Impact of Indus River discharge on productivity and preservation of organic carbon in the Arabian Sea over the twentieth century

Lückge, Andreas; Deplazes, Gaudenz; Schulz, Hartmut; Scheeder, Georg; Suckow, Axel; Kasten, Sabine; Haug, Gerald H.

doi:10.1130/g32608.1

Cited by 18 publications

(12 citation statements)

References 35 publications

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“…In our study the DO oscillations and the current interglacial period are traced in high resolution by the L * record and Ni (%) that show a high correlation with organic matter contents. Organic petrographic analyses indicate that the organic matter is predominantly of marine origin [ Lückge et al ., , ]. The observed signal cannot be the result of dilution by carbonate or siliciclastic contents as they show a different pattern, for example, during the deglaciation.…”

Section: Discussionmentioning

confidence: 99%

“…The observed multiproxy pattern could alternatively or additionally indicate increased nutrient injection via the Indus River provoking enhanced marine productivity in the region that is influenced by the Indus River plume and subsequent sediment deposition. The importance of fluvial nutrient delivery on coastal productivity at the study site has been suggested for recent times [ Lückge et al ., ] and for other locations on various time scales [ Peterson et al ., ; Dagg et al ., ]. The importance of riverine nutrient delivery during glacial times might have been underestimated in the northeastern Arabian Sea.…”

Section: Discussionmentioning

confidence: 99%

“…Today, sediments are mainly deposited within the innermost shelf and at the delta, whereas the outer shelf (>~90 m) is characterized by a lack of deposition [von Rad and Tahir, 1997]. The most recent evolution of sediment transport by the Indus River is additionally influenced by extensive damming in the catchment area [Milliman et al, 1984;Clift et al, 2008;Lückge et al, 2012].…”

Section: Terrestrial Siliciclastic Signature and Depositional Regimementioning

confidence: 99%

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Weakening and strengthening of the Indian monsoon during Heinrich events and Dansgaard-Oeschger oscillations

et al. 2014

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The Dansgaard-Oeschger oscillations and Heinrich events described in North Atlantic sediments and Greenland ice are expressed in the climate of the tropics, for example, as documented in Arabian Sea sediments. Given the strength of this teleconnection, we seek to reconstruct its range of environmental impacts. We present geochemical and sedimentological data from core SO130-289KL from the Indus submarine slope spanning the last~80 kyr. Elemental and grain size analyses consistently indicate that interstadials are characterized by an increased contribution of fluvial suspension from the Indus River. In contrast, stadials are characterized by an increased contribution of aeolian dust from the Arabian Peninsula. Decadal-scale shifts at climate transitions, such as onsets of interstadials, were coeval with changes in productivity-related proxies. Heinrich events stand out as especially dry and dusty events, indicating a dramatically weakened Indian summer monsoon, potentially increased winter monsoon circulation, and increased aridity on the Arabian Peninsula. This finding is consistent with other paleoclimate evidence for continental aridity in the northern tropics during these events. Our results strengthen the evidence that circum-North Atlantic temperature variations translate to hydrological shifts in the tropics, with major impacts on regional environmental conditions such as rainfall, river discharge, aeolian dust transport, and ocean margin anoxia.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Terrestrial Siliciclastic Signature and Depositional Regimementioning

confidence: 99%

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Weakening and strengthening of the Indian monsoon during Heinrich events and Dansgaard-Oeschger oscillations

et al. 2014

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“…This procedure was carried out as δ 15 N in sediments is impacted by several factors in addition to the δ 15 N of nitrate upwelled or mixed from subsurface waters. Nitrogen fixation or an allochthonous supply of nitrogen from rivers or the atmosphere can reduce δ 15 N in particulate matter (Agnihotri et al, 2011(Agnihotri et al, , 2008(Agnihotri et al, , 2009Lückge et al, 2012;Montoya and Voss, 2006). Upwelling from different water depths and the incomplete utilization of nitrate supplied by upwelling may furthermore lead to a gradient with increasing δ 15 N values offshore of the upwelling areas (Naqvi et al, 2003).…”

