Distal slope and basin depositional systems in deep waters of the Pará-Maranhão Basin, Equatorial Brazil, are investigated using a high-resolution 3D seismic volume, borehole data and multispectral satellite imagery. A Neogene calciclastic submarine fan and a series of channel-levee systems are analysed at water depths of 100–3,500 m. Channel-levee systems have sinuous and straight morphologies and are of different sizes. Their origin is related to turbidity flows sourced and funnelled from the carbonate shelf to submarine canyons and gullies, as well as from areas with marked slope instability. A mixed calciclastic-siliciclastic sediment input is recognised with autochthonous calcarenites and calcilutites comprising the bulk of sediment on the mid and outer continental shelf. Minor amounts of siliciclastic sediment sourced from small rivers occur on the inner shelf. Sedimentation processes of a distally steepened carbonate ramp are discussed considering a general depositional setting dominated by fluctuations in relative sea-level. Cross-sectional and planar parameters of mixed calciclastic-siliciclastic channel-levee systems are compared to their siliciclastic counterparts. Morphological results show similarities between calciclastic and siliciclastic channel-levee systems. As a corollary, three types of channel-levee systems are described: (a) channels related to calciclastic submarine fans, (b) low-sinuosity, aggradational channels, and (c) high-sinuosity channels.

中文翻译：

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深水赤道边缘混合碎屑-硅质碎屑系统的沉积和地貌模式

使用高分辨率 3D 地震体积、钻孔数据和多光谱卫星图像研究了巴西赤道帕拉-马拉尼昂盆地深水中的远端斜坡和盆地沉积系统。在 100-3,500 m 的水深对新近纪碎屑海底扇和一系列河道堤系统进行了分析。渠道堤防系统具有蜿蜒和直线形态，并具有不同的大小。它们的起源与从碳酸盐架到海底峡谷和沟壑以及斜坡不稳定区域的浊流源和漏斗有关。混杂的钙质-硅质碎屑沉积物输入被识别为原生钙质岩和方解石质，其中包括中外大陆架上的大部分沉积物。内陆架上有少量来自小河流的硅质碎屑沉积物。考虑到由相对海平面波动主导的一般沉积环境，讨论了远端陡峭碳酸盐斜坡的沉积过程。将混合钙质-硅质碎屑通道-堤防系统的横截面和平面参数与其对应的硅质碎屑进行比较。形态学结果表明碎屑和硅质碎屑河堤系统之间存在相似性。作为推论，描述了三种类型的河道堤坝系统：(a) 与碎屑海底扇相关的河道，(b) 低弯曲度、积聚性河道和 (c) 高弯曲度河道。考虑到由相对海平面波动主导的一般沉积环境，讨论了远端陡峭碳酸盐斜坡的沉积过程。将混合钙质-硅质碎屑通道-堤防系统的横截面和平面参数与其对应的硅质碎屑进行比较。形态学结果表明碎屑和硅质碎屑河堤系统之间存在相似性。作为推论，描述了三种类型的河道堤坝系统：(a) 与碎屑海底扇相关的河道，(b) 低弯曲度、积聚性河道和 (c) 高弯曲度河道。考虑到由相对海平面波动主导的一般沉积环境，讨论了远端陡峭碳酸盐斜坡的沉积过程。将混合钙质-硅质碎屑通道-堤防系统的横截面和平面参数与其硅质碎屑对应物进行比较。形态学结果表明碎屑岩和硅质碎屑河堤系统之间存在相似性。作为推论，描述了三种类型的河道堤坝系统：(a) 与碎屑海底扇相关的河道，(b) 低弯曲度、积聚性河道和 (c) 高弯曲度河道。形态学结果表明碎屑和硅质碎屑河堤系统之间存在相似性。作为推论，描述了三种类型的河道堤坝系统：(a) 与碎屑海底扇相关的河道，(b) 低弯曲度、积聚性河道和 (c) 高弯曲度河道。形态学结果表明碎屑和硅质碎屑河堤系统之间存在相似性。作为推论，描述了三种类型的河道堤坝系统：(a) 与碎屑海底扇相关的河道，(b) 低弯曲度、积聚性河道和 (c) 高弯曲度河道。