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.

朝着天文学的高分辨率底栖同位素地层进行，用于古新世和早期的Ecocenejames Zachos，加利福尼亚大学，圣克鲁西尔大学-0959117abstractthe the Gate the Geatrathe the Geatrathe the Gearocene to Greatecene to to to to to to to the Greatecene to to to to Encorene早期（〜58至52 mya）（〜58至52 Mya）是地球上最稳定的动态时期之一。它的特征是逐渐长变暖的趋势，最终在最后90 M.Y.的最温暖条件下，始新世早期的气候最佳。 然而，最近的调查发现，长期的变暖趋势被几个短暂的（瞬态）变暖事件（持续时间数万年）打断，称为高温或始新世热最大值。 这些事件包括极端的古新世热最大值（PETM，〜56 mya），被认为具有共同的起源，可能涉及轨道强迫通过碳循环反馈扩增。 其他提出的驾驶机制，特别是对于PETM，包括火山量大和/或海洋甲烷水合物的分解。 为了评估PETM和其他热最大值是由轨道还是其他强迫触发的，我们打算在气候和Cabon循环中建立这些事件与长期背景变异性（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，我们将建造第一个高分辨率，天文调节的底栖有孔虫稳定的碳和氧同位素时间序列，以〜5-6M.Y。上古始新世的段。 这些记录和其他记录将使我们能够建立热最大值在碳循环中的相对时机和相相位，从而提供了定量评估气候性质的约束？碳循环在变暖期间。 除此应用外，天文调整的同位素时间序列还将用作标准同位素参考部分，通过该部分可以比较所有其他古新世和早期始新世深海序列。 以这种能力，可以使用碳同位素将海洋沉积切片的段与我们的调整记录相关联和校准，从而显着提高了年龄模型的准确性。 这将有助于将天文学校准转移到具有特殊磁层学的部分，从而将地面极性时间尺度转移。