Monsoon-influenced variation of clay mineral compositions and detrital Nd-Sr isotopes in the western Andaman Sea (IODP Site U1447) since the late Miocene

Lee, Jongmin; Kim, Sunghan; Lee, Jae Il; Cho, Hyen Goo; Phillips, Stephen C.; Khim, Boo‐Keun

doi:10.1016/j.palaeo.2019.109339

Cited by 22 publications

(17 citation statements)

References 49 publications

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“…Magnetic records from the Chinese Loess Plateau are interpreted to show a long-term intensification of the East Asian summer monsoon (EASM) from ∼ 8.2 to 2.6 Ma (Ao et al, 2016). A late Miocene strengthening of Asian winter monsoons is inferred from South China Sea Jia et al, 2003;Wan et al, 2007) and Andaman Sea (Lee et al, 2020) records. In the Arabian Sea, an intensification of upwelling and productivity at ∼ 8 Ma is interpreted to reflect a strengthening of the South Asian summer monsoon (SASM) (Kroon et al, 1991;Singh and Gupta, 2014;Gupta et al, 2004), although other studies find evidence contrary to this (Tripathi et al, 2017;Huang et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Secular and orbital-scale variability of equatorial Indian Ocean summer monsoon winds during the late Miocene

Bolton

Gray

Kuhnt³

et al. 2022

Clim. Past

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Abstract. In the modern northern Indian Ocean, biological productivity is intimately linked to near-surface oceanographic dynamics forced by the South Asian, or Indian, monsoon. In the late Pleistocene, this strong seasonal signal is transferred to the sedimentary record in the form of strong variance in the precession band (19–23 kyr), because precession dominates low-latitude insolation variations and drives seasonal contrast in oceanographic conditions. In addition, internal climate system feedbacks (e.g. ice-sheet albedo, carbon cycle, topography) play a key role in monsoon variability. Little is known about orbital-scale monsoon variability in the pre-Pleistocene, when atmospheric CO2 levels and global temperatures were higher. In addition, many questions remain open regarding the timing of the initiation and intensification of the South Asian monsoon during the Miocene, an interval of significant global climate change that culminated in bipolar glaciation. Here, we present new high-resolution (<1 kyr) records of export productivity and sediment accumulation from International Ocean Discovery Program Site U1443 in the southernmost part of the Bay of Bengal spanning the late Miocene (9 to 5 million years ago). Underpinned by a new orbitally tuned benthic isotope stratigraphy, we use X-ray fluorescence-derived biogenic barium variations to discern productivity trends and rhythms. Results show strong eccentricity-modulated precession-band productivity variations throughout the late Miocene, interpreted to reflect insolation forcing of summer monsoon wind strength in the equatorial Indian Ocean. On long timescales, our data support the interpretation that South Asian monsoon winds were already established by 9 Ma in the equatorial sector of the Indian Ocean, with no apparent intensification over the latest Miocene.

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Section: Introductionmentioning

confidence: 99%

Secular and orbital-scale variability of equatorial Indian Ocean summer monsoon winds during the late Miocene

Bolton

Gray

Kuhnt³

et al. 2022

Clim. Past

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“…9). IODP Site U1447 and NGHP-01 Site 17 in the Andaman accretionary wedge are rich in smectitegroup clays (14 % to 83 % smectite, 19 % to 47 % illite of the < 2 µm fraction) (Lee et al, 2020;Phillips et al, 2014b). In contrast, IODP Sites U1445 and U1446 in the Mahanadi Basin are located near NGHP-01 Sites 18 and 19, which are more illite-rich (9 % to 28 % smectite, 29 % to 54 % illite of the < 2 µm fraction) (Phillips et al, 2014b).…”

Section: Underestimation Of Clay Content and Overestimation Of Carbonatementioning

confidence: 99%

Comparison of sediment composition by smear slides to quantitative shipboard data: a case study on the utility of smear slide percent estimates, IODP Expedition 353, northern Indian Ocean

Phillips

Littler

2022

Sci. Dril.

