The Lower–Middle Miocene Lagos-Portimão Formation at Portimão, southern Portugal, consists of three main heterozoan carbonate facies: mollusc-rich rudstone in a matrix of skeletal packstone/grainstone (MR), fine-to-medium skeletal packstone/grainstone (SPG), and quartz-rich skeletal packstone (QSP). These facies occur in different arrangements and indicate deposition on a wave-dominated open shelf with a well-established heterozoan fauna, most likely related to increased trophic resources where continent supply and upwelling contributed nutrients. These facies form belts inferred to have lain roughly parallel to the strike lines of the shelf, with the MR occupying the more landward, shallower areas and the SPG and QSP extending progressively offshore on the open shelf. Bryozoan abundance in the QSP facies indicates a deep setting on the middle/outer shelf, whereas the absence of rhodalgal components is attributed to a combination of temperature decrease and seafloor eutrophication during the late Langhian and Serravallian, coeval with the “Middle Miocene climatic cooling”. The large photosymbiont-bearing foraminifers and the absence of calcareous algae and zooxanthellate corals point to deposition under warm-temperate conditions. Two main orders of cyclicity are present. Small-scale sequences, 40–60 cm thick, may represent minor sea-level changes related to fifth-order sequences modulated by (~ 100-kyr) eccentricity forcing. Six large-scale sequences, 3–9 m in thickness, are recognized. Based on LAD and FAD of planktic foraminifers and the occurrence of two erosive surfaces related to major sea-level falls (Lang2/Ser1 and Ser4/Tor1), five Miocene sequences (Bu, L1, S1, S2, and S3) are correlated with third-order eustatic cycles.

中文翻译：

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Portimão（葡萄牙Lagos-Portimão组）中新世开陆架暖温带碳酸盐岩相和层序分析

位于葡萄牙南部 Portimão 的下-中中新世 Lagos-Portimão 组由三种主要的杂碳酸盐岩相组成：在骨架灰岩 / 颗粒岩 (MR) 矩阵中的富含软体动物的砂岩 (MR)、细至中等骨架灰岩 / 颗粒岩 (SPG) ) 和富含石英的骨架灰岩 (QSP)。这些相以不同的排列出现，表明沉积在以波浪为主的开放式陆架上，具有完善的杂种动物群，很可能与大陆供应和上升流提供营养的营养资源增加有关。这些相形成的带被推断大致平行于陆架的走向线，MR 占据了更向陆、更浅的区域，而 SPG 和 QSP 在开放式陆架上逐渐向近海延伸。QSP 相中苔藓虫的丰度表明中/外陆架的深层环境，而红藻成分的缺失归因于朗格阶和塞拉瓦利亚晚期的温度下降和海底富营养化的结合，与“中中新世气候变冷”同时期. 带有光共生体的大型有孔虫以及没有钙质藻类和虫黄藻珊瑚表明它们是在暖温带条件下沉积的。存在两个主要的循环顺序。40-60 厘米厚的小尺度序列可能代表与由 (~ 100-kyr) 偏心率强迫调制的五阶序列相关的微小海平面变化。已识别出 6 个厚度为 3-9 m 的大规模层序。