Is evolution of calcareous phytoplankton related to shallow marine carbonate system dynamics?

IOPD远征359，海平面，洋流和印度洋季风演变将调查马尔代夫海岭，该海岭向南延伸穿过印度洋，作为珊瑚环礁的双链。这些环礁沿着火山脊分布，火山脊是在印度板块向北移动时在地幔热点上形成的。随着海脊冷却，它下沉，在海面上被一系列环礁所取代，而在环礁之间则是更深的海槽，在这些海槽内，海脊形成的大量碳酸盐沉积物与开阔的海洋沉积物混合在一起。这些沉积物提供了一个独特的机会，研究开放的海洋碳酸盐和浅海碳酸盐之间的关系-这通常是很难比较。该项目试图利用这一机会，看看在生产中上层碳酸盐的颗石藻和浅海碳酸盐系统的变化之间是否有任何一致的相关性。如果这种相关性确实发生，它将提供强有力的证据表明，非生物因素，如温度和海水化学对这些系统的大规模演变有很强的影响。相反，如果不能观察到这样的联系，那么将在多大程度上把例如颗石藻丰度或钙化的变化解释为由非生物因素引起的问题。演替的巨大厚度也意味着可以比通常可能的分辨率更高的分辨率来研究浮游生物组合的突变间隔。这将提供一个机会来测试这种变化是否是由环境事件引起的。该项目将特别侧重于颗石藻的主要群体reiticulofenestrids的大小变化。该组显示出长期的尺寸减小，但这是由一系列突然的尺寸减小事件形成的，这些事件被尺寸增加的延长间隔所分隔。这将是第一次在一个地方系统地研究从中新世中期到最近的一系列尺寸减小事件，并测试它们是否与环境代理的变化或浅海碳酸盐系统的变化相关。

IOPD Expedition 359, Sea Level, Currents, and Monsoon Evolution in the Indian Ocean will be investigating the Maldives Ridge which stretches southward through the Indian Ocean as a double chain of coral atolls. These atolls lie along a volcanic ridge which formed over a mantle hotspot as the Indian plate moved northwards. As the ridge cooled it subsided to be replaced at the surface by the string of atolls and between them deeper troughs.Within these troughs vast thicknesses of carbonate sediments derived from the ridge have built up intermixed with open ocean sediments. These sediments provide a unique opportunity to examine the relationships between open ocean planktonic carbonates and shallow marine carbonates - which normally are difficult to compare. This project seeks to exploit this opportunity to see whether there are any consistent correlations between changes in the pelagic carbonate producing coccolithophores and the shallow marine carbonate system. If such correlations do occur it will provide strong evidence that abiotic factors such as temperature and sea water chemistry have strong influences on large scale evolution of these systems. Conversely if no such linkages can be observed it will cal into question the degree to which changes in for instance coccolithophore abundance or calcification are interpreted as being caused by abiotic factors.The great thicknesses of the successions also mean that intervals of abrupt change in plankton assemblages can be studied at higher resolution than is normally possible. This will provide the opportunity to test if such changes are caused by environmental events. The project will specifically focus on size variation in the dominant group of coccolithophores the reiticulofenestrids. This group shows a long term size reduction but this is formed of series of abrupt size reduction events separated by extended intervals of size increase. This will be the first time the set of size reduction events from the middle Miocene to the recent have been studied systematically in one place as well as testing to see if they correlate with change in environmental proxies or changes in the shallow marine carbonate system.