Tectonic signatures in carbonate platform sequences and diagenesis proximal and distal to convergent margins

目前关于碳酸盐岩台地系统的知识主要来自构造相对稳定的地质环境，如沿着大陆后缘、远离会聚边缘的前陆盆地内部以及板块内部的海洋台地。拟议的研究将调查的沉积稳定性，地层几何形状和成岩作用的碳酸盐岩平台，以响应当地和区域构造。两个地质区域允许研究距离会聚（俯冲）板块边界不同距离的构造特征。(1)在加拿大中部（东南部安大略），一个晚奥陶世（4.5亿年）碳酸盐台地覆盖在一个区域性（200 km长）断层系统之上，该断层系统位于下方浅埋（< 1 km）的结晶基底内。局部断层复活和沉积响应与远源（~1000 km）俯冲同步已得到证实，但进一步的研究将确定台地的区域结构、受构造影响的海平面变化的作用以及碳酸盐生成及其蚀变的相应响应。这段历史将与纽芬兰西部板块边界变形前沿近端的当代平台和超越古代断层系统轴线但远离板块边界的当代平台进行比较。这样的比较可以提取构造控制海平面和平台的发展。(2)在智利中部，侏罗纪至早白垩世（1.4亿至9000万年）的碳酸盐台地发育在一个狭窄的狭长（约1000 km）盆地中，该盆地平行于并邻近于碰撞板块边界进行伸展（加宽）。这是一个难得的机会来研究平台架构和成岩作用，以及构造作用对紧邻俯冲带的平台的影响。 研究成果将引起全球地质界的兴趣。这项研究将扩大目前对碳酸盐沉积体系构造敏感性的有限认识，并对比碰撞板块边界近端和远端位置的台地结构。这项研究将有助于描述从会聚边界进入板块内部的沉积不稳定性的潜在构造梯度，并解决继承结构的重新激活对年轻沉积体系中地层模式的影响。将通过地质会议和同行评审期刊（国家、国际）传播成果。社区一级将对安大略省的项目感兴趣，因为古老的断层系统位于许多农村和城市社区的下面，并毗邻活跃的西部魁北克地震带。这种接近强调了潜在的断层复活作为一个现代，而不仅仅是古代，地质后果。

The current state of knowledge about carbonate platform systems is dominated by modern and ancient examples from relatively tectonically stable geologic settings such as found along continental trailing margins; in the interior of foreland basins distant from convergent margins; and, on oceanic platforms within plate interiors. The proposed study will investigate the depositional stability, stratigraphic geometry, and diagenesis of carbonate platforms in response to local and regional tectonism. Two geologic regions allow study of tectonic signatures at different distances from convergent (subducting) plate boundaries. (1) In central Canada (SE Ontario), a Late Ordovician (450 million years) carbonate platform overlies a regional (200 km long) fault system within the underlying and shallowly buried (< 1 km) crystalline basement. Local fault reactivation and depositional response synchronous with distal (~1000 km) subduction has been demonstrated, but further study will define the regional architecture of the platform, the role of tectonically influenced sea-level change, and the corresponding response of carbonate production and its alteration. This history will be compared with a contemporary platform proximal to the plate-boundary deformation front in western Newfoundland and contemporary platforms beyond the axis of the ancient fault system but distal to the plate boundary. Such comparisons allow extraction of tectonic controls on sea level and platform development. (2) In central Chile, carbonate platforms of Jurassic to Early Cretaceous age (140 to 90 million years) developed in a narrow elongate (~1000 km) basin undergoing extension (widening) parallel to and adjacent to the collisional plate boundary. This is a rare opportunity to study platform architecture and diagenesis and the impact of tectonism on platforms immediately adjacent to a subduction zone. Research outcomes will be of interest to the global geological community. The research will expand on the current limited knowledge about tectonic sensitivity of carbonate depositional systems, and contrasting platform architecture in proximal to distal positions from collisional plate boundaries. The study will help characterize a potential tectonic gradient of depositional instability directed into the plate interior from convergent boundaries, and address the impact of reactivation of inherited structure on stratigraphic patterns in younger sedimentary systems. Dispersal of results will be through geological conferences and peer-reviewed journals (national, international). There will be community-level interest in the Ontario-based project because the ancient fault system underlies many rural and urban communities, and lies adjacent to the active Western Quebec Seismic Zone. Such proximity underscores potential fault reactivation as a modern, not just ancient, geological consequence.