Holocene marine 14C reservoir age variability: evidence from 230Th-dated corals in the South China Sea
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Date
2010-09
Journal Title
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Publisher
American Geophysical Union
Abstract
The South China Sea (SCS) is well connected with the western Pacific and influenced by the East Asian monsoon. We have examined temporal variations in radiocarbon marine reservoir ages (R) and regional marine reservoir corrections (ΔR) of the SCS during the Holocene using paired measurements of AMS 14C and TIMS 230Th on 20 pristine corals. The results show large fluctuations in both R and ΔR values over the past 7500 years (yrs) with two distinct plateaus during 7.5–5.6 and 3.5–2.5 thousand calendar years before present (cal ka BP). The respective weighted mean ΔR values of these plateaus are 151 ± 85 and 89 ± 59 yrs, which are significantly higher than its modern value of −23 ± 52 yrs. This suggests that using a constant modern ΔR value to calibrate 14C dates of the SCS marine samples will introduce additional errors to the calibrated ages. Our results provide the first database for the Holocene R and ΔR values of the SCS for improved radiocarbon calibration of marine samples. We interpret the two ΔR plateaus as being related to two intervals with weakened El Niño - Southern Oscillation (ENSO) and intensified East Asian summer monsoon (EASM). This is because the 14C content of the SCS surface water is controlled by both the 14C concentration of the Pacific North Equatorial Current (NEC) which is in turn influenced by ENSO-induced upwelling along the Pacific equator and vertical upwelling within the SCS as a result of moisture transportation to midlatitude region to supply the EASM rainfall. © 2010 American Geophysical Union.
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Keywords
Quaternary period, Asia, Monsoons, China Sea, Carbon 14, Age estimation
Citation
Yu, K., Hua, Q., Zhao, J.-X., Hodge, E., Fink, D., & Barbetti, M. (2010). Holocene marine 14C reservoir age variability: evidence from 230Th-dated corals in the South China Sea. Paleoceanography and Paleoclimatology, 25(3), PA3205. doi:10.1029/2009PA001831