Evidence for massive discharges of icebergs into the North Atlantic ocean during the last glacial period

Bond, Gérard C.; Heinrich, Hartmut; Broecker, Wallace S.; Labeyrie, Laurent D; McManus, Jerry F; Andrews, John T.; Huon, Sylvain; Jantschik, Ruediger; Clasen, Silke; Simet, Christine; Tedesco, Kathy; Klas, Mieczyslawa; Bonani, Georges; Ivy, Susan

doi:10.1038/360245a0

Cited by 1,441 publications

(916 citation statements)

References 15 publications

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“…Therefore, after the LGM-RSL, the Central Andes deglaciation onset could have happened earlier or later, depending on the temperature evolution in both terrestrial hemispheres ( Figure 12): (a) First, between~19 and~9 ka, the Surface Sea Temperature (SST) westward of the Iberian Peninsula (SSTN; [109]) got warmer by 6 • C in 10 ka. However, it was not a gradual trend, because it was broken by abrupt cold episodes due to AMOC shutdowns: H1 (e.g., [110,111]) and YD (e.g., [112]), which appear reflected in the SST N curve,~18 and~12 ka ago, respectively. (b) Secondly, the humidity increases due to cold boreal events, which is well recorded in the Andean Altiplano lacustrine evidence; e.g., -At the Coropuna latitude (~16 • S), one clear evidence of moister conditions is the strong decrease in the Titicaca salinity~21-10 ka ago, as shown by the great abundance (>80%) of freshwater plankton, nowadays extinct, in the lake sediments [113].…”

Section: Paleoclimatic Frameworkmentioning

confidence: 99%

Prospecting Glacial Ages and Paleoclimatic Reconstructions Northeastward of Nevado Coropuna (16° S, 73° W, 6377 m), Arid Tropical Andes

et al. 2018

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This work investigates the timing, paleoclimatic framework and inter-hemispheric teleconnections inferred from the glaciers last maximum extension and the deglaciation onset in the Arid Tropical Andes. A study area was selected to the northeastward of the Nevado Coropuna, the volcano currently covered by the largest tropical glacier on Earth. The current glacier extent, the moraines deposited in the past and paleoglaciers at their maximum extension have been mapped. The present and past Equilibrium Line Altitudes (ELA and paleoELA) have been reconstructed and the chlorine-36 ages have been calculated, for preliminary absolute dating of glacial and volcanic processes. The paleoELA depression, the thermometers installed in the study area and the accumulation data previously published allowed development of paleotemperature and paleoprecipitation models. The Coropuna glaciers were in maximum extension (or glacial standstill) 20-12 ka ago (and maybe earlier). This last maximum extension was contemporary to the Heinrich 2-1 and Younger Dryas events and the Tauca and Coipasa paleolake transgressions on Bolivian Altiplano. The maximum paleoELA depression (991 m) shows a colder (−6.4 • C) and moister climate with precipitation ×1.2-×2.8 higher than the present. The deglaciation onset in the Arid Tropical Andes was 15-11 ka ago, earlier in the most southern, arid, and low mountains and later in the northernmost, less arid, and higher mountains.

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Section: Paleoclimatic Frameworkmentioning

confidence: 99%

Prospecting Glacial Ages and Paleoclimatic Reconstructions Northeastward of Nevado Coropuna (16° S, 73° W, 6377 m), Arid Tropical Andes

et al. 2018

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“…Based on a detailed and AMS-14 C-dated stratigraphy for the last glacial cycle, we particularly focus on the short-term, i.e. decadal to centennial, changes in monsoonal climate and trace their timing, phase relationship, and linkages in general to global climate changes such as Heinrich and=or Dansgaard-Oeschger (D-Oe) events defined in the North Atlantic realm (Bond et al, 1992(Bond et al, , 1997Cortijo et al, 1995) and the associated changes in the global thermohaline circulation (Broecker et al, 1988;Sarnthein et al, 1994b;Seidov et al, 1996). Similar teleconnections were recently found and=or postulated by Kennett and Ingram (1995) and Kotilainen and Shackleton (1995) by studying paleoclimatic sediment records from the eastern and northwestern Pacific margins.…”

