An alliance to address the Red Sea's record of past global climate and earthquakes

解决红海过去全球气候和地震记录的联盟

• 批准号: NE/X002519/1
• 负责人: Neil Mitchell
• 金额: $ 10.27万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX002519%2F1
• 关键词: alliance; address; Red; Sea; record

Evaporation in the desert climate causes the Red Sea to lose the isotope O-16 preferentially over O-18 and as a result Red Sea waters tend to be enriched in O-18. This tendency is particularly enhanced at times when global sea-levels were lower because the connection of the Red Sea with the Indian Ocean is very small (at Bab el Mandeb Strait). The sediments formed of the shells of pelagic organisms record this oxygen isotope signal. Researchers have used this, with the help of oceanographic models, to work out how sea-level has fluctuated for the past 500 thousand years. Meanwhile, other information (seismic reflection images) has revealed that the sediments within the Red Sea were being moved around by currents in the Pliocene, a period extending back to 5.3 million years. This generally does not happen today, as the Red Sea deep waters are very slow moving.A new partnership with Prof. Kaminski will allow us to date the sediments in legacy cores collected in the 1970s by the Deep Sea Drilling Project and left unused since then. We will measure oxygen isotopes where shells have not been badly altered, work out if the shells record information on the varying currents and measure the sizes of finer particles originating from the continents, also a potential measure of current speeds. Oxygen isotopes will be used to help evaluate the variability of sea-level in the Pliocene and earlier Pleistocene. The work with Prof. Kaminiski will be essential for working out the timing of these changes, as well as the use of shells to determine currents.Changes of sea-level also affect the strength of the sediments on the bed of the Red Sea because more extreme salinity tends to lead to aragonite (a form of calcium carbonate) precipitating directly from the water. With Prof. Jonsson, we will exploit this tendency to date the layering in seismic reflection images due to be collected with a device that is towed deeply near the seabed (towing deeply allows the device to collect much sharper images than we would normally get by collecting them from the sea surface). This will allow us, for the first time, evaluate the extent to which giant faults underlying the bed of the Red Sea are presently active and/or when they last slipped. This is important, as many coastal cities lie close to major active faults that present a threat to their populations, another focus of Prof. Jonsson's work with satellite methods. If we could work out the frequency with which earthquakes occur, this could help with disaster planning. Demonstrating the method in the Red Sea could create interest in using it in some of these other locations and thus be of broader benefit.

沙漠气候中的蒸发导致红海优先失去同位素O-16，而不是O-18，因此红海沃茨中的O-18趋于富集。在全球海平面较低的时候，这种趋势特别明显，因为红海与印度洋的连接非常小（在曼德海峡）。由远洋生物的外壳形成的沉积物记录了这种氧同位素信号。研究人员利用这一点，在海洋学模型的帮助下，计算出海平面在过去50万年里是如何波动的。与此同时，其他信息（地震反射图像）显示，红海内的沉积物在上新世被水流移动，这一时期可以追溯到530万年前。这种情况在今天通常不会发生，因为红海的深层沃茨流动非常缓慢。与卡明斯基教授的新合作将使我们能够对深海钻探项目在20世纪70年代收集的遗留岩心中的沉积物进行年代测定，这些岩心自那时以来一直未被使用。我们将测量贝壳没有被严重改变的氧同位素，研究贝壳是否记录了变化的电流信息，并测量来自大陆的更细颗粒的大小，这也是对电流速度的潜在测量。氧同位素将用于帮助评估上新世和更新世早期海平面的变化。与卡米尼斯基教授的合作对于确定这些变化的时间以及使用贝壳来确定水流至关重要。海平面的变化也会影响红海海底沉积物的强度，因为更极端的盐度往往会导致文石（碳酸钙的一种形式）直接从水中沉淀出来。与Jonsson教授一起，我们将利用这一趋势来确定地震反射图像中的分层，这些分层是由一个在海底附近被拖曳的设备收集的（拖曳深度允许设备收集比我们通常从海面收集的图像更清晰的图像）。这将使我们能够第一次评估红海海床下的巨型断层目前活动的程度和/或它们最后一次滑动的时间。这一点很重要，因为许多沿海城市靠近对人口构成威胁的主要活动断层，这是Jonsson教授使用卫星方法工作的另一个重点。如果我们能计算出地震发生的频率，这将有助于灾难规划。在红海演示该方法可能会引起人们对在其他一些地点使用该方法的兴趣，从而产生更广泛的好处。