Paleogene-Neogene coals are widespread in Malaysia, cover a wide age spectrum and are considered the source rock of hydrocarbons in Malaysia. However, they have not been studied systematically up to now. Moreover, the black shales associated with these coals were not taken into consideration in previous studies. Therefore, this study presents systematic inorganic and Rock-Eval analyses of the Paleogene-Neogene coals and their associated black shales to examine their origin, depositional environment and hydrocarbon potential. With the exception of coals from the Tanjong Formation, Sabah, the Paleogene-Neogene coals are characterized by very low ash yields and low concentrations of trace and rare earth elements including hazardous trace elements. The black shales are composed of quartz, illite, kaolinite and traces of pyrite in some samples. Al2O3/TiO2 ratios in the coals (6�62) and black shales (16�34) suggest a mixture of felsic and intermediate igneous rocks as sources for their detrital fractions, which is supported by the Zr-Ti binary plot. V/(V+Ni) ratios average between 0.8 and 0.7, V/Ni between 13.5 and 3, and Ni/Co between 1.7 and 3.8 for coal and black shale samples; respectively, indicating suboxic to anoxic depositional conditions for both groups of samples. Rock-Eval analysis indicates that coal and black shale samples contain mixed Type II�III kerogens, which suggest similar organic input from terrestrial high plants. The samples also contain immature to mature organic matter and can produce gas and oil. These characteristics along with the high TOC contents (very good to excellent) indicate that the Paleogene-Neogene coals and black shales are potential source rocks for oil and gas fields in Malaysia. The coals and black shales from different ages and localities were shown to have similar source area composition, climate conditions during their deposition, terrestrial organic input as well as suboxic to anoxic depositional conditions. However, coals and black shales from the early-middle Miocene Tanjong Formation exhibit higher Al2O3/SiO2 ratios than the rest of coals and black shales suggesting a prevalence of wetter climatic conditions during formation. In addition, coals and black shales from the early-middle Miocene Tanjong Formation and upper Pliocene Liang Formation show higher values for redox proxies such as V/(V+Ni), V/Ni, Ni/Co and Ce* compared with other formations, indicating the dominance of reducing conditions during the deposition of these formations. © 2018 Elsevier B.V.

中文翻译：

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马来西亚古近系-新近系煤和黑色页岩的地球化学特征：对它们的起源和油气潜力的影响

古近纪-新近纪煤在马来西亚广泛分布，涵盖广泛的年龄谱，被认为是马来西亚碳氢化合物的源岩。然而，到目前为止，它们还没有被系统地研究过。此外，之前的研究没有考虑与这些煤相关的黑色页岩。因此，本研究对古近系-新近系煤及其伴生的黑色页岩进行了系统的无机和岩石评估分析，以检查它们的起源、沉积环境和油气潜力。除了来自沙巴丹戎组的煤外，古近纪-新近纪煤的特点是灰分产量非常低，痕量和稀土元素（包括有害微量元素）浓度低。黑色页岩由石英、伊利石、高岭石和一些样品中的微量黄铁矿组成。煤 (6-62) 和黑色页岩 (16-34) 中的 Al2O3/TiO2 比率表明长英质和中火成岩的混合物作为其碎屑部分的来源，这得到了 Zr-Ti 二元图的支持。煤和黑色页岩样品的 V/(V+Ni) 比值平均在 0.8 到 0.7 之间，V/Ni 比在 13.5 到 3 之间，Ni/Co 在 1.7 到 3.8 之间；分别表明两组样品的低氧至缺氧沉积条件。Rock-Eval 分析表明煤和黑色页岩样品含有混合的 II-III 型干酪根，这表明来自陆地高等植物的类似有机输入。样品还含有未成熟到成熟的有机物，可以生产天然气和石油。这些特征以及高 TOC 含量（非常好到极好）表明古近系-新近系煤和黑色页岩是马来西亚油气田的潜在烃源岩。不同年代和地点的煤和黑色页岩具有相似的源区组成、沉积期间的气候条件、陆地有机输入以及低氧到缺氧的沉积条件。然而，中新世早中新世 Tanjong 组的煤和黑色页岩的 Al2O3/SiO2 比高于其他煤和黑色页岩，表明在形成期间普遍存在较潮湿的气候条件。此外，来自中早中新世丹戎组和上新世梁组的煤和黑色页岩显示出更高的氧化还原代理值，如 V/(V+Ni)、V/Ni、Ni/Co 和 Ce* 与其他地层相比，表明在这些地层沉积过程中还原条件占主导地位。© 2018 Elsevier BV