南海ODP1143站底栖有孔虫Cibicidoides与Uvigerina稳定氧碳同位素值的均衡试验

Stable Isotope Equilibrium Test between Benthic Foraminifer Cibicidoides and Uvigerina at ODP Site 1143, Southern South China Sea

从南海南部ODP184航次 114 3站上部合成深度 190 .77m共 1992个样品中 ,由老到新挑选了 6 4个样品 ,测试了同一样品中底栖有孔虫Uvigerinaperegerina与Cibicidoideswuellerstorfi的δ18O和δ13 C值 ,结果表明 114 3站U .peregerina与C .wuellerstorfi的δ18O差值的平均值约为 (0 .6 14± 0 .0 7)× 10 -3 ,而δ13 C差值的平均值约为 (0 .6 92± 0 .0 4 )× 10 -3 .114 3站U .peregerina与C .wuellerstorfi的δ18O差值与大西洋和东太平洋的标准差值 0 .6 4× 10 -3 比较接近 ,而δ13 C的差值却比大西洋和东太平洋的标准差值 0 .9× 10 -3 轻 0 .2 0 8× 10 -3 ,可能是由于南沙珊瑚礁区较低的生产力缩小了沉积物与海水之间的δ13 C的差异而引起的 .该均衡试验为南海甚至西太平洋的古海洋学研究提供了上述 2种底栖有孔虫氧碳同位素值转换的标准 .

Stable oxygen and carbon isotope records from ODP Site 1143 (9°21.72′N, 113°17.11′E, 2 772 m) in the southern South China Sea (SCS) are presented for the benthic foraminifers Cibicidoides wuellerstorfi and Uvigerina peregerina in 64 samples. The results show that the average δ^(18)O difference between Cibicidoides wuellerstorfi and Uvigerina peregerina of 64 samples at Site 1143 is (0.614±0.07)×10^(-3), close to 0.64×10^(-3) of the standard oxygen isotopic difference in the Atlantic and the east Pacific, whereas the average δ^(13)C difference of these two species at Site 1143 is (0.692±0.04)×10^(-3), much lighter than 0.9×10^(-3) of the standard carbon isotopic difference in the Atlantic and the east Pacific. The lighter value of δ^(13)C difference at Site 1143 may be caused by the low productivity in reef areas which had decreased the δ^(13)C difference between the depositions and the sea water. This test at Site 1143 provides an adjustive standard of oxygen and carbon isotope values between benthic foraminiferal Cibicidoides wuellerstorfi and Uvigerina peregerina for the paleoceanographic study in the South China Sea and even in the west Pacific.