Collaborative Research: Plio-Quaternary History of Basin Evolution, Climate Change, and Fold Growth in the Qaidam Basin-Investigating Wind-enhanced Climate-Tectonic Feedback

该项目旨在记录由于中国极度干旱的柴达木盆地西部风蚀增加而导致褶皱增长的加速，从而将提供地球上风增强构造的第一个例子。除了了解气候-构造反馈外，该项目还将获得柴达木盆地西部在上新世晚期气候崩溃和北半球冰川开始期间的环境变化的多个高分辨率记录。这一综合的流域尺度数据集将为这种气候变化导致的荒漠化率提供证据，并可能作为今天观测到的可比气候变化的模拟物。此外，由此产生的新的地层和构造数据集将被纳入地球科学实验室，并通过科学教育资源中心免费提供给全国的教育工作者作为教学工具。该项目通过培训研究生和本科生来发展STEM劳动力，国际合作为这些学生提供了国际研究经验的机会。该项目由地球科学部构造学计划和国际科学与工程办公室（国际与综合活动办公室）支持。在上新世-更新世过渡时期（3.6 ~ 2.6 Ma），全球气候变冷、变干旱，引起了全球范围内的环境变化。在许多地区，这一时期的同步构造活动引发了气候-构造反馈的假设，但观测到的沉积变化与局部构造之间的因果关系难以量化。气候增强构造的一种可能机制包括褶皱峰顶的集中侵蚀，或由于湖泊水位下降而减少的覆盖层，这两种机制都将增强隆起的均衡响应。该项目将与兰州大学（中国）和雷恩大学（法国）的科学家合作，验证一个假设，即大约3 Ma的气候变化（表现为中亚干旱加剧）在中国柴达木盆地西部引发了幕式和空间不均匀的风蚀，进而导致褶皱生长的加速和增强。本研究以柴达木盆地内分布均匀、位于活动背斜两侧的8个地层剖面为研究对象，包括：详细剖面测量；磁性地层学;磁化率、O和C稳定同位素的测量；岩相、层厚、生长地层和地层内不整合面填图；以及三维结构模型的构建和褶皱的弹性运动学修复。将对每个褶皱的数据进行综合，以验证以下假设：约3.0 Ma的全球气候干旱化导致的湖泊干旱化促进了风蚀，从而增强了盆地底部褶皱的生长；柴达木盆地西部在上第四纪—第四纪冰期和间冰期分别经历了低水位和高水位交替的时期，与东部黄土高原的黄土—古土壤演替相一致。该研究项目将提供干旱化和变形之间关系的流域尺度数据，从而可以测试风蚀是否导致褶皱加速生长。

The project aims to document acceleration in fold-growth due to increased wind erosion within the hyperarid western Qaidam Basin, China, and thus would provide the first example of wind-enhanced tectonics on Earth. In addition to understanding climate-tectonic feedbacks, this project will yield multiple high-resolution records of environmental change in the western Qaidam Basin across the late Pliocene climate crash and onset of Northern Hemisphere glaciations. This integrated, basin-scale dataset will provide evidence for desertification rates resulting from this climate shift, and may be useful as an analogue for comparable climate changes observed today. Moreover, the resultant new stratigraphic and structural datasets will be incorporated into a geoscience lab and made freely available via the Science Education Resource Center for educators across the country to use as a teaching tool. The project develops STEM workforce by training of graduate and undergraduate and the international collaboration provides an opportunity for international research experiences for those students. The project is supported by the Tectonics Program (Division of Earth Sciences) and International Science and Engineering (Office of International and Integrative Activities).Global climate changed to cooler, more arid conditions near the Plio-Pleistocene transition (3.6 to 2.6 Ma), causing environmental changes worldwide. In many regions, concurrent tectonic activity during this time period has evoked hypotheses of climate-tectonic feedbacks, but a causal relationship between observed depositional changes and local tectonics is difficult to quantify. One possible mechanism for climate-enhanced tectonics includes focused erosion across fold crests, or decreased overburden due to lake-level drop, both of which would enhance the isostatic response of uplift. This project, in collaboration with scientists from Lanzhou University (China) and Universite de Rennes (France), will test the hypothesis that climate change (manifested by enhanced aridity in central Asia) at about 3 Ma initiated episodic and spatially non-uniform wind erosion in the western Qaidam Basin in China, which in turn led to an acceleration and enhancement of fold growth. This research focuses on 8 stratigraphic sections spaced evenly throughout the Qaidam Basin and located on the flanks of active anticlines and involves: measurement of detailed sections; magnetostratigraphy; measurements of magnetic susceptibility, O and C stable isotopes; mapping of lithofacies, bed thickness, growth strata, and intraformational unconformities; and construction of 3-D structural models and palinspastic kinematic restorations of the folds. Data from each fold will be synthesized to test hypotheses that lake desiccation resulting from global climate aridification at about 3.0 Ma facilitated wind-erosion that enhanced fold growth on the basin floor; and that the western Qaidam Basin underwent alternating episodes of lake-level lowstands (and wind deflation) and lake-level highstands during Plio-Quaternary glacial and interglacial periods, respectively, in phase with the loess-paleosol successions of the Loess Plateau located to the east. The research project will provide basin-scale data on the relationship between aridification and deformation, allowing a test of whether wind erosion led to accelerated fold-growth.