Stratigraphic and Geochronologic Constraints on Tectonic, Biologic and Geochemical Events, Vendian to Cambrian Nama Group, Namibia

纳米比亚旺迪系至寒武系纳马群的构造、生物和地球化学事件的地层和年代学约束

• 批准号: 9205479
• 负责人: John Grotzinger
• 金额: --
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-15 至 1996-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9205479&HistoricalAwards=false
• 关键词: Stratigraphic; Geochronologic; Constraints; Tectonic; Biologic

The time interval represented by the Vendian period and its transition into the Cambrian is one of the most significant in the evolution of the earth. Major tectonic, biologic and geochemical events occurred on a global scale and include the growth and reorganization of supercontinent, significant fluctuations in sea level and climate, the advent of soft-bodied and small shelly metazoans, the isotopic and trace element composition of seawater, and the composition of the atmosphere. Most of these events are represented in the record of sediments that spans the Vendian- Cambrian transition, and which is preserved on all continents. The research will be a detailed investigation of the stratigraphy, sedimentology, and geochronology of the Nama basin (Namibia) developed during Vendian and early Cambrian time. This work will test specific hypotheses concerning, for example, the mechanisms(s) of basin subsidence, origin of stratigraphic sequences and boundaries, and the absolute ages of critical fossil and trace fossil assemblages (e.g. Ediacaran fauna, Cloudina, Phycodes pedum, the Precambrian-Cambrian boundary, and carbon isotopic and strontium isotopic curves. The work will be supplemented by high resolution U-Pb zircon dating of numerous volcanic ash beds intercalated throughout the sequence, thereby providing one of the best calibrated sections in the world through this critical time interval.

以旺迪亚时期及其向寒武纪过渡为代表的时期是地球演化过程中最重要的时期之一。 全球范围内发生的重大构造、生物和地球化学事件包括超大陆的生长和重组、海平面和气候的显着波动、软体和小型贝壳后生动物的出现、海水的同位素和微量元素组成以及大气的组成。 大多数这些事件都体现在跨越旺迪安-寒武纪过渡时期的沉积物记录中，并且在所有大陆上都得到了保存。 该研究将对文迪纪和寒武纪早期发育的纳马盆地（纳米比亚）的地层学、沉积学和地质年代学进行详细调查。 这项工作将测试有关盆地沉降机制、地层序列和边界的起源以及关键化石和痕迹化石组合（例如埃迪卡拉动物群、Cloudina、Phycodes pedum、前寒武纪-寒武纪边界以及碳同位素和锶同位素曲线）的绝对年龄的具体假设。 辅以高分辨率 U-Pb 锆石定年法，对整个序列中插入的众多火山灰层进行测年，从而在这一关键时间间隔内提供了世界上最好的校准剖面之一。