Collaborative Research: Stratigraphic Signatures of Orogeny: Assessing the Timing of Initial Andean Crustal Shortening

合作研究：造山运动的地层特征：评估安第斯地壳初始缩短的时间

• 批准号: 0710793
• 负责人: Brian Horton
• 金额: $ 12.89万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0710793&HistoricalAwards=false
• 关键词: Collaborative; Research; Stratigraphic; Signatures; Orogeny

The nature of the stratigraphic signature of orogeny continues to be a subject of debate, and in many cases stratigraphic estimates for the onset of orogeny lag significantly behind estimates based on structural, metamorphic, and geochronological data. As the type-example of a high-elevation retroarc thrust belt, the central Andes provide an opportunity to test conflicting models for synorogenic stratigraphic evolution. This project addresses a fundamental aspect of Andean orogeny - the timing of initial mountain building owing to crustal shortening and thickening. To this end, a team of researchers from the University of Arizona, the University of Texas, and the University of Wyoming in collaboration with Argentinean scientists are documenting the evolution of Paleogene basins in northwestern Argentina. Three models for basin evolution are being tested: (1) post-rift thermal subsidence, (2) foreland basin subsidence, and (3) intermontane basin development during tectonic disruption of the Andean foreland. Each model makes specific predictions about depositional environments, sediment distribution patterns, provenance, basin architecture, subsidence, and thermal history. The research team is collecting sedimentological data (lithofacies, thickness, paleocurrent directions, provenance) and chronological data (40Ar/39Ar tuff ages, palynology, U-Pb zircon and apatite ages, and apatite fission track ages) from Paleogene strata in a roughly 30,000 square kilometer region. Expected products of the research include a comprehensive dataset on the Paleogene stratigraphy of northwestern Argentina, and a concerted application of two new methods (detrital zircon and apatite U-Pb geochronology) to early Cenozoic tectonic problems in the central Andes. Moreover, the results will directly address the issue of how to read orogenic signatures in the stratigraphic record.The Andes are widely regarded as the type area for mountain belts formed in response to subduction of oceanic lithosphere beneath continents and models based on the Andes are regularly used to understand the development of ancient mountain belts around the globe. Nevertheless, a fundamental aspect of Andean orogeny - the age of initial mountain building owing to crustal shortening and thickening -remains controversial. Through application of new analytical techniques and interpretation of the sedimentary record, this project would resolve this controversy for the Central Andes. The project would provide geologists with new methods to determine the timing of major mountain building events in the geological past.

造口的地层特征的性质仍然是一个争论的主题，并且在许多情况下，基于结构，变质和地质学数据的造口质量的地层估计值显着落后于估计值。作为高海拔逆转推力带的类型示例，中央安第斯山脉为测试矛盾的模型进行了同步地层演化的模型。该项目介绍了安第斯造山基础的基本方面 - 由于地壳缩短和增厚，初始山区建筑的时机。为此，亚利桑那大学，得克萨斯大学和怀俄明大学与阿根廷科学家合作的一组研究人员正在记录阿根廷西北部的古纪盆地的演变。正在测试盆地进化的三个模型：（1）裂谷后热沉降，（2）前陆盆地沉降，（3）安第斯前陆构造中断期间跨蒙坦盆地发育。每个模型都对沉积环境，沉积物分布模式，出处，盆地结构，沉降和热历史做出具体预测。研究团队正在收集沉积学数据（岩相，厚度，古流向，出处）和年代学数据（40AR/39AR TUFF AGES，PALYNOLOGY，U-PB锆石和磷灰石年龄，以及磷灰石裂变年龄），来自大约30,000平方公里的地区的古生元阶层。该研究的预期产品包括有关阿根廷西北部古近纪地层学的全面数据集，以及两种新方法（碎屑锆石和Apatite U-PB年代学）的一致应用到中部安第斯山脉的早期新生代构造问题。此外，结果将直接解决如何在地层记录中阅读造山学特征的问题。安第斯山脉被广泛认为是响应大陆下海洋岩石圈的俯冲而形成的山带类型区域，并且基于安第斯山脉的模型经常用于了解全球范围内的古老山脉的发展。然而，安第斯造山基础的基本方面 - 由于结层缩短和增厚 - 引起争议的山地建筑时代。通过应用新的分析技术和沉积记录的解释，该项目将解决中央安第斯山脉的这一争议。该项目将为地质学家提供新的方法，以确定地质过去重大山区建筑事件的时机。