FN Archimer Export Format
PT J
TI Cyclic magnetite dissolution in Pleistocene sediments of the abyssal northwest Pacific Ocean: Evidence for glacial oxygen depletion and carbon trapping
BT 
AF KORFF, Lucia
   VON DOBENECK, Tilo
   FREDERICHS, Thomas
   KASTEN, Sabine
   KUHN, Gerhard
   GERSONDE, Rainer
   DIEKMANN, Bernhard
AS 1:1,2;2:1,2;3:1,2;4:1,2,3;5:1,2,3;6:1,2,3;7:4;
FF 1:;2:;3:;4:;5:;6:;7:;
C1 Univ Bremen, MARUM Ctr Marine Environm Sci, Bremen, Germany.
   Univ Bremen, Fac Geosci, Bremen, Germany.
   Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Bremerhaven, Germany.
   Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, Potsdam, Germany.
C2 UNIV BREMEN, GERMANY
   UNIV BREMEN, GERMANY
   INST A WEGENER, GERMANY
   INST A WEGENER, GERMANY
IF 3.254
TC 49
UR https://archimer.ifremer.fr/doc/00421/53247/54725.pdf
LA English
DT Article
CR IMAGES 3-IPHIS-MD106
BO Marion Dufresne
DE ;northwest Pacific Ocean;carbon trapping;magnetite dissolution;mid-Pleistocene transition;tephra layers;abyssal sediments
AB The carbonate-free abyss of the North Pacific defies most paleoceanographic proxy methods and hence remains a blank spot in ocean and climate history. Paleomagnetic and rock magnetic, geochemical, and sedimentological methods were combined to date and analyze seven middle to late Pleistocene northwest Pacific sediment cores from water depths of 5100 to 5700m. Besides largely coherent tephra layers, the most striking features of these records are nearly magnetite-free zones corresponding to glacial marine isotope stages (MISs) 22, 12, 10, 8, 6, and 2. Magnetite depletion is correlated with organic carbon and quartz content and anticorrelated with biogenic barite and opal content. Within interglacial sections and mid-Pleistocene transition glacial stages MIS 20, 18, 16, and 14, magnetite fractions of detrital, volcanic, and bacterial origin are all well preserved. Such alternating successions of magnetic iron mineral preservation and depletion are known from sapropel-marl cycles, which accumulated under periodically changing bottom water oxygen and redox conditions. In the open central northwest Pacific Ocean, the only conceivable mechanism to cause such abrupt change is a modified glacial bottom water circulation. During all major glaciations since MIS 12, oxygen-depleted Antarctic Bottom Water (AABW)-sourced bottom water seems to have crept into the abyssal northwest Pacific below similar to 5000m depth, thereby changing redox conditions in the sediment, trapping and preserving dissolved and particulate organic matter and, in consequence, reducing and dissolving both, biogenic and detrital magnetite. At deglaciation, a downward progressing oxidation front apparently remineralized and released these sedimentary carbon reservoirs without replenishing the magnetite losses. 
PY 2016
PD MAY
SO Paleoceanography
SN 0883-8305
PU Amer Geophysical Union
VL 31
IS 5
UT 000378699900007
BP 600
EP 624
DI 10.1002/2015PA002882
ID 53247
ER

EF