Abstract Middle Eocene carbonates and mixed carbonate-siliciclastic deposits occur in disconnected outcrops in the San Jacinto Fold Belt in northern Colombia. Three lithofacies were distinguished: A) claystones and siltstones with planktonic components; B) packstones/rudstones with red algae and claystone-siltstone rip-up clasts in medium to thick plane-parallel, plane-convex, and channel-shaped beds; and C) poorly-bedded rhodolith rudstones with minor larger benthic foraminifers. The latter are interpreted as rhodolith beds accumulated in middle-ramp settings. Lithofacies B consists of bioclasts from the middle ramp redeposited as sediment gravity flows in individual beds and in small channel-lobe systems in the outer ramp and slope. The autochthonous sedimentation basinward from the middle ramp was dominated by hemipelagic claystones and siltstones (Lithofacies A). In outcrops with exposure of vertical successions, these facies are arranged in a transgressive pattern. The limited continuity of outcrops prevents any assessment of the original extension of ramps and lateral dimensions of channel-lobe systems. Comparison with modern tropical rhodolith beds suggests that the middle Eocene carbonate factories in the southern Caribbean developed on ramps under mesotrophic conditions.

中文翻译：

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加勒比海南部（哥伦比亚西北边缘）中始新世混合碳酸盐岩-硅质碎屑岩系统

摘要 中始新世碳酸盐岩和混合碳酸盐硅质碎屑沉积物出现在哥伦比亚北部圣哈辛托褶皱带不连续的露头中。区分了三种岩相： A) 具有浮游成分的粘土岩和粉砂岩；B) 在中等至厚的平行平面、平面凸面和槽形床层中含有红藻和粘土-粉砂岩撕裂碎屑的灰岩/砂岩；和 C) 层状较差的红石岩，带有较小的较大底栖有孔虫。后者被解释为在中间斜坡环境中积累的红石床。岩相 B 由来自中间斜坡的生物碎屑组成，这些生物碎屑随着沉积物重力流在单个床层和外部斜坡和斜坡的小河道-叶系统中重新沉积。中斜坡向盆地的原生沉积以半远洋黏土岩和粉砂岩为主（岩相A）。在垂直序列暴露的露头中，这些相以海侵模式排列。露头的有限连续性妨碍了对坡道的原始延伸和渠道-波瓣系统的横向尺寸的任何评估。与现代热带红石床的比较表明，加勒比海南部始新世中期碳酸盐工厂在中营养条件下的斜坡上发展起来。