| 伦北盆地古近系牛堡组页岩地球化学特征及地质意义 |
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| 引用本文：陈冲,申怀明,陈云,季长军.2025.伦北盆地古近系牛堡组页岩地球化学特征及地质意义[J].地球学报,46(3):577-586. |
| DOI：10.3975/cagsb.2025.041121 |
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| 基金项目:西藏自治区科技计划项目(编号: XZ202401YD0006; XZ202403ZY0040)、深地国家科技重大专项(编号: 2024ZD1001005)、国家自然科学基金委项目(编号: U24A20597)和西藏自然资源厅矿产资源勘查专项项目(编号: GZFCG2024-20492) |
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| 中文摘要:藏北高原的伦北盆地构造演化及油气资源潜力的认识薄弱, 尚未系统开展油气勘探。为进一步明确伦北盆地是否适合油气勘探, 本文通过对古近系牛堡组的野外露头样品, 开展了一系列的地球化学研究。通过总有机碳含量分析、岩石热解分析和气相色谱分析, 表明牛堡组的页岩为一套优质的生油岩。其有机质类型以Ⅱ型和Ⅱ型、Ⅲ型混合为主, 处于还原性的湖相沉积环境。沉积时期水体盐度的差异导致了烃源岩有机质丰度的非均质性。牛堡组的页岩整体处于成熟阶段, 具备大规模生油的能力。通过油源对比认为牛堡组的油砂来源于同层位页岩的贡献。火山凝灰岩形成过程中引发的异常热事件, 导致页岩和油砂具有较高丰度的多环芳烃。基于热成熟度参数和多环芳烃比值可将本次分析的油砂样品划分为2大类, 即Ⅰ类未受凝灰岩形成过程引发热异常的影响, Ⅱ类明显受到凝灰岩形成过程引发热异常的影响, 综合分析认为火山作用引发的热异常进一步促进了烃源岩的快速生烃。 |
| 中文关键词:伦北盆地 页岩 生物标志物 成熟度 油源对比 |
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| Geochemical Characteristics and Significance of Paleogene Niubao Formation Shales in the Lunbei Basin |
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| Abstract:The structural evolution and hydrocarbon potential of the Lunbei Basin in the northern Tibetan Plateau remain poorly understood, and systematic oil and gas exploration has yet to be conducted. To assess the suitability of the Lunbei Basin for petroleum exploration, this study conducted geochemical analyses on outcrop samples from the Paleogene Niubao Formation. Analyses of total organic carbon content, rock py-rolysis, and gas chromatography indicate that the Niubao Formation shale comprises high-quality source rocks. The organic matter is predominantly a mixture of Type II and Type III, deposited in a reducing la-custrine environment. Variations in water salinity during deposition led to source rock heterogeneity, while the geochemical characteristics of petroleum remained largely similar. The entire Niubao Formation shale is in the mature stage and has significant oil-generating potential. The source rock for the Niubao Formation oil sands is shale from the same stratigraphic horizon. Thermal anomalies from volcanic tuff formation result in elevated PAH ratios between shale and oil sands. Based on thermal maturity parameters and PAH ratios, the samples are classified into two groups: Class I, which is unaffected by thermal anomalies from tuff formation, and Class II, which is significantly affected. A comprehensive analysis indicates that thermal anomalies from volcanism accelerate hydrocarbon generation in source rocks. |
| keywords:Lunbei Basin shale biomarkers maturity oil-source correlation |
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