FN Archimer Export Format
PT J
TI The Amplitude and Timescales of 0‐15 ka Paleomagnetic Secular Variation in the Northern North Atlantic
BT 
AF Reilly, Brendan T.
   Stoner, Joseph S.
   Ólafsdóttir, Sædís
   Jennings, Anne
   Hatfield, Robert
   Kristjánsdóttir, Gréta Björk
   Geirsdóttir, Áslaug
AS 1:1;2:2;3:3;4:4;5:5;6:6;7:7;
FF 1:;2:;3:;4:;5:;6:;7:;
C1 Lamont‐Doherty Earth Observatory Columbia University Palisades NY 10964 ,USA
   College of Earth and Atmospheric Sciences Oregon State University Ocean Corvallis OR 97331, USA
   Reykjavík Energy Reykjavík , Iceland
   University of Colorado INSTAAR Boulder CO 80309, USA
   Department of Geological Sciences University of Florida Gainesville FL 32611, USA
   School of Engineering and Natural Sciences University of Iceland Reykjavík , Iceland
   Faculty of Earth Sciences University of Iceland Reykjavík, Iceland
C2 UNIV COLUMBIA, USA
   UNIV OREGON STATE, USA
   REYKJAVIK ENERGY, ICELAND
   UNIV COLORADO, USA
   UNIV FLORIDA, USA
   UNIV ICELAND, ICELAND
   UNIV ICELAND, ICELAND
IF 3.9
TC 1
UR https://archimer.ifremer.fr/doc/00842/95396/103172.pdf
   https://archimer.ifremer.fr/doc/00842/95396/103173.pdf
LA English
DT Article
CR MD 114 / IMAGES V GINNA
BO Marion Dufresne
DE ;paleomagnetism;marine sediments;North Atlantic;paleomagnetic secular variation (PSV);radiocarbon;dynamic time warping (DTW)
AB We investigate the amplitude and frequency of directional geomagnetic change since 15 ka in the Northern North Atlantic (∼67o N) using 5 ‘ultra-high’ resolution continental shelf sediment cores deposited at rates greater than 1 m/kyr. The ages of these cores are constrained by 103 radiocarbon dates with reservoir ages assessed through tephra correlation to terrestrial archives. Our study aims to address many of the uncertainties that are common in sedimentary paleomagnetic studies, including signal attenuation in low to moderate resolution archives and difficulty to demonstrate reproducibility in higher resolution archives. The ‘ultra-high’ accumulation rates of our cores reduce ‘lock-in’ and smoothing uncertainties associated with magnetic acquisition processes. Abundant radiocarbon dates along with an objective alignment algorithm provide a test of signal reproducibility at sub-millennial timescales. The PSV signal, evaluated as individual records and as a new stack (GREENICE15k), validates prior results, but provides stronger geochronological constraints, demonstrates a reproducible PSV signal and amplitude, and extends through the abrupt Bølling–Allerød and Younger Dryas climate transitions of the latest Pleistocene. While broadly consistent with time-varying spherical harmonic models and varve dated records from Northern Europe, we demonstrate greater variance and higher amplitudes—particularly at sub-millennial timescales. This robust variability on centennial timescales is rarely observed or discussed, but is likely important to our understanding of some of the most intriguing aspects of the geodynamo. Key Points Sediment cores with ultra-high accumulation rates are used to study directional changes in the Northern North Atlantic’s geomagnetic field Study addresses uncertainties in sedimentary paleomagnetic research, such as signal attenuation, chronology, and reproducibility Study reveals robust variability on centennial timescales with greater variance than generally observed over the last 15,000 years Plain Language Summary Our study used mud from the seafloor to investigate changes in Earth's magnetic field in the Northern North Atlantic region over the past 15 thousand years. Magnetic minerals eroded from rocks and deposited on the seafloor can preserve a record of the geomagnetic field, like little compass needles suspended in mud. We obtained sediment cores from areas near land with very high accumulation rates, which are rare in the modern ocean, that can record short magnetic field variations that occur on the timescale of centuries. We used radiocarbon dating to determine the ages of the sediment samples and a new alignment algorithm to verify the accuracy and consistency of the magnetic signal we observed. Understanding these short geomagnetic field variations is challenging, but it is key to unlocking many mysteries about the past and future of Earth's magnetic field. 
PY 2023
PD JUL
SO Journal Of Geophysical Research-solid Earth
SN 2169-9313
PU American Geophysical Union (AGU)
VL 128
IS 6
UT 001022758300001
DI 10.1029/2023JB026891
ID 95396
ER

EF