Comparison of paleoenvironmental changes between both hemispheres

在本项目实施的第一年，我们获得了北太平洋西北部沉积物岩心记录的近400 ka的烯酮海表温度和浮游有孔虫氧同位素剖面数据。第二年，在R/V米拉伊MR 03-K 04巡航期间，在智利边缘区、麦哲伦海峡、东南印度洋海脊和凯尔格伦高原共采集了6个长尺寸沉积物柱样。第三年和第四年，对上述地区陆上沉积物柱样进行了化学古硫化物、烯酮、浮游有孔虫氧同位素比值、蛋白石、~（210）Pb、放射性碳、有孔虫组合分析，另一方面，对北太平洋高纬度和鄂霍次克海沉积物柱样进行了分析。采用10 ~ 100年时间分辨率重建了近100 ka的海表温度。此外，还讨论了从中层到深层水团的通风变化 关于我们 在北太平洋西北部重建了百年-千年时间尺度的结果。结果表明，在新仙女木冷却期（11 ka）之前，博林-阿洛罗德间隙（12 ka）的通风速度迅速下降。这种放缓的通风的中间水团在12万年对应的时间记录在十胜区的沉积物岩心中的巨大的甲烷dyphoses释放。为了重建麦哲伦海峡太平洋侧口的海表温度，分析了一种可靠的古温度计-kenon，研究了北太平洋西北部中层水团的通气变化对区域碳循环的影响。温度变化范围为8.7 ~ 12℃，从底部到600 cm深度，温度逐渐升高。在520 cm深度处，链核温度急剧下降（<10℃）。在520 cm深度的烯酮低温事件之后，烯酮温度再次上升到12℃。根据碳同位素<14>数据或岩心顶部的碳同位素数据，烯酮温度在4-5 kyrBP时开始急剧下降，需要更多高质量的南半球沉积物岩心，以高时间分辨率与北方半球的古环境变化进行对比。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