To help define the habitat of modern marine stromatolites, wave-dominated flow and sediment transport were studied in the shallow subtidal region (1-2 m depth) along the slightly concave, windward face of Highborne Cay, Exuma, Bahamas - the only face of the cay that includes a population of stromatolites concentrated near the region of highest curvature of the beach. Wave energy impacting this island's most exposed beach was driven by local wind forcing which increases largely in response to the passage of atmospheric disturbances that typically affect the region for periods of a few days. Although some wave energy is almost always noted (maximum horizontal orbital speeds at the bottom are rarely <10 cm s(-1)), wave conditions remain comparatively calm until local winds increase above speeds of approximately 3-4 m s(-1) at which point maximum wave speeds rapidly increase to 50-80 cm s(-1). Stromatolites, which are largely restricted to the shoreward side of a shallow platform reef, are sheltered by the reef beyond which wave speeds are one to four times higher (depending on tidal stage). Moreover, stromatolite populations are predominantly found along a region of this wave-exposed beach that experiences comparatively reduced wave energy because of the curved morphology of the island's face. Maximum wave speeds are 1.4 to 2 times higher along more northern sections of the beach just beyond the locus of stromatolite populations. A quantitative model of sediment transport was developed that accurately predicted accumulation of suspended sediment in sediment traps deployed in the shallow subtidal zone along this beach. This model, coupled with in situ wave records, indicates that gross rates of suspended sediment deposition should be two to three times higher northward of the main stromatolite populations. Regions of the beach containing stromatolites nevertheless should experience significant rates of gross suspended sediment deposition averaging 7-10 g cm(-2) day(-1) ( approximately 4-6 cm day(-1)). Results suggest that one axis of the habitat of modern marine stromatolites may be defined by a comparatively narrow range of flow energy and sediment transport conditions.

中文翻译：

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沿现代叠层石居住的浅潮下沙滩的波浪和沉积物动力学。

为了帮助定义现代海洋叠层岩的生境，在浅潮下带（1-2 m深度）沿巴哈马群岛埃克苏马高地礁的轻微下凹迎风面（主要是巴哈马群岛的唯一面）研究了波浪主导的水流和泥沙输送。包括一群叠层石的岩层，聚集在海滩曲率最高的区域附近。影响岛上最裸露的海滩的波浪能是由当地的强迫风驱动的，这种强迫随着对大气干扰的传递而增加，这种干扰通常会影响该地区几天。尽管几乎总是注意到一些波能（底部的最大水平轨道速度很少<10 cm s（-1）），直到局部风的速度增加到大约3-4 ms（-1）以上，最大风速迅速增加到50-80 cm s（-1）时，海浪条件才保持相对平静。层间岩主要被限制在浅平台礁石的岸边，被礁石掩盖，超过该礁石时，波速要高出一到四倍（取决于潮汐阶段）。此外，层层岩种群主要分布在该波浪暴露海滩的某个区域，该区域由于岛面的弯曲形态而经历了相对减少的波浪能量。沿着海滩的更多北部区域，在叠层岩种群所在地之外，最大波速高出1.4至2倍。建立了泥沙运移的定量模型，可以准确预测沿该海滩位于浅潮下带的泥沙陷阱中悬浮泥沙的积累。该模型与原位波记录相结合，表明悬浮沉积物的总沉积速率应比主要叠层岩种群向北高2至3倍。尽管如此，包含叠层石的海滩区域应该经历显着的总悬浮沉积物沉积速率，平均为7-10 g cm（-2）天（-1）（约4-6 cm天（-1））。结果表明，现代海洋叠层岩生境的一个轴可能是由相对较窄的流动能和沉积物输送条件所限定。再加上原位波浪记录，表明悬浮沉积物的总沉积速率应比主要叠层岩种群向北高2至3倍。尽管如此，包含叠层石的海滩区域应该经历显着的总悬浮沉积物沉积速率，平均为7-10 g cm（-2）天（-1）（约4-6 cm天（-1））。结果表明，现代海洋叠层岩生境的一个轴可能是由相对较窄的流动能和沉积物输送条件所限定。再加上原位波浪记录，表明悬浮沉积物的总沉积速率应比主要叠层岩种群向北高2至3倍。尽管如此，包含叠层石的海滩区域应经历显着的总悬浮沉积物沉积速率，平均为7-10 g cm（-2）天（-1）（约4-6 cm天（-1））。结果表明，现代海洋叠层岩生境的一个轴可能是由相对较窄的流动能和沉积物输送条件所限定。尽管如此，包含叠层石的海滩区域应该经历显着的总悬浮沉积物沉积速率，平均为7-10 g cm（-2）天（-1）（约4-6 cm天（-1））。结果表明，现代海洋叠层岩生境的一个轴可能是由相对较窄的流动能和沉积物输送条件所限定。尽管如此，包含叠层石的海滩区域应该经历显着的总悬浮沉积物沉积速率，平均为7-10 g cm（-2）天（-1）（约4-6 cm天（-1））。结果表明，现代海洋叠层岩生境的一个轴可能是由相对较窄的流动能和沉积物输送条件所限定。