Quartz content and mass accumulation rates at DSDP Hole 86-576A

The amount and the accumulation rate of quartz were measured in 33 samples from Hole 576A. The amount and source of mineral aerosol being deposited in the northwest Pacific during the Cenozoic are evaluated using these data. When Hole 576A is compared to a Cenozoic record in the central North Pacific, a strong uniformity in the composition of the mineral aerosol across the North Pacific is seen. The data suggest that Hole 576A entered the influence of the westerlies about 15 m.y. ago and that since that time the rates of sediment deposition have increased. Only the dramatic change in quartz accumulation 2.5 m.y. ago can be clearly related to a climatic event, but a gradual increase in quartz accumulation through the Miocene and early Pliocene is probably a result of increasing Northern Hemisphere aridity and intensified atmospheric activity associated with global cooling during the interval.

对576A钻孔（Hole 576A）的33个样品中的石英含量及其堆积速率进行了测定。本研究利用上述数据，对新生代期间西北太平洋沉积的矿物气溶胶的含量与来源开展了评估。将576A钻孔与北太平洋中部的新生代沉积记录进行对比后，可见整个北太平洋海域的矿物气溶胶组分具有高度均一性。数据表明，576A钻孔约在15百万年前（15 m.y.）开始受到西风带的影响，自此之后沉积物堆积速率显著提升。仅有约2.5百万年前（2.5 m.y.）石英堆积量的剧烈变化可明确与某一气候事件相关联；但中新世至上新世早期石英堆积量的逐渐增加，大概率是该时期北半球干旱化加剧、以及伴随全球变冷而来的大气活动增强共同作用的结果。