An Astronomically-tuned High Resolution Benthic Isotope Stratigraphy for the Late Paleocene and Early Eocene

天文调谐的古新世晚期和始新世早期高分辨率底栖同位素地层学

• 批准号: 0959117
• 负责人: James Zachos
• 金额: $ 18万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-15 至 2013-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0959117&HistoricalAwards=false
• 关键词: Astronomically; tuned; Resolution; Benthic; Isotope

TOWARD AN ASTRONOMICALLY-TUNED HIGH-RESOLUTION BENTHIC ISOTOPE STRATIGRAPHY FOR THE PALEOCENE AND EARLY EOCENEJAMES ZACHOS, UNIVERSITY OF CALIFORNIA, SANTA CRUZEAR-0959117ABSTRACTThe late Paleocene to early Eocene (~58 to 52 Mya) represents one of the most climatically dynamic periods of Earth?s past. It is characterized by a gradual long warming trend that culminates in the warmest conditions of the last 90 m.y., the Early Eocene Climatic Optimum. Recent investigations, however, have found that the long-term warming trend was punctuated by several short-lived (transient) warming events (tens of thousands of years in duration), referred to as hyperthermals or Eocene thermal maxima. These events, which include the extreme Paleocene-Eocene Thermal Maximum (PETM, ~56 Mya), are thought to have a common origin, possibly involving orbital forcing amplified by carbon cycle feedbacks. Other proposed driving mechanisms, particularly for the PETM, include volcanic outgassing and/or the decomposition of marine methane hydrates. To assess whether the PETM and other thermal maxima were triggered by orbital or other forcing, we intend to establish the temporal relationship of these events to the long-term background variability (i.e., periodicity) in climate and the cabon cycle. To this end, utilizing a deep sea core recovered from the south Atlantic, we will construct the first high-resolution, astronomically-tuned benthic foraminiferal stable carbon and oxygen isotope time series for a ~5-6 m.y. segment of the upper Paleocene-lower Eocene. These and other records will allow us to establish the relative timing and phasing of the thermal maxima to excursions in the carbon cycle, thus providing constraints for quantitatively evaluating the nature of climate ? carbon cycle coupling during periods of warming. In addition to this application, the astronomically-tuned isotope time-series will serve as a standard isotope reference section by which all other Paleocene and early Eocene deep-sea sequences can be compared. In this capacity, it will be possible to use the carbon isotopes to correlate and calibrate segments of marine sedimentary sections to our tuned record, thereby significantly improving the accuracy of age models. This will facilitate transfer of the astronomical calibrations to sections with exceptional magnetostratigraphy, and thus the geomagnetic polarity time-scale.

针对古新世和早始新世的天文调谐高分辨率底栖同位素地层学 JAMES ZACHOS，加利福尼亚大学圣克鲁斯分校 - 0959117摘要古新世晚期到始新世早期（约 58 至 52 Mya）代表了最古老的地层之一。地球过去的气候动态时期。它的特点是逐渐长期变暖的趋势，并在过去 90 年来最温暖的条件下达到顶峰，即始新世早期气候最适宜期。 然而，最近的调查发现，长期变暖趋势被几次短暂（短暂）变暖事件（持续数万年）所打断，这些事件被称为高温或始新世热最大值。 这些事件，包括古新世-始新世极端热最大值（PETM，~56 Mya），被认为具有共同的起源，可能涉及碳循环反馈放大的轨道强迫。 其他提出的驱动机制，特别是 PETM 的驱动机制，包括火山放气和/或海洋甲烷水合物的分解。 为了评估 PETM 和其他热最大值是否是由轨道或其他强迫触发的，我们打算建立这些事件与气候和碳循环的长期背景变化（即周期性）的时间关系。为此，利用从南大西洋回收的深海核心，我们将构建第一个高分辨率、经过天文调整的底栖有孔虫稳定碳和氧同位素时间序列，时间序列约为 5-6 m.y。上古新世-下始新世的部分。 这些和其他记录将使我们能够确定热最大值与碳循环中偏移的相对时间和阶段，从而为定量评估气候性质提供约束？变暖期间的碳循环耦合。 除了此应用之外，经过天文学调整的同位素时间序列将作为标准同位素参考部分，通过它可以比较所有其他古新世和早始新世深海序列。 通过这种能力，将有可能使用碳同位素将海洋沉积剖面的各个部分与我们调整的记录进行关联和校准，从而显着提高年龄模型的准确性。 这将有助于将天文校准转移到具有特殊磁地层学的部分，从而转移到地磁极性时间尺度。