The Upper Cretaceous to Eocene sedimentary succession of the Dorado North exploration well in the Mannar Basin has been studied for paleoenvironment (organic matter richness, its composition, and depositional environment) and petroleum source rock potential. In this study, drillcore cuttings (n = 142) were analyzed using CHNS elementary analyzer. Results indicated that Lower Campanian sediments were depleted by total organic carbon content (TOC = 0.45%), under arid climate. The Lower Campanian to Upper Maastrichtian sedimentary sequence contains organic carbon rich (TOC = 1.64%) terrestrial (C/N ratio = 27.13) sediments. Consequently, this sedimentary sequence can be identified as a good source rock for gas generation. The formation of organic matter rich terrestrial sediments has been linked to sea-level changes and tectonic activities during the Late Cretaceous. Carbonate carbon contents are rich in the Lower Campanian to Upper Maastrichtian sedimentary sequence that indicates diversification of microorganisms under warm climatic conditions. The Paleocene to Eocene sedimentary sequence indicates poor to fair source rocks for possibly oil generation. However, the depositional environment was drastically changed from oxic (Early-Late Paleocene) to anoxic (Late Paleocene-Late Eocene) conditions. Consequently, the Eocene epoch is characterized by weak oceanic circulation in the Indian Ocean under greenhouse climate. In contrast, the deposition of carbonate platforms since the Late Paleocene (CaCO₃ = 29.3%) can be related to the northward movement of the Indian plate into warmer tropical latitudes.

研究了曼纳尔盆地多拉多北部勘探井的上白垩统至始新世沉积演替的古环境（有机质丰富度，其组成和沉积环境）和石油烃源岩潜力。在这项研究中，钻芯岩屑（n＝ 142）使用CHNS元素分析仪进行分析。结果表明，在干旱气候下，较低的Campanian沉积物被总有机碳含量（TOC = 0.45％）所消耗。下坎帕尼至马斯特里赫特上层沉积层序含有丰富的有机碳（TOC = 1.64％）陆地（C / N比= 27.13）沉积物。因此，该沉积序列可以被确定为天然气生成的良好烃源岩。白垩纪晚期，富含有机物的陆地沉积物的形成与海平面的变化和构造活动有关。下部坎帕尼至马斯特里赫特上层沉积序列中的碳酸盐碳含量丰富，这表明在温暖的气候条件下微生物的多样性。古新世至始新世的沉积层序表明烃源岩较差至公平，可能会产生石油。但是，沉积环境从有氧（早晚古新世）到缺氧（晚古新世-晚始新世）条件发生了巨大变化。因此，始新世时期的特征是在温室气候下印度洋的海洋环流较弱。相反，晚古新世以来的碳酸盐台地沉积（CaCO₃ = 29.3％）可能与印度洋板块向北移入较热的热带纬度有关。