Remagnetization signature of Paleozoic sedimentary rocks from the Patterson Creek Mountain anticline in West Virginia

• Published in: Physics and chemistry of the earth. Parts A/B/C 2002-01, Vol.27 (25), p.1141-1150
• Main Authors: Lewchuk, Michael T, Douglas Elmore, R, Evans, Mark
• Format: Article
• Language: English
• Subjects: Appalachians; Deformation; Fold test; Kiaman remagnetization; Marine; Paleomagnetism; Strain
• ISSN: 1474-7065; 1873-5193
• DOI: 10.1016/S1474-7065(02)00109-2

Paleomagnetic analysis of five adjacent Lower Silurian to Lower Devonian sedimentary units (Oriskany, Helderberg, Tonoloway, Williamsport and McKenzie) plus a carbonate vein, within a single large fold in West Virginia, reveals a secondary, reversed, Permian, magnetization in all rocks. Similar unblocking temperatures (∼350–550 °C) were observed for the characteristic magnetization throughout the study implying similar origins for their magnetization. Unfolding estimates, with 95% confidence intervals, were, Helderberg (60±11%), Tonoloway (69±9%), Williamsport (65±25%), Oriskany (78±11%) and McKenzie (80±4%). Since all units were sampled on a single fold, their burial, temperature and stress histories should be identical. Identification of the mechanism for remagnetization and an explanation of the differences in the fold test results involve awkward interpretations. Hypotheses for remagnetization mechanisms such as fluid migration, clay alteration, partial thermoviscous resetting and strain all appear to be flawed for this data set and true differences in the timing of remagnetization relative to folding would require a very complex multi-stage remagnetization event. The actual mechanism for remagnetization may yet be unidentified. An alternative possibility is that these units have been affected by multiple remagnetizing mechanisms simultaneously and then the magnetization has been modified by minor strain to produce the variation in the results of the fold tests.