Carbonate platform development responding to tectonic, oceanographic, and biotic transitions

为了理解“全球变化”在当今世界的潜在影响，有必要了解环境变化本身的性质和速度;了解环境是否可以抵抗变化;以及了解变化是否是可逆的（即，环境恢复）。现代地球系统只提供了环境的“时间快照”。缺少的是历史框架。地质记录（在露头、采石场和岩芯中）就是这样一个档案，当与现代系统的数据结合时，为公众了解地球系统的潜在动力学提供了唯一可靠的基础。两种对当地和全球外部环境压力非常敏感的地质背景是热带和温带碳酸盐大陆架。碳酸盐沉积物的产生（无论是无机的还是生物的）对海水中微妙的物理和地球化学变化很敏感。沿着这些现代大陆架的海底沉积物通常被视为地球健康的“晴雨表”。拟议的研究将检查三个不同年龄的古代碳酸盐大陆架;在百万年，~570（乌拉圭），~440（安大略）和~25（新西兰）。每一个记录不同的，在两种情况下不断变化，构造，古气候，海洋学和生物进化的框架在大陆架发展。通过研究沉积历史和古生物学记录所记录的环境变化，这项研究将有助于更好地了解这些类型的大陆架如何应对竞争性环境压力、变化率以及哪些压力在抑制或增强环境变化方面占主导地位。这项工作将有助于了解现代沉积体系。此外，其中两个平台（乌拉圭、安大略）将提供关于地球系统如何应对与海洋学和生物转型有关的突出环境危机的信息。安大略地台还将提供关于长期（6亿年）构造运动历史的信息，该构造运动沿着加拿大地盾内的一个断层系统。

To understand the potential impact of "global change" in today's world, it is necessary to appreciate the character and rate of environmental change itself; to understand if an environment can resist change; and, to understand if change is reversible (i.e., the environment recovers). Modern earth systems provide only a "temporal snapshot" of the environment. Missing is the historical framework. The geologic record (in outcrops, quarries, and drill cores) is such an archive, and, when incorporated with data from modern systems, provides the only sound basis for public understanding of the potential dynamics of the Earth system. Two geologic settings very sensitive to local and global external environmental pressures are tropical- and temperate-latitude carbonate shelves. Production of carbonate sediment (whether by inorganic or biological means) is sensitive to subtle physical and geochemical changes in the ocean water. Seafloor sediments along these modern shelves are often viewed to be the "barometers" of the Earth's health. The proposed research will examine three ancient carbonate shelves of different ages; in million years, ~570 (Uruguay), ~440 (Ontario) and ~25 (New Zealand). Each records different, and in two cases changing, frameworks of tectonism, paleoclimate, oceanography, and biotic evolution during shelf development. By examining environmental change as documented by the history of sedimentation and the paleontological record, the research will help better understand how these types of shelves can respond to competing environmental pressures, the rates of change, and what sets of pressures are dominant in suppressing or augmenting environmental change. The work will be transferable to help understand modern day depositional systems. In addition, two of the platforms (Uruguay, Ontario), will provide information about how the earth system responded to prominent environmental crisis associated with oceanographic and biotic transitions. The Ontario platform will also provide information about the history of long-lived (600 million year) tectonism along a fault system within the otherwise stable Canadian Shield.