Age determination of late Quaternary sediment cores from the South Tasman Rise@en

We use sediment cores from the South Tasman Rise (STR) to reconstruct deep- water circulation in the southwest Pacific sector of the Southern Ocean. Sediment cores MD972106 (45° 09' S, 146° 17' E, 3310 m water depth) and GC34 (45° 06' S, 147° 45' E, 4002 m water depth) preserve records covering the last 160 kyr, with chronology controlled by calibrated accelerator mass spectrometry radiocarbon dates and benthic foraminiferal d18O tied to SPECMAP. The STR benthic foraminiferal d13C records provide new d13C values for Southern Ocean deep water spanning the last 160 kyr at sites unlikely to be affected by variations in productivity. The records establish that glacial benthic foraminifera (Cibicidoides spp.) d13C values are lower relative to interglacial values and are comparable to previous glacial benthic d13C records in the Indian and Pacific sectors of the Southern Ocean. Comparisons of the benthic foraminiferal d13C time series at the STR are made with the equatorial Pacific (V19-30 and Site 846) and the equatorial Atlantic (GeoB1115). The similarity of benthic d13C records at the STR to the equatorial Pacific suggest the Southern Ocean deep-water mass closely tracked those of the deep Pacific, and the presence of a d13C gradient between the STR and the equatorial Atlantic suggests there was continual production of northern source deep water over the past 160 kyr.本研究采用塔斯曼海岭（South Tasman Rise, STR）的沉积物岩芯，重建南大洋西南太平洋扇区的深水环流演化过程。沉积物岩芯MD972106（南纬45°09′、东经146°17′，水深3310米）与GC34（南纬45°06′、东经147°45′，水深4002米）保存了过去16万年的沉积记录，其年代框架由校准后的加速器质谱放射性碳测年数据，以及绑定于SPECMAP标准曲线的底栖有孔虫δ18O同位素序列共同限定。塔斯曼海岭的底栖有孔虫δ13C记录，为过去16万年南大洋深水环境提供了新的碳同位素数据，且所选研究站位基本不受生产力变化的影响。该记录显示，冰期环境下的底栖有孔虫（卷包虫属，Cibicidoides spp.）的δ13C值低于间冰期，这一结果与此前南大洋印度洋与太平洋扇区的冰期底栖δ13C记录相一致。本研究将塔斯曼海岭的底栖有孔虫δ13C时间序列，与赤道太平洋站位V19-30、846站以及赤道大西洋GeoB1115站位的相关记录进行了对比。塔斯曼海岭与赤道太平洋的底栖δ13C记录具有较高相似性，表明南大洋深水团块的演化与太平洋深层水团的变化高度同步；而塔斯曼海岭与赤道大西洋之间存在的δ13C梯度，则说明过去16万年中一直有北部源深水团块持续形成。