Section: Introductionmentioning

confidence: 99%

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

et al. 1999

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Based on the study of 10 sediment cores and 40 core-top samples from the South China Sea (SCS) we obtained proxy records of past changes in East Asian monsoon climate on millennial to bidecadal time scales over the last 220,000 years. Climate proxies such as global sea level, estimates of paleotemperature, salinity, and nutrients in surface water, ventilation of deep water, paleowind strength, freshwater lids, fluvial and=or eolian sediment supply, and sediment winnowing on the sea floor were derived from planktonic and benthic stable-isotope records, the distribution of siliciclastic grain sizes, planktonic foraminifera species, and the U K 37 biomarker index. Four cores were AMS-14 C-dated. Two different regimes of monsoon circulation dominated the SCS over the last two glacial cycles, being linked to the minima and maxima of Northern Hemisphere solar insolation. (1) Glacial stages led to a stable estuarine circulation and a strong O 2 -minimum layer via a closure of the Borneo sea strait. Strong northeast monsoon and cool surface water occurred during winter, in part fed by an inflow from the north tip of Luzon. In contrast, summer temperatures were as high as during interglacials, hence the seasonality was strong. Low wetness in subtropical South China was opposed to large river input from the emerged Sunda shelf, serving as glacial refuge for tropical forest. (2) Interglacials were marked by a strong inflow of warm water via the Borneo sea strait, intense upwelling southeast of Vietnam and continental wetness in China during summer, weaker northeast monsoon and high sea-surface temperatures during winter, i.e. low seasonality. On top of the long-term variations we found millennial-to centennial-scale cold and dry, warm and humid spells during the Holocene, glacial Terminations I and II, and Stage 3. The spells were coeval with published variations in the Indian monsoon and probably, with the cold Heinrich and warm Dansgaard-Oeschger events recorded in Greenland ice cores, thus suggesting global climatic teleconnections. Holocene oscillations in the runoff from South China centered around periodicities of 775 years, ascribed to subharmonics of the 1500-year cycle in oceanic thermohaline circulation. 102=84-year cycles are tentatively assigned to the Gleissberg period of solar activity. Phase relationships among various monsoon proxies near the onset of Termination IA suggest that summer-monsoon rains and fluvial runoff from South China had already intensified right after the last glacial maximum (LGM) insolation minimum, coeval with the start of Antarctic ice melt Wang et al. / Marine Geology 156 (1999) prior to the δ 18 O signals of global sea-level rise. Vice versa, the strength of winter-monsoon winds decreased in short centennial steps only 3000-4000 years later, along with the melt of glacial ice sheets in the Northern Hemisphere.

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“…3), HL 4 is characterized by a rather broad peak shape, whereas HL 5 is narrower (Grousset et al, 2001). The distribution of IRD in the sediment is not limited to the interval defined by foraminifer minima and IRD maxima (Heinrich, 1988;Bond et al, 1992), but is more widespread Authigenic P e 10 mL 1mol/L Na-acetate buffered to pH 4 with acetic acid (5 hr), 10 mL 1mol/L MgCl 2 (2 hr), 10 mL 1mol/L MgCl 2 (2 hr), 10 mL H 2 O (2 hr)…”

Section: Resultsmentioning

confidence: 99%

“…Along with ambient marine organic matter, several continental sources have been postulated, including ancient soils from periglacial regions and organic matter-bearing rocks from the geological basement (e.g., carbonate rocks; Bond et al, 1992;Rosell-Melé et al, 1997).…”

Section: Selective Preservation or Change In The Source Of Organic Mamentioning

confidence: 99%

Dysaerobic conditions during Heinrich events 4 and 5: Evidence from phosphorus distribution in a North Atlantic deep-sea core

Tamburini

Huon

Steinmann

et al. 2002

Geochimica et Cosmochimica Acta

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Abstract-Reactive phosphorus undergoes diagenetic transformation once transferred into marine sediments. The degree of regeneration and redistribution of phosphorus depends on early diagenetic and environmental conditions, which may be linked to larger scale phenomena, such as bottom water circulation, water column ventilation, and organic carbon flux. Phosphorus phases of the Ͻ50-m-sized fraction of deep-sea sediments from core SU 90-09 (North Atlantic, 43°31'N, 30°24'W, 3375 m below sea level) have been analyzed using a sequential extraction technique (SEDEX method) to reconstruct phosphorus geochemistry during Heinrich events 4 and 5. Comparison with Holocene samples from the same site indicates that postdeposition diagenetic transformation has not affected phosphorus distribution in the deep part of the sediments. Total and reactive phosphorus average 0.40 Ϯ 0.04 mg/g and 0.30 Ϯ 0.05 mg/g, respectively, and are comparable to values found in analog deep-sea environments in the North Atlantic. Detrital phosphorus, the phase linked to igneous-and metamorphic-derived material, sharply increases during Heinrich events and covaries with the ice-rafted debris record, whereas authigenic and Fe-bound phosphorus phases, both influenced by redox conditions, decrease or even disappear. These findings suggest that during the deposition of Heinrich layers (HLs), environmental parameters hampered the precipitation of these phases. Large freshwater discharges in relation to iceberg surges may have provoked a temporary stratification of the water column. Accordingly, dysaerobic conditions in the sediments may have fostered the loss of dissolved phosphorus from the sediments to the water column, in a direct and rapid response to the changed conditions. Decreasing trends in organic matter elemental ratios (total organic carbon/organic phosphorus) and Rock-Eval oxygen index values, along with the presence of partly authigenic dolomite and ankerite within HLs, also support this assumption.

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Evidence for massive discharges of icebergs into the North Atlantic ocean during the last glacial period

Cited by 1,441 publications

References 15 publications

Prospecting Glacial Ages and Paleoclimatic Reconstructions Northeastward of Nevado Coropuna (16° S, 73° W, 6377 m), Arid Tropical Andes

Prospecting Glacial Ages and Paleoclimatic Reconstructions Northeastward of Nevado Coropuna (16° S, 73° W, 6377 m), Arid Tropical Andes

East Asian monsoon climate during the Late Pleistocene: high-resolution sediment records from the South China Sea

Dysaerobic conditions during Heinrich events 4 and 5: Evidence from phosphorus distribution in a North Atlantic deep-sea core

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