Abstract Here we developed and validated a new Benthic Foraminiferal Salinity (BFS) index from marginal-marine environments by analysing benthic foraminifera from the Holocene Guadalquivir estuary sediments (SW Spain). This index is formulated utilising only four species: Ammonia tepida and Haynesina germanica with higher tolerance to brackish waters and indicating lower salinity, and Elphidium translucens and Elphidium granosum indicative of greater marine influence and pointing to higher salinity. Thus, the BFS index is calculated easily and rapidly, and therefore it makes it possible to analyse a higher number of samples in less time. The BFS index values from the studied cores enabled the detailed description of subtle changes in the Guadalquivir estuary restriction during the Holocene. For this purpose, three degrees of salinity, depending on marine influence, were defined: higher (BFS index = 0.0–0.4, high marine influence), moderate (BFS index = 0.4–0.7, moderate marine influence), and lower (BFS index = 0.7–1.0, low marine influence). Before 2000 BCE, the estuary was moderately open and well-connected to the Atlantic Ocean. From 2000 BCE, the estuary experienced a greater marine influence, increasing in extension, as a consequence of a sea-level rise and subsidence. Immediately afterwards, it began to experience restriction processes due to southward shoreline progradation related to the growth of littoral spits and sediment supply. From 1400 to 1000 BCE, gradual restriction transformed the open estuary into a semiclosed estuary. A last phase of estuary restriction occurred from 1000 BCE to the present day, leading to the lowest salinity and the highest estuary restriction. Finally, the BFS index was successfully applied in two other marginal-marine environments: a Pleistocene lagoon in northern Italy, and a Pliocene coastal bay in southeastern Spain. The index allowed assessment of the degree of restriction in these different environments, supporting its utility in different regions, environments and timescales.

中文翻译：

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边缘海洋环境中的底栖有孔虫盐度指数：来自西班牙西南部全新世瓜达尔基维尔河口的案例研究

摘要 在这里，我们通过分析全新世瓜达尔基维尔河口沉积物（西班牙西南部）的底栖有孔虫，开发并验证了来自边缘海洋环境的新底栖有孔虫盐度 (BFS) 指数。该指数仅利用四种物种制定：Ammonia tepida 和 Haynesina Germanica 对咸水具有更高的耐受性并表明盐度较低，而 Elphidium translucens 和 Elphidium granosum 表明对海洋的影响更大并表明盐度较高。因此，可以轻松快速地计算 BFS 指数，从而可以在更短的时间内分析更多的样本。来自研究岩心的 BFS 指数值能够详细描述全新世期间瓜达尔基维尔河口限制的细微变化。为此，三度盐度，取决于海洋影响，定义为：较高（BFS 指数 = 0.0-0.4，高海洋影响）、中等（BFS 指数 = 0.4-0.7，中等海洋影响）和较低（BFS 指数 = 0.7-1.0，低海洋影响） . 公元前 2000 年之前，该河口适度开放，与大西洋连接良好。从公元前 2000 年开始，由于海平面上升和下沉，河口经历了更大的海洋影响，并扩大了范围。紧接着，它开始经历与沿海沙嘴和沉积物供应相关的向南海岸线进积的限制过程。从公元前 1400 年到公元前 1000 年，逐渐的限制将开放的河口转变为半封闭的河口。河口限制的最后阶段发生在公元前 1000 年至今，导致最低的盐度和最高的河口限制。最后，BFS 指数成功应用于另外两个边缘海洋环境：意大利北部的更新世泻湖和西班牙东南部的上新世沿海海湾。该指数允许评估这些不同环境中的限制程度，支持其在不同地区、环境和时间尺度上的效用。