(Appendix) Ostracodes at DSDP Leg 72 Holes

From the study of the ostracodes of Sites 516, 517, and 518 in comparison with those of Sites 21, 22, and 357, we can show that a time lag (early to late Oliogene) existed between the formation of the deep water masses (mid-bathyal ± 2000 m) and those of intermediate depths (upper bathyal ± 1000 m). The ostracode faunas suggest that while the Antarctic Intermediate Water (O2 = 4.5 to 5 ml/l) was flowing through the Vema Trough to fill the northern basins, the returning less-dense, warmer water (O2 = 3.5 to 5 ml/l) originating in Tethys was being gradually displaced upslope.
Efforts to identify shallow (less than 200 m) faunas were unsuccessful. No evidence of significant changes in paleodepth or close proximity to islands could be found that could not be better explained by water-mass changes.
Studies of the genera Poseidonamicus and Krithe suggest an important water mass change at about 14 Ma (late-middle Miocene), but the cause of this event is not yet understood.

通过对比516、517、518号站位与21、22、357号站位的介形虫（ostracodes）组合特征，本研究证实深水团块（半深海中层，水深±2000米）与中层水深水体（半深海上层，水深±1000米）的形成之间存在跨度为渐新世（Oligogene）早-晚期的时间滞后。介形虫动物群显示，当南极中层水（Antarctic Intermediate Water，溶解氧含量4.5~5 ml/L）流经维玛海槽（Vema Trough）并填充北部海盆时，源自特提斯洋（Tethys）、密度更低且温度更高的回流海水（溶解氧含量3.5~5 ml/L）正逐步向坡上迁移。
针对水深小于200米的浅水区动物群的识别工作未取得有效成果。未发现古水深（paleodepth）发生显著变化或研究区域邻近岛屿的可靠证据，此类现象均可通过水团变化得到更为合理的解释。
对海神介属（Poseidonamicus）与克里特介属（Krithe）的研究表明，约1400万年前（中新世中晚期，14 Ma）曾发生一次重要的水团转变，但该事件的成因目前尚未明确。