Surface Gravity Measurements Research Articles

Geological significance of surface gravity measurements in the vicinity of the Illinois Deep Drill Holes

A gravity study of northeastern Illinois and southwestern Wisconsin was undertaken to determine the three‐dimensional geometry of the Precambrian granitic body encountered in the Illinois deep drill holes. Gravity data acquired during this study and existing observations show a marked negative gravity anomaly in the vicinity of these drill holes which is interpreted as originating from a negative density contrast between the granitic body and the intruded crystalline rocks. A fifteenth‐order polynomial surface fitted to the Bouguer anomaly data (which includes only wave‐lengths greater than ∼35 km) was chosen as best displaying the effects of the granitic body, and profiles of this surface were modeled employing a variety of techniques and assumptions. The preferred model of the causitive body has a depth to the top of 2 km, a density contrast of −100 kg m−3, and a maximum vertical extent of 5 km. An isopach map of the body constructed from the modeling places the Illinois deep drill holes on the edge of an oval‐shaped mass.

Densities determined from surface and subsurface gravity measurements : Sissons, B A Geophysics, V46, N11, Nov 1981, P1568–1571

Densities determined from surface and subsurface gravity measurements : Sissons, B A Geophysics, V46, N11, Nov 1981, P1568–1571

The mass of the anomalous cepheid in the globular cluster NGC 5466

view Abstract Citations (37) References (31) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The mass of the anomalous cepheid in the globular cluster NGC 5466. Zinn, R. ; King, C. R. Abstract The effective temperature and surface gravity of the anomalous Cepheid V19 in NGC 5466 have been measured from spectrophotometric scans. The position of V19 in the θe -log g diagram rules out the possibilities that it is an RR Lyrae or a BL Herculis variable, which strengthens the already strong case that V19 is an unusual Cepheid variable and a member of NGC 5466. It had been shown earlier by Zinn and Dalin that V19 has the same radial velocity as NGC 5466 and a period (0.82 days) and luminosity (Mυ = -1.27) that are similar to those of the anomalous Cepheids in the dwarf spheroidal galaxies. Our observations of V19 have been compared with similar ones of three horizontal branch (HB) stars in NGC 5466 and the type c RR Lyrae variable TV Boo. The following mass ratios are obtained: M(V19)/(HB) = 1.64±0.76 and M(V19)/M(TV Boo) = 2.03±0.62. The surface gravity measurements indicate that V19 is pulsating in the first harmonic rather than the fundamental mode. Assuming the first harmonic mode for V19 and TV Boo, the Q = P<ρ>l/2 relation yields: M1(V19)/(TV Boo) = 2.33 ± 0.40. Thus, it appears that V19 is approximately twice as massive as HB stars. The Q = P<ρ>l/2 relation yields the most precise estimate for V19's mass, l.56+0.23-0.03 Msun, which is consistent with the theory that the large masses of the anomalous Cepheids result from the transfer of mass in close binary systems. Publication: The Astrophysical Journal Pub Date: November 1982 DOI: 10.1086/160462 Bibcode: 1982ApJ...262..700Z Keywords: Cepheid Variables; Globular Clusters; Stellar Mass; Stellar Oscillations; Variable Stars; Giant Stars; Horizontal Branch Stars; Stellar Gravitation; Stellar Temperature; Astrophysics full text sources ADS | data products SIMBAD (5)

On: “Densities determined from surface and subsurface gravity measurements,” by B. A. Sissons (Geophysics, v. 46, p. 1568–1571).

There is one point of general interest not mentioned by the author of this careful investigation. The final result was that the mean density determined by gravity measurements was 4 percent less than the mean yielded by sample measurements, and the author reasonably attributes this to voids not sampled by laboratory specimens. On the other hand, Stacey and Tuck (1981), in proposing a possible scale effect on the value of the gravitational constant G, pointed out that all previous experiments of this type (which were recorded in sufficient detail to permit G to be calculated) gave the opposite result, suggesting that G on the geophysical scale has a value greater by approximately 1 percent than that determined in the laboratory. The new results discussed by Sissons therefore present the first evidence against such a hypothesis.

Densities determined from surface and subsurface gravity measurements

A least‐squares method for the direct inversion of surface and subsurface gravity measurements to obtain in situ density estimates is presented. The method is applied to a set of measurements made in a tunnel through the flank of an andesitic volcano. Densities obtained are [Formula: see text] for material in the top 100 m increasing to [Formula: see text] at about 200 m depth. The average density for rocks penetrated by the tunnel is, from laboratory measurements, [Formula: see text] i.e., about 4 percent higher. The difference is ascribed to joints and voids present in situ and not sampled in the laboratory specimens.

The role of the geoid in four‐dimensional geodesy

An adequate conceptual definition of the geoid is essential for the unambiguous combination of satellite tracking data, satellite al‐timetry, and surface gravity measurements to obtain sea surface ...

The Paleozoic Rocks Found in Deep Wells in Wisconsin and Northern Illinois

Next article FreeThe Paleozoic Rocks Found in Deep Wells in Wisconsin and Northern IllinoisF. T. ThwaitesF. T. Thwaites Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 31, Number 7Oct. - Nov., 1923 Article DOIhttps://doi.org/10.1086/623045 Views: 52Total views on this site Citations: 2Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:O. W. Aiken, G. R. Keller, W. J. Hinze Geological significance of surface gravity measurements in the vicinity of the Illinois Deep Drill Holes, Journal of Geophysical Research: Solid Earth 88, no.B9B9 (Sep 2012): 7307–7314.https://doi.org/10.1029/JB088iB09p07307 Arthur E. Flint Stratigraphic Relations of the Shakopee Dolomite and the St. Peter Sandstone in Southwestern Wisconsin, The Journal of Geology 64, no.44 (Sep 2015): 396–421.https://doi.org/10.1086/626373