Abstract Geochemical and palynological proxies were determined for 31 samples representing the upper Coniacian-lowermost Campanian Abu Roash A Member, collected from the BED2-3 well. This was done to assess the prevailing paleoredox conditions, productivity levels, and water-column settings to: (1) understand controls and mechanisms related to accumulation of organic carbon within the sedimentary record; (2) assess principal environmental processes that triggered the preservation of organic matter-poor, calcareous shale and limestone facies of the Abo Roash A Member; and (3) to interpret the paleoceanographic settings and confirm the occurrence of either Oceanic Anoxic Event 3 (OAE3) or Cretaceous Oceanic Red Beds (CORBs) within the Abu Gharadig Basin in the southern part of the Tethyan Ocean, Egypt. Sedimentation rates were reconstructed based on the biostratigraphic-age constraints of marine dinoflagellate cysts (dinocysts). Trace elements-based ratios and relationships were used in order to study the role of clastic terrestrial input. Three groups of dinocysts and freshwater Pediastrum algae were used to study the water-column conditions. Results showed that the Abu Roash A Member was deposited under oxic to intermittently dysoxic conditions in a distal inner to middle neritic environment, with varying sedimentation rates from 32 to 119 mm kyr−1. Productivity appeared to be a significant factor for determining magnitudes of the organic carbon accumulation; however, low productivity was prevalent during deposition. Carbonate content was high, which resulted in dilution of organic matter during varied rates of sediment input. Such results indicate that the paleoceanographic conditions in the southern Tethys witnessed the absence of prevalent oceanic anoxia (i.e., the Coniacian-Santonian OAE 3) and deposition of the CORBs as in several parts of the Tethys, the Pacific, and the Indian oceans.

中文翻译：

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Coniacian-Santonian 事件期间的沉积和有机碳控制机制：来自特提斯南部（埃及）的初步结果

摘要 确定了从 BED2-3 井收集的 31 个样品的地球化学和孢粉学指标，这些样品代表了 Coniacian 上层 - 最下层 Campanian Abu Roash A 段。这样做是为了评估普遍的古氧化还原条件、生产力水平和水柱环境，以：(1) 了解与沉积记录中有机碳积累相关的控​​制和机制；(2) 评估引发 Abo Roash A 段有机质贫乏、钙质页岩和石灰岩相保存的主要环境过程；(3) 解释古海洋环境并确认在埃及特提斯洋南部的阿布加拉迪格盆地内发生了大洋缺氧事件 3 (OAE3) 或白垩纪大洋红层 (CORB)。基于海洋甲藻囊肿（甲藻）的生物地层年龄限制重建了沉积率。使用基于微量元素的比率和关系来研究碎屑陆地输入的作用。使用三组双胞藻和淡水Pediastrum藻类来研究水柱条件。结果表明，Abu Roash A 段在有氧到间歇性缺氧条件下沉积，沉积在远内到中浅海环境中，沉积速率从 32 到 119 mm kyr-1 不等。生产力似乎是决定有机碳积累量的重要因素；然而，在沉积过程中普遍存在低生产率。碳酸盐含量高，这导致在不同的沉积物输入速率下有机物被稀释。