Research Article| November 01, 1973 Remagnetization Hypothesis Discounted: A Paleomagnetic Study of the Trenton Limestone, New York State MICHAEL W. McELHINNY; MICHAEL W. McELHINNY 1Research School of Earth Sciences, Australian National University, Canberra, A.C.T., Australia Search for other works by this author on: GSW Google Scholar NEIL D. OPDYKE NEIL D. OPDYKE 2Lamont-Doherty Geological Observatory, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1973) 84 (11): 3697–3708. https://doi.org/10.1130/0016-7606(1973)84<3697:RHDAPS>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation MICHAEL W. McELHINNY, NEIL D. OPDYKE; Remagnetization Hypothesis Discounted: A Paleomagnetic Study of the Trenton Limestone, New York State. GSA Bulletin 1973;; 84 (11): 3697–3708. doi: https://doi.org/10.1130/0016-7606(1973)84<3697:RHDAPS>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Twenty-nine samples collected from an 80-m section of the Trenton Limestone give almost vertical directions of natural remanent magnetization (NRM), but these become nearly horizontally directed after magnetic cleaning (D = 173°, I = 18°, α95 = 5°). The result is confirmed by thermal demagnetization experiments, and the consequent low latitude suggested for the time of deposition is supported by the paleoclimatic evidence. Samples collected from a penecontemporaneous slump bed demonstrate that both the NRM and cleaned directions are postdepositional. Magnetic-anisotropy measurements show good agreement between the mean principal axis of maximum susceptibility and the cleaned remanence direction, suggesting that the alignment of the long axes of magnetic grains was controlled by the ancient magnetic field direction. This can only have arisen through a postdepositional precompaction in situ rotation of the magnetic grains, a process originally suggested by Irving and Major (1964) from laboratory deposition experiments. This study represents the first positive demonstration that such a process occurs naturally.The Ordovician paleomagnetic pole position for North America deduced from these rocks (lat 36° S., long 66° W.) is in complete conflict with the predictions of the remagnetization hypothesis, which requires near-polar conditions at that time. The result, however, is in excellent agreement with that obtained from igneous rocks of similar age from the Front Range of Colorado and shows that the Ordovician pole position lies close to the late Paleozoic position. A consequence of this conclusion is the existence of an Ordovician proto-Atlantic Ocean, as has been suggested independently from geological evidence. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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McElhinny et al. (1973) studied this question.