Abstract We reconstructed the paleoenvironmental conditions of the Mazarron Basin during MIS 7 and MIS 1 based on their alkane and fatty acid contents, their mineralogy and the fossil content of an amino-acid-dated sediment sequence. The n-alkane and fatty acid indices proved to be excellent paleoenvironmental proxies for studying the paleo-hydrogeological and paleoclimatological evolution of this marshland. Three geochemical units (GUs) were identified from the abundance of the C25 n-alkane and the ACL, TARHC and Paq values, confirming the importance of phases with terrestrial plant input or aquatic macrophyte predominance. These GUs were used to define three paleoenvironmental episodes (PEs) during MIS 7. In PE7.1, the contribution of algal and aquatic macrophytes predominated in a temporarily flooded saline muddy plain. In PE7.2, the major contribution was from aquatic macrophytes (flooded marsh), although it was marked by episodes of emersion with greater terrestrial contribution. At the top of the MIS 7 record (PE7.3), there was a significant reduction in the water depth, with the main input deriving from terrestrial plants in a muddy alluvial plain. Six PEs were established during MIS 1 (Holocene), of which three predominately received organic matter derived from aquatic macrophytes, while the major contribution in the other three came from terrestrial plants. The two sets of PEs were linked to episodes of increased and decreased water level, respectively. This interpretation is consistent with the characteristics of the sediment facies, with PE1.1, 1.3 and 1.5 corresponding to a marsh with deeper water and a greater input of detrital materials, and PE1.2, 1.4 and 1.6 to a shallow environment with carbonates and gypsum deposits. Direct marine influence was limited, so the oscillations in the water level in the marsh were likely to be more related to climatic changes (drier/wetter phases) and recent tectonics than to large changes in sea level. Emersion led to degradation of the organic matter and enrichment in short-chain and branched saturated fatty acids.

中文翻译：

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沿海沼泽地的生物标志物：中更新世 (MIS 7) 和全新世 (MIS 1) 期间马萨龙盆地的环境特征

摘要 我们根据 MIS 7 和 MIS 1 期间马扎龙盆地的烷烃和脂肪酸含量、矿物学和氨基酸年代沉积序列的化石含量重建了马扎龙盆地的古环境条件。正构烷烃和脂肪酸指数被证明是研究该沼泽地古水文地质和古气候演化的极好古环境指标。从 C25 正构烷烃的丰度和 ACL、TARHC 和 Paq 值中确定了三个地球化学单元 (GU)，证实了陆生植物输入或水生大型植物优势阶段的重要性。这些 GU 用于定义 MIS 7 期间的三个古环境事件 (PE)。在 PE7.1 中，藻类和水生大型植物的贡献在暂时淹没的盐渍泥泞平原中占主导地位。在 PE7.2 中，主要贡献来自水生大型植物（淹没的沼泽），尽管其特点是出现了较大的陆地贡献。在 MIS 7 记录 (PE7.3) 的顶部，水深显着减少，主要输入来自泥泞冲积平原中的陆生植物。在MIS 1（全新世）期间建立了六个PE，其中三个主要接收来自水生大型植物的有机物质，而其他三个的主要贡献来自陆生植物。两组 PE 分别与水位升高和降低的事件相关。该解释与沉积相特征一致，PE1.1、1.3、1.5对应水深、碎屑物质输入量大的沼泽，PE1.2、1.4、1对应。6 到有碳酸盐和石膏沉积物的浅层环境。直接的海洋影响是有限的，因此沼泽中水位的波动可能更多地与气候变化（干/湿阶段）和最近的构造有关，而不是与海平面的大变化有关。出现导致有机物降解和短链和支链饱和脂肪酸的富集。