Abstract
The Colorado Plateau Coring Project Phase 1 (CPCP-1) acquired three continuous drill cores from Petrified Forest National Park (PFNP), Arizona, U.S.A., two of which (CPCP-PFNP13-1A and CPCP-PFNP13-2B) intersected the Upper Triassic Chinle Formation, Lower(?)-Middle Triassic Moenkopi Formation (MF) and Permian Coconino Sandstone. We examined both cores to construct a high-resolution magnetostratigraphy of MF strata, and progressive demagnetization data yield well-defined, interpretable paleomagnetic results. Each lithostratigraphic member of the MF (Wupatki, Moqui, and Holbrook members) contains authigenic and detrital hematite as the dominant magnetic carrier with distinguishing rock magnetic characteristics. Magnetostratigraphy of MF strata in both CPCP-1 cores consists of six normal and six reverse polarity magnetozones, from the youngest to the oldest, MF1n to MF6r. Recent single-crystal chemical abrasion–thermal ionization mass spectrometry (CA-TIMS) U-Pb data from a sample in magnetozone MF1n yield a latest Anisian/earliest Ladinian (241.38 ± 0.43 Ma) age. Correlation of the CA-TIMS-calibrated magnetostratigraphy with the astronomically tuned polarity timescale for the Middle Triassic deep-marine Guandao (GD) section of South China ties the magnetozone MF1n with GD8 and MF6r with GD2r, and implies that the MF spans, at most, the earliest Anisian (Aegean) to latest Anisian (Illyrian)/earliest Ladinian stages (ca. 246.8 to 241.5 Ma). This age estimate for the MF suggests that the timespan of the regional, pre-Norian disconformity is about 17 Ma, which demonstrates that MF vertebrate fossil assemblages in east-central Arizona are millions of years (minimally 3–4 Ma) younger than previously suggested and are all Anisian in age, with no indications of substantial hiatuses in the MF section.
| Original language | English (US) |
|---|---|
| Article number | e2021JB021899 |
| Number of pages | 28 |
| Journal | Journal of Geophysical Research: Solid Earth |
| Volume | 126 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 2021 |
Bibliographical note
Funding Information:This project was funded by the National Science Foundation (NSF) collaborative grants EAR 0958976 (to Paul E. Olsen and John W. Geissman), 0958723 (to Roland Mundil), 0958915 (to Randall B. Irmis), 0959107 (to George E. Gehrels), and 0958859 (to Dennis V. Kent), and by Deutsche Forschungsgemeinschaft for the International Continental Scientific Drilling Program. The authors thank the National Park Service, especially superintendent Brad Traver at Petrified Forest National Park, for permission to core in the park and for logistical support during site selection and drilling. The authors thank the LacCore Facility (University of Minnesota) management for on-site and laboratory core processing, scanning, and archiving. The authors specifically thank Anders Noren, Kristina Brady, and Ryan O'Grady, Justin Clifton, Bob Graves, Ed Lamb, Max Schnurrenberger, and Riley Black for their exceptional around-the-clock efforts, and drilling manager Doug Schnurrenberger for overseeing the overall coring project. The authors also thank James Browning for his assistance during subsequent sampling of the core at the Rutgers Core Repository. Travel support to Ziaul Haque was provided by the Wilhelm Family endowment to the Department of Geosciences at UTD. Paleomagnetic samples preparation and measurements were conducted in the Paleomagnetic and rock magnetic laboratory at the Department of Geoscience, University of Texas at Dallas. Scanning electron microscopy (SEM) was conducted in the Micro Imaging Laboratory at the University of Texas, Dallas, and we thank Leah Thompson for assisting with SEM analysis. This is Petrified Forest National Park Paleontological Contribution Number 82. The views expressed herein are those of the authors and do not represent the official views of the United States Government.
Funding Information:
This project was funded by the National Science Foundation (NSF) collaborative grants EAR 0958976 (to Paul E. Olsen and John W. Geissman), 0958723 (to Roland Mundil), 0958915 (to Randall B. Irmis), 0959107 (to George E. Gehrels), and 0958859 (to Dennis V. Kent), and by Deutsche Forschungsgemeinschaft for the International Continental Scientific Drilling Program. The authors thank the National Park Service, especially superintendent Brad Traver at Petrified Forest National Park, for permission to core in the park and for logistical support during site selection and drilling. The authors thank the LacCore Facility (University of Minnesota) management for on‐site and laboratory core processing, scanning, and archiving. The authors specifically thank Anders Noren, Kristina Brady, and Ryan O'Grady, Justin Clifton, Bob Graves, Ed Lamb, Max Schnurrenberger, and Riley Black for their exceptional around‐the‐clock efforts, and drilling manager Doug Schnurrenberger for overseeing the overall coring project. The authors also thank James Browning for his assistance during subsequent sampling of the core at the Rutgers Core Repository. Travel support to Ziaul Haque was provided by the Wilhelm Family endowment to the Department of Geosciences at UTD. Paleomagnetic samples preparation and measurements were conducted in the Paleomagnetic and rock magnetic laboratory at the Department of Geoscience, University of Texas at Dallas. Scanning electron microscopy (SEM) was conducted in the Micro Imaging Laboratory at the University of Texas, Dallas, and we thank Leah Thompson for assisting with SEM analysis. This is Petrified Forest National Park Paleontological Contribution Number 82. The views expressed herein are those of the authors and do not represent the official views of the United States Government.
Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.
Keywords
- Anisian
- magnetostratigraphy
- Triassic
- vertebrate biostratigraphy
- Wupatki-, Moqui-, and Holbrook- Member
Continental Scientific Drilling Facility tags
- CPCP
