Radiocarbon in the Atmosphere and Deep Ocean: New Methods and New Data from the Last Glacial Period to the Holocene

Seismic hazard evaluations on major faults in Earth's crust are based on their slip histories, which reflect the frequency of earthquakes that ruptured a fault in the past. On a 100 000-year timescale, the slip rate of a fault can be determined by dating geomorphic surfaces that are offset by a fault. Application of this method to alluvial fan surfaces and river terraces offset by thrust faults in Tibet yields long-term slip rates of less than 1mm/a. Slip rates on a 10 000-year timescale are derived from paleoseismologic data and document that faults experience considerable slip rate variations on timescales of 100 to 1000 years. In particular, slip rates are often considerable higher in the present interglacial, the Holocene, than during the last glacial period, the Late Pleistocene. The causes of this behavior have remained enigmatic but their assessment is essential for an accurate evaluation of a fault's past and future seismicity. Numerical experiments show that the retreat of lakes and glaciers at the end of the last glacial period can cause an increase in the Holocene slip rate of a fault. Such a correlation between enhanced seismicity and climate-driven mass fluctuations on Earth's surface is best documented for the Wasatch Fault, Utah.

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Causes and climatic influence of centennial-scale denitrification variability in the southeastern Arabian Sea since the last glacial period

Quaternary Research ◽

10.1017/qua.2020.118 ◽

2021 ◽

pp. 1-13

Author(s):

Sidhesh Nagoji ◽

Manish Tiwari

Keyword(s):

Arabian Sea ◽

Asian Summer Monsoon ◽

Intermediate Water ◽

Glacial Period ◽

South Asian Summer Monsoon ◽

Last Glacial Period ◽

The Holocene ◽

Last Glacial ◽

Southeastern Arabian Sea ◽

The Last Glacial

Abstract Denitrification occurring in the oxygen minimum zone of the Arabian Sea produces nitrous oxide, a powerful greenhouse gas. Therefore, it is important to understand the mechanisms controlling denitrification's intensity and evaluate its influence on the global climate at various timescales. We studied multiple geochemical and isotopic proxies in a sediment core from the southeastern Arabian Sea (SEAS) at a high (centennial-scale) resolution. We find that since the last glacial period, both the ventilation and the productivity caused by the South Asian summer monsoon played a major role in controlling the denitrification variability in SEAS. During the Last Glacial Maximum (LGM) and since the Holocene, denitrification increased in SEAS despite reduced monsoon-induced productivity. During the LGM, weakened thermohaline circulation resulted in reduced ventilation of the intermediate waters of SEAS, causing increased denitrification. During the Holocene, the increase in denitrification is caused by an enhanced inflow of oxygen-depleted Red Sea and Persian Gulf waters into the intermediate depth of SEAS owing to a rising sea level that prohibited ventilation by the Antarctic Intermediate Water. We further find millennial-scale synchronicity between denitrification in SEAS, global monsoons, and the North Atlantic climate, implying systematic linkages via greenhouse gases abundance.

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Abrupt sea surface pH change at the end of the Younger Dryas in the central sub-equatorial Pacific inferred from boron isotope abundance in corals (<i>Porites</i>)

Biogeosciences Discussions ◽

10.5194/bgd-7-1959-2010 ◽

2010 ◽

Vol 7 (2) ◽

pp. 1959-1993 ◽

Cited By ~ 5

Author(s):

E. Douville ◽

M. Paterne ◽

G. Cabioch ◽

P. Louvat ◽

J. Gaillardet ◽

...

Keyword(s):

