thumbnail

Geometrical analysis of structural data collected at high South latitude: A modular arithmetic method that addresses meridional convergence

Open-File Report 2007-1047-SRP-061

By:
,
DOI: 10.3133/ofr20071047SRP061

Links

Abstract

The convergence of meridians toward the South Pole causes unique problems for geometrical comparison of structural geological and geophysical datasets from Antarctica. The true North reference direction ordinarily is used for measuring and reporting vector data (strike, trend) in Antarctica, as elsewhere. However, over a latitude distance of just 100 km at 85° South, the angular difference in the true North direction exceeds 10°. Consequently, when performing a regional tectonic analysis of vector data (strike, trend) for structures such as faults, dike arrays, or geophysical lineaments oriented with respect to North at different sites, it is necessary to rotate the data to a common reference direction. A modular arithmetic function, performed as a spreadsheet calculation, offers the means to unify data sets from sites having different longitude position, by rotation to a common reference direction. The function is SC ≡ SM + ∆L (mod 360), where SC = converted strike; SM = measured strike; ∆L = angle in degrees longitude between reference longitude and study site; and 360, the divisor, is the number of degrees in Earth’s circumference. The method is used to evaluate 1) paleomagnetic rotation of the Ellsworth-Whitmore Mountains with respect to the Transantarctic Mountains, and 2) orogenic curvature of the Ross Orogen

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Geometrical analysis of structural data collected at high South latitude: A modular arithmetic method that addresses meridional convergence
Series title:
Open-File Report
Series number:
2007-1047-SRP-061
DOI:
10.3133/ofr20071047SRP061
Year Published:
2007
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Description:
Report: 5 p.; Plate: XLS file
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Larger Work Title:
Antarctica: A Keystone in a Changing World--Online Proceedings for the Tenth International Symposium on Antarctic Earth Sciences. Santa Barbara, California, U.S.A.--August 26 to September 1, 2007
Other Geospatial:
Antarctica
Additional Online Files(Y/N):
Y