Orbital-scale denitrification changes in the Eastern Arabian Sea during the last 800 kyrs

Kim, Jieun; Khim, Boo‐Keun; Ikehara, Minoru; Lee, Jongmin

doi:10.1038/s41598-018-25415-7

Cited by 24 publications

(29 citation statements)

References 51 publications

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“…The smectite/(illite + chlorite) ratio at Site U1456 has been demonstrated to ultimately be controlled by the chemical weathering intensity in the source regions associated with variability of the ISM (Cai et al, ; Chen et al, ). The sediment δ 15 N and total organic carbon (TOC) contents, which have been used as indicators of denitrification in the Arabian Sea, are generally related to monsoon‐induced productivity (Kim et al, ; Tripathi et al, ). Consequently, based on provenance constraints ( 87 Sr/ 86 Sr ratios and εNd values), downcore variations in siliciclastic MAR, magnetic susceptibility (Pandey et al, ), smectite/(illite + chlorite) values (Cai et al, ), sediment δ 15 N and TOC contents (Tripathi et al, ), the CIA values (this study), and K/Al ratio (this study) at Site U1456 are compared with previously published ISM (Altabet et al, ; An et al, ; Clemens et al, ; Gupta et al, ) and sea level records (Rohling et al, ) in an attempt to understand the paleoclimate and paleoenvironment variations in the source areas during the different phases identified since 3.8 Ma (Figure ).…”

Section: Discussionmentioning

confidence: 99%

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Depositional History and Indian Summer Monsoon Controls on the Silicate Weathering of Sediment Transported to the Eastern Arabian Sea: Geochemical Records From IODP Site U1456 Since 3.8 Ma

Cai

Clift

et al. 2019

Geochem Geophys Geosyst

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Systematic variation in elemental and Sr-Nd isotopic compositions of the clay-sized (<2 μm) siliciclastic fraction from the International Ocean Discovery Program (IODP) Site U1456 (Laxmi Basin) provides valuable insights into dynamic changes in continental weathering intensity in the western Himalayas and sediment inputs from the Indus River and Deccan Traps to the eastern Arabian Sea. Long-term, high-resolution proxy records from the sediment core reveal that the main sources (i.e., Indus River and Deccan Trap basalts) of the fine-grained detrital sediments have significantly changed with Indian summer monsoon variation over the studied time interval. During two depositional periods (3.8-3.3 and 2.7-1.2 Ma) corresponding to a weak Indian summer monsoon, the Indus River contributed fine-grained sediments with high K/Al, high 87 Sr/ 86 Sr, and low εNd to the study site. Between 3.3 and 2.7 Ma and between 1.2 and 0 Ma, deposition in the eastern Arabian Sea was governed by large inputs of Deccan Trap-derived basaltic sediments, characterized by high Mg/Al and Fe/Al, low 87 Sr/ 86 Sr and chemical index of alteration values, and high εNd values, associated with a change to a stronger Indian summer monsoon driving stronger chemical weathering. Synchronous changes in the geochemical proxies since 3.8 Ma highlight that variations in the inputs of siliciclastic sediments and Indian summer monsoon development are closely coupled. Plain Language SummaryThe Indian summer monsoon is an extremely important part of the Earth's climate system. Weathering and erosion of sediments are deeply affected by monsoon rainfall. Since 3.8 Ma, the geochemical records suggest that the clay-sized siliciclastic fractions at Site U1456 were mainly derived from the Indus River when the Indian summer monsoon was generally weak. In contrast, the siliciclastic sediment supply from the Deccan Traps increased when the monsoon intensified. In particular, we propose that chemical weathering intensities can be tracked using K/Al ratios and chemical index alteration and the smectite/(illite + chlorite) in the fine fraction of marine sediments from the eastern Arabian Sea since 3.8 Ma. Conducting research in the region is of great importance for understanding past and present climatic conditions.

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Section: Discussionmentioning

confidence: 99%

“…We use the chronostratigraphic framework for the top ~500 m of the site based on 11 paleomagnetic and biostratigraphic data points (Pandey et al, ) together with the oxygen isotope stratigraphy developed by Kim et al () for the upper 141 m (Figure S1). Biostratigraphy suggests that there is a hiatus of ~0.45 m.y.…”

Section: Methodsmentioning

confidence: 99%

Depositional History and Indian Summer Monsoon Controls on the Silicate Weathering of Sediment Transported to the Eastern Arabian Sea: Geochemical Records From IODP Site U1456 Since 3.8 Ma

Cai

Clift

et al. 2019

Geochem Geophys Geosyst

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“…The overall variability of the clay isotopic composition increases dramatically at c. 3.5 Ma, probably reflecting the link between monsoon strength and glacial-interglacial cycles following the onset of Northern Hemisphere glaciation (e.g. An et al 2011;Kim et al 2018). Shorter timescale fluctuations occurred over at least the last 800 ka where 87 Sr/ 86 Sr and ε Nd are shown to vary quasi-cyclically (Khim et al 2018) and are interpreted to be controlled by sediment transport dominated by sea-level variations and possibly the Indian summer monsoon (Yu et al 2019).…”

