Lithofaciological analysis was performed in 21 exposures of the Upper Aptian Itapecuru Formation along the Itapecuru river, and in an outcrop on the MA-020 state highway, in the northeastern side of the Parnaíba Basin, Maranhão State, Brazil. The analysis aimed to contribute to the paleoenvironmental understanding of the siliciclastic sedimentation in continental (terrestrial and aquatic) and marine environments of the formation. The stratigraphic and sedimentological interrelationships and paleoenvironmental knowledge of the deposit's origin are hampered due to the lack of adequate outcrops and of integrated multidisciplinary studies, as well as to the few accurate biostratigraphic data. The Itapecuru Formation sediments reach 700 m of thickness in the subsurface of the Parnaíba Basin and were deposited near to the paleoequator at the end of the rift stage, a tectonic event responsible for the Gondwana breakup in the Early Cretaceous. In the analyzed sedimentary succession (totalizing 89.3 m thickness) it was defined 12 lithofacies, grouped in two architectural elements – mixed flat and tidal channel. These elements integrate two estuarine systems dominated by tidal currents, with the older system corresponding to a high-energy marine dominated zone of the estuary, and the younger one representing a low-energy central zone of the estuary. The marine conditions identified by the architectural elements in deposits where there are no recovered marine palynomorphs were important for tracking marine action in the Late Aptian. The results described here help understand the evolutionary scenario of the Equatorial Atlantic Segment in Brazil in relation to temporally distinct depositional sequences.

在巴西的马拉尼昂州帕尔纳巴盆地东北侧，沿着伊塔佩库鲁河沿上阿普提安伊塔佩库鲁组进行了21次曝露，并在MA-020国道的露头处进行了岩石岩相分析。该分析旨在有助于古环境理解地层（陆地和水生）和海洋环境中的硅质碎屑沉积。由于缺乏足够的露头和综合的多学科研究以及少量准确的生物地层学数据，使得该矿床的地层和沉积学相互关系以及古环境知识受到阻碍。Itapecuru组沉积物在Parnaíba盆地的地下达到700 m的厚度，并在裂谷阶段结束时沉积在古赤道附近，这是导致早白垩世冈瓦纳破裂的构造事件。在分析的沉积演替过程中（总厚度为89.3 m），定义了12个岩相，分为两个建筑元素-平坦的和潮汐混合通道。这些元素整合了两个以潮流为主的河口系统，较旧的系统对应于河口的一个高能量海洋主导区，而较年轻的系统则对应于河口的一个低能量中心区。由沉积物中的建筑元素所识别的海洋条件，其中没有回收的海洋古怪物，对于追踪晚阿普提安的海洋活动非常重要。