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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=751174
• 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.

沉积岩为地球上的生命提供了最重要的记录，也记录了大气和海洋的历史。拟议的调查项目涉及白垩纪时期沉积的沉积岩，大约在1.03亿到8300万年前，位于现在的不列颠哥伦比亚省东北部、阿尔伯塔省和萨斯喀彻温省。当时，草原地区被一片浅海所占据，这片浅海有时连接着北冰洋和墨西哥湾。在西部，不断上升的落基山脉将沉积物向东流入海道，形成了三角洲和沿海平原，这些平原既支持了郁郁葱葱的针叶树植物群，也在大约1.04亿年前之后，迅速形成了多样化的开花植物群。从沙质海岸到内陆河谷和洪泛平原的环境中，生活着许多种类的恐龙，其中鸭嘴龙、甲龙和各种兽脚亚目恐龙尤为常见。人们对这些动物的认识主要来自它们在沉积物中留下的大量脚印；骨头很少被保存下来。加拿大地盾在萨斯喀彻温省和曼尼托巴省北部形成了一个低洼的陆地区域，沉积物向西流入海道。我们发现，曾经有一段时间，一个巨大的三角洲从东岸延伸出来，完全挡住了海道。不断上升的落基山脉使地壳向东凹陷了约1000公里，从而形成了向西变厚的楔形沉积物。由于沉积发生在浅水和低洼的沿海平原，即使海平面的微小变化也会随着水的交替加深和变浅而引起海岸线位置的横向移动。盆地沉降速率的变化也导致了古海岸线位置的重大变化。岸线运动可以通过研究陆地、岸线和近海沉积物的垂直演替和横向分布来推断。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，可以重建盆地的地理演变，并评估海平面（主要由气候变化控制）和沉降或隆起（由板块构造控制）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动物、植物进化、海平面变化和山脉形成的详细记录，而且还提供了丰富的自然资源，对该省的经济至关重要。沉积在海道中心的海洋泥岩含有藻类组织，这些藻类组织在加热、压力和时间的作用下产生了天然气和石油，这些天然气和石油聚集在多孔的沙质海岸线沉积物中。低洼的沿海平原积累了厚厚的泥炭，后来被压实成高质量的煤炭，这对格兰德卡什（Grande Cache）和汤伯勒岭（Tumbler Ridge）等城镇具有重要的经济意义。