Section: D2 Evidence For Control Of Sediment Provenance By Glaciamentioning

confidence: 99%

Clay-fraction strontium and neodymium isotopes in the Indus Fan: implications for sediment transport and provenance

et al. 2020

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Reconstructing the provenance of siliciclastic marine sediment is important for understanding sediment pathways and constraining palaeoclimate and erosion records. However, physical fractionation of different size fractions can occur during sediment transport, potentially biasing records derived from bulk sediment. In this study, records of radiogenic Sr and Nd isotopic composition and K/Al ratio of the separated clay fraction, as well as bulk grain size, are presented, measured from deep-sea sediments recovered from International Ocean Discovery Program (IODP) Sites U1456 and U1457 in the Arabian Sea. These new records are compared with published bulk sediment records to investigate the influence of sediment transport on these proxies and to constrain provenance evolution and its relationship to climate variability since middle Miocene time. Correlations between grain size and the bulk sediment isotopic composition confirm that transport processes are influencing the bulk sediment record. This relationship, although present, is not as strong in the clay-fraction isotopic records. Heterogeneity of bulk sediment likely drives differences between bulk and clay records, thought to be largely controlled by sediment transport processes. The isotopic records reveal variations in provenance that correlate with climatic change at 8–7 Ma, as well as an increase in overall provenance variability beginning at c. 3.5 Ma, likely linked to monsoon strength and glacial–interglacial cycles. The clay-fraction records highlight the potential value of measuring proxy records from multiple size fractions to help constrain provenance records as well as investigate sediment transport and/or weathering and erosion processes recorded in deep-sea sediment archives.

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“…S1 in the Supplementary Material available at https://doi.org/10.1017/ S0016756818000596). The details of the age model construction are described in Kim et al (2018). Briefly, a total of 260 samples were collected from a composite section of Unit I consisting of Holes U1456A and U1456C.…”

Section: Chronologymentioning

confidence: 99%

“…Down-core profiles of δ 18 OLR04(Lisiecki & Raymo, 2005), δ 18 O values of G. ruber(Kim et al 2018), 87 Sr/ 86 Sr values, εNd ratios, magnetic susceptibility (MS), and mean grain size of Unit I at Site U1456 during the last 800 ka. The blue and red dots in the left panel are δ 18 O data from Holes U1456A and U1456C, respectively.…”

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Detrital Sr–Nd isotopes, sediment provenances and depositional processes in the Laxmi Basin of the Arabian Sea during the last 800 ka

et al. 2018

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Abstract87Sr/86Sr ratios and εNd values of detrital particles at International Ocean Discovery Program (IODP) Site U1456 in the Laxmi Basin of the Arabian Sea were measured to trace changes in sediment provenance over glacial–interglacial cycles. Based on the correlation of planktonic foraminiferal (Globigerinoides ruber) δ18O fluctuations with the LR04 stack of benthic foraminifera δ18O values, combined with shipboard biostratigraphic and palaeomagnetic data, the studied interval spans ∼1.2 Ma. Over the past 800 ka, 87Sr/86Sr values ranged from 0.711 to 0.726 while εNd values ranged between −12.5 and −7.3 in the detrital particles. By comparing 87Sr/86Sr ratios and εNd values of the possible sources of river sediments with our data, we found that sediments in the Laxmi Basin were influenced to various degrees by proportions of at least three sediment sources (i.e. Tapi River, Narmada River and Indus River). The Indus River might be a more important contributor to glacial sediments. Although 87Sr/86Sr ratios and εNd values varied quasi-cyclically, this pattern did not correspond precisely to the glacial–interglacial cycles. In particular, low-magnetic-susceptibility (low-MS) intervals coinciding with pelagic carbonates were characterized by low 87Sr/86Sr ratios and high εNd values, whereas high-MS intervals matching turbidite deposits showed high 87Sr/86Sr ratios and low εNd values. Thus, this study reveals that differences in the depositional processes between glacial and interglacial periods, governed by changes in sea level and monsoon activity, are an important factor in deciding 87Sr/86Sr ratios and εNd values of the detrital fraction in the Indus Fan of the Arabian Sea.

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Orbital-scale denitrification changes in the Eastern Arabian Sea during the last 800 kyrs

Cited by 24 publications

References 51 publications

Depositional History and Indian Summer Monsoon Controls on the Silicate Weathering of Sediment Transported to the Eastern Arabian Sea: Geochemical Records From IODP Site U1456 Since 3.8 Ma

Depositional History and Indian Summer Monsoon Controls on the Silicate Weathering of Sediment Transported to the Eastern Arabian Sea: Geochemical Records From IODP Site U1456 Since 3.8 Ma

Clay-fraction strontium and neodymium isotopes in the Indus Fan: implications for sediment transport and provenance

Detrital Sr–Nd isotopes, sediment provenances and depositional processes in the Laxmi Basin of the Arabian Sea during the last 800 ka

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