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

该项目旨在记录柴达木盆地西部极度干旱的中国地区由于风蚀加剧而加速褶皱生长的情况，从而提供地球上第一个风增强构造的例子。除了了解气候构造反馈外，该项目还将产生柴达木盆地西部跨上新世晚期气候崩溃和北半球冰川开始的多个高分辨率环境变化记录。这一流域范围的综合数据集将提供这种气候变化造成的荒漠化速度的证据，并可作为当今观察到的可比气候变化的类比。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用作教学工具。该项目通过培养研究生和本科生来培养STEM劳动力，国际合作为这些学生提供了一个获得国际研究经验的机会。该项目得到了构造计划(地球科学部)和国际科学与工程部(国际和综合活动办公室)的支持。全球气候在上新世-更新世过渡(3.6至2.6 Ma)附近变得更凉爽、更干旱，导致全球环境变化。在许多地区，这一时期的同步构造活动引起了气候-构造反馈假说，但所观察到的沉积变化与当地构造之间的因果关系很难量化。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，这两者都将增强隆起的均衡响应。该项目与兰州大学(中国)和法国雷恩大学的科学家合作，将检验这一假说，即约3 Ma的气候变化(表现为中亚干旱加剧)在中国的柴达木盆地西部引发了阶段性和空间上的不均匀风蚀，进而导致褶皱生长的加速和增强。本次研究以柴达木盆地活动背斜两侧均匀分布的8个地层剖面为研究对象，内容包括：详细剖面测量；磁性地层学；磁化率、氧、碳稳定同位素测量；岩相、地层厚度、生长地层和层内不整合的填图；褶皱的三维构造模型和古运动学恢复。将综合每个褶皱的数据来检验这样的假设：大约3.0 Ma的全球气候干旱化导致的湖泊干化促进了盆地底部褶皱的生长；柴达木盆地西部在上第四纪冰期和间冰期分别经历了湖平面低水位(和风蚀)和湖平面高位的交替时期，与位于东部的黄土高原的黄土-古土壤序列同步。该研究项目将提供关于干旱和变形之间关系的盆地范围的数据，从而能够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.