Abstract The Lower Cenomanian Bahariya Formation forms the most prolific hydrocarbon reservoir in the Western Desert of Egypt, and represents a good example to illustrate the paleogeographical evolution of the southern Neo-Tethys region during the Early Cenomanian. It is also particularly important for its diverse vertebrate fauna including dipnoans, chelonians, crocodyliforms, squamates, plesiosaurs, decapod crustaceans and dinosaurs, which reflect sustained regional biostratigraphical and paleoenvironmental significance. It consists of fluvio-marine siliciclastic rocks (sandstones and mudrocks). A multidisciplinary approach of fieldwork, petrography and bulk-rock geochemistry of the sandstones of the Bahariya Formation was used to constrain their provenance, tectonic setting, source area-paleoweathering and paleoclimatic conditions within the Neo-Tethyan realm. Petrographically, the studied sandstones are mainly of quartz-arenite type with subordinate sub-arkose and sublithic ones. Quartz types, trace and rare earth element concentrations and ratios indicate the sandstones were sourced from felsic granitic rocks with a rare contribution of felsic gneisses. The modal analysis reflects that the sandstones are mainly of cratonic interior and quartzose recycled tectonic provenance. The chondrite-normalized REE distribution pattern of the Bahariya sandstones are characterized by enriched LREE and flat HREE similar to those of UCC with negative Eu/Eu* anomalies. Major and trace elements of the sandstones suggest their deposition on a Neo-Tethys passive continental margin related to the Early Cretaceous rifting. The weathering indices (CIA, CIW, PIA and ICV) and the Al2O3-(CaO+Na2O)-K2O diagram suggest moderate to severe chemical weathering in the source area under semi-humid to humid climatic conditions. In conclusions, the Bahariya sandstones could be sourced by a fluvial reworking of moderately- to intensively-weathered Precambrian granites and gneisses of the surrounding Gebel Uweinat Massive (at the southwest of the study area), and were deposited in a low-lying basin (Bahariya area) of a Neo-Tethys passive continental margin. In a broad interest, results of this study play an important role in reconstructing the paleoclimatic conditions and paleogeographical evolution of the southern Neo-Tethys region during the Early Cenomanian.

中文翻译：

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埃及巴哈里亚绿洲巴哈里亚组砂岩的来源、构造环境、古风化和古气候：对早期森诺曼纪南部新特提斯地区古地理的启示

摘要 下赛诺曼阶Bahariya组是埃及西部沙漠中储量最多的油气藏，是描述新特提斯南部地区早期赛诺曼阶古地理演化的一个很好的例子。它还因其多样化的脊椎动物群而特别重要，包括龙类、龟类、鳄鱼、有鳞类、蛇颈龙、十足目甲壳类和恐龙，它们反映了持续的区域生物地层和古环境意义。它由河流-海相硅质碎屑岩（砂岩和泥岩）组成。Bahariya 组砂岩的实地工作、岩石学和大块岩石地球化学的多学科方法被用于限制它们的来源、构造环境、源区——新特提斯领域内的古风化和古气候条件。岩相学上，所研究的砂岩以石英砂岩为主，次长石质和亚岩质砂岩。石英类型、痕量和稀土元素的浓度和比率表明砂岩来自长英质花岗岩，其中少有长英质片麻岩。模态分析反映砂岩主要为克拉通内部和石英岩再生构造物源。Bahariya 砂岩球粒陨石归一化 REE 分布模式的特征是富集 LREE 和平坦的 HREE，与 UCC 相似，具有负 Eu/Eu* 异常。砂岩的主要和微量元素表明它们沉积在与早白垩世裂谷有关的新特提斯被动大陆边缘。风化指数（CIA、CIW、PIA 和 ICV）和 Al2O3-(CaO+Na2O)-K2O 图表明在半湿润至湿润气候条件下，源区存在中度至重度化学风化。综上所述，Bahariya 砂岩的来源可以是中度至强烈风化的前寒武纪花岗岩和周围 Gebel Uweinat Massive 片麻岩（在研究区的西南部）的河流改造，并沉积在一个低洼盆地中（新特提斯被动大陆边缘的巴哈里亚地区。从广泛的兴趣来看，这项研究的结果对重建新特提斯南部地区早期森诺曼纪的古气候条件和古地理演化具有重要作用。PIA 和 ICV) 和 Al2O3-(CaO+Na2O)-K2O 图表明在半湿润至湿润气候条件下源区存在中度至重度化学风化。综上所述，Bahariya 砂岩的来源可以是中度至强烈风化的前寒武纪花岗岩和周围 Gebel Uweinat Massive 片麻岩（在研究区的西南部）的河流改造，并沉积在一个低洼盆地中（新特提斯被动大陆边缘的巴哈里亚地区。从广泛的兴趣来看，这项研究的结果对重建新特提斯南部地区早期森诺曼纪的古气候条件和古地理演化具有重要作用。PIA 和 ICV) 和 Al2O3-(CaO+Na2O)-K2O 图表明在半湿润至湿润气候条件下源区存在中度至重度化学风化。综上所述，Bahariya 砂岩的来源可以是中度至强烈风化的前寒武纪花岗岩和周围 Gebel Uweinat Massive 片麻岩（在研究区的西南部）的河流改造，并沉积在一个低洼盆地中（新特提斯被动大陆边缘的巴哈里亚地区。从广泛的兴趣来看，这项研究的结果对重建新特提斯南部地区早期森诺曼纪的古气候条件和古地理演化具有重要作用。Bahariya 砂岩的来源可以是中度至强烈风化的前寒武纪花岗岩和周围 Gebel Uweinat Massive（研究区西南部）的片麻岩的河流改造，并沉积在低洼盆地（Bahariya 地区）新特提斯被动大陆边缘。从广泛的兴趣来看，这项研究的结果对重建新特提斯南部地区早期森诺曼纪的古气候条件和古地理演化具有重要作用。Bahariya 砂岩的来源可以是中度至强烈风化的前寒武纪花岗岩和周围 Gebel Uweinat Massive（研究区西南部）的片麻岩的河流改造，并沉积在低洼盆地（Bahariya 地区）新特提斯被动大陆边缘。从广泛的兴趣来看，这项研究的结果对重建新特提斯南部地区早期森诺曼纪的古气候条件和古地理演化具有重要作用。