Collaborative Research: A new appraisal of tectonic mobility in the northern Cordillera using connections between the Coast Mountains batholith and Alberta foreland basin

合作研究：利用海岸山脉岩基和阿尔伯塔前陆盆地之间的联系对北部科迪勒拉山脉的构造活动性进行新评估

• 批准号: 2142272
• 负责人: George Gehrels
• 金额: $ 24.27万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-15 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2142272&HistoricalAwards=false
• 关键词: Collaborative; Research; new; appraisal; tectonic

Western North America is made up of a collage of exotic terranes – blocks of crust that originated in other locations and were later accreted to the continental margin. Myriad studies have been performed to reconstruct the geologic and geographic histories of these blocks and to develop a chronology of how western North America was assembled. One of the enduring controversies is how far-travelled are some of these terranes. In particular, researchers debate the distance that one exotic block – the Insular superterrane – has been translated. Some argue that it has migrated 1500 kilometers northward – and perhaps eastward – along the North American margin, while others believe it has always remained near its present-day latitude. We propose to evaluate these end-member hypotheses by looking for connections between zircons crystallizing in the Coast Mountains batholith (part of the Insular superterrane) and those that have been recycled into sedimentary rocks of interior Canada. The presence or absence of the distinctive Coast Mountains batholith zircon fingerprint in rocks at similar latitudes will either refute or support the idea that the Coast Mountains were far away at the time of deposition of the targeted sedimentary strata. The proposed research will support students at the undergraduate and graduate levels, as well as a postdoctoral scholar. It will broaden and diversify the STEM workforce through promotion of early career female scientists and the inclusion of underrepresented minority students from Hispanic-serving institutions. One of the most critical unresolved questions in the tectonics of the North American Cordillera concerns the degree of tectonic mobility of terranes during Late Jurassic and Cretaceous time. End-member hypotheses posit that terranes presently located in British Columbia and southeast Alaska were either: 1) translated from the latitude of (Baja) California, and perhaps outboard of the Mezcalera Ocean basin, or 2) have remained near their present position and along the continental margin. The debate between the two forms the basis for the enduring “Baja-BC” controversy, which has been reinvigorated by discussion in recently published syntheses. We will test these end-member hypotheses by determining whether detrital zircons in foreland basin strata of Alberta, Canada (part of stable North America) were derived from the Coast Mountains batholith (CMB; part of the purportedly mobile terrane). This test is enabled by the recent recognition that zircons from igneous rocks of the CMB are isotopically and geochemically distinct from other coeval arcs along the margin (e.g. the Sierra Nevada and Idaho batholiths). Our study will: (1) define zircon age, Hf isotopic composition and trace element trends in plutons of the CMB, (2) generate similar data for plutons of the Omineca belt (a second suite of Cretaceous plutons in British Columbia), and (3) compare these igneous records with new studies of zircons in Cretaceous-Paleogene strata of the foreland basin in the northern Cordillera. Establishing connections between the CMB and inland foreland basin strata would provide strong support for models that invoke limited tectonic mobility, whereas the lack of such connections would support models that involve large-scale north-south and/or east-west displacements.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.

北美西部是由一个异国情调的地形学院组成的，该学院起源于其他地方，后来被接纳为连续的边缘。已经进行了无数的研究，以重建这些区块的地质和地质历史，并开发出北美西部如何组装的年表。持久的争议之一是其中一些人地板有多远。特别是，研究人员辩论了一个异国情调的块 - 岛上的超级岩 - 已经翻译了。一些人认为，它已经向北迁移了1500公里，甚至向东迁移，沿着北美的边缘迁移，而另一些人则认为它始终保持在当今的纬度附近。我们建议通过寻找在海岸山脉浴（Insular超级岩的一部分）和已回收到加拿大内部沉积岩石中的锆石之间的连接来评估这些末日的假设。在类似纬度的岩石中，独特的海岸山脉浴锆石指纹的存在或不存在将驳斥或支持在靶向沉积stratta沉积时海岸山脉遥远的想法。拟议的研究将支持本科和研究生级别的学生以及博士后科学。它将通过促进早期职业女性科学家以及从西班牙裔服务机构中纳入代表性不足的少数族裔学生来扩大和多样化STEM劳动力。在北美哥尔达勒拉的构造中，最关键的尚未解决的问题之一是侏罗纪和白垩纪时间期间地层的构造流动性程度。由成员组成的假设肯定，在不列颠哥伦比亚省和阿拉斯加东南部展示的地形要么是：1）从加利福尼亚（巴哈）的纬度中翻译，也许是Mezcalera Ocean Pasin的外部，或者2）一直保持在其目前的位置和连续的边缘。两者之间的辩论构成了持久的“ Baja-BC”争议的基础，这在最近发表的合成中的讨论中得到了振奋。我们将通过确定加拿大艾伯塔省前陆盆地盆地（稳定的北美的一部分）是否源自海岸山山地浴（CMB；据称是移动地形的一部分）来检验这些结束的假设。最近认识到，CMB火成岩的锆石是同位素和地球化学上与边缘沿边缘的其他同时弧不同的（例如，内华达州内华达山脉和爱达荷州浴场）的地球化学上不同的。我们的研究将：（1）定义锆石的年龄，HF同位素组成和CMB的痕量元素趋势，（2）（2）生成相似的Omineca带岩体的数据（在不列颠哥伦比亚岛的第二套白垩纪plut子），以及（3）将这些点燃的记录与北方层次的新研究进行了比较。建立CMB和内陆前陆盆地阶层之间的联系将为构成有限的构造流动性提供强大的支持，而缺乏这种连接的模型将支持涉及大规模南北和/或东西方流离失所的模型。该奖项反映了NSF的法定任务，并通过评估了基金会的范围和广泛的cr依支持了NSF的任务。