Preprints
https://doi.org/10.5194/gchron-2021-19
https://doi.org/10.5194/gchron-2021-19

  16 Jun 2021

16 Jun 2021

Review status: this preprint is currently under review for the journal GChron.

Paleomagnetic secular variation for a 21,000-year sediment sequence from Cascade Lake, north-central Brooks Range, Arctic Alaska

Douglas P. Steen1, Joseph S. Stoner2, Jason P. Briner3, and Darrell S. Kaufman1 Douglas P. Steen et al.
  • 1School of Earth and Sustainability, Northern Arizona University, Flagstaff, Arizona, 86011-4099, USA
  • 2College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, 97331-5503, USA
  • 3Department of Geology, University at Buffalo, Buffalo, New York, 14260-1350, USA

Abstract. Two > 5-m-long sediment cores from Cascade Lake (68.38° N, 154.60° W), Arctic Alaska, were analyzed to quantify their paleomagnetic properties over the past 21,000 years. Alternating-field demagnetization of the natural remanent magnetization, anhysteretic remanent magnetization, isothermal remanent magnetization, and hysteresis experiments reveal a strong, well-defined characteristic remanent magnetization carried by a low coercivity magnetic component that increases up core. Maximum angular deviation values average < 2°, and average inclination values are within 4° of the geocentric axial dipole prediction. Radiometric ages based on 210Pb and 14C were used to correlate the major inclination features of the resulting paleomagnetic secular variation (PSV) record with those of other regional PSV records, including two geomagnetic field models and the longer series from Burial Lake, located 200 km to the west. Following around 6 ka (cal BP), the ages of PSV fluctuations in Cascade Lake begin to diverge from those of the regional records, reaching a maximum offset of about 2000 years at around 4 ka. Several correlated cryptotephra ages from this section (reported in a companion paper by Davies et al., this volume) support the regional PSV-based chronology and indicate that some of the 14C ages at Cascade Lake are variably too old.

Douglas P. Steen et al.

Status: open (until 28 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gchron-2021-19', Anonymous Referee #1, 19 Jul 2021 reply
  • RC2: 'Comment on gchron-2021-19', Anonymous Referee #2, 21 Jul 2021 reply

Douglas P. Steen et al.

Douglas P. Steen et al.

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Short summary
Paleomagnetic data from Cascade Lake (Brooks Range, Alaska) extend the radiometric-based age model of the sedimentary sequence extending back 21 kyr. Correlated ages based on prominent features in paleomagnetic secular variations (PSV) diverge from the radiometric ages in the upper 1.6 m, by up to about 2000 years at around 4 ka. Four late Holocene cryptotephra in this section support the PSV chronology and suggest the influence of hard water or aged organic material.