Younger Dryas ◽

Equatorial Pacific ◽

Sea Surface ◽

Glacial Period ◽

Ph Change ◽

Last Glacial Period ◽

Surface Ph ◽

The Holocene ◽

Last Glacial ◽

The Last Glacial

Abstract. The "δ11B-pH" technique was applied to modern and ancient Porites from the sub-equatorial Pacific areas (Tahiti and Marquesas) spanning a time interval from 0 to 20 720 calendar years to determine the amplitude of pH changes between the Last Glacial Period and the Holocene. Boron isotopes were measured by Multi-Collector-Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) with an external reproducibility of 0.25‰, allowing a precision of ±0.025 pH-units. The boron concentration [B] and isotopic composition of modern samples indicate that the temperature strongly controls the partition coefficient KD for different aragonite species. Modern coral δ11B values and the reconstructed sea surface pH values for different Pacific areas match the measured pH expressed on the Sea Water Scale and confirm the calculation parameters that were previously determined by laboratory calibration exercises. Most ancient sea surface pH reconstructions near Marquesas are higher than modern values. These values range between 8.20 and 8.26 for the Holocene and reached 8.31 at the end of the last glacial period (20.7 kyr BP). At the end of the Younger Dryas (11.50±0.1 kyr BP), the central sub-equatorial Pacific experienced a dramatic drop of up to 0.2 pH-units from the average pH of 8.2 before and after this short event. Using the CO2SYS program, we recalculated the aqueous pCO2 to be 400±24 ppmV at around 11.5 kyr BP for corals at Marquesas and ~500 ppmV near Tahiti where it was assumed that pCO2 in the atmosphere was 250 ppmV. Throughout the Holocene, the difference in pCO2 between the ocean and the atmosphere at Marquesas (ΔpCO2) indicates that the surface waters behave as a moderate CO2 sink (−67 to −11 ppmV) during El Niño-like conditions. In contrast, during the last glacial/interglacial transition, this area was a moderate source of CO2 (−9 to 56 ppmV) for the atmosphere, highlighting predominant La Niña-like conditions. Such conditions were particularly pronounced at the end of the Younger Dryas with a large amount of CO2 released with ΔpCO2 of +140 ppmV. This last finding provides further evidence of the marked changes to the water mass pH and temperature properties in the equatorial Pacific at the Younger Dryas- Holocene transition and the strong impact of oceanic dynamic on the atmospheric CO2 content.

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Deep Ocean storage of heat and CO 2 in the Fram Strait, Arctic Ocean during the last glacial period

Paleoceanography and Paleoclimatology ◽

10.1029/2021pa004216 ◽

2021 ◽

Author(s):

Mohamed M. Ezat ◽

Tine L. Rasmussen ◽

Mathis P. Hain ◽

Mervyn Greaves ◽

James W. B. Rae ◽

...

Keyword(s):

Arctic Ocean ◽

Deep Ocean ◽

Fram Strait ◽

Glacial Period ◽

Last Glacial Period ◽

Last Glacial ◽

The Last Glacial

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Contrasting Patterns in Abrupt Asian Summer Monsoon Changes in the Last Glacial Period and the Holocene

Paleoceanography and Paleoclimatology ◽

10.1002/2017pa003294 ◽

2018 ◽

Vol 33 (2) ◽

pp. 214-226 ◽

Cited By ~ 5

Author(s):

Dianbing Liu ◽

Yongjin Wang ◽

Hai Cheng ◽

R. L. Edwards ◽

Xinggong Kong ◽

...

Keyword(s):

Summer Monsoon ◽

Asian Summer Monsoon ◽

Glacial Period ◽

Last Glacial Period ◽

The Holocene ◽

Last Glacial ◽

Asian Summer ◽

The Last Glacial

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Abrupt sea surface pH change at the end of the Younger Dryas in the central sub-equatorial Pacific inferred from boron isotope abundance in corals (<i>Porites</i>)

Biogeosciences ◽

10.5194/bg-7-2445-2010 ◽

2010 ◽

Vol 7 (8) ◽

pp. 2445-2459 ◽

Cited By ~ 44

Author(s):

E. Douville ◽

M. Paterne ◽

G. Cabioch ◽

P. Louvat ◽

J. Gaillardet ◽

...

Keyword(s):

