Collaborative Research: Suturing the Heart of Asia: Tectonics of the Mongol-Okhotsk Ocean Closure

整个地质历史上洋盆的闭合和超大陆的形成直接影响了自然灾害和自然资源的分布。海洋盆地和陆地分布的变化也影响了地球气候的历史和生命的进化。今天的亚洲大陆是由古老大陆的残余物、海洋盆地的残余物和数亿年形成的岛链碎片组成的。古代蒙古-鄂霍次克海是最大的海洋之一，以前将亚洲大陆的核心部分分开，但对它的了解却少得惊人。本研究通过多学科方法，包括野外测绘和关键岩石类型的测年，研究了蒙古-鄂霍次克海洋关闭的时间和机制。该项目支持来自美国和蒙古大学的不同科学家之间的合作，以及对美国和蒙古学生的培训和指导。与此项目相关的推广工作包括为美国和国际学生提供新的教育资源，以及为中学生提供关于板块构造、超级大陆和地质时间的新教育模块。本项目整合了蒙古-鄂霍次克缝合带的地层、古地磁、构造和地质年代学数据集，在关于洋盆闭合和大陆碰撞模式的竞争性端元假设背景下进行评估，例如与剪刀状缝合相比，主要的造山口弯曲。该项目还研究了走滑断裂在海洋闭合过程中的作用及其与随后的造山带崩塌的关系。研究成果是多学科的，包括：1)地层分析，以记录海洋-非海洋相转变，更好地划定残余海洋盆地的亚型；2)记录Hangay Dome附近标称西部铰区变形的结构数据集；3)验证现有的小体积古磁学数据集和新的参考极，以改进APWP的比较；4)主要岩石类型的总体地质年代学框架的发展。该项目包括与专注于区域岩浆作用和成矿作用的国际团队合作。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。

The closure of ocean basins and formation of supercontinents throughout geologic history have directly influenced the distribution of natural hazards and natural resources. Changes in the distribution of ocean basins and land masses have also impacted the history of Earth's climate and the evolution of life. The modern-day continent of Asia consists of remnants of old continents, relict ocean basins, and fragments of island chains assembled over hundreds of millions of years. The ancient Mongol-Okhotsk Ocean was one of the largest oceans that previously separated fragments of the present core of the Asian continent, and yet remarkably little is known about it. This study examines the timing and mechanisms of the closure of the Mongol-Okhotsk Ocean through a multidisciplinary approach that includes field mapping and dating of key rock types. The project supports collaborations between diverse scientists from universities in the US and Mongolia, and training and mentoring of US and Mongolian students. Outreach efforts associated with this project include new educational resources for US and international students, along with new educational modules on plate tectonics, supercontinents, and geologic time for secondary school students.This project integrates stratigraphic, paleomagnetic, structural, and geochronologic datasets for the Mongol-Okhotsk suture that are assessed in the context of competing end-member hypotheses regarding modes of ocean basin closure and continental collision, such as major oroclinal bending as compared with scissor-like suturing. The project also investigates the role of strike-slip faulting during ocean closure and its relationship to subsequent orogenic collapse. Research outcomes are multidisciplinary and include: 1) stratigraphic analyses to document marine-nonmarine facies transitions and better delineate subtypes of remnant ocean basins; 2) structural datasets that document deformation in the nominal western hinge zone near the Hangay Dome; 3) verification of existing low-volume paleomagnetic data sets and new reference poles to improve APWP comparisons; and 4) development of an overarching geochronologic framework for key rock types. The project includes collaboration with international teams focused on regional magmatism and metallogeny.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.