Holocene Oxygen and Carbon Isotopic Records of Core OR102-3 off Southeastern Taiwan: Paleoceanographic Implications

The Holocene carbon and oxygen isotopic records of the planktonic foraminifera Globigerinoides sacculifer from core OR102-3 off southeastern Taiwan are presented. The isotopic values for this taxon from the Holocene period show ranges from -2.45‰ to -1.70‰ for δ^(18)O and from 2.47‰to 1.72‰ for δ^(13)C, respectively. Paleo-temperatures revealed from transfer function estimates of foraminifera assemblages in this core and in nearby core OR216-17 show that the surface waters in this region remained relatively warm and constant during the Holocene. The δ^(18)O values of the surface seawaters overlying the two core locations during the Holocene were then calculated using the paleotemperature equation. Results show that oxygen isotopic variations of the local surface waters during the Holocene were within 1‰ for core OR102-3 and 0.5‰ for core OR216-17, respectively. Two freshwater spikes are detected for core OR102-3 at about 2400yrs B.P. and 5700yrs B.P., but these spikes are not found in core OR216-17. These two freshwater spikes may be related to precipitation increases over eastern Taiwan during those two periods. Carbon isotopic records indicate that the δ^(13)C of the total dissolved CO^(2) in surface waters were almost the same for both cores during the Holocene.