Collaborative Research: Reevaluating the Timing and Driver of Escarpment Retreat in Southeast Australia

悬崖是绵延数百英里的陡坡，将两个相对平坦的地区分开，一个沿着大陆的海岸，另一个在内陆。在数百万年前由于板块构造而与另一个大陆分离的许多大陆的边缘都发现了悬崖。如果悬崖是在大陆分离时形成的，科学家们不明白今天的悬崖是如何到达它们的位置，并在这么长时间内保持着景观的显著特征。此外，一些科学家认为悬崖形成的时间更晚，与大陆分离无关。研究人员将调查澳大利亚东南部的大悬崖是什么时候形成的，以及它到达现在位置的速度有多快。他们将利用悬崖周围岩石中记录的过去侵蚀率的信息和可以模拟悬崖形成和退缩过程的计算机模型来做到这一点。为这个项目生成的新数据和模型将帮助他们了解世界各地悬崖的起源。该项目支持两名早期职业女性pi，研究生和本科教育，并通过一个旨在支持K-12学习的视频系列支持课程向K-12推广。该项目旨在对澳大利亚东南部的悬崖撤退时间进行新的限制，其更广泛的目标是重新评估悬崖形成和撤退的原因。澳大利亚东南部的断崖通常与大约100-85 Ma开始的大陆裂谷有关。然而，最近的模型和观测对悬崖形成的时间和起源提出了疑问。为了区分陡崖起源假说，研究人员将从垂直于澳大利亚东南部陡崖的基岩样样样中收集磷灰石4He/3He数据集，这些数据集将记录陡崖撤退期间景观演化模型预测的适度挖掘。他们将利用磷灰石4He/3He对冷却时间和幅度的限制，为新的、成对的景观演化和热运动学模型提供信息。这将使他们能够重新评估近半个世纪以来关于澳大利亚东南部地貌演变的范式。在此过程中，他们将对大陆裂谷如何塑造被动边缘的长期地形演化，以及地幔热条件等其他因素在推动岩石隆起和悬崖形成中的重要性有更深入的了解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Escarpments are steep slopes that extend for hundreds of miles and separate two relatively flat areas, one along the coast of a continent and the other further inland. Escarpments are found along the edges of many continents that separated from another continent millions of years ago due to plate tectonics. If escarpments form when the continents separate, scientists do not understand how present-day escarpments reach their locations and then remain prominent features of landscapes for so long. Additionally, some scientists think escarpment formation occurs more recently, unrelated to the continents separating. The researchers will investigate when the Great Escarpment in southeast Australia formed and how quickly it reached its present-day location. They will do this using both information about past erosion rates recorded in rocks around the escarpment and computer models that can mimic the process of an escarpment forming and retreating. The new data and models generated for this project will help them understand the origin of escarpments around the world. This project supports 2 early career women PIs, graduate and undergraduate education, and outreach to K-12 through an established video series supported curriculum that is designed to support K-12 learning. This project aims to place new constraints on the timing of escarpment retreat in southeast Australia, with the broader goal of reevaluating the cause of escarpment formation and retreat. The southeast Australian escarpment is often linked with continental rifting beginning ca. 100-85 Ma. Recent models and observations, however, raise questions about the timing and therefore origin of escarpment formation. To discriminate between escarpment origin hypotheses, the researchers will collect apatite 4He/3He datasets from a bedrock sample transect perpendicular to the southeast Australian escarpment, which will record the modest amounts of exhumation predicted by landscape evolution models during escarpment retreat. They will use the apatite 4He/3He constraints on the timing and magnitude of cooling to inform new, paired landscape evolution and thermo-kinematic models. This will enable them to reevaluate a nearly half-century old paradigm about the geomorphic evolution of southeast Australia. In doing so, they will develop a more robust understanding of how continental rifting shapes the long-term topographic evolution of passive margins, and of the importance of other factors like mantle thermal conditions in driving rock uplift and escarpment formation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.