New magnetostratigraphy and paleopole from the Whitmore Point Member of the Moenave Formation at Kanab, Utah
Journal Title: Volumina Jurassica - Year 2014, Vol 12, Issue 2
Abstract
The entire Whitmore Point Member of the Moenave Formation was sampled in close stratigraphic sequence (+0.3 m) from a vertical exposure in southwestern Utah. The polarity sequence in the Whitmore Point Member is essentially normal polarity, with five or more very short reversed intervals interspersed and a <1 m reversed interval at the top of the sequence. This polarity pattern dates the Whitmore Point Member as Hettangian. In the earliest Jurassic, the North American plate rotated even further westward from its Late Triassic position, and the movement appears to have been accompanied by an abrupt increase in plate motion because of the similarity in position of many Late Triassic paleopoles. The Moenave pole forms the ‘J-1 cusp’ of the North American apparent polar wander curve. The paleopole obtained by this study is somewhat further westward than those of previous studies. Within the 27 m of a mostly normal polarity sequence, the data show multiple, exceedingly short polarity intervals. The magnetization carrier is a maghemite-magnetite mineral, with the magnetization of an additional hematite carrier superposed. The lithostratigraphic sequence of the Moenave Formation is terminated by an unconformable surface, overlain by the Springdale Sandstone. Paleomagnetic directions of the Whitmore Point Member are exceedingly similar to those of the overlying Springdale Sandstone. Even though the two lithologic bodies are separated by a clear disconformity, the similarity in pole positions suggests that the two are closely related in time. It is possible that this disconformity represents the termination of the westward excursion of North America in earliest Jurassic time.
Authors and Affiliations
Maureen STEINER
Keywords
Related Articles
- EP ID EP67980
- DOI 10.5604/17313708 .1130122
- Views 71
- Downloads 0
Pozycja stratygraficzna i paleogeograficzne znaczenie bajoskich wapieni krynoidowych w ewolucji pienińskiego basenu skałkowego
STRATEGICZNA WSPÓŁPRACA JST I BANKÓW LOKALNYCH WARUNKIEM ROZWOJU MŚP
Rozwój mikro, małych i średnich przedsiębiorstw jest uzależniony od strategicz-nej koordynacji rozwoju społeczności lokalnych reprezentowanych przez JST i banków spółdziel-czych. Najbliższe lata będą rozstrzygające zarów...
News and Reviews – International Subcommission on Jurassic Stratigraphy (ISJS) – Chairman's Report
-
Dinoflagellate cyst assemblages across the Oxfordian/Kimmeridgian boundary (Upper Jurassic) at Flodigarry, Staffin Bay, Isle of Skye, Scotland – a proposed GSSP for the base of the Kimmeridgian
Examination of seven ammonite-calibrated palynological samples across the Oxfordian/Kimmeridgian boundary in the Flodigarry sections at Staffin Bay, Isle of Skye, northern Scotland, has revealed dinoflagellate cyst assem...
Zróżnicowanie litofacjalne osadów keloweju w rejonie Zawiercia