Paul Bown - IODP Expedition 320 participation

1. 在始新世-中新世区间进行船载和船后钙质纳米化石生物地层学研究，并将这些数据与其他泥炭地层学家的数据进行整合。完成天文校准的古近系地层“巨型拼接”是第320/321远征队的主要目标。2. 始新世高温和始新世最佳气候条件下的钙质纳米化石演化始新世早期至中期，纳米化石多样性上升至新生代最大值。我将调查这种增长的时间和结构，并研究气候变化是否在当时海洋浮游生物的进化中发挥了重要作用。如果早始新世的高温层段被恢复，我将以高分辨率研究纳米化石的响应，以测试温度和/或海洋化学变化（如酸化）对纳米化石丰度、多样性和进化速率的强迫效应。3. 气候、碳酸盐聚集和纳米化石演化通过中至晚始新世碳酸盐和二氧化硅聚集事件已经在赤道太平洋的先前记录中被确定，并与浮游生物生产力的变化和全球气候变化联系起来。这段时间间隔也见证了纳米化石多样性的急剧下降，这一群体可以说从未完全恢复。我将在短时间尺度和长时间尺度上生成定量的纳米化石丰度和多样性记录，以研究纳米化石生产力与演化、碳酸盐聚集和古气候/古海洋之间的关系。详细地说，我对中始新世气候最佳（MECO; 42Ma）的纳米化石记录以及始新世/渐新世过渡（48-34Ma）之后和之前的生物聚集和碳酸盐补偿深度（CCD）事件感兴趣。我还将研究随着地点接近CCD，纳米化石保存的性质，特别是其对保存的多样性和代理记录的影响。4. 始新世-渐新世过渡（EOT）——研究海洋化学与浮游生物进化之间的联系。始新世-渐新世过渡期间浮游生物生态系统的重大重构表明，南极冰盖的扩张与低纬度表层海洋环境的显著扰动是一致的。来自钙质纳米化石组合的证据表明，这可能是由于营养物质供应的广泛增加。在EOT之前，CCD的明显浅滩化阻碍了从深海沉积物中获得可比记录。我们建议测量绝对的纳米化石物种丰度，并结合旋回地层年龄模型，量化整个EOT的纳米化石积累速率。我们还将积极与PEAT科学家合作，生产碳酸盐、二氧化硅、纳米化石和有孔虫的全系列积累率。5. 早中新世期（Mi-1）相对较短但意义重大的早中新世期（Mi-1）在某些方面与EOT气候事件相似。然而，浮游生态系统对Mi-1几乎没有观察到反应。我们将把目标4中使用的方法应用于Mi-1 （PEAT-6C）。这是目标4的延伸，我们将与PEAT纳米化石生物地层学家合作，他们将这一区间作为主要目标。

1. Intercalibration of stratigraphic datums from the Paleogene PEAT splice Undertake shipboard and post-cruise calcareous nannofossil biostratigraphy for the Eocene-Miocene interval and integrate these data with those from other PEAT stratigraphers. The completion of a astronomically calibrated Paleogene stratigraphic 'mega-splice' is an Expeditions 320/321 primary objective. 2. Calcareous nannofossil evolution through Eocene hyperthermals and the Eocene climatic optimum The early to middle Eocene saw a rise in nannofossil diversity to a Cenozoic maximum. I will investigate the timing and structure of this increase and examine whether climatic shifts played a significant role in the evolution of the oceanic plankton at this time. If early Eocene hyperthermal intervals are recovered I will investigate the nannofossil response at high resolution to test for the forcing effects of temperature and/or ocean chemistry changes (e.g. acidification) on nannofossil abundance, diversity and evolutionary rates. 3. Climate, carbonate accumulation and nannofossil evolution through the middle to late Eocene Carbonate and silica accumulation events have been identified in previous records from the equatorial Pacific and linked to changes in planktonic productivity and global climate shifts. This time interval also saw a precipitous decline in the diversity of nannofossils from which the group has arguably never completely recovered. I will generate quantitative nannofossil abundance and diversity records on short and long timescales in order to examine the relationships between nannofossil productivity and evolution, carbonate accumulation and paleoclimate/paleoceanography. In detail, I am interested in the nannofossil record across the Middle Eocene climatic optimum (MECO; 42Ma) and the biogenic accumulation and carbonate compensation depth (CCD) events that follow, and precede the Eocene/Oligocene transition (48-34Ma). I will also investigate the nature of nannofossil preservation as sites approach the CCD, in particular its influence on preserved diversity and proxy records. 4. Eocene-Oligocene transition (EOT) - investigating links between ocean chemistry and plankton evolution A major restructuring in plankton ecosystems across the EOT suggests that the expansion of Antarctic ice sheets is coincident with a significant perturbation in low-latitude surface ocean environments. Evidence from calcareous nannofossil assemblages indicates that this may be due to a widespread increase in nutrient availability. A marked shoaling of the CCD immediately prior to the EOT has hampered the production of a comparable record from deep-sea sediments. We propose to measure absolute nannofossil species abundances and, combined with the cyclostratigraphic age model, quantify nannofossil accumulation rates across the EOT. We would also actively collaborate with PEAT scientists in the production of the full range of carbonate, silica, nannofossil and foraminiferal accumulation rates. 5. Early Miocene glaciation (Mi-1) and the plankton ecosystem The relatively short but significant early Miocene glacial episode, Mi-1, is in some ways similar to the EOT climate event. There has, however, been little observed response within planktonic ecosystems to Mi-1. We would apply the methodology used in objective 4 to Mi-1 (PEAT-6C). This is an extension of objective 4 and we will collaborate with PEAT nannofossil biostratigraphers who have this interval as a primary objective.