The Genesis of Cyclic Limestones and Unconformities in the Northern Bahamas: Recent Processes and Ancient Analogs

巴哈马群岛的浅层石灰岩呈脉冲状堆积。间冰期海洋的每一次上升都会淹没河岸，并在前者的遗迹上叠加另一个沉积循环。为了了解过去几次海平面上升的地质记录，更重要的是，为了促进对世界范围内旋回石灰岩的了解，该项目重点研究了巴哈马最新的沉积旋回和盘状内部和斜坡边缘泻湖研究地点分隔它们的侵蚀面。本阶段的研究将集中于(1)作为沉积环境函数的有机组分的碳同位素信号，(2)被海平面侵蚀修改后印在岸顶不连续表面上的古生态信息光谱，(3)现代沉积旋回和下伏岩石旋回的地质/地球化学性质；(4)从旋回沉积/侵蚀耦合中得出的可适用于古代类似物的地质/地球化学标准。巴哈马群岛浅层石灰岩以脉冲形式堆积。间冰期海洋的每一次上升都会淹没河岸，并在前者的遗迹上叠加另一个沉积循环。为了了解过去几次海平面上升的地质记录，更重要的是，为了促进对世界范围内旋回石灰岩的了解，该项目重点研究了巴哈马最新的沉积旋回和盘状内部和斜坡边缘泻湖研究地点分隔它们的侵蚀面。

The shallow limestones of the Bahamas accumulate in pulses. Each rise of the interglacial sea floods the banktops and superimposes another sediment cycle upon the remains of the former. To understand the geologic record of the last few sealevel rises, and more importantly, to contribute to the understanding of cyclic limestones worldwide, this project is focussed on the latest Bahamian depositional cycles and the erosional surfaces that separate them in both dished interior and ramped margin lagoonal study sites. The present phase of the study will concentrate on (1) the carbon isotopic signal of the organic fraction as a function of the depositional environment, (2) the spectrum of paleoecological information imprinted upon banktop discontinuity surfaces as they are modified by sealevel encroachment, (3) the geological/ geochemical nature of the present sediment cycle and the subjacent rock cycles, and (4) the geological/geochemical criteria derived from the cyclic deposition/erosion couplet that can be applied to ancient analogs. %%% The shallow limestones of the Bahamas accumulate in pulses. Each rise of the interglacial sea floods the banktops and superimposes another sediment cycle upon the remains of the former. To understand the geologic record of the last few sealevel rises, and more importantly, to contribute to the understanding of cyclic limestones worldwide, this project is focussed on the latest Bahamian depositional cycles and the erosional surfaces that separate them in both dished interior and ramped margin lagoonal study sites.