Since their first occurrence in the late Cretaceous, seagrasses have played a major role in carbonate production and sedimentation across shallow-water and nearshore environments, sustaining a prolific carbonate factory and contributing to sediment accumulation through the combination of baffling and trapping effects. Most reported Palaeogene seagrass occurrences developed in oligo−mesotrophic shallow warm-water habitats and are characterized by distinct associations of small and larger benthic foraminifers adapted to low terrigenous influence. This study describes a number of seagrass episodes interbedded in the Bartonian (middle Eocene) of San Fausto–Lazkua area (Navarra region, North Spain), within a nearshore to inner-ramp succession that, in spite of being deposited under general transgressive conditions, was highly influenced by terrigenous supply from the adjacent land. Up to twelve different seagrass bed intervals occur interbedded in a cyclical manner with high-energy nearshore siliciclastics and inner ramp bioclastic carbonates rich in mesophotic−oligophotic foraminifers and heterozoan biota (red algae, echinoderms, bryozoans). Seagrass deposits exhibit typical unsorted textures, abundant bioturbation and moderate to high terrigenous content, and comprise a characteristic skeletal association of epiphytic foraminifers, red algae and, most particularly, of abundant encrusting acervulinids, commonly with distinct hooked and tubular growth forms. This abundance of suspension-feeders relative to autotrophs and mixotrophs may be indicative of temperate waters, although the taxonomic diversity of the foraminiferal assemblages in both seagrass and non-seagrass embedding deposits supports the interpretation of shallow, warm-water conditions. The studied seagrass deposits provide evidence that high siliciclastic supply and associated nutrient input may determine the occurrence of temperate-like seagrass deposits in warm-water settings, analogous to extensive heterozoan carbonate production in modern shallow-tropical environments. Thus, the identification and correct interpretation of past seagrass-vegetated environments are crucial for reconstructing palaeoecological conditions in ancient shallow-marine environments. Therefore, in comparison with carbonate-dominated environments, the mixed terrigenous−carbonate seagrass deposits are volumetrically less important, presenting a more irregular, patchy distribution, and a skeletal assemblage dominated by heterotrophs, regardless of the water temperature.

中文翻译：

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始新世中期（乌尔巴萨-安迪亚高原、西比利牛斯、西班牙北部）受陆源影响的内坡环境中的海草发育

自从在白垩纪晚期首次出现以来，海草在浅水和近岸环境中的碳酸盐生产和沉积中发挥了重要作用，维持了一个多产的碳酸盐工厂，并通过阻隔和捕集效应的结合促进了沉积物的积累。大多数报道的古近纪海草发生在贫中营养浅层温水栖息地，其特征是适应低陆源影响的小型和大型底栖有孔虫的明显关联。本研究描述了在 San Fausto-Lazkua 地区（西班牙北部纳瓦拉地区）的 Bartonian（中始新世），在近岸到内匝道序列中的许多海草期，尽管这些海草是在一般海侵条件下沉积的，受邻近土地的陆源供应影响很大。多达 12 个不同的海草床间隔以周期性方式与高能近岸硅质碎屑岩和富含中光-寡光有孔虫和杂虫生物群（红藻、棘皮动物、苔藓虫）的内斜坡生物碎屑碳酸盐互层。海草沉积物表现出典型的未分类结构、丰富的生物扰动和中到高的陆源含量，并包括附生有孔虫、红藻，尤其是丰富的结壳藻类的特征骨架，通常具有明显的钩状和管状生长形式。相对于自养生物和混合养生物而言，这种丰富的悬浮饲养者可能表明温带水域，尽管海草和非海草包埋沉积物中有孔虫组合的分类多样性支持对浅水温水条件的解释。研究的海草沉积物提供的证据表明，高硅质碎屑供应和相关的养分输入可能决定温水环境中温带状海草沉积物的出现，类似于现代浅热带环境中广泛的杂环碳酸盐生产。因此，识别和正确解释过去的海草植被环境对于重建古代浅海环境中的古生态条件至关重要。因此，与以碳酸盐为主的环境相比，陆源-碳酸盐混合海草沉积在体积上不那么重要，呈现出更不规则的、