Collaborative Research: Strike-Slip History of the East Gobi Fault Zone, Mongolia: Modes of Intraplate Deformation, Sedimentary Basin Evolution, and Regional Fault Linkages

合作研究：蒙古东戈壁断裂带走滑历史：板内变形模式、沉积盆地演化和区域断裂联系

• 批准号: 0537318
• 负责人: Cari Johnson
• 金额: $ 24.4万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0537318&HistoricalAwards=false
• 关键词: Collaborative; Research; Strike; Slip; History

This research contributes to the understanding of how continents deform in response to major tectonic events such as continent--continent collisions. The continent of Asia is a natural laboratory to address questions such as: How has the interior of Asia deformed in response to the collision of India and Asia? How and why might the modes of deformation have changed over time? How does the sedimentary record reflect such events? This project employs tools of structural geology, geochronology, and sedimentary basin analysis to reconstruct displacement history and sedimentary basin evolution along the East Gobi Fault Zone, Mongolia. Preliminary data suggest that this major intracontinental shear zone was reactivated at least four times since the late Paleozoic; this work documents two of the least-constrained episodes of left-lateral slip (early Mesozoic and early Cenozoic). Due to paucity of data from southeastern Mongolia, the East Gobi Fault Zone is essentially played as a wildcard against models of evolution of the Asian tectonic "collage." For example, published models estimate left-lateral offset ranging from approximately 200 km of early Mesozoic slip to approximately 400 km of purely Cenozoic slip, citing regional map relations that have not been field-tested. The latter interpretation implies a pre-Miocene linkage between the Altyn Tagh fault and hypothesized--but as yet largely undocumented--strike-slip faults extending through southeastern Mongolia to the Sea of Okhotsk. This study tests whether this kinematic linkage is permissible via mapping near the China-Mongolia border zone, southwest from control sites where Cenozoic strike-slip faulting has been established in the East Gobi Fault Zone, and provides the first field and analytical constraints on the timing and magnitude of slip. These results bear further on mechanisms favoring initiation and reactivation of shear zones by testing the hypothesis that the East Gobi Fault Zone reactivates a Paleozoic suture. Geochronologic data are collected to evaluate the timing of intraplate deformation in southeastern Mongolia as a function of far field forces and evolving boundary conditions. Thus, this research is relevant to models of continental block extrusion and continuum shortening during Asia's history of collisions from Mesozoic-Recent. The great variety of structural levels exposed and lithologies involved in deformation in the East Gobi Fault Zone provide an excellent opportunity to investigate rheologic controls on shear zone/fault zone development in the upper crust and at depth. Furthermore, investigation of the relationship between deformational phases of the East Gobi Fault Zone and sedimentary rocks in the East Gobi region constrain mechanisms of initiation, stratigraphic development, and subsequent dismembering of "poly-history" sedimentary basins in wrench-tectonic settings. The multidisciplinary nature of the collaboration highlights the power of integration of diverse geologic datasets to address a complex set of questions. Results of this study contribute to the greater understanding of an understudied and mineral resource-rich region of our planet. The international nature of this work fosters collaboration between Mongolian and American geologists, including two early-career female investigators. Additionally, two Ph.D. students and undergraduate students from Utah and Syracuse participate in all aspects of the study and are trained in the use of technology to solve scientific problems.Support for the project is provided by the Tectonics Program and by the East Asia and Pacific Group of the Office of International Science and Engineering.

这项研究有助于理解大陆如何响应主要构造事件（例如大陆 - 联合碰撞）。亚洲大陆是一个自然实验室，可以解决以下问题：以下问题：亚洲内部如何响应印度和亚洲的碰撞？变形模式如何随着时间而变化？沉积记录如何反映此类事件？该项目采用结构地质，地质学和沉积盆地分析的工具来重建位移历史和沿蒙古东戈比断层区的沉积盆地进化。初步数据表明，自晚古生代以来，这个主要的室内剪切区至少重新激活了四次。这项工作记录了左侧滑动最小约束的两集（早期中生代和早期的新生代）。由于蒙古东南部的数据匮乏，东戈比断层区实质上是一种通配符，与亚洲构造“拼贴”的进化模型相比。例如，发布的模型估计左侧偏移量的范围从大约200公里的中生代滑移到大约400 km的纯碳酸盐滑移，理由是尚未经过现场测试的区域地图关系。后一种解释意味着阿尔蒂·塔格（Altyn Tagh）断层与假设的中新世之间的联系 - 但仍在很大程度上没有证明的 - trike滑动断层，延伸到蒙古东南部到奥克斯克（Okhotsk）的海洋。这项研究测试了这种运动学连锁是否可以通过在中西部边界区附近的映射，西南部的控制地点，该控制地点是在East Gobi断层区建立了Cenozoic Skike-Slip Slip断层的，并提供了第一个领域和分析的限制，并在滑动的时机和幅度上。这些结果进一步基于有利于剪切区开始和重新激活剪切区的机制，即通过测试东戈比断层区重新激活古生代缝合线的假设。收集了地质数据，以评估蒙古东南部的板岩内变形的时机，这是远场力和不断发展的边界条件的函数。因此，这项研究与亚洲中生代造成的碰撞历史期间大陆阻滞挤压和连续缩短的模型有关。东戈比断层区域变形涉及的各种结构水平和岩性提供了一个极好的机会，可以研究对上皮和深度的剪切区/断层区发育的流变控制。此外，对东戈比（East Gobi）断层区的变形阶段与东戈比地区的沉积岩之间的关系研究限制了扳手基于扳手建立环境中“多层”沉积盆地的起始，地层发展的机制。协作的多学科性质突出了各种地质数据集集成以解决一系列问题的力量。这项研究的结果有助于对我们星球的研究且资源丰富的地区有更深入的了解。这项工作的国际性质促进了蒙古和美国地质学家之间的合作，包括两名早期职业女性调查员。此外，两位博士学位来自犹他州和锡拉丘兹的学生和本科生都参与了研究的各个方面，并接受了技术解决科学问题的培训。该项目的支持者由构造学计划以及东亚和国际科学和工程办公室提供。