The Great Barrier Reef (GBR) is the world's largest extant mixed silicilastic–carbonate margin. Previous research on the Great Barrier Reef has suggested that the extensive barrier reef system may act as an impermeable barrier and limit the development of delta systems during lowstands, but sufficient geophysical data to support this hypothesis are lacking. We use dense sparker seismic and sub-bottom profiler data to better understand the structure of a large lobe-shaped feature (∼ 10 km × 10 km) on the shelf edge of the central GBR and the interactions between siliciclastic and carbonate sedimentary systems. Interpreted sparker seismic contains prograding clinoforms and suggest that the lobe-shaped feature was a river-dominated shelf-edge delta. A delta on the shelf edge implies that the presence of an exposed barrier reef was not a major impediment to deposition and that other adjacent lobe-shaped features are also deltaic deposits. The shelf-edge deltas were deposited onto a broad upper-slope terrace that allowed continued progradation and limited incision when sea level fell below the shelf edge. Delta foresets are commonly colonized by coral reefs, but the spatial and temporal relationship between reefs and some deltaic units remains unclear. The presence of multiple shelf-edge deltas that link to previously mapped Burdekin River paleo-channels indicates a complex history of sedimentation, with the Burdekin River delta migrating up to 100 km along the GBR margin during the late Quaternary. Regional bathymetric data suggest that large modern or recent shelf-edge deltas are rare on the GBR and that there was a broad range of sedimentary processes operating along the margin of the GBR during periods of low sea level.

中文翻译：

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大堡礁中部硅质碳酸盐混合边缘的缘缘三角洲和礁石发育

大堡礁（GBR）是世界上现存最大的硅质碳酸盐混合岩屑边缘。先前对大堡礁的研究表明，广泛的堡礁系统可能充当不可渗透的屏障，并在低潮期限制了三角洲系统的发展，但缺乏足够的地球物理数据来支持这一假设。我们使用密集的电火花地震和亚底剖面资料，以更好地了解中央GBR架缘上的大叶状特征（约10 km×10 km）的结构以及硅质碎屑岩和碳酸盐岩沉积系统之间的相互作用。解释性的火花地震包含渐进的倾斜形态，并表明该叶状特征是河流主导的陆缘三角洲。架子边缘的三角洲意味着裸露的礁石的存在不是沉积的主要障碍，其他相邻的叶状特征也是三角洲的沉积物。架子边缘的三角洲沉积在宽阔的上坡阶地上，当海平面下降到架子边缘以下时，可以继续繁殖并限制切口。三角洲前缘通常被珊瑚礁定殖，但珊瑚礁与某些三角洲单位之间的时空关系仍不清楚。与先前测绘的伯德金河古河道相连的多个陆架边缘三角洲的存在表明了沉积的复杂历史，在第四纪晚期，伯德金河三角洲沿GBR边缘迁移了100 km。