An integrated geophysics cruise to map the northern edge in the Chukchi Borderland and the adjacent Canada Basin - constraints on basin history and crustal structure

在过去的50年里，我们了解到海洋盆地相对年轻。了解它们的历史对于了解古老的相邻大陆是必要的。北冰洋的美亚海盆是一个谜。虽然它是一个海洋盆地，但海底扩张造成的熟悉模式并不明显。因此，无法了解盆地的历史。该项目将研究美亚盆地三个相邻地物的历史：楚科奇边界、阿尔法海岭和加拿大盆地。该项目计划在一艘研究船上使用丹麦和格陵兰地质调查局（GEUS）的便携式、灵活的多道地震反射系统。该系统已在厚浮冰区成功运行，将收集MCS数据，用于地层和结构解释，并为全面的地壳折射工作提供足够的震源强度。在加拿大海盆的两个地点用海底地震仪（OBS）将获得对地壳深部结构的更强约束。折射数据也将在MCS剖面测量期间用声纳浮标获取，并将用于模拟上地壳结构。这些数据的收集和分析将为我们提供有关美亚盆地形成的新知识，并提高我们对欧亚大陆东北部和北美西北部历史的理解。该项目还将帮助教育新一代北极海洋地球科学家，支持科学的海洋钻探，以采样海底以下的沉积物，并帮助确定美国在北冰洋的领土范围。在大多数情况下，目前对美亚盆地的理解是基于对邻近大陆的观测和对形成盆地的构造位移的假设。一种基于在相邻地物之间建立关键关系的新方法，将有可能通过按比例放大局部关系来重现海洋的构造历史。楚科奇边界是一个嵌在深水美亚盆地中的伸展大陆地壳块。为了理解盆地的开放，有必要将边疆恢复到开放前的位置。这个位置的选择区分盆地的构造模型，没有很好地约束观测。在以前的工作中，从楚科奇大陆架过渡到边境地区的2- MCS调查确定，自早白垩世以来，只有轻微的位移。下一步是了解边界地区北方边缘的结构和历史，这主要是从测深数据中了解的。在这一地区，美亚盆地的三个主要结构相交：边境地区，阿尔法岭和加拿大盆地。在这一地区进行专门的MCS调查将提高我们对这些结构及其在北部和东部沉积物覆盖层以下的终止或延续的了解。在这个项目中，监测、监视和折射测量将阐明明显的大陆性高地块与周围地壳之间的关系，周围地壳可能部分也是大陆性的。观测楚科奇边疆区的北方边缘和邻近的深水区，通过区分地壳类型，将对美亚盆地的历史提供新的限制。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Over the last fifty years, we have learned the ocean basins are relatively young. Knowing their history is necessary to understand the ancient, adjacent continents. The Amerasia Basin of the Arctic Ocean is a mystery. While it is an ocean basin, the familiar patterns created by seafloor spreading are not obvious. As a result, it has not been possible to understand the basin history. This project will study the history of three adjacent features in the Amerasia Basin: the Chukchi Borderland, the Alpha Ridge and the Canada Basin This project plan to use the Geological Survey of Denmark and Greenland (GEUS) portable, flexible multi-channel seismic reflection (MCS) system on a research vessel. This system, which has been successfully operated in thick pack ice, will collect MCS data, for stratigraphic and structural interpretation, and provide sufficient source strength for full crustal refraction work. Stronger constraint on the deep crustal structure will be obtained in two locations in the Canada Basin with ocean bottom seismometers (OBS). Refraction data will also be acquired with sonobuoys during MCS profiling and will be used to model upper crustal structure. The collection and analysis of the data will provide new knowledge about the formation of the Amerasia Basin and improve our understanding of the history of northeast Eurasia and northwest North America. This project will also help educate a new generation of Arctic marine geoscientists, support scientific ocean drilling to sample the sediments below the seafloor and help define the extent of US territory in the Arctic Ocean. For the most part, current understanding of the Amerasia Basin is based on observations made on the adjacent continents and an assumption about the tectonic displacements that formed the basin. A new approach based on establishing critical relationships between adjacent features will make it possible to recreate the tectonic history of the ocean by scaling up from local relationships. The Chukchi Borderland is a block of extended continental crust embedded in the deep water Amerasia Basin. To understand the basin opening, it is necessary to restore the Borderland to its pre-opening position. The choice of this position distinguishes tectonic models of the basin which are not well constrained by observations. In previous work, a 2- MCS survey across the transition from the Chukchi Shelf to Borderland established that there have been only slight displacements across this boundary since Early Cretaceous. Understanding the structure and history of the northern edge of the Borderland, known primarily from bathymetric data, is the next step. In this area, three of the major structures of the Amerasia Basin intersect: the Borderland, Alpha Ridge and the Canada Basin. A dedicated MCS survey in this area will improve our understanding of these structures and their termination or continuation below the sediment cover to the north and east. In this project, MCS and refraction surveys will elucidate the relations between the overtly continental, high-standing block and the surrounding crust, which may be, in part, of continental composition as well. Observing the northern edge of the Chukchi Borderland and adjacent deeper water areas will, by distinguishing crustal types, provide new constraints on the history of the Amerasia Basin.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.