Collaborative Research: Evaluating controls on orogenic structural style by constraining the spatio-temporal evolution of a retroarc thrust belt

合作研究：通过约束弧后冲断带时空演化来评估对造山构造样式的控制

基本信息

批准号：
1728214
负责人：
William Guenthner
金额：
$ 23万
依托单位：
University of Illinois at Urbana-Champaign
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-07-01 至 2020-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1728214&HistoricalAwards=false
关键词：
Collaborative Research Evaluating controls orogenic

项目摘要

Though all continental mountain belts form as continental crust is shortened in regions of plate convergence, they exhibit major variations in width, elevation, and types of rocks involved. Given that many of these mountain belts are associated with some of Earth's most significant geological hazards and host prolific petroleum and mineral deposits, there is considerable societal and scientific interest in identifying the main factors responsible for their differences. This research will test a hypothesis that major differences in these mountain belts result from variations in the types and strengths of rocks that are present prior to the beginning of mountain building. This contribution is significant because it is expected to redefine the relative importance of these variations in influencing not only the geometry of mountain belts, but also the mechanisms through which they form. In addition to the scientific contributions of the project, important societal outcomes include workforce development through the education of graduate and undergraduate students in an important science, technology, engineering and mathematics (STEM) discipline. It fosters scientific literacy of the public through outreach efforts aimed at K-12 students that will result in the training and attraction of students to STEM careers. The project supports broadening of underrepresented groups in STEM. The project contributes to STEM educator development for high school teachers in the northern Rocky Mountain region through the implementation of a field-based course for high school science teachers in the northern Rockies. Results of the research will be disseminated through presentations at professional society meetings and peer-reviewed scientific literature. The principal investigators will construct a structural, sedimentary, and thermochronologic record of the spatial and temporal transition in structural style--"thin-skinned" deformation of primarily sedimentary units or "thick-skinned" deformation of basement units--in east-central Idaho and southwestern Montana and compare it to the timing of "Laramide" flat subduction beneath Wyoming. The central hypothesis to be tested is that the transition in structural style along the proposed transect, which is outside the classic Laramide region, developed as a result of the pre-orogenic stratigraphic architecture of the upper plate. This work will provide a critical test of whether an intrinsic property of the upper plate, rather than a change in plate boundary geodynamics such as flat-slab subduction, can be a dominant mechanism for controlling orogenic structural style. The team will test the central hypothesis using 1) structural and stratigraphic investigations in east-central Idaho and southwestern Montana to constrain the spatial pattern of structural styles and coeval depocenters and 2) thermochronometry of thrust sheets to constrain the timing of exhumation related to thrusting and coeval foreland sedimentation. The research design includes zircon and apatite uranium-lead and (uranium-thorium)/helium dating, as well as apatite fission track thermochronometry in the context of field-based structural and stratigraphic investigations; these results will be used to build a regional kinematic model to evaluate the hypothesized non-flat-slab control on the spatio-temporal transition in structural style. Results from this work thus have the potential to transform our knowledge of the causal relationship between thin- and thick-skinned portions of continental fold-thrust belts and could warrant reevaluation of the importance of the pre-orogenic upper crustal architecture in affecting the first order geometries of modern and ancient continental mountain belts.

尽管所有大陆山带都是随着大陆地壳在板块汇聚区域缩短而形成的，但它们在宽度、海拔和所涉及的岩石类型方面表现出巨大的变化。鉴于许多这些山脉都与地球上一些最严重的地质灾害有关，并蕴藏着丰富的石油和矿藏，因此社会和科学界对确定造成其差异的主要因素有很大的兴趣。这项研究将检验一个假设，即这些山脉的主要差异是由于造山开始之前存在的岩石类型和强度的变化造成的。这一贡献意义重大，因为它有望重新定义这些变化的相对重要性，不仅影响山带的几何形状，而且影响它们形成的机制。除了该项目的科学贡献外，重要的社会成果还包括通过对研究生和本科生进行重要的科学、技术、工程和数学 (STEM) 学科教育来促进劳动力发展。它通过针对 K-12 学生的外展活动来培养公众的科学素养，从而培训和吸引学生从事 STEM 职业。该项目支持扩大 STEM 中代表性不足的群体。该项目通过为落基山脉北部高中科学教师实施实地课程，为落基山脉北部地区高中教师的 STEM 教育者发展做出贡献。研究结果将通过专业协会会议上的演讲和同行评审的科学文献进行传播。主要研究人员将构建中东部构造样式时空变迁的构造、沉积和热年代学记录——主要沉积单元的“薄皮”变形或基底单元的“厚皮”变形。爱达荷州和蒙大拿州西南部，并将其与怀俄明州下方“拉拉米德”平坦俯冲的时间进行比较。要测试的中心假设是，沿着所提议的横断面（位于经典拉拉米德地区之外）的结构样式转变是由于上部板块的造山前地层结构而发展起来的。这项工作将提供一个关键的测试，以确定上板块的内在特性，而不是板块边界地球动力学的变化，如平板俯冲，是否可以成为控制造山构造样式的主导机制。该团队将使用 1）爱达荷州中东部和蒙大拿州西南部的结构和地层调查来测试中心假设，以限制结构样式和同时代沉积中心的空间模式，以及 2）逆冲片的热测时法以限制与逆冲和冲断相关的折返时间。同时代的前陆沉积。研究设计包括锆石和磷灰石铀-铅和（铀-钍）/氦测年，以及在现场结构和地层调查背景下的磷灰石裂变径迹测温法；这些结果将用于建立区域运动学模型，以评估假设的非平板控制对结构样式时空转变的影响。因此，这项工作的结果有可能改变我们对大陆褶皱逆冲带薄皮部分和厚皮部分之间因果关系的认识，并可能需要重新评估造山前上地壳结构在影响第一级的重要性。现代和古代大陆山带的几何形状。