Comparison of paleoenvironmental changes between both hemispheres

在资助的第一年，我们获得了在北太平洋西北部收集的沉积物岩心中记录的过去400 ka的烯烃海表温度和浮游有孔虫氧同位素剖面数据集。第二年，在r/V MIRAI MR03-K04巡航期间，在智利边缘地区、麦哲伦海峡、东南印度洋脊和Kelgueren高原共采集了6个长粒径沉积物岩心。在第3年和第4年，对上述地区采集的沉积物岩心的化学古氧化物、烯烃、浮游有孔虫氧同位素比值、蛋白石、210Pb、放射性碳、有孔虫组合进行了陆上分析。另一方面，对北太平洋和鄂霍次克海高纬度沉积物岩心进行了近100ka的年代际-百年尺度的海温重建。此外，用百-千年时间尺度的结果重建了北太平洋西北部中深水团的通气变化。结果表明，在新仙女木期冷却期（11ka）之前，Bolling-Allorod间隙（12ka）的通风速度迅速下降。12 ka时中间水团的缓慢通气与Tokachi地区沉积物岩心记录的大量甲烷水合物释放时间相对应。中间水团通气量的变化可能影响北太平洋西北部区域碳循环。为了重建麦哲伦海峡太平洋侧河口的海表温度，对alkenon古测温仪进行了分析。Alkenon温度在8.7 ~ 12℃之间变化，从底部到600cm深度逐渐升高。在深度520cm处，烯酮温度急剧下降（<10℃）。在520cm深度发生低烯烃温度事件后，烯烃温度再次高达12℃。根据岩心顶部^<14>C的数据，烯酮温度的急剧冷却始于4-5 kyrBP。要与北半球的古环境变化进行高时间分辨率的对比，需要更多来自南半球的高质量沉积物岩心。少

During the first year of the term of this grant, we couls obtained the data set of alkenone sea surface temperature and oxygen isotopic profile of planktonic foraminifera over the past 400 ka recorded in the sedimnet cores collected in the northwestern North Pacific. In the second year, total six long-size sediment cores were collected in the Chilean marginal area, Magellan strait, south eastern Indian Ridge, and Kelgueren Plateau during r/V MIRAI MR03-K04 cruise. During the third and forth years, chemical paleo proxides, alkenone, oxygen isotopic ratio of planktonic foraminifera, opal, 210Pb, radiocarbon, foraminiferal assemblanges of sediment cores collected in the above area has been analyzed onshore.On the other hand, for the sediment cores in high latitude of the North Pacific and the Okhotsk Sea, sea surface temperature was reconstructed with decadal-centennial time resolution over the past 100ka. In addition, variation of ventilation of water mass from the intermediate to deep w … More as reconstructed in the northwestern North Pacific with centennial - millennial time scale resulution. As a result, ventilation speed was rapidly down at the Bolling-Allorod interstatial (12 ka) when is just before the Younger Dryas cooling period (11ka). This slow down of ventilation of the intermediate water mass at 12 ka corresponded to the timing of enormous methane dydrate release recorded in the sediment cores Off Tokachi area. The change in the ventilation of intermediate water mass might affect the regional carbon cycle in the northwestern North Pacific.In order to reconstruct of sea surface temperature at the Pacific side mouth of Magellan strait, alkenon, which is a robust paleothermometer was analyzed. Alkenon temperature varied from 8.7℃ to 12℃ and garadually increased from the bottom to 600cm depth. We could find a sharp decrease in alkenon temperature (<10℃) at 520cm depth. After the low alkenone temperature event at 520cm depth, alkenone teperature again up to 12℃. According to the ^<14>C data or core top, the dramatic cooling of alkenone temperature had started at 4-5 kyrBP.More high quality sediments cores from the southern hemisphiere are necessary to compare with teh paleoenvironmental changes in the northern hemisphere with high time resolution. Less