Depositional Cyclicity and Evolution of Convergent-Margin Basins

会聚边缘盆地（CMB）的典型特征是快速的隆升和沉降，陡峭而短的河流集水区，以及高沉积速率。因此，沉积物的积累率显着大于在克拉通前陆盆地和被动边缘的CMB，这是表现在独特的地层结构和保存的周期性沉积模式。拟议的研究旨在描述CMB中的浅海地层，以了解这些系统如何随时间演变，包括解决气候和地震周期性。研究将侧重于两个CMB，并涉及为盆地制定一个他地层框架，并确定整个盆地的周期性沉积模式。 大多数建议的研究集中在加拿大温哥华岛格鲁吉亚盆地的下纳奈莫群。格鲁吉亚盆地是一个弧前盆地（CMB）和下部纳奈莫群局部厚度超过1公里。将以高分辨率记录沿着河流暴露的连续露头，并进行相分析，以确定地层重要表面。然后，将使用表面沿沿着和横跨沉积走向细分地层，并采集碎屑锆石数据，以测试和完善他地层对比。解决下纳奈莫组的沉积旋回性将利用相分析，识别震积岩（地震旋回性）和沉积的横向和垂直变化（气候旋回性）。被认为是构造作用和气候的指示性循环将与地球化学代用指标（包括d13 C和C：N比值）相证实。 台湾西部前陆盆地是一个快速上升的CMB，在台湾西部密集的露头中出露较厚的年轻地层序列（< 6 Ma）。露头的年龄已在生物地层学上得到很好的确定，因此有可能在时间相当的沉积物中评估沿走向和下倾相的关系，并研究地震和气候周期的产物。研究重点是上新世晚期的阔丘林组和更新世早期的卓兰组。将详细记录露头，并使用地球化学数据（d13 C、d18 O和C：N比率）来解析和细化气候和地震周期。基于无人机的3D摄影测量将用于重建露头并量化床层厚度和地层结构。 这项工作的影响是多方面的。在格鲁吉亚盆地，我们将为纳奈莫组下部建立全盆地的异地层框架，评估循环沉积并解决沉积中心和沉降/构造作用的变化。结合台湾的研究，这项工作的结果将产生全球性的影响，因为我们将开发识别和解决浅海地层中气候和地震周期的工具和模型，以及将其与相对海平面变化引起的周期区分开来的标准。

Convergent-margin basins (CMBs) are typified by rapid uplift and associated subsidence, steep and short river catchments, and elevated sedimentation rates. As a consequence, sediment accumulation rates are significantly greater in CMBs than in intracratonic foreland basins and passive margins, and this is manifested in distinctive stratal architectures and preservation of cyclical sedimentation patterns. The proposed research aims to characterize shallow-marine strata in CMBs to understand how these systems evolve through time, including resolving both climate and earthquake cyclicity. Research will focus on two CMBs and involves developing an allostratigraphic framework for the basins and identifying cyclical sedimentation patterns across the basins. Most of the proposed research focuses on the lower Nanaimo Group in the Georgia Basin, Vancouver Island, Canada. The Georgia Basin is a forearc basin (CMB) and the lower Nanaimo Group locally exceeds 1 km in thickness. Continuous outcrops exposed along rivers will be logged at high resolution and facies analysis will be employed to identify stratigraphically important surfaces. Surfaces will then be used to subdivide strata along and across depositional strike, and detrital zircon data will be acquired to test and refine allostratigraphic correlations. Resolving depositional cyclicity in the lower Nanaimo Group will utilize facies analysis, and recognition of both seismites (earthquake cyclicity) and lateral and vertical changes in sedimentation (climate cyclicity). Cycles considered indicative of tectonism and climate will be corroborated with geochemical proxies, including d13C and C:N ratios. The Western Foreland Basin, Taiwan is a rapidly uplifting CMB and thick sequences of young strata (< 6 Ma) are exposed in closely spaced outcrops in western Taiwan. The ages of outcrops are well established biostratigraphically, and hence it is possible to assess alongstrike and down-dip facies relations in time-equivalent deposits and to study the products of earthquakes and climate cycles. Research will focus on the late Pliocene Kuechulin Formation and early Pleistocene Cholan Formation. Outcrops will be logged in detail and geochemical data (d13C, d18O and C:N ratios) will be used to resolve and refine climate and earthquake cycles. Drone-based 3D photogrammetry will be used to reconstruct outcrops and quantify both bed thicknesses and stratal architectures. The impacts of this work are multiple. In the Georgia Basin, we will produce a basin-wide allostratigraphic framework for the lower Nanaimo Group, assess cyclic deposition and resolve changes in depocenters and subsidence/tectonism. When combined with research in Taiwan, the results of this work will have a global impact in that we will develop tools and models for recognizing and resolving climate and earthquake cycles in shallow-marine strata, and criteria for distinguishing them from cycles induced by changes in relative sea level.