scholarly journals Geology, geochemistry, and age of Archean and early Proterozoic rocks in the Marenisco-Watersmeet area, northern Michigan; and Geologic interpretation of gravity data, Marenisco-Watersmeet area, northern Michigan

1984 ◽  
Author(s):  
P.K. Sims ◽  
Z.E. Peterman ◽  
W.C. Prinz ◽  
F.C. Benedict ◽  
J.S. Klasner
Keyword(s):  
Gravity Data ◽  
Early Proterozoic ◽  
Geologic Interpretation ◽  
Northern Michigan

On: “Diapiric Salt Volume Offshore Louisiana,” by T. R. LaFehr and Alan T. Herring (GEOPHYSICS, December 1971, p. 1205–1251)

Geophysics ◽  
1972 ◽  
Vol 37 (5) ◽  
pp. 907-907
Author(s):  
Lewis R. Tucker
Keyword(s):  
Gulf Of Mexico ◽  
Gravity Data ◽  
Large Family ◽  
Actual Knowledge ◽  
Geologic Interpretation ◽  
Calculated Quantity

In the interest of brevity, I will summarize the points I raised and the conclusions I drew in my somewhat extended correspondence with LaFehr and Herring concerning my objections to their paper. 1) Any geologic interpretation of gravity data includes a number of assumptions. 2) Of all these assumptions, the most tenuous one is that concerning a “regional.” 3) Once assumptions have been made, the answer is only the end result of an arithmetical exercise; the conclusion has been established already. 4) In the specific case of the calculated quantity of salt in the study area in the Gulf of Mexico, many of the “facts” that had to be included in the reduction of the data are actually assumptions that, through constant repetition, are now thought of as actual knowledge. 5) The conclusion in their paper as to the quantity of salt is only one of a large family of results, though it may be in the correct magnitude.

A geological interpretation of gravity and magnetic data, northwest Saskatchewan

1970 ◽  
Vol 7 (3) ◽  
pp. 858-868 ◽  
Author(s):  
R. H. Wallis
Keyword(s):  
Gravity Data ◽  
Magnetic Data ◽  
Early Proterozoic ◽  
Geological Interpretation ◽  
Metasedimentary Rocks ◽  
Lower Proterozoic ◽  
Gravity And Magnetic ◽  
Northern Saskatchewan ◽  
Gravity And Magnetic Data ◽  
Sedimentary Unit

The striking 'fit' of aeromagnetic and gravity data from the Precambrian of northwest Saskatchewan, combined with known and nearby analogous, geological relationships, suggests the presence of a northeast-trending belt, 250 × 20 miles (400 × 30 km), of early Proterozoic (?) metasedimentary rocks, probably magnetite-bearing meta-arkoses. This structural–sedimentary unit might have economic possibilities analogous to other northeast-striking, Precambrian, lower Proterozoic (?), metasedimentary belts of northern Saskatchewan, the Virgin River Belt, and the Wollaston Trend.

Basin architecture and density structure beneath the Strait of Georgia, British Columbia

2003 ◽  
Vol 40 (7) ◽  
pp. 965-981 ◽  
Author(s):  
C Lowe ◽  
S A Dehler ◽  
B C Zelt
Keyword(s):  
Seismic Velocity ◽  
Gravity Data ◽  
Velocity Model ◽  
Seismic Structure ◽  
Strait Of Georgia ◽  
3 Dimensional ◽  
The North ◽  
Georgia Basin ◽  
Geologic Interpretation ◽  
Velocity Information

Georgia Basin is located within one of the most seismically active and populated areas on Canada's west coast. Over the last decade, geological investigations have resolved important details concerning the basin's shallow structure and composition. Yet, until recently, relatively little was known about deeper portions of the basin. In this study, new seismic velocity information is employed to develop a 3-dimensional density model of the basin. Comparison of the calculated gravity response of this model with the observed gravity field validates the velocity model at large scales. At smaller scales, several differences between model and observed gravity fields are recognized. Analysis of these differences and correlation with independent geoscience data provide new insights into the structure and composition of the basin-fill and underlying basement. Specifically, four regions with thick accumulations of unconsolidated Pleistocene and younger sediments, which were not resolved in the velocity model, are identified. Their delineation is particularly important for studies of seismic ground-motion amplification and offshore aggregate assessment. An inconsistency between the published geology and the seismic structure beneath Texada and Lasqueti Islands in the central Strait of Georgia is investigated; however, the available gravity data cannot preferentially validate either the geologic interpretation or the seismic model in this region. We interpret a northwest-trending and relatively linear gradient extending from Savory Island in the north to Boundary Bay in the south as the eastern margin of Wrangellia beneath the basin. Finally, we compare Georgia Basin with the Everett and Seattle basins in the southern Cascadia fore arc. This comparison indicates that while a single mechanism may be controlling present-day basin tectonics and deformation within the fore arc this was not the case for most of the Mesozoic and Tertiary time periods.

Edge enhancement of potential-field data using normalized statistics

Geophysics ◽  
2008 ◽  
Vol 73 (3) ◽  
pp. H1-H4 ◽  
Author(s):  
Gordon R. J. Cooper ◽  
Duncan R. Cowan
Keyword(s):  
Standard Deviation ◽  
Potential Field ◽  
Field Data ◽  
Gravity Data ◽  
Edge Enhancement ◽  
Potential Field Data ◽  
Geologic Interpretation ◽  
Derivatives Of ◽  
High Pass ◽  
Detection Filter

Edge enhancement in potential-field data helps geologic interpretation. There are many methods for enhancing edges, most of which are high-pass filters based on the horizontal or vertical derivatives of the field. Normalized standard deviation (NSTD), a new edge-detection filter, is based on ratios of the windowed standard deviation of derivatives of the field. NSTD is demonstrated using aeromagnetic data from Australia and gravity data from South Africa. Compared with other filters, the NSTD filter produces more detailed results.

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