Morphological features on low-latitude continental shelves have recorded past sea level fluctuations. This study aims to recognize and interrogate, on the Rio Grande do Norte (RN, NE Brazil) outer shelves, specific seabed morphologies that could have been produced by the punctuated relative sea level rise of the last deglaciation. These sea floor morphologies, imaged by single-beam bathymetric data from two areas of the North and East outer Shelves, ~ 160 km apart, reveal terraces, submerged paleo-shorelines, reefs, and incised valleys, which act as regional archives of past sea levels. The North and East outer shelves, covered by carbonate sediments, display steep gradients (~ 0.5°), variable widths (up to 13 km), and are bound between a well-defined shelf break at 75 m water depth and a beachrock ridge at 25 m. A steep step on the sea floor occurs between depths of 60 and 70 m in both areas. Though interrupted by the Açu Incised Valley, two distinct continuous terraces, 3 and 4 km in width, at depths of 49 m (± 5 m) (T1n) and 33 m (±3 m) (T2n), respectively, extend for 60 km along the North Shelf. Three nearly continuous terraces occur along the East Shelf on either the north or south sides of the Natal Canyon. A first, 6 km wide, lower terrace occurs at a depth of 54 m (± 4 m) (T1e). A second terrace, 2 km wide, at 40 m (± 2 m) (T2e), and a third 2 km wide upper terrace at 30 m (±2 m) (T3e) are also found. Patch reefs scattered over the terraces rise in average to 3 m in height. Based upon their depth occurrences, the established limited neotectonics in the study areas, and correlations with well-established archives from other morphological features of similar outer shelves, we hypothesize that these reefs and terraces were likely formed during the last deglacial interval spanning from the end of the MWP-1A (70–60 m), through the MWP-1B (50–40 m), and to subsequent punctuated millennial sea level rise events (30–25 m) occurring prior to the 8.2 kyr cooling event.

中文翻译：

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巴西东北外陆架沿线的梯田、礁石和山谷：冰消期海平面档案？

低纬度大陆架的形态特征记录了过去的海平面波动。本研究旨在识别和询问北里奥格兰德（RN，巴西东北部）外陆架上的特定海床形态，这些形态可能由上次冰消期的间断性相对海平面上升产生。这些海底形态由来自北外陆架和东外陆架两个区域的单波束测深数据成像，相距约 160 公里，揭示了阶地、淹没的古海岸线、珊瑚礁和下切山谷，这些都是过去海洋的区域档案水平。被碳酸盐沉积物覆盖的北部和东部外陆架显示出陡峭的梯度（~ 0.5°）、可变的宽度（高达 13 公里），并在 75 m 水深的明确定义的陆架断裂和位于25 米。在这两个区域的 60 和 70 m 深度之间，海底有一个陡峭的台阶。虽然被 Açu Incised Valley 中断，但两个不同的连续阶地，宽度分别为 3 和 4 公里，深度分别为 49 m (± 5 m) (T1n) 和 33 m (±3 m) (T2n)，延伸 60公里沿北大陆架。三个几乎连续的阶地出现在纳塔尔峡谷北侧或南侧的东陆架上。第一个 6 公里宽的较低阶地出现在 54 m (± 4 m) (T1e) 的深度。还发现了位于 40 m (± 2 m) (T2e) 处的第二个 2 km 宽的阶地和位于 30 m (±2 m) (T3e) 处的第三个 2 km 宽的上阶阶地。散布在梯田上的斑礁平均高度上升到 3 m。根据它们的产状深度，研究区内已建立的有限新构造，