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上Magdalena河谷(UMV)盆地是位于哥伦比亚中科迪勒拉山脉和东科迪勒拉山脉之间的山间盆地,其中沉积了290m厚的中白垩统黑色页岩层序,我们对该层序进行了有机地化分析和显微分析。通过研究,我们可以(1)划分出四种有机相类型;(2)评价其生油岩潜力;(3)将这些有机相综合为一个层序地层格架。这四种有机相类型分别是C、BC、B和D型。在高水位期和低水位期沉积的C型具有明显的陆源有机质组分。BC型有机相以海相有机质含量较高且保存较好为特征,并发育在海进体系域的下部。因为B型有机相在缺氧条件下保存最好,所以海相有机质含量最高。由于缺乏生物扰动作用和富集微量金属,表明其沉积为缺氧沉积。B型有机相发育在海侵体系域上部,其生油岩潜力最佳。B型有机相形成于高水位期,尤其与土仑期南美洲北部的最大海泛有关。D型有机相也与高水位期沉积有关,但表现为高速率有机质改造和降解作用。
Upper Magdalena River Valley (UMV) Basin is a mountain basin between the Cordillera Mountains of Colombia and the East Cordillera Range, in which a 290-m-thick Meso-Cretaceous black shale sequence was deposited. We conducted this sequence Organic geochemical analysis and microscopic analysis. Through research, we can (1) classify four organic facies types; (2) evaluate the potential of petroleum derived rocks; and (3) integrate these organic phases into a sequence stratigraphic framework. The four organic types are C, BC, B and D respectively. Type C deposited in high water level and low water level has obvious terrigenous organic matter components. The BC-type organic phase is characterized by high marine organic matter content and good conservation, and is developed in the lower part of the marine system tract. Because B-type organic phase is best preserved under anaerobic conditions, marine organic matter content is the highest. The lack of bioturbation and enrichment of trace metals suggest deposition as anoxic deposition. The B-type organic phase is developed in the upper part of the transgressive system tract and has the best potential for source rock formation. The B-type organic phase is formed at a high water level, especially related to the largest sea pan in the northern part of South America in the Tulunian period. The D-type organic phase is also related to deposition in the high water level period, but appears to be a modification and degradation of high-rate organic matter.