OCE-PRF An integrated study of the closure of the Central American Seaway: Exploring paleoceanography as a tool for broadening participation in ocean sciences

概述：中美洲航道的关闭和由此产生的巴拿马地峡在很大程度上影响了我们对物种在北美和南美洲之间的适应和迁徙以及太平洋和加勒比海洋物种多样化的理解。直到最近，CAS一直被认为在大约9-2 Ma之间闭合；然而，对巴拿马地质的新研究表明，地峡在中新世早期(约23 Ma)被地下暴露。由于戏剧性的全球变化被归因于之前接受的这一门户事件的时间安排，新的发现提出了许多关于关闭可能对海洋环流、气候和古生态产生的作用的问题。在这个项目中，研究员将通过开发远远超过推定的中新世晚期关闭日期的加勒比水团分布的钕(ND)同位素记录，并将这些数据与CAS浅滩的海洋模型模拟直接比较，进一步调查CAS关闭的时间和海洋学影响。这项拟议的工作将在佛罗里达大学(UF)地质科学系进行，由Ellen E.Martin博士赞助。知识价值：为了重建中科院浅滩的长期历史，将对从加勒比海钻探计划地点998、999和1000处发现的化石鱼牙进行ND同位素分析，样本可以追溯到大约50 Ma。这一记录将被用来评估巴拿马最近的地质发现所预测的较老的完整或脉冲关闭事件的存在，并提供浅滩之前的条件基线。研究人员假设，较早的浅滩事件产生了更负的大西洋类型的ND同位素偏移值，这些偏移值早于在晚中新世沉积物中观察到的值；然而，这些偏移量本质上必须是瞬时的，以与加勒比地区在大约14至10 Ma之间记录的太平洋特征相一致。这种漂移的存在将证实最近的研究表明巴拿马地峡上升的时间要早得多，需要重新评估相关的全球海洋环流、气候和生物地理数据，而如果没有这种漂移，将使人质疑对巴拿马早先完整的空中暴露的解释。通过整合新产生的水团重建，汇编文献中的海洋和陆地记录，以及与同事合作建立海洋环流模型，将记录中科院长期的古海洋浅滩历史，并根据这一新信息重新评估其与全球海洋环流和气候的普遍接受的联系。更广泛的影响：该项目将在通过巴拿马运河项目--国际研究和教育伙伴关系研究地峡崛起的不同科学界正在进行的努力中增加一个海洋学部分。这位研究员将指导并与两名少数族裔女性研究生合作，在其他面向陆地的部门进行补充海洋研究的项目。两名本科生将被选中，目标是扩大参与，他们将接受指导，并参与拟议研究的所有方面；其中一名学生还将在完成相关荣誉论文的过程中接受指导。此外，该研究员将设计和实施海洋科学模块的动手介绍，使用加勒比海中新世的重大碳酸盐溶解事件作为现代海洋酸化的模拟。该单元将被纳入加州科学、技术、工程和数学(STEM)教师伙伴关系的更广泛的课程，该伙伴关系使高中教育工作者以及他们的学生接触到独特的国际科学机会，以促进发现和理解，并促进教学、培训和学习的社区。来自两个拉美裔人口众多的圣克鲁斯学区的六名教师将参加，以便向数千名不同的高中生传播海洋意识，并鼓励以海洋科学为重点的STEM追求。最后，将通过UF、佛罗里达海洋科学教育卓越中心(COSEE)、海洋赠款和史密森热带研究所积极参与外联和教育活动，使公众广泛接触海洋科学和古海洋学研究。这次参与将包括，但不限于，为一年一度的“你能挖到吗？”开发一个古海洋学摊位。在佛罗里达自然历史博物馆举行的活动。

Overview: The closure of the Central American Seaway (CAS) and resulting Isthmus of Panama have shaped much of our understanding of the adaptation and migration of species between North and South America, as well as the diversification of Pacific and Caribbean marine species. Until recently, the CAS was thought to have closed between approximately 9 and 2 Ma; however, new studies of Panamanian geology suggest the isthmus was sub-aerially exposed by the Early Miocene (approximately 23 Ma). As dramatic global change has been ascribed to the previously accepted timing of this gateway event, the new findings raise many questions regarding the role the closure may have had on ocean circulation, climate, and paleoecology. In this project, the fellow will further investigate the timing and oceanographic impacts of the CAS closure through the development of neodymium (Nd) isotopic records of Caribbean water mass distribution that extend well beyond the presumed Late Miocene closure date, and direct comparison of these data to oceanic model simulations for CAS shoaling. The proposed work will be conducted in the Department of Geological Sciences at the University of Florida (UF) with the sponsorship of Ellen E. Martin, PhD. Intellectual Merit: In order to reconstruct a long-term history of CAS shoaling, Nd-isotopic analyses will be performed on fossil fish teeth recovered from Caribbean Ocean Drilling Program Sites 998, 999, and 1000 for samples extending back to approximately 50 Ma. This record will be used to evaluate the presence of older complete or pulsed closure events predicted by recent geologic findings from Panama, and provide a baseline of conditions prior to shoaling. The fellow hypothesizes that earlier shoaling events produced excursions towards more negative, Atlantic-type, Nd-isotope values that predate those observed in late Miocene sediments; however, these excursions must be transient in nature to reconcile the Pacific signatures documented for the Caribbean between approximately 14 to 10 Ma. The existence of such excursions would corroborate recent studies showing a much earlier rise of the Isthmus of Panama and require a re-evaluation of the associated global ocean circulation, climate, and biogeographic data, while the absence of such excursions would call into question interpretations of earlier complete sub-aerial exposure of Panama. Through the integration of newly generated water mass reconstructions, compilations of marine and terrestrial records from the literature, and modeling of oceanic circulation in collaboration with colleagues, the long-term paleoceanographic shoaling history of the CAS will be documented and its generally accepted associations with global ocean circulation and climate re-evaluated in light of this new information. Broader Impacts: This project will add an oceanographic component to the ongoing efforts of a diverse scientific community studying the rise of the Isthmus via the Panama Canal Project - Partnership for International Research and Education. The fellow will mentor and collaborate with two female minority graduate students pursuing complementary marine research on the project in otherwise terrestrially oriented departments. Two undergraduate students, selected with the goal of broadening participation, will be mentored and involved in all aspects of the proposed research; one of these students will also be supervised in the completion of a related Honors thesis. Additionally, the fellow will design and implement a hands-on introduction to an ocean science module using a major Miocene carbonate dissolution event in the Caribbean as an analog for modern ocean acidification. The module will be integrated into the broader curricula for the California Science, Technology, Engineering and Mathematics (STEM) Teachers Partnership that exposes high school educators, and by extension their students, to unique international science opportunities in order to advance discovery and understanding, and promote a community of teaching, training, and learning. Six teachers from two Santa Cruz school districts with substantial Hispanic populations will participate, allowing for dissemination of ocean awareness to thousands of diverse high school students and encouraging STEM pursuits with a focus on ocean sciences. Finally, broad exposure of the public to ocean science and paleoceanographic research will be achieved via active participation in outreach and education initiatives through the UF, Center for Ocean Sciences Education Excellence (COSEE) Florida, Sea Grant, and the Smithsonian Tropical Research Institute. This participation will include, though not be limited to, development of a paleoceanography booth for the annual "Can you dig it?" event at the Florida Museum of Natural History.