Effects of intensification of the Indian Summer Monsoon on northern Andaman Sea sediments during the past 700 years

ABSTRACT Recent studies have revealed an intensification of the Indian Summer Monsoon (ISM) over the past 700 years, but its influence on the sediments in the northern Andaman Sea is unclear. To examine this influence, we used radiocarbon‐dated sediment core StMY6, acquired 100 km offshore in the no...

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Bibliographic Details
Published in:Journal of quaternary science 2017-05, Vol.32 (4), p.528-539
Main Authors: Ota, Yuki, Kawahata, Hodaka, Murayama, Masafumi, Inoue, Mayuri, Yokoyama, Yusuke, Miyairi, Yosuke, Aung, Thura, Hossain, H. M. Zakir, Suzuki, Atsushi, Kitamura, Akihisa, Moe, Kyaw Thu
Format: Article
Language:English
Subjects:
Andaman Sea
Ayeyarwady River
Carbon 14
Carbonates
Catchments
Geochemistry
Grain size distribution
Indian Summer Monsoon
Influence
Monsoons
Organic carbon
palaeoenvironments
Particle size
River catchments
River mouth
River water
Rivers
Sedimentation
Sedimentation rates
Sediments
Size distribution
Summer
Summer monsoon
Total organic carbon
Water discharge
Weathering
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Summary:ABSTRACT Recent studies have revealed an intensification of the Indian Summer Monsoon (ISM) over the past 700 years, but its influence on the sediments in the northern Andaman Sea is unclear. To examine this influence, we used radiocarbon‐dated sediment core StMY6, acquired 100 km offshore in the northern Andaman Sea from the Ayeyarwady River mouth, and obtained a 700‐year‐long record of the grain‐size distribution and geochemistry of the sedimentary sequence. The ISM influences precipitation surrounding the Ayeyarwady River, and thus the river water and sediment discharges to the northern Andaman Sea near the river mouth in the Ayeyarwady River and the weathering intensity in the river catchment. Based on the system, we propose that higher sedimentation rates and larger modal grain size (the most abundant size in the grain‐size distribution of sediments) and lower carbonate concentrations after about AD 1600 can be attributed to higher ISM intensity. Profiles of total organic carbon (TOC) content and carbon/nitrogen (C/N) ratios, however, did not show any trends after about AD 1600, which suggests that the ISM has had little influence on these proxies at this site.
ISSN:0267-8179
1099-1417
DOI:10.1002/jqs.2947