FN Archimer Export Format
PT J
TI Decreasing magnetization, lithospheric flexure and rejuvenated hydrothermalism off the Japan-Kuril subduction zone
BT 
AF Choe, Hanjin
   Dyment, Jerome
AS 1:1;2:1;
FF 1:;2:;
C1 Université de Paris, Institut de physique du globe de Paris, CNRS; Paris , France
C2 IPGP, FRANCE
IF 4.72
TC 5
UR https://archimer.ifremer.fr/doc/00614/72611/71621.pdf
LA English
DT Article
DE ;hydrothermal circulation;marine magnetic anomaly;subduction zone;outer rise;bending oceanic crust
AB Seafloor spreading magnetic anomalies formed at mid‐ocean ridges initially display strong amplitudes that decay within the first 10 million years as a result of pervasive hydrothermal circulation and alteration. The amplitudes do not vary much for older oceanic crust, suggesting that the thickening sediments hinder heat advection. Here we show, however, that a systematic loss of ~20 % in the amplitude of the anomalies arises between the outer rise and the trench on old ocean crust approaching the Japan and Kuril subduction zones. We interpret this decay as reflecting the opening of normal faults and fissures caused by extension on the outer flexural rise, and the subsequent renewed circulation of seawater into the oceanic crust, resulting in additional alteration of the magnetic minerals. This interpretation is supported by higher heat flow and seismic velocity changes observed toward the trench. Plain Language Summary Seafloor spreading magnetic anomalies formed at mid‐ocean ridges initially display strong amplitudes that decrease within the first 10 million years as a result of the widespread circulation of hot seawater within the oceanic crust and the resulting alteration of its magnetic minerals. The amplitudes do not vary much for older oceanic crust, suggesting that the thickening sediments hinder the free exchange of seawater between the crustal aquifer and overlying ocean. Here we show, however, that a systematic loss of ~20 % in the amplitude of the anomalies appear between the outer rise, an elevation caused by the flexure of the plate entering subduction, and the trench on old ocean crust approaching the Japan and Kuril subduction zones. We interpret this decrease as reflecting the opening of faults and cracks caused by extension at the top of the bent oceanic plate and the subsequent renewed circulation of seawater into the oceanic crust, resulting in additional alteration of the magnetic minerals. This interpretation is supported by higher heat flow and seismic velocity changes observed toward the trench. 
PY 2020
PD MAY
SO Geophysical Research Letters
SN 0094-8276
PU American Geophysical Union (AGU)
VL 47
IS 9
UT 000536639500036
DI 10.1029/2019GL085975
ID 72611
ER

EF