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

在整个地质历史中，洋盆的关闭和超大陆的形成直接影响了自然灾害和自然资源的分布。海洋盆地和陆块分布的变化也影响了地球气候的历史和生命的进化。今天的亚洲大陆由古老大陆的残骸、残留的海洋盆地和经过数亿年拼凑而成的岛链碎片组成。古代蒙古-鄂霍次克海是以前分隔亚洲大陆现今核心碎片的最大海洋之一，但令人惊讶的是，人们对它知之甚少。这项研究通过包括野外测绘和关键岩石类型测年在内的多学科方法，研究了蒙古-鄂霍次克海关闭的时间和机制。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。与该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、超大陆和地质时代的新教育模块。该项目整合了蒙古-鄂霍次克缝合线的地层学、古地磁、构造和地质年代学数据集，这些数据集是在终端成员关于洋盆关闭和大陆碰撞模式的相互竞争的假设的背景下进行评估的，例如与剪刀式缝合相比的主要造山斜弯曲。该项目还调查了走滑断层在海洋闭合过程中的作用及其与随后造山带坍塌的关系。研究成果涉及多学科，包括：1)地层学分析以记录海-陆相的转变并更好地划定残余洋盆的亚型；2)构造数据集记录汉盖穹顶附近名义上的西部铰链区的变形；3)核实现有的低容量古地磁数据集和新的参照极，以改进对APWP的比较；4)建立关键岩石类型的总体地质年代学框架。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NSF的法定使命，并通过使用基金会的智力优势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.