A ∼25ka Indian Ocean monsoon variability record from the Andaman Sea

Rashid, Harunur; Flower, B. P.; Poore, Richard Z.; Quinn, T. M.

doi:10.1016/j.quascirev.2007.07.002

Cited by 187 publications

(180 citation statements)

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“…Mn showed significant enrichment (1-4%) in the top 12 cm and low Mn content in the deeper samples due to clay mineral Mn or carbonate-Mn [2] and suggested that Mn enrichment in the upper sediment are due to hydrothermal process which played a major role. In the present study, higher level of Ba, which is a productivity proxy, is observed upto ~14 ka BP during B/A but reduced Ba content during 15-40 ka BP (MIS 2-3) due to the "Late glacial" interval suggesting a near collapse of productivity [6]. Downward metal concentration varied similarly to those observed for P (between ~20 and 80 μg/g), with lower concentrations occurring during glacial intervals (H1) and higher concentrations during interglacial intervals (Fig.…”

Section: Ca Fe and Mn Enrichment In The Authigenic Fractionsupporting

confidence: 46%

“…It is clearly seen in the figure 4 that REE contents in the sediments at depths 290 to 225 cm decrease significantly, possibly influenced by freshwater input during de-glaciation. It is clearly evidenced from the previous findings that rapid climate change during the last deglaciation and Holocene included substantial hydrologic changes in the Indian Ocean Monsoon system that were coherent with the larger Asian monsoon [6].…”

Section: Ca Fe and Mn Enrichment In The Authigenic Fractionmentioning

confidence: 70%

“…Previous studies on sediment geochemistry [2,3], isotope composition [4], REE concentrations of surface waters [5,6] and monsoon variability of the Andaman Sea [7] were reported. However, the authigenic Fe-Mn oxides in the Andaman Sea sediments were not studied to understand the formation and delivery of this fraction.…”

Section: Introductionmentioning

confidence: 99%

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Determination of rare earth, major and trace elements in authigenic fraction of Andaman Sea (Northeastern Indian Ocean) sediments by Inductively Coupled Plasma-Mass Spectrometry

Alagarsamy

You

Nath

et al. 2010

Microchemical Journal

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Downcore variation of rare-earth elements (REEs) in the authigenic Fe-Mn oxides of a sediment core (covering a record of last ~40 kyr) from the Andaman Sea, a part of Indian Ocean show distinctive positive Ce and Eu anomalies. These positive Ce anomalies (Ce*=1.1~1.8) are ascribed to be due to oxidation of deep sea sediments. The large positive Eu anomalies (i.e., Eu* >1.8 to 3.2) occur within a time span near the glacial/interglacial transition (~7,000-14,000 yr BP) which could be due to the past hydrothermal activity or to the effects arising from sea level changes. During glacial times, the Andaman Sea was almost completely isolated due to low sea level, leading to a reduction in sediment supply from the Ayeyarwady river. The variations of metal abundances (i.e., Ca, Al, Mn, and Fe) in the authigenic fraction provided independent information to evaluate the water column physicochemical changes during the glacial/interglacial transition period. The studied sediment core record changes in riverine inputs and reflect depositional changes related to sea level fluctuations and climatic events over the past 40 kyr in the Andaman Sea.

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Section: Ca Fe and Mn Enrichment In The Authigenic Fractionsupporting

confidence: 46%

Section: Ca Fe and Mn Enrichment In The Authigenic Fractionmentioning

confidence: 70%

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Determination of rare earth, major and trace elements in authigenic fraction of Andaman Sea (Northeastern Indian Ocean) sediments by Inductively Coupled Plasma-Mass Spectrometry

Alagarsamy

You

Nath

et al. 2010

Microchemical Journal

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“…During the last two decades, the variability of the Indian summer monsoon (ISM) in the Holocene has been reconstructed from various types of paleoclimatic archive and proxies, such as stalagmite oxygen isotope (δ 18 O) records Fleitmann et al, 2003, marine sediments (Contreras-Rosales et al, 2014;Gupta et al, 2003;Rashid et al, 2007), and lake and peatland sediments (Bird et al, 2014;Chen et al, 2014;Cook et al, 2013;Demske et al, 2009;Fuchs and Buerkert, 2008;Jarvis, 1993;Kramer et al, 2010;Prasad et al, 2014;Sarkar et al, 2015;C. Shen et al, 2006;J.…”

