Integrated high-resolution stratigraphy: Deciphering fundamental controls on basin evolution

综合高分辨率地层学：破译盆地演化的基本控制因素

• 批准号: RGPIN-2018-05039
• 负责人: Plint, Alexander
• 金额: $ 2.19万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=683491
• 关键词: Integrated; resolution; stratigraphy; Deciphering; fundamental

Sedimentary rocks provide the most important record of life on Earth, as well as recording the history of the atmosphere and oceans. The proposed programme of investigation is concerned with sedimentary rocks deposited during the Cretaceous Period, between about 108 and 83 million years ago in what is now NE British Columbia, Alberta and Saskatchewan. At that time, the Prairie region was occupied by a shallow sea that at times connected the Arctic Ocean with the Gulf of Mexico. To the west, the actively-rising Rocky Mountain chain was shedding sediment eastward into the Seaway, building deltas and coastal plains that supported a lush flora of both conifers, and, after about 104 million years ago, a rapidly diversifying assemblage of flowering plants. Environments ranging from the sandy sea shore to inland river valleys and floodplains were inhabited by many types of dinosaur, with hadrosaurs, ankylosaurs, and various theropods being particularly common. These animals are known mainly from the abundant footprints that they left in the sediments; - bones are rarely preserved. The Canadian Shield formed a low-lying land area in northern Saskatchewan and Manitoba that shed sediment westward into the seaway. We have discovered that at one time, a huge delta built out from the eastern shore to completely block the seaway. The mass of the rising Rocky Mountains depressed the crust for about 1000 km to the east, allowing a westward-thickening wedge of sediment to accumulate. Because deposition occurred in shallow water and on low-lying coastal plains, even small changes in sea-level caused lateral shifts in the shoreline position as the water alternately deepened and shallowed. Changes in the rate at which the basin subsided also caused major changes in the position of the ancient shoreline. Shoreline movements can be deduced by studying the vertical succession and lateral distribution of terrestrial, shoreline and offshore sediments. By mapping the distribution of these rock types using abundant exploration borehole data, as well as through outcrop study, it is possible to reconstruct how the geography of the basin evolved, and to assess the relative influence of sea-level (mostly controlled by changing climate), and subsidence or uplift (controlled by plate tectonics), on basin geography.***The Cretaceous rocks of Western Canada provide not only a detailed record of evolving animals, plants, sea-level change and mountain-building, but also a wealth of natural resources, of vital interest to Provincial economies. Marine mudstones deposited in the centre of the seaway contain algal tissues that, with heat, pressure, and time, generated natural gas and petroleum that accumulated in the porous sandy shoreline sediments. Low-lying coastal plains accumulated thick peat deposits that later compacted to high-quality coal, that is of major economic significance in towns like Grande Cache and Tumbler Ridge. **

沉积岩提供了地球上最重要的生命记录，也记录了大气和海洋的历史。拟议的调查方案涉及白垩纪时期沉积的沉积岩，约在1.08亿至8300万年前，即现在的不列颠哥伦比亚省东北部、艾伯塔省和萨斯喀彻温省。当时，草原地区被一片有时连接北冰洋和墨西哥湾的浅海占据。在西面，活跃上升的落基山脉正在将沉积物向东排入海道，建造三角洲和沿海平原，支撑着郁郁葱葱的两种针叶树群落，以及在大约1.04亿年前之后，迅速多样化的开花植物群落。从沙质海岸到内河峡谷和泛滥平原的环境中生活着许多类型的恐龙，其中鸭嘴龙、甲龙和各种兽脚类动物尤为常见。这些动物主要是从它们在沉积物中留下的大量脚印中获知的；-骨骼很少被保存下来。加拿大盾在萨斯喀彻温省北部和马尼托巴省形成了一个低洼的陆地区域，将沉积物向西流入海道。我们发现，曾经有一个巨大的三角洲从东岸形成，完全封锁了海道。不断上升的落基山脉使地壳向东挤压了约1000公里，使向西增厚的楔形沉积物得以积累。由于沉积发生在浅水和低洼的沿海平原上，即使海平面的微小变化也会导致海岸线位置的横向移动，因为海水交替加深和变浅。盆地下沉速度的变化也导致了古代海岸线位置的重大变化。通过研究陆相、岸线和近海沉积物的垂向序列和横向分布，可以推断岸线运动。通过利用丰富的勘探钻孔数据绘制这些岩石类型的分布图，以及通过露头研究，有可能重建盆地地理是如何演变的，并评估海平面(主要受气候变化控制)和下沉或隆起(受板块构造控制)对盆地地理的相对影响。*加拿大西部的白垩纪岩石不仅提供了进化中的动物、植物、海平面变化和造山的详细记录，而且还提供了丰富的自然资源，对省级经济至关重要。沉积在海道中央的海相泥岩含有藻类组织，随着温度、压力和时间的推移，这些藻类组织产生天然气和石油，并聚集在多孔的砂质海岸线沉积物中。地势低洼的沿海平原积累了厚厚的泥炭矿藏，这些泥炭后来被压实成高质量的煤炭，这在Grande Cach和Tumbler Ridge等城镇具有重要的经济意义。**