Marine siliciclastic red beds are common in the geological record; however, distinguishing them from continental red beds can be challenging without detailed sedimentological and stratigraphic analyses. Owing to the common tendency in the geological literature to relate the reddish color to the oxidization processes within the vadose zone, siliciclastic red beds of marine genesis can be misinterpreted as continental deposits. Unlike the other Toarcian successions in the Tethyan basins surrounding Arabia, the sedimentological and stratigraphic characteristics of the Marrat Formation of Arabia in general and its middle unit's red siliciclastic beds, in particular, have not been well constrained. For more than 50 years, the red siliciclastic beds of the Toarcian Marrat Formation have been interpreted as continental to marginal marine deposits based on their reddish color and the absence of fossils. The lack of supporting sedimentological and stratigraphic evidence to this interpretation raises critical concerns regarding its validity.

Along the Jurassic outcrop belt in central Arabia, three outcrop localities of the middle Marrat reddish siliciclastic deposits (with a total thickness of more than 120 m) demonstrate sedimentological and ichnological features that are contrary to the non-marine to marginal marine interpretation. The integration between sedimentology and ichnology reveals the existence of asymmetrical wave-dominated shorelines with evidence of river hyperpycnal flows and tidal processes during the middle Marrat time. A total of seventeen facies are identified and grouped into four facies associations: mixed wave and river-dominated delta front to prodelta mudstone (FA1), shoreface (strandplain) and underlying shelf mudstone (FA2), tidally-influenced distributary channel (FA3), and offshore carbonates (FA4). Stratigraphically, six major parasequences (each with a thickness of ~ 3–13 m) were mapped and correlated between the three measured sections with clear overall progradational to retrogradational stacking patterns.

To the best of our knowledge, this study is the first to document the presence of Toarcian shallow-marine siliciclastic red beds on the Arabian Plate. It displays an example of a case study where ichnology and process-based sedimentology were integrated to constrain the depositional environment of these red beds. This study provides new insights into the depositional settings of the Toarcian red siliciclastic beds of the Marrat Formation, with implications to the stratigraphy of Arabia and the Early Jurassic paleogeography of the western Tethys and, in particular, the Arabian Plate.

在地质记录中，海洋硅质碎屑红层很普遍。然而，如果不进行详细的沉积学和地层分析，将其与大陆红层区分开可能是一项挑战。由于地质文献中普遍的趋势是将红色带入渗流带内的氧化过程，因此海洋成因的硅质碎屑红层可能被误认为是大陆性沉积。与围绕阿拉伯的特提斯盆地的其他Toarcian演替不同，阿拉伯的Marrat组及其特别是中部单元的红色硅质碎屑岩层的沉积学和地层特征并未受到很好的约束。50多年来，Toarcian Marrat组的红色硅质碎屑岩床因其颜色偏红和缺少化石而被解释为大陆到边缘海相沉积。缺乏支持性的沉积学和地层学证据的解释引起了人们对其有效性的关注。

在阿拉伯中部的侏罗纪露头带上，马拉特中部的三个露头微红硅质碎屑沉积物（总厚度超过120 m）显示出与非海洋到边缘海洋解释相反的沉积学和岩石学特征。沉积学和鱼类学的整合揭示了不对称波浪主导的海岸线的存在，并在马拉特中段期间出现了河道高潮流和潮汐过程的证据。总共确定了17个相并将其分为4个相联系：混合波和以河为主的三角洲前缘到前三角洲泥岩（FA1），岸面（strandplain）和下伏陆架泥岩（FA2），潮汐影响的分流河道（FA3），和离岸碳酸盐（FA4）。在地层上

据我们所知，这项研究是第一个记录阿拉伯板中Toarcian浅海硅质碎屑红层存在的研究。它显示了一个案例研究的示例，其中结合了鱼类学和基于过程的沉积学来限制这些红层的沉积环境。这项研究提供了对马拉特组Toarcian红色硅质碎屑岩沉积环境的新见解，对阿拉伯地层和特提斯西部，特别是阿拉伯板块的早侏罗世古地理学产生了影响。