CAREER: Deciphering the Beat of a Timeless Rhythm- The Future of Astrochronology

职业生涯：破译永恒节奏的节拍--天体年代学的未来史蒂芬·迈尔斯威斯康星大学EAR-1151438地质记录提供了唯一可用的长期环境变化文件，但为了准确地解释这一记录并评估变化速度，我们需要一种判断时间的方法。通过天体年代学对沉积矿床进行测年，已成为建立最先进的地质年表的最重要工具之一。这种方法利用气候振荡的地质记录--归因于地球轨道和自转的准周期变化--直接测量重复沉积层的时间流逝。天体年代学对“深部时间”量化的影响是真正革命性的，这种方法现在甚至被用来微调(例如，校准)放射性同位素数据并测试其准确性。然而，尽管该方法导致了超高分辨率时间尺度的发展，但深时间天体年表中的不确定性几乎一致地受到很差的约束。这个职业项目将使用一种新的计算方法解决深时间天体年代学领域面临的三个基本挑战，目的是提高天文调谐地质时标的精确度和精确度。深时间天体年代学面临的第一个挑战是几乎无处不在地缺乏充分的独立时间控制(例如，具有足够小误差的放射性同位素数据)，无法明确地将观测到的空间节奏校准为时间周期，这使得无法直接证实拟议的天文节奏。这一缺陷导致了许多混乱，包括对给定地层记录的多种不相容的解释，也引发了人们对天体年代学准确性的怀疑。第二个主要挑战是轨道辐射信号在通过气候系统传播并进入各种沉积系统(包括沉积速率变化和间歇期)时的破坏，这最终可能使保存的天文特征无法识别，或者更糟糕的是，导致对保存的节奏的错误推断。深时间天体年代学面临的第三大挑战是缺乏超过~50 Ma的准确轨道辐射解决方案，这就需要区分“浮动”和“锚定”天体年代学。将在第四纪古气候、旋回地层学、地质年代学和地球物理学等领域内统一和发展重要的科学进展，以应对这三个挑战。新的计算方法将为实现天文调谐显生体时间尺度提供基本的方法学进展，并将更全面地了解在地球历史的冰室和温室间隔期间，轨道日照变化如何影响地表地球系统。作为新方法的测试案例，该项目将评估始新世绿河组，这是一个对旋回地层学领域具有重要历史意义的地层单位。这个职业项目的一个主要特点是研究和教育的融合。参与威斯康星大学麦迪逊分校的人计划让年轻人参与科学发现，并增加未被充分代表的少数群体参与地球科学。与威斯康星大学麦迪逊地质博物馆的同事合作将最终开发出一种新的地质时间展示，每年将有大约45,000名参观者观看，参与他们的科学推广计划将导致一种新的铁路展览模型(“深度时间快车”)将被部署在大型公共活动中。建立一个天体年代学和放射性同位素时间刻度相互校准的国家研究中心将在地质年代学领域建立社区，并将促进为该项目编制的软件和教程的分发。最后，发展年代地层学和旋回地层学课程，再加上学生参与研究，将为天体年代学和放射性同位素时间尺度的结合提供独特的跨学科培训，从而培养地质年代学领域的未来领导者。

CAREER: Deciphering the Beat of a Timeless Rhythm - The Future of AstrochronologyStephen MeyersUniversity of WisconsinEAR-1151438The geologic record provides the only available documentation of long-term environmental change, but in order to accurately interpret this record and evaluate rates of change we require a means to tell time. The dating of sedimentary deposits via astrochronology has become one of the most important tools for construction of the state-of-the-art geologic time scale. This method utilizes the geologic record of climate oscillations - those ascribed to quasi-periodic changes in the Earth's orbit and rotation - to measure the passage of time directly from repetitive sedimentary layers. The impact of astrochronology on the quantification of 'deep-time' has been truly revolutionary, and the approach is now even employed to fine-tune (e.g., calibrate) radioisotopic data and to test their veracity. However, although the method has resulted in the development of extraordinary high-resolution time scales, the uncertainties in deep-time astrochronologies are almost uniformly poorly constrained. This CAREER project will address the three fundamental challenges to the field of deep-time astrochronology using a new computational approach, with the goal of enhancing the accuracy and precision of an astronomically tuned geologic time scale.The first of the challenges to deep-time astrochronology arises from the near ubiquitous lack of adequate independent time control (e.g., radioisotopic data with sufficiently small errors) to unambiguously calibrate observed spatial rhythms to temporal periods, which prohibits direct confirmation of the proposed astronomical tempo. This shortcoming has resulted in much confusion, including multiple incompatible interpretations for a given stratigraphic record, and has also roused suspicion about the veracity of astrochronology. The second major challenge is the corruption of the orbital insolation signal as it propagates through the climate system and into various depositional systems (including sedimentation rate changes and hiatus), which may ultimately render the preserved astronomical signature unidentifiable, or worse yet, result in erroneous inferences about the preserved tempo. The third major challenge to deep-time astrochronology is the lack of accurate orbital insolation solutions beyond ~50 Ma, which necessitates the distinction between 'floating' and 'anchored' astrochronologies. These three challenges will be addressed by uniting and building upon important scientific advances within the fields of Quaternary paleoclimate, cyclostratigraphy, geochronology and geophysics. The new computational approach will provide fundamental methodological advances towards the achievement of an astronomically tuned Phanerozoic time scale, and will yield a more complete understanding of how orbital insolation changes influenced the surficial Earth System during both icehouse and greenhouse intervals of Earth history. As a test case for the new methodology, this project will evaluate the Eocene Green River Formation, a stratigraphic unit of great historical significance to the field of cyclostratigraphy. A central feature of this CAREER project is the integration of research and education. Involvement in the UW-Madison PEOPLE program engages youth in scientific discovery, and increases underrepresented minority participation in Geoscience. Partnership with colleagues at the UW-Madison Geology Museum will culminate in the development of a new geologic time display that will be seen by ~45,000 visitors per year, and participation in their science outreach program will result in a new model railroad exhibit (the 'Deep-Time Express') to be deployed at large public events. Establishment of a national research hub for the intercalibration of astrochronologic and radioisotopic time scales will build community within the field of geochronology, and will facilitate the distribution of software and tutorials generated for the project. Finally, the development of courses in chronostratigraphy and cyclostratigraphy, coupled with student participation in research, will provide a unique interdisciplinary training for the integration of astrochronologic and radioisotopic time scales, thus cultivating future leaders in the field of geochronology.