Trace fossils and lithofacies have been studied for the first time in the Numidian Formation (Upper Oligocene–Lower Miocene) of the Ouarsenis Mountains in Algeria to interpret their depositional environment. Twenty-two ichnogenera have been recognized in eight lithofacies of three main facies associations in four representative sections. Distribution of the trace fossils is dependent on the facies. Most trace fossils are dominated by post-depositional forms (62%) and occur in fine-grained, thin-bedded sandstones of facies F4. They belong to the Ophiomorpha rudis, Paleodictyon and the Nereites ichnosubfacies of the Nereites ichnofacies. The O. rudis ichnosubfacies is recorded in 1) medium- to very thick-bedded sandstones of the facies association FA1, interbedded with thinner sandstone beds of the facies F2 and F4 in the upper unit of the sections studied, which were deposited in channel fill and levee-overbank environments, and in 2) medium- to thin-bedded sandstones of the facies association FA2 in the lower unit of the Kef Maiz and the Ain Ghanem sections, which were deposited in isolated narrow channels within the mud-dominated part of the depositional system and occasionally fed with turbiditic sand. The Paleodictyon ichnosubfacies occurs in thin- to medium-bedded sandstones (FA2) of the lower units in the Ain Ghanem and Kef Maiz sections and the lowest part of the upper unit of the Kef Maiz section, which were deposited in channel margin or foremost channel-to-levee-overbank areas. The Nereites ichnosubfacies is recorded in thin-bedded sandstones (FA2), which were deposited in crevasse-splays or small lobes on a basin floor invaded occasionally by turbidites against a background of pelagic and hemipelagic sedimentation.

首次对阿尔及利亚瓦尔塞尼斯山脉努米底亚组（上渐新统—下中新统）的微量化石和岩相进行了研究，以解释其沉积环境。在4个代表性剖面的3个主要相组合的8个岩相中发现了22个ichnogenera。痕迹化石的分布取决于相。大多数痕迹化石以沉积后形式为主（62％），并出现在F4相的细粒、薄层砂岩中。它们属于蛇形蛇形目、古字典和Nereites ichnofacies的Nereites ichnosubfacies。O. rudisichnosub相记录于 1) FA1 相组合的中至极厚层状砂岩，与所研究剖面上部单元 F2 和 F4 相较薄的砂岩层互层，沉积在河道充填区和堤坝上2) Kef Maiz 和 Ain Ghanem 剖面下部单元的 FA2 相组合的中至薄层砂岩，它们沉积在沉积系统的泥浆占主导地位的孤立狭窄通道中，以及偶尔喂以浊砂。古字典亚相见于 Ain Ghanem 和 Kef Maiz 剖面下部单元的薄层至中层砂岩 (FA2) 以及 Kef Maiz 剖面上部单元的最低部分，沉积在河道边缘或最重要的河道到-堤岸上的区域。Nereites ichnosubfacies 记录在薄层砂岩（FA2）中，这些砂岩沉积在盆地底部的裂隙或小裂片中，在远洋和半远洋沉积的背景下，偶尔会被浊积岩侵入。