The timing and amplitude of Pleistocene sea-level lowstands and deglacials from U-Th chronology of Great Barrier Reef corals (Expedition 325)

根据大堡礁珊瑚 U-Th 年表得出的更新世海平面低位和冰消期的时间和幅度（第 325 次探险）

• 批准号: NE/H014136/1
• 负责人: Gideon Henderson
• 金额: $ 15.9万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH014136%2F1
• 关键词: timing; amplitude; Pleistocene; sea; level

The study of past sea level is of great interest to researchers seeking to understand the Earth's climate. Sea level is a proxy for the amount of water locked up on the land as ice sheets. The study of sea level therefore can tell us about the past state of the climate - low sea levels reflect colder, glacial, periods in Earth history when ice sheets were larger; high sea levels reflect warmer, interglacial, intervals. Our knowledge of how modern ice sheets will respond to anthropogenic warming is not yet comprehensive. One of the most important questions surrounding ice sheet behaviour is the determination of collapse rates in response to warming, which will influence future rates of sea level rise. One way to approach this question is to examine past rates of sea level rise associated with known periods of ice sheets collapse under the non-anthropogenic conditions Quaternary glacial-interglacial transition. Fossil corals provide an indirect measurement of past sea level and therefore answering questions about how (and when) it has changed in the past. Coral only live below sea level and it is also possible to determine how far below sea level they grew. This water depth estimation is based on the types of coral we find and the other fauna and flora we find associated with them. Along with the elevation that we recovered the coral from, this water depth estimation enables us to reconstruct the height of past sea level. The time that this reconstructed sea level represents can also be measured from the coral. We use the uranium (and the product of its radioactive decay - thorium) naturally incorporated into the coral's skeleton during growth to calculate an age for the coral. This U-Th dating technique can find the age of corals from 1 to 600,000 years old. There is, however, a problem in investigating past sea levels which were much lower than present (during the most recent glacial period sea level was c. 120m below modern levels). The corals that grew when sea level was low are hard to access now sea level has risen to its modern level - they are deep underwater. To solve this problem and recover samples from deeper localities, there will be an IODP drilling expedition to the Great Barrier Reef. This Expedition will drill into fossil coral reefs that have been identified by their morphology by a previous site survey. These fossil reefs are at water depths of 44 to 123m and preserve an archive of corals from lower sea levels. It is our plan to take samples from these fossil reefs, use U-Th dating to determine their ages, and then reconstruct sea level for glacial periods while sea level was low. These estimates of low stand sea level will be used to investigate mechanisms that drive the Earth's natural climate system. The timing and rate of changes from low to high sea level are particularly important in this respect, allowing us to test any lead-lag relationship between a potential forcing (changes in the Earth's orbit around the Sun, or internal climate forcing such as atmospheric CO2 concentration) and climatic response (sea level).

过去的海平面研究对寻求了解地球气候的研究人员引起了极大的兴趣。海平面是冰片上锁在土地上的水量的代理。因此，对海平面的研究可以告诉我们有关气候的过去状态 - 低海平面反映了冰盖更大的地球历史上的冷，冰川时期。高海平面反映了温暖，间隔间的间隔。我们对现代冰盖将如何对人为变暖的反应的了解尚不全面。围绕冰盖行为的最重要问题之一是确定响应变暖的崩溃率，这将影响未来的海平面上升速度。解决这个问题的一种方法是检查与已知的冰片期相关的过去海平面上升速率在非人为条件下倒塌的冰期冰川冰期过渡。化石珊瑚提供了过去海平面的间接测量，因此回答了有关其过去（何时）发生变化的问题。珊瑚只生活在海平面以下，还可以确定它们生长的范围以下。这种水深估计基于我们发现的珊瑚类型以及我们发现与之相关的其他动物动植物。随着我们从中恢复珊瑚的海拔，这种水深估计使我们能够重建过去的海平面。该重建的海平面代表的时间也可以从珊瑚中测量。我们在生长过程中使用铀（及其放射性衰减的产物 - th）自然掺入珊瑚骨骼中，以计算珊瑚的年龄。这项约会技术可以找到1至60万年历史的珊瑚年龄。但是，研究过去的海平面的问题远低于现在（在最近的冰川时期，海平面比现代水平低120m）。现在海平面上升到现代水平，在海平面低时生长的珊瑚很难进入 - 它们在水下深处。为了解决这个问题并从更深层次的地方恢复样品，将进行一次IODP钻探探险。这次探险将钻入化石珊瑚礁，这些珊瑚礁已通过先前的现场调查来鉴定出其形态。这些化石礁处的水深度为44至123m，并保留了较低海平面的珊瑚档案。我们的计划是从这些化石珊瑚礁中采集样品，使用U-th Dating来确定其年龄，然后在海平面较低时重建海平面的海平面。这些对海平面的估计值将用于研究驱动地球自然气候系统的机制。在这方面，从低海平面到高海平面的变化的时机和变化速率尤其重要，从而使我们能够测试潜在强迫（地球周围的地球轨道变化，或内部气候强迫，例如大气二氧化碳浓度）和气候反应（海平面）。

项目成果

Intensification of the meridional temperature gradient in the Great Barrier Reef following the Last Glacial Maximum.

• DOI: 10.1038/ncomms5102
• 发表时间: 2014-06-17
• 期刊: Nature communications
• 影响因子: 16.6
• 作者: Felis T;McGregor HV;Linsley BK;Tudhope AW;Gagan MK;Suzuki A;Inoue M;Thomas AL;Esat TM;Thompson WG;Tiwari M;Potts DC;Mudelsee M;Yokoyama Y;Webster JM
• 通讯作者: Webster JM

Coral Record of Younger Dryas Chronozone Warmth on the Great Barrier Reef

• DOI: 10.1029/2020pa003962
• 发表时间: 2020-12
• 期刊: Paleoceanography and Paleoclimatology
• 影响因子: 3.5
• 作者: Logan D. Brenner;B. Linsley;J. Webster;D. Potts;T. Felis;M. Gagan;M. Inoue;H. McGregor;A. Suzuki;A. Tudhope;T. Esat;Alex L. Thomas;W. Thompson;S. Fallon;M. Humblet;M. Tiwari;Y. Yokoyama

Assessing subsidence rates and paleo water-depths for Tahiti reefs using U-Th chronology of altered corals

使用蚀变珊瑚的 U-Th 年表评估塔希提岛珊瑚礁的沉降率和古水深

• DOI: 10.1016/j.margeo.2011.12.006
• 发表时间: 2012
• 期刊: Marine Geology
• 影响因子: 2.9
• 作者: Thomas A