Paleogene orbitally calibrated climate cycles

古近纪轨道校准气候周期

基本信息

批准号：
NE/D000343/1
负责人：
Heiko Pälike
金额：
$ 4.6万
依托单位：
University of Southampton
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FD000343%2F1
关键词：
Paleogene orbitally calibrated climate cycles

项目摘要

Just as tree rings can be used to count astronomical years back into the past and ancient coral growth rings can be used to estimate the number of days per year in the past, layers of undisturbed sedimentary rocks can potentially record cyclical variations in the orbital configuration of Earth and other planets. These astronomical variations affect the amount of sunshine received at the top of the atmosphere, filtered through the climate system (e.g. ice ages), which finally influences the amount and type of sediment deposited in, e.g., the deep sea. Changes of these astronomical parameters: the Earth's eccentricity, obliquity (tilt), and climatic precession (wobble of the spin axis), occur on time scales of thousands to hundreds of thousands of years. The necessary geological records from the deep sea have only recently become available through the international Ocean Drilling Program, which recovers sediment cores from hundreds of metres below the sea bed in waters several miles deep. Previous work has already exploited the various opportunities that arise from having a built-in 'metronome' in the rock record, and particularly if these same sediment layers contain additional information about, for example, the direction of the Earth's magnetic field, magnetic lineations on the sea-floor that tell us how quickly, for example, North America and Eurasia are drifting apart, and most importantly, climate indicators that can be more accurately dated, and thus give information on how fast climatic change can occur, and with what response of the Earth system to an applied forcing or perturbation. Such research has essentially been proceeded from the present into the past, and very good records were just recently published back to the Eocene/Oligocene geological boundary ca. 34 million years ago. Our medium term aim is to extend these calibrations and climate records at high resolution back to the age when the dinosaurs went extinct, ca. 65 million years ago, also known as the Cenozoic. To achieve this goal, for a time period when crocodiles were known to live within the Arctic circle, and the world was in a warmer, 'green-house' state, we want to analyse the chemical composition of fossilised marine fossils the size of a pin-head ('foraminifera') to gain information about climate cycles, the temperature at certain locations in the world's oceans, and the amount of water that was trapped as ice in glaciers and around the Earth's poles, particularly Antarctica. By analysing carbon atoms in carbonate fossil shells, we also investigate the evolution of carbon dioxide consumers and producers, which have been known to respond to climate cycles. To extend the 'astronomical clock' of the rock record back in time, to around two thirds of our longer term goal, we have obtained new samples through drilling into the sea-floor, in order to recover undisturbed sediments that are deposited at a rate of around 1 to 2 cm per thousand years.

正如树环可以用来计算过去的天文年代，而古老的珊瑚生长环可以用来估计过去每年的天数一样，不受干扰的沉积岩石层也可以在地球和其他星球的轨道构型中可能记录周期性的变化。这些天文学变化会影响大气顶部接收到的阳光量，该阳光通过气候系统（例如冰年龄）过滤，最终影响沉积在深海中的沉积物的数量和类型。这些天文学参数的变化：地球的偏心，倾斜（倾斜）和气候进攻（旋转轴的摇摆）出现在数千到数十万年的时间尺度上。深海的必要地质记录直到最近才通过国际海洋钻井计划获得，该计划从几百英里深的海床以下几百米处恢复了沉积物核心。先前的工作已经利用了岩石记录中具有内置的“节拍器”而产生的各种机会，尤其是如果这些相同的沉积物层包含有关地球磁场的方向，海上磁场的方向的其他信息，例如，在海上磁性线索，例如告诉我们，例如，北美和欧洲大部分地区的流动性更高，以及更重要的范围，并在适当的情况下进行了更快的范围，并且可以在适当的情况下进行更改，并且可以及时地进行气氛，并且可以及时地进行气氛，并且可以及时地进行气候，并且可以及时地进行调整。地球系统对施加的强迫或扰动的响应。从现在到过去进行了这项研究，最近才发表了非常好的记录，回到了始新世/渐新世地质边界。 3400万年前。我们的中期目的是将这些校准和气候记录扩展到高分辨率，以追溯到恐龙灭绝的年龄，加利福尼亚。 6500万年前，也称为新生代。为了实现这一目标，在众所周知，已知鳄鱼生活在北极圈中，世界处于温暖，“绿色室”状态，我们想分析化石海洋船体的化学成分，可以在某些地方和在世界各地的温度，以及在世界各地的温度，以及在世界上的冰上和海洋中的一流的信息，以获取针刺的大小（“有孔虫”），并在世界各地的温度中获得了群体，并在世界各地的海洋中，以及遍及世界上的海洋，这是海洋的范围。地球杆，特别是南极。通过分析碳酸盐化石壳中的碳原子，我们还研究了二氧化碳消费者和生产商的演变，这些消费者和生产商已知会对气候周期做出反应。为了使岩石记录的“天文钟”及时扩展到我们长期目标的三分之二的大约三分之二，我们通过在海底钻探获得了新的样品，以收回以每千年约1至2 cm的速度沉积的未触及的沉积物。