Section: Integration and Averaging Of Sst And δ 15 N Reconstructionsmentioning

confidence: 99%

Glacial–interglacial changes and Holocene variations in Arabian Sea denitrification

et al. 2018

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Abstract. At present, the Arabian Sea has a permanent oxygen minimum zone (OMZ) at water depths between about 100 and 1200 m. Active denitrification in the upper part of the OMZ is recorded by enhanced δ 15 N values in the sediments. Sediment cores show a δ 15 N increase during the middle and late Holocene, which is contrary to the trend in the other two regions of water column denitrification in the eastern tropical North and South Pacific. We calculated composite sea surface temperature (SST) and δ 15 N ratios in time slices of 1000 years of the last 25 kyr to better understand the reasons for the establishment of the Arabian Sea OMZ and its response to changes in the Asian monsoon system. Low δ 15 N values of 4-7 ‰ during the last glacial maximum (LGM) and stadials (Younger Dryas and Heinrich events) suggest that denitrification was inactive or weak during Pleistocene cold phases, while warm interstadials (ISs) had elevated δ 15 N. Fast changes in upwelling intensities and OMZ ventilation from the Antarctic were responsible for these strong millennial-scale variations during the glacial. During the entire Holocene δ 15 N values > 6 ‰ indicate a relatively stable OMZ with enhanced denitrification. The OMZ develops parallel to the strengthening of the SW monsoon and monsoonal upwelling after the LGM. Despite the relatively stable climatic conditions of the Holocene, the δ 15 N records show regionally different trends in the Arabian Sea. In the upwelling areas in the western part of the basin, δ 15 N values are lower during the mid-Holocene (4.2-8.2 ka BP) compared to the late Holocene (< 4.2 ka BP) due to stronger ventilation of the OMZ during the period of the most intense southwest monsoonal upwelling. In contrast, δ 15 N values in the northern and eastern Arabian Sea rose during the last 8 kyr. The displacement of the core of the OMZ from the region of maximum productivity in the western Arabian Sea to its present position in the northeast was established during the middle and late Holocene. This was probably caused by (i) reduced ventilation due to a longer residence time of OMZ waters and (ii) augmented by rising oxygen consumption due to enhanced northeast-monsoon-driven biological productivity. This concurs with the results of the Kiel Climate Model, which show an increase in OMZ volume during the last 9 kyr related to the increasing age of the OMZ water mass.

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“…Lückge et al . () have demonstrated an anthropogenic influence on sedimentation in a much more distal location on the upper slope and so it would seem unlikely that this would have no impact closer to the river mouth. We do know that the number of sandy layers is of a similar order to the maximum age of the core.…”

Section: Sediment Delivery To the Canyon Headmentioning

confidence: 99%

Sediment storage and reworking on the shelf and in the Canyon of the Indus River‐Fan System since the last glacial maximum

et al. 2014

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The transport of sediment from the mouth of the Indus River on to the deep-water submarine fan is complicated by temporary storage within large clinoforms on the shelf on either side of the submarine canyon, where most of the sedimentation since the start of the Holocene has occurred. In contrast, shelf edge clinoform deltas represent the products of forced regression and not the progradation of highstand clinoforms as far as the shelf edge. Clinoform sediments have a mixed provenance that involves significant reworking of older sediment deposited during or before the last glacial maximum. Recent sedimentation in the canyon head has been very rapid in the last few centuries (ca. 10 cm year À1 ), but has been starved of sand probably because of 20th century damming. Sandy layers appear to represent annual monsoonal floods with a particularly large flood every 50-70 years. This canyon head sediment is also reworked by currents flowing along the canyon axis before being deposited deeper into the canyon. The last sandy sediment to reach the mid-canyon (ca. 1300 m depth) was transported around 7000 year BP at a time of rising sea-levels, and might reflect reworking by the transgression, or local slumping from the walls of the canyon. Dating of the uppermost in a series of terraces in the mid-canyon area suggests that the canyon may have been partly filled and emptied of sediment at least three times since ca. 50 ka. We conclude from the Holocene record that sediment flux to the deep-water fan experiences major buffering, reworking and recycling both on the shelf and within the submarine canyon prior to its deposition, so that turbidite sands in the deep Arabian Sea cannot be used to correlate with climatic or tectonic events onshore over timescales of 10 3 -10 5 years.

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Impact of Indus River discharge on productivity and preservation of organic carbon in the Arabian Sea over the twentieth century

Cited by 18 publications

References 35 publications

Weakening and strengthening of the Indian monsoon during Heinrich events and Dansgaard-Oeschger oscillations

Weakening and strengthening of the Indian monsoon during Heinrich events and Dansgaard-Oeschger oscillations

Glacial–interglacial changes and Holocene variations in Arabian Sea denitrification

Sediment storage and reworking on the shelf and in the Canyon of the Indus River‐Fan System since the last glacial maximum

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