Origin and internal architecture of an offshore mudstone belt

泥岩的研究相对较少，尽管它们占地质记录中所有沉积岩的50%以上，但大多被忽视。过去几年，人们对泥岩重新产生了兴趣，部分原因是页岩气和盆地中心气的经济潜力。本次研究的重点将是犹他州白垩纪Mancos页岩泥岩带。白垩纪是地球历史上一个自然形成的温室时期，当时恐龙占据了统治地位，从加拿大北极到墨西哥湾的北美西部内陆被海水淹没。当时全球海平面比现在高出250米。白垩纪西部内陆海将北美大陆分成两部分：多山的西部半部分和地势较低的东部半部分。西半部在构造上很活跃，只有一片狭窄的沿海平原将山脉和海洋隔开。中小水流湍急的河流排干了山脉东部，并将大量沉积物输送到珊瑚礁，沉积了厚厚的沙子、淤泥和粘土。经过沉积和岩化作用，这些沉积岩被缓慢抬升，形成了美国西部内陆的壮丽景色。最壮观的地区之一是犹他州中东部的峡谷地区，那里有世界上最长的连续悬崖线之一，300公里长的图书悬崖。这项研究的主要目的是增加关于近海泥岩带成因和内部结构的基本新知识。这项研究的长期目标是揭示陆架泥岩的泥沙输送机制和主导方向，并开发适用于陆架泥岩的模型。揭示Mancos页岩泥质带的起源和内部结构将有助于更好地了解浅海沉积模式、海平面变化(即速率、幅度、旋回性)、盆地历史和环境随时间的变化。后者对于将我们的现代“早期”温室条件置于正确的历史视角中是至关重要的。

Mudrocks are relatively understudied and are mostly ignored despite the fact that they comprise over 50 % of all sedimentary rocks in the geologic record. There has been a renewed interest in mudrocks over the past few years partly in response to the economic potential of shale gas and basin center gas. The focus of this research will be the Cretaceous Mancos Shale mudstone belt in Utah. The Cretaceous was a naturally occurring greenhouse period in Earth's history when the dinosaurs reigned supreme and the Western Interior of North America from Arctic Canada to the Gulf of Mexico was flooded with sea water. Global sea level was up to 250 m higher than present day. The Cretaceous Western Interior Seaway (CWIS) dissected the North American continent into two parts: a mountainous western half and a lower-lying eastern half. The western half was tectonically active with only a narrow coastal plain separating the mountains from the sea. Small- to moderate-sized, fast-flowing rivers drained the eastern part of the mountains and transported a significant volume of sediments into the CWIS, depositing a thick succession of sands, silts and clays. Following deposition and lithification, these sedimentary rocks were slowly uplifted to form the magnificent scenery in the western interior of the United States. One of the most spectacular regions is the Canyonlands-area of east-central Utah which is home to one of the longest continuous cliff-lines in the world, the 300-km-long Book Cliffs. The main objective of this research is to add fundamental new knowledge regarding the origin and internal architecture of offshore mudstone belts. Long-term goals for this research are to unravel the sediment delivery mechanisms and dominant direction of sediment transport on the shelf, and to develop appropriate models for shelf mudstones. Unravelling the origin and internal architecture of the Mancos Shale mud belt will lead to a better understanding of shallow marine sedimentation patterns, sea level change (i.e. rate, magnitude, cyclicity), basin history and environmental change through time. The latter is essential for placing our modern "early stage" greenhouse conditions into their proper historical perspective.