Integrated High-Resolution Cretaceous Stratigraphy & Basin Analysis

综合高分辨率白垩纪地层学

• 批准号: 122393-2013
• 负责人: Plint, Guy
• 金额: $ 1.97万
• 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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633788
• 关键词: Integrated; Resolution; Cretaceous; Stratigraphy; Basin

Approximately one hundred million year old Cretaceous rocks beneath the Plains of western Canada are globally-significant because they provide one of the most complete records of Cretaceous climate and sea-level change. Abundant records from oil and gas boreholes allow us to map rock layers in great detail, reconstructing ancient shorelines, rivers, deltas and flood- plains. One of the most interesting results coming from our mapping is that sea-level oscillated up and down by perhaps 5-20 m on time-scales of about 20,000 to 400,000 yrs. Such changes are most logically attributed to the growth and melting of modest ice-caps on the Antarctic continent. This however is contrary to the popular conception of the Cretaceous climate as being a 'greenhouse', ice-free world with very high atmospheric CO2 levels. Our results from western Canada have led us to collaborate with scientists in Canada, the UK, US, Czech Republic and Poland to study paleoclimate, high-precision radiometric dating, biostratigraphic and sequence-stratigraphic correlation in an attempt to demonstrate that sea-level changes observed in Canada are of global extent, - proof of which would greatly strengthen the argument for waxing and waning Antarctic ice caps, and cause serious re-thinking of the nature of the 'Cretaceous greenhouse'. In addition to interpretation of sea-level changes, our subsurface and outcrop mapping of Cretaceous strata have allowed us to better understand how the Western Canada Basin subsided under the weight of the growing Rocky Mountains. Our results show that the advance of the deforming and uplifting Rocky Mountains took place in discrete segments, typically 200-300 km long. The adjacent basin was pushed down, forming a semi-circular moat-shaped depression, which rapidly filled with sediment. As stress was relieved in one sector of the mountains, another part, located several hundred km away, would start to deform. As a result, the crust subsided as a series of overlapping, lozenge-shaped sub-basins, rather than one simple basin. Few studies appear to have recognized this complexity.

加拿大西部平原下约有一亿年历史的白垩纪岩石在全球范围内具有重要意义，因为它们提供了白垩纪气候和海平面变化的最完整记录之一。石油和天然气钻孔的大量记录使我们能够详细地绘制岩石层，重建古老的海岸线，河流，三角洲和洪水。来自我们的映射的最有趣的结果之一是，在约20,000至400,000年的时间尺度上，海平面上下振荡了5-20 m。从逻辑上讲，这种变化归因于南极大陆上适中的冰盖的生长和融化。然而，这与白垩纪气候的流行概念是一个“温室”，无冰的世界，具有很高的大气二氧化碳水平。我们来自加拿大西部的结果导致我们与加拿大，英国，美国，捷克共和国和波兰的科学家合作，研究古气候，高精确的辐射测定，生物地层学和序列 - 地层相关性，以试图证明加拿大的海平面变化是全球性的，以证明是全球范围的，并且可以强大的距离，并宣布了越来越强大的参数，并强化了纽约的参数，并遵守了纽约的范围，并宣布了港口的范围，并宣布了镇定的范围和镇定的W.重新思考“白垩纪温室”的性质。除了对海平面变化的解释外，我们对白垩纪地层的地下和露头映射还使我们能够更好地了解加拿大西部盆地如何在不断发展的落基山脉的重量下消退。我们的结果表明，变形和令人振奋的落基山的进步发生在离散的细分市场中，通常为200-300公里。将相邻的盆地推下，形成半圆形护城河形凹陷，迅速充满了沉积物。由于山区的一个区域缓解了压力，位于几百公里之外的另一部分将开始变形。结果，外壳作为一系列重叠的片片片的子碱而不是一个简单的盆地消退。很少有研究似乎认识到这种复杂性。