Archean Sedimentation Adjacent To An Orogenic Belt-Examples From Zimbabwe With Implications For Archean Tectonics

造山带附近的太古代沉积——津巴布韦的例子对太古代构造的影响

• 批准号: 9104876
• 负责人: Kenneth Eriksson
• 金额: $ 9.23万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-06-15 至 1995-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9104876&HistoricalAwards=false
• 关键词: Archean; Sedimentation; Adjacent; Orogenic; Belt

The Limpopo Province in southern Africa is a high-grade metamorphic belt that represents the exhumed root of a continent- continent collision zone. Granite-greenstone terranes of the Zimbabwe Province, to the north, and Kaapvaal Province to the south, flank the Limpopo Province. On the Kaapvaal craton, the Witwatersrand Supergroup is interpreted as a foreland-basin fill, representing the sedimentary response to collisional events in the Limpopo orogeny. A sedimentary succession of comparable lateral extent, thickness, and lithology to the Witwatersrand Supergroup is not present in the Zimbabwe Craton adjacent to the northern marginal zone of the Limpopo Province. Instead, five local and lithologically distinct stratigraphic successions of different age are present in the greenstone belts. At least four of these successions, developed in the lower and upper greenstones, are of comparable age to the Witwatersrand Supergroup. The absence of a Witwatersrand equivalent in Zimbabwe raises several important questions regarding the evolution of the southern African Archean in specific, and Archean tectonics and sedimentation patterns in general: 1) What are the detailed characteristics of two of the 3.0-2.7 Ga Zimbabwean basins, including source-area composition, source-area age, source-area location, sediment dispersal patterns, depositional environments, basin configuration, basin evolution, and tectonic setting? 2) What was the genetic relationship of the Zimbabwe sedimentary basins with respect to the evolution of the Limpopo orogeny? 3) Was the Limpopo orogeny of Pyrenean or Himalayan type? A multidisciplinary approach, involving detailed field mapping, structural analysis, sedimentologic-stratigraphic analysis, and geochemistry, will be applied to two of the stratigraphic successions to address the above questions.

南部非洲的林波波省是一个高等级的 代表大陆被挖出的根部的变质带 大陆碰撞带 花岗岩-绿岩 津巴布韦省，北部，和卡普瓦尔省， 南面是林波波省的侧翼 在卡普瓦尔克拉通， 威特沃特斯兰德超群被解释为前陆盆地充填， 代表了沉积反应的碰撞事件， 林波波造山运动。 一个可比较的横向沉积序列 威特沃特斯兰德超群的范围、厚度和岩性 不存在于与北方相邻的津巴布韦克拉通 林波波省的边缘地带。 五个地方和 不同时代的岩性不同的地层序列 存在于绿岩带中。 至少有四个这样的 继承，发展在较低和较高的绿岩，是 与威特沃特斯兰德超群年龄相当 不存在 津巴布韦的Witwatersrand对等机构提出了几个重要的 关于南部非洲太古代演化的问题 具体来说，太古代的构造和沉积模式， 一般：1）其中两个的详细特征是什么？ 3.0-2.7 Ga津巴布韦盆地，包括源区组成， 源区年龄、源区位置、沉积物扩散模式、 沉积环境，盆地构型，盆地演化， 和地质构造背景 2)这是什么样的遗传关系， 津巴布韦沉积盆地的演化 林波波省？ 3)是比利牛斯山脉的林波波河还是 喜马拉雅类型？ 多学科方法，涉及详细的领域 填图，构造分析，沉积地层学 分析和地球化学，将应用于两个 地层序列来解决上述问题。