Integrated High-Resolution Cretaceous Stratigraphy & Basin Analysis

加拿大西部平原下约一亿年前的白垩纪岩石具有全球意义，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。 丰富的石油和天然气钻孔记录使我们能够非常详细地绘制岩层地图，重建古代海岸线，河流，三角洲和洪泛平原。 从我们的地图中得出的最有趣的结果之一是，海平面在大约20，000到400，000年的时间尺度上上下摆动了5-20米，这种变化最合乎逻辑地归因于南极大陆上适度冰盖的增长和融化。然而，这与白垩纪气候的流行概念相反，白垩纪气候是一个“温室”，无冰的世界，大气中二氧化碳含量非常高。我们在加拿大西部的研究结果使我们与加拿大、英国、美国、捷克共和国和波兰的科学家合作，研究古气候、高精度放射性测年、生物地层学和层序地层学相关性，试图证明在加拿大观察到的海平面变化具有全球范围的影响，这一证据将大大加强南极冰盖的消长，并引起人们对“白垩纪温室”性质的认真反思。 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测绘使我们能够更好地了解加拿大西部盆地如何在不断增长的落基山脉的重压下下沉。 我们的研究结果表明，变形和隆升的落基山脉的前进发生在离散的片段，通常200-300公里长。 邻近的盆地被推下，形成半圆形的护城河状凹陷，迅速被泥沙填满。 当山脉的一部分应力被释放时，数百公里外的另一部分就会开始变形。 因此，地壳沉降为一系列重叠的菱形子盆地，而不是一个简单的盆地。 似乎很少有研究认识到这种复杂性。

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.