Publication Date:
2024-06-25
Description:
The strength and geometry of the Atlantic meridional overturning circulation is tightly coupled to climate on glacial-interglacial and millennial timescales, but has proved difficult to reconstruct, particularly for the Last Glacial Maximum. Today, the return flow from the northern North Atlantic to lower latitudes associated with the Atlantic meridional overturning circulation reaches down to approximately 4,000 m. In contrast, during the Last Glacial Maximum this return flow is thought to have occurred primarily at shallower depths. Measurements of sedimentary 231Pa/230Th have been used to reconstruct the strength of circulation in the North Atlantic Ocean, but the effects of biogenic silica on 231Pa/230Th-based estimates remain controversial. Here we use measurements of 231Pa/230Th ratios and biogenic silica in Holocene-aged Atlantic sediments and simulations with a two-dimensional scavenging model to demonstrate that the geometry and strength of the Atlantic meridional overturning circulation are the primary controls of 231Pa/230Th ratios in modern Atlantic sediments. For the glacial maximum, a simulation of Atlantic overturning with a shallow, but vigorous circulation and bulk water transport at around 2,000 m depth best matched observed glacial Atlantic 231Pa/230Th values. We estimate that the transport of intermediate water during the Last Glacial Maximum was at least as strong as deep water transport today.
Keywords:
162-983A; 172-1055C; 172-1056A; 172-1058A; 172-1063B; 172-1063D; 177-1089A; 177-1089B; 293; 38GGC; 55GGC; 58GGC; 71GGC; 82GGC; Accumulation rate, opal; Accumulation rate, opal, error, relative; AGE; Agulhas Ridge; Amazon Fan; ANT-XI/2; Argentine Basin; Atlantic Caribbean Margin; Atlantic Ocean; Azores; Blake-Bahama Outer Ridge, North Atlantic Ocean; Blake Outer Ridge, North Atlantic Ocean; Brazil Basin; C1_PC-ENG111; C2_PC-21210009; CALYPSO; Calypso Corer; Carolina Slope, North Atlantic Ocean; CEPAG; DAPC2; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; DRILL; Drilling/drill rig; DSDP/ODP/IODP sample designation; Event label; GC; GeoB1515-1; GeoB1523-1; GeoB1711; GeoB1711-4; GeoB2104-3; GeoB2107-3; GeoB2109-1; GeoB2112-3; GeoB3722-2; GeoB3935-2; GeoB3936-1; GeoB3937-2; GeoB9508-5; GGC5; Gravity corer; Gravity corer (Kiel type); GS06-144-02; Iceland; IMAGES I; Joides Resolution; KL; Knorr; KNR140; KNR140-12JPC; KNR140-2-12JPC; Latitude of event; Leg162; Leg172; Leg177; Le Suroît; Longitude of event; M16/2; M20/2; M23/2; M34/2; M34/4; M35/1; M35003-4; M45/5_86; M45/5_90; M45/5a; M65/1; Marion Dufresne (1995); MD02-2588; MD02-2588Q; MD02-2594; MD08-3182; MD09-3242; MD09-3253; MD09-3254; MD09-3256; MD09-3256Q; MD09-3257; MD101; MD128; MD173; MD952014; MD95-2014; MD952015; MD95-2015; MD952027; MD95-2027; MD952037; MD95-2037; ME69-17; Meteor (1986); Namibia continental slope; Newfoundland Slope; North Atlantic; Northern Cape Basin; OCE326-GGC5; Ocean Drilling Program; ODP; Opal, biogenic silica; Opal, biogenic silica, error, relative; PALEOCINAT; PALEOCINAT II; PC; Piston corer; Piston corer (BGR type); Polarstern; Protactinium-231/Thorium-230, error, relative; Protactinium-231/Thorium-230 ratio; PS2489-2; PS28; PS28/256; RC13; RC13-189; RC16; RC16-66; RC24; RC24-1; RC24-12; RC24-7; Reference/source; RETRO-2; Reykjanes Ridge; Robert Conrad; Sample code/label; SL; South Atlantic; South Atlantic Ocean; Southern Ocean; SU81-18; SU90-03; SU90-08; SU90-09; SU90-11; SU90-44; SU92; SU92-18; SWAF; TN057-13; TN057-21; V22; V22-182; V30; V30-40; Vema
Type:
Dataset
Format:
text/tab-separated-values, 1444 data points
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