were acquired using a Lacoste and Romberg G128 land gravity meter and Scintrex CG-5 auto-levelling gravimeter. A total of 74 gravity stations were measured at 150-200 m intervals adjacent to roadways and along two transects within the crater basin.. Diurnal and tidal gravity variations were recorded by re-occupation of a base station at 2-3 hr intervals. The station positions and elevations were measured using a D-GPS (Promark 3) with a horizontal and vertical positional error of <1 cm. Gravity data reduction included corrections for instrument drift, tidal variation, free-air, and Bouguer cap using the methods outlined by Holoum and Oldow (2007). The absolute Bouguer gravity was calculated with reference to measurements at a Canadian Gravity Standardization Network station (CGSN 9907-1999) located 30 km to the east at Gananoque. The new observations were merged with available vintage gravity data from Beals, (1960). and levelled using a linear correction factor established where points from the two data sets overlapped. In a final step, the merged data were terrain corrected in Geosoft Oasis using a high-resolution (2-m graticule) digital elevation model (DEM) (LIO, 2014). Both the Bouguer cap and terrain corrections employed a density value of 2.67 gcm-3. The terrain-corrected Bouguer gravity data were gridded and interpolated using ordinary Kriging with a 100 m grid cell size . Beals C.S. 1960. A probable meteorite crater of Precambrian age at Holleford, Ontario. Publications of the Dominion Observatory 24:6 (Ottawa) https://doi.org/10.4095/8727 Holoum D. I. and Oldow J. S. 2007. Gravity reduction spreadsheet to calculate the Bouguer anomaly using standardized methods and constants. Geosphere 3(2): 86-90. https://doi.org/10.1130/GES00060.1 LIO 2014. Digital Raster Acquisition Project Eastern (DRAPE) Ontario (2014). Land Information Ontario, Ontario. https://geohub.lio.gov.on.ca/documents/digital-raster-acquisition-project-eastern-ontario-drape-2014/about

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