南中国海8KL岩芯氧同位素第6期以来的氧、碳稳定同位素记录与堆积速率研究

A Studies on Stable Oxygen and Carbon Isotope Records and Acuomulation Rates in Core 8KL of the South China Sea from Oxygen Isotope Stage 6

通过对南中国海重力活塞岩芯８ＫＬ的４个浮游有孔虫种和２个底栖有孔虫的δ１８Ｏ和δ１３Ｃ则定，发现浮游和底栖有孔虫种的氧同位素记录可清晰地划分出１８６Ｋａ以来的氧同位素的１—６期。浮游有孔虫的碳同位素记录了氧同位素１／２和５／６期界限处两个明显变轻的事件。反映了由冰期向间冰期过渡时存在着显著的中层水和底层水上涌现象。根据浮游有孔虫种的氧同位素组成判断，各浮游有孔虫种的生存深度由浅至深依次为，Ｇｌｏｂｉｄｅｒｉｎｏｉｄｅｓｒｕｂｅｒ（ｐｉｎｋ），Ｇ·ｒｕｂｅｒ和Ｇ．ｓａｃｃｕｌｉｆｅｒ。氧同位素地层学研究表明，南中国海冰期时的沉积速率和沉积通量要明显大于间冰期。

Abstract The data of 518O and δ13C were measured from planlctoric foraminifera for 4 species and foraminifea for 2 species in piston core 8 SKL of the South China Sea(S. C. S.). The oxygen isotope records of planltonic and benthic foraminifera can be recognized stage 1～6 distinctly. A research on biostratigraphy of the planktonic forams indicated that the last appearance datum (LAD) of Globigerinoides ruber(pink) occured at oxygen isotope stage 5. 5 (≈ 120ka). The curvres of planktonic carbon isotope composition clearly recorded two lightest events at 128ha (stage 5/6) and 12ka(stage 1/2), especially for 128ka. This phenomenon was discoverd in different cores such as SCS 15A and 15B in the southern port of S. C. S., 37KL in the northern part of S. C. S. and V19-30 in the East Pacific Ocean as well as the cores in Mexico Gulf. Therefore,the two events might be existed in the whole ocean. Due to the lighter δ13C value was recorded in deeper planktonic forams, so it can be infered that the two lightest events reflected on existence of welling watermasses from intermediate and bottom waters in transitional duration from glaciation to interglaciation. In terms of the oxygen siotope records from planktonic forams, the dewelling water depth of planktonic foraminifera species from shallower to deeper was G. ruber(pink), G. ruber and G. sacculifer in turn.Based on oxygen isotope geostratigraphic scale, the sedimentary rates and fluxes were calculated for each stage. The results show that the sedimental rates and fluxes are 2. 7cm/ka and 17. 6g/m2. yr for stage 1 ; 1. 9cm/ka and 16. 0g/m2. yr for stage 51 6. 7cm/ka and 57. 3g/m2.yr for stage 6, 7. 2cm/ka and 59. 0g/m2. yr for the last glaciation (stage 2, 3, 4). All in all, the sedimently rates and fluxes in glacial times were much greater than that in interglacial ages.