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Abstract. Smear slide petrography has been a standard technique during scientific ocean drilling expeditions to characterize sediment composition and classify sediment types, but presentation of these percent estimates to track downcore trends in sediment composition has become less frequent over the past 2 decades. We compare semi-quantitative smear slide composition estimates to physical property (natural gamma radiation, NGR) and solid-phase geochemical (calcium carbonate, CaCO3 %) measurements from a range of marine depositional environments in the northern Indian Ocean (Bay of Bengal, Andaman Sea, Ninetyeast Ridge) collected during International Ocean Discovery Program (IODP) Expedition 353. We show that presenting smear slide estimates as percentages, rather than abundance categories, reveals similar downcore variation in composition to the more quantitative core analyses. Overall downcore trends in total calcareous components from smear slides (foraminifers + nannofossils + shell fragments + authigenic carbonate) follow similar downcore trends to samples measured by CaCO3 coulometry. Total lithogenic components (clay + mica + quartz + feldspars + lithic grains + vitric grains + glauconite + heavy minerals + iron oxides) and clay from smear slides track reasonably well with NGR measurements. Comparison of site averages of absolute percentages of total calcium carbonate from coulometry and total calcareous components from smear slide observations reveals an overestimation in carbonate percentages in smear slides (likely due in part to underestimation of the clay fraction), especially in sediments rich in smectite clays. Differences in sediment color between sites and settling of clay particles during slide preparation may contribute to this discrepancy. Although smear slide estimates range in accuracy depending on the training of the operator, we suggest that sedimentologists describing cores obtained during scientific drilling can use the percent estimates of sedimentary components in smear slides to identify trends and cyclicity in marine sediment records.

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“…In addition, the strengthened intermediate-to-deep water flow would have supplied non-radiogenic material from the Andaman Sea to the Ninetyeast Ridge (Liao et al 2020). Indeed, the ε Nd of Andaman Sea sediments (− 11.2 to − 8.7; Lee et al 2020), sourced from the Irrawaddy (− 7.3 to − 6.8; Giosan et al 2018) and Salween (− 14.7 to − 15.4; Damodararao et al 2016), is similar to the non-radiogenic values found in the cores HI1808-GPC04 and ODP 758.…”

Section: The New ε Nd Record Of Hi1808-gpc04 and Comparison With Odp 758 And Sk 129mentioning

confidence: 99%

Deep-Water Circulation over the Last Two Glacial Cycles Reconstructed from Authigenic Neodymium Isotopes in the Equatorial Indian Ocean (Core HI1808-GPC04)

et al. 2021

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We reconstructed the past deep-water character of the equatorial Indian Ocean using the isotope ratio of neodymium (εNd) in the Fe–Mn coating of mixed-species foraminifera. When compared with previous εNd records at the same site (ODP 758) and at another site to the west (SK 129), the three datasets were consistent and showed glacial-interglacial variations, even though the other two records were extracted from different media (cleaned foraminifera and bulk sediment leach). This confirms that while the foraminiferal coating is the preferred medium for reconstructing past bottom water εNd records, for carbonate-dominated lithologies, weak acid extraction of bulk sediment is also a viable option offering high-resolution capabilities. When the lithology includes volcanic particles or high organics, the extraction protocol may need to be adjusted to guard against detrital contamination or a slight correction may need to be applied. During glacials, the deep waters bathing the equatorial Indian Ocean had a larger AABW component and during interglacials a larger NADW component. Our HI1808-GPC04 record supplements the ODP 758 record in the interval with prominent AABW signal (MIS 6/5 transition and MIS 7) and reveals regional effects in some non-radiogenic intervals. The smaller differences between the HI1808-GPC04/ODP 758 and SK 129 records seem to reflect regional Nd input from river systems and non-radiogenic Nd from the boundaries.

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Monsoon-influenced variation of clay mineral compositions and detrital Nd-Sr isotopes in the western Andaman Sea (IODP Site U1447) since the late Miocene

Cited by 22 publications

References 49 publications

Secular and orbital-scale variability of equatorial Indian Ocean summer monsoon winds during the late Miocene

Secular and orbital-scale variability of equatorial Indian Ocean summer monsoon winds during the late Miocene

Comparison of sediment composition by smear slides to quantitative shipboard data: a case study on the utility of smear slide percent estimates, IODP Expedition 353, northern Indian Ocean

Deep-Water Circulation over the Last Two Glacial Cycles Reconstructed from Authigenic Neodymium Isotopes in the Equatorial Indian Ocean (Core HI1808-GPC04)

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