Paleogene Sedimentary Basin Development in the Bolivian Altiplano and Implications for Initial Mountain Building in the Central Andes

玻利维亚高原古近纪沉积盆地发育及其对安第斯山脉中部早期造山的影响

• 批准号: 0231543
• 负责人: Brian Horton
• 金额: $ 0.55万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-01-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0231543&HistoricalAwards=false
• 关键词: Paleogene; Sedimentary; Basin; Development; Bolivian

9908003Brian K. HortonThe Altiplano plateau of the central Andes contains up to 10 km of Tertiary sedimentary rocks and is arguably the type example of a sedimentary basin in the center of a contractional orogenic belt. Despite numerous hypotheses regarding the history of the Altiplano's surface, particularly the timing and mechanism(s) of surface uplift, there has been no systematic analysis of the exposed Tertiary sedimentary rocks which ultimately contain the most complete record of surface processes. This project aims to evaluate the Paleogene succession of the north-central Altiplano in order to provide an understanding of the early-middle Tertiary tectonic-sedimentary evolution of the region and a detailed assessment of local stratigraphic geometries (including thickening trends, facies transitions, and unconfonnities) and regional correlations that will aid syntheses of the tectonic-sedimentary development of the central Andes. The project will evaluate four hypotheses regarding Paleogene basin development in the Altiplano. First, that it was a single integrated foreland basin receiving sediment from an early fold-thrust belt to the west. Second, that it was composed of a number of sub-basins, probably related to strike-slip deformation, that received sediment from localized source areas. Third, that it was a rift system flanked by sediment sources to the east and west. Or fourth, that it represents simple ponding (or "trapping") of sediment in a closed topographic basin. The hypotheses are distinguishable on the basis of the age of the deposits, sediment dispersal patterns, location and composition of sediment source areas, and subsidence histories-unknowns that will be determined by stratigraphic, sedimentologic, and 4OAr/39Ar geochronologic research. This study will place constraints on the early-middle Tertiary history of the plateau, thus improving modeling efforts aimed at understanding Altiplano uplift, and would provide a conceptual basis (and possibly new hypotheses) for the origin of sedimentary basins in the cores of mountain belts.

9908003Brian K. Horton安第斯山脉中部的阿尔蒂普拉诺高原包含长达10公里的第三纪沉积岩，可以说是收缩造山带中心沉积盆地的典型例子。 尽管有许多关于阿尔蒂普拉诺地表历史的假设，特别是地表隆起的时间和机制，但没有对暴露的第三纪沉积岩进行系统分析，这些沉积岩最终包含最完整的地表过程记录。 该项目旨在评估阿尔蒂普拉诺中北部的古近纪序列，以了解该地区早-中第三纪的构造-沉积演化，并详细评估当地地层几何形状（包括增厚趋势、相变和不整合）和区域对比，这将有助于综合安第斯山脉中部的构造-沉积发展。 该项目将评估关于高原古近纪盆地发展的四个假设。 首先，它是一个单一的完整的前陆盆地，接受来自西部早期褶皱冲断带的沉积物。 第二，它是由一些子盆地，可能与走滑变形，接受沉积物从本地源区。 第三，它是一个裂谷系统，东西两侧都有沉积物来源。 或者第四，它代表了一个封闭的地形盆地中沉积物的简单积水（或“捕获”）。 根据沉积物的年龄、沉积物分散模式、沉积物源区的位置和组成以及沉降历史- 这项研究将对高原早-中第三纪的历史进行限制，从而改善旨在了解高原隆升的建模工作，并将为山区带核心的沉积盆地的起源提供概念基础（可能是新的假设）。