Section: Introductionmentioning

confidence: 99%

Holocene Asian monsoon evolution revealed by a pollen record from an alpine lake on the southeastern margin of the Qinghai–Tibetan Plateau, China

et al. 2016

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Abstract. We present the results of pollen analyses from a 1105 cm long sediment core from Wuxu Lake in southwestern China, which depict the variations of the East Asian winter monsoon (EAWM) and the Indian summer monsoon (ISM) during the last 12.3 ka. During the period of 12.3 to 11.3 cal ka BP, the dominance of Betula forest and open alpine shrub and meadow around Wuxu Lake indicates a climate with relatively cold winters and dry summers, corresponding to the Younger Dryas event. Between 11.3 and 10.4 cal ka BP, further expansion of Betula forest and the retreat of alpine shrubs and meadows reflect a greater seasonality with cold winters and gradually increasing summer precipitation. From 10.4 to 4.9 cal ka BP, the dense forest understory, together with the gradual decrease in Betula forest and increase in Tsuga forest, suggest that the winters became warmer and summer precipitation was at a maximum, corresponding to the Holocene climatic optimum. Between 4.9 and 2.6 cal ka BP, Tsuga forest and alpine shrubs and meadows expanded significantly, reflecting relatively warm winters and decreased summer precipitation. Since 2.6 cal ka BP, reforestation around Wuxu Lake indicates a renewed humid period in the late Holocene; however, the vegetation in the catchment may also have been affected by grazing activity during this period. The results of our study are generally consistent with previous findings; however, the timing and duration of the Holocene climatic optimum from different records are inconsistent, reflecting real contrast in local rainfall response to the ISM. Overall, the EAWM is broadly inphase with the ISM on the orbital timescale, and both monsoons exhibit a trend of decreasing strength from the early to late Holocene, reflecting the interplay of solar insolation receipt between the winter and summer seasons and El Niño-Southern Oscillation strength in the tropical Pacific.

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“…The ISM is the product of a pressure difference resulting from tropospheric heating between the high Tibetan Plateau and tropical Indian Ocean. This seasonal low atmospheric pressure at the Tibetan Plateau relative to higher pressure over the cooler Indian Ocean sets the stage for the cyclonic summer-monsoon wind patterns (Webster et al 1998;Rashid et al 2007). The cyclonic wind intensifies upwelling at the Somali margin, bringing up cold, nutrient rich waters that stimulate high productivity (Honjo et al 1999;Heinz and Hemleben 2006;Rao et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Late Glacial to Holocene Indian Summer Monsoon Variability Based upon Sediment Records Taken from the Bay of Bengal

Rashid¹,

England²,

Thompson³

et al. 2011

Terr. Atmos. Ocean. Sci.

145

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Paleoclimatic records from the Bay of Bengal are rare. We reconstruct the sea-surface temperature (SST) 18 O sw values suggest that the monsoon was stronger and wetter resulting in a humid climate. After ~5 ka the Indian summer monsoon weakened significantly, indicating less dilution of the sea surface by the Ganges-Brahmaputra-Meghna outflow and/or less direct rainfall. We hypothesize that the prevailing late Holocene dry climate may have caused the diminishment and subsequent abandonment of the settlements of the great Indus Valley Civilizations. Our Bay of Bengal climate records are consistent with those from the Andaman Sea, corroborating broad regional changes in the Indian summer monsoon during the last 25 ka. The general pattern and timing of monsoon variability in the Bay of Bengal and Andaman Sea seems to parallel the Arabian Sea, Africa, and Asian ice cores and speleothem records suggesting that a common tropical forcing may have induced these abrupt climate changes.

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A ∼25ka Indian Ocean monsoon variability record from the Andaman Sea

Cited by 187 publications

References 90 publications

Determination of rare earth, major and trace elements in authigenic fraction of Andaman Sea (Northeastern Indian Ocean) sediments by Inductively Coupled Plasma-Mass Spectrometry

Determination of rare earth, major and trace elements in authigenic fraction of Andaman Sea (Northeastern Indian Ocean) sediments by Inductively Coupled Plasma-Mass Spectrometry

Holocene Asian monsoon evolution revealed by a pollen record from an alpine lake on the southeastern margin of the Qinghai–Tibetan Plateau, China

Late Glacial to Holocene Indian Summer Monsoon Variability Based upon Sediment Records Taken from the Bay of Bengal

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