Younger Dryas ◽

Equatorial Pacific ◽

Sea Surface ◽

Glacial Period ◽

Last Glacial Period ◽

Surface Ph ◽

The Holocene ◽

Last Glacial ◽

Ph Values ◽

The Last Glacial

Abstract. The "δ11B-pH" technique was applied to modern and ancient corals Porites from the sub-equatorial Pacific areas (Tahiti and Marquesas) spanning a time interval from 0 to 20.720 calendar years to determine the amplitude of pH changes between the Last Glacial Period and the Holocene. Boron isotopes were measured by Multi-Collector – Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) with an external reproducibility of 0.25‰, allowing a precision of about ±0.03 pH-units for pH values between 8 and 8.3. The boron concentration [B] and isotopic composition of modern samples indicate that the temperature strongly controls the partition coefficient KD for different aragonite species. Modern coral δ11B values and the reconstructed sea surface pH values for different Pacific areas match the measured pH expressed on the seawater scale and confirm the calculation parameters that were previously determined by laboratory calibration exercises. Most ancient sea surface pH reconstructions near Marquesas are higher than modern values. These values range between 8.19 and 8.27 for the Holocene and reached 8.30 at the end of the last glacial period (20.7 kyr BP). At the end of the Younger Dryas (11.50±0.1 kyr BP), the central sub-equatorial Pacific experienced a dramatic drop of up to 0.2 pH-units from the average pH of 8.2 before and after this short event. Using the marine carbonate algorithms, we recalculated the aqueous pCO2 to be 440±25 ppmV at around 11.5 kyr BP for corals at Marquesas and ~500 ppmV near Tahiti where it was assumed that pCO2 in the atmosphere was 250 ppmV. Throughout the Holocene, the difference in pCO2 between the ocean and the atmosphere at Marquesas (ΔpCO2) indicates that the surface waters behave as a moderate CO2 sink or source (−53 to 20 ppmV) during El Niño-like conditions. By contrast, during the last glacial/interglacial transition, this area was a marked source of CO2 (21 to 92 ppmV) for the atmosphere, highlighting predominant La Niña-like conditions. Such conditions were particularly pronounced at the end of the Younger Dryas with a large amount of CO2 released with ΔpCO2 of +185±25 ppmV. This last finding provides further evidence of the marked changes in the surface water pH and temperature in the equatorial Pacific at the Younger Dryas-Holocene transition and the strong impact of oceanic dynamic on the atmospheric CO2 content.

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Fragilariopsis kerguelensis size variability from the Indian subtropical Southern Ocean over the last 42 000 years

Antarctic Science ◽

10.1017/s095410201600050x ◽

2016 ◽

Vol 29 (2) ◽

pp. 139-146 ◽

Cited By ~ 5

Author(s):

Sunil Kumar Shukla ◽

Xavier Crosta

Keyword(s):

Southern Ocean ◽

Sea Ice ◽

Glacial Period ◽

Last Glacial Period ◽

Subtropical Zone ◽

The Holocene ◽

Last Glacial ◽

Size Variability ◽

The Last Glacial ◽

Valve Area

AbstractIn the open Southern Ocean (SO), both modern and past size changes of the diatom Fragilariopsis kerguelensis appear to be strongly controlled by iron availability. Conversely, sea surface temperatures (SST) and sea ice seasonal dynamics take over in the seasonal sea-ice zone where iron is not limiting. No information exists on F. kerguelensis biometry from the subtropical SO, on the other extreme of the thermal and nutrient gradients. We present here new data on mean valve area of F. kerguelensis (FkergArea) from a sediment core covering the last ~42 cal kyrs from the southern Subtropical Front (SSTF) of the Indian sector of the SO, where iron and silica stocks are thought to have been consistently low over this period. Our results suggest that larger F. kerguelensis valves occurred during the Last Glacial period, and declined during the Holocene period. These findings indicate that more favourable SST, within the F. kerguelensis ecological range, during the Last Glacial period may have enabled F. kerguelensis to make better use of the low silica stocks prevailing in the subtropical zone leading to larger valves. Conversely, declining FkergArea during the deglacial and the Holocene periods may have been a result of higher SST which hampered the utilization of silica.

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Paleoclimate reconstruction for the Holocene and the last glacial period based on environmental magnetic record from Lake Biwa, central Japan

Quaternary International ◽

10.1016/j.quaint.2012.08.322 ◽

2012 ◽

Vol 279-280 ◽

pp. 191

Author(s):

Akira Hayashida

Keyword(s):

Lake Biwa ◽

Glacial Period ◽

Central Japan ◽

Paleoclimate Reconstruction ◽

Last Glacial Period ◽

The Holocene ◽

Last Glacial ◽

Magnetic Record ◽

The Last Glacial

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How Ice Rafting Events Affect Asian Monsoon Hydroclimate

Eos ◽

10.1029/2018eo096271 ◽

2018 ◽

Vol 99 ◽

Author(s):

Sarah Stanley

Keyword(s):

Asian Monsoon ◽

Glacial Period ◽

Last Glacial Period ◽

The Holocene ◽

Isotopic Evidence ◽

Last Glacial ◽

Heinrich Events ◽

Ice Rafting ◽

The Last Glacial

Cave stalagmites provide isotopic evidence that Bond events and Heinrich events have more variable effects on Asian monsoon hydroclimate during the last glacial period than during the Holocene.

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