The middle-upper Pleistocene Borj Edouane unit records a singular spectrum of terrestrial carbonates in a shallow depression on Cretaceous rocks in north Tunisia. This study aims to decipher the depositional system and reveal the climatic and paleohydrological conditions of the carbonate facies deposition. They are grouped into two facies associations: (1) a calcrete–palustrine and (2) a composite microbialite-travertine, surrounded by a marginal alluvial association along the western and northern borders of the basin. The calcrete–palustrine association extends along the westernmost south–north strip of the basin, reflecting calcrete development on distal alluvial fan deposits and pedogenic modification (palustrine facies) of shallow fresh-water carbonates. The composite microbialite-travertine, extending along north–south strips in the middle and eastern areas of the basin, consists of microbialite, clastic microbialite–travertine, and travertine associations. Microbialites were developed in fluvio-lacustrine environments within the central strip and pass eastward into the travertines through the clastic microbialite–travertine association. The latter was deposited from currents and in shallow ponds along a bench next to the travertine-depositing springs, linked to a fault system in the eastern margin of the basin. The carbonate depositional system shows an asymmetrical distribution of facies that parallels the paleohydrological asymmetry along the basin. Water supply was restricted in the western part of the basin and abundant in its eastern areas linked to spring waters that kept stable lake levels in the basin center, favoring the genesis of microbialites. The presence of lacustrine carbonates in the studied area indicates higher water availability during the Middle-Late Pleistocene and that climate in North Africa was wetter than today.

中文翻译：

---

突尼斯北部中上更新世的湿气候陆地碳酸盐记录

中上更新世 Borj Edouane 单元记录了突尼斯北部白垩纪岩石浅洼地中陆地碳酸盐的奇异光谱。本研究旨在破译沉积系统，揭示碳酸盐岩相沉积的气候和古水文条件。它们被分为两个相组合：(1) 钙质-沼泽相和 (2) 复合微生物岩-石灰华，被盆地西部和北部边界的边缘冲积组合物包围。钙质-沼泽组合沿盆地最西端的南-北带延伸，反映了远端冲积扇沉积和浅层淡水碳酸盐岩的成土改造（沼泽相）的钙质沉积物。复合微生物岩-钙华，沿盆地中东部南北带延伸，由微生物岩、碎屑微生物岩-钙华、钙华组合组成。微生物岩在中央带内的河湖环境中发育，并通过碎屑微生物岩钙华组合向东进入石灰华。后者是从水流和浅水池中沿着钙华沉积泉旁边的一条长凳沉积的，与盆地东缘的断层系统相连。碳酸盐沉积系统显示出与盆地古水文不对称平行的不对称相分布。流域西部供水受限，东部地区供水丰富，与泉水相连，保持流域中心湖泊水位稳定，有利于微生物岩的发生。研究区域内湖相碳酸盐的存在表明，中-晚更新世期间可用水量更高，北非的气候比今天更潮湿。