摘要:
为了探讨异常地热对烃源岩沉积有机质热演化的影响，采集了三塘湖盆地大黑山东剖面附近一辉绿岩侵入体南侧石炭系哈尔加乌组上部黑色泥岩层系的8块样品（W008~W015），其与辉绿岩岩体的距离分别是20 cm、50 cm、100 cm、180 cm、300 cm、500 cm、1 000 cm和1 700 cm,通过分析这八块样品的有机质成熟度Ro、H/C原子比、O/C原子比和氯仿沥青“A”与总烃含量变化等基础地球化学特征，同时有选择地分析了其中5块样品的饱和烃色质总离子流特征可以看出，当泥岩样品距岩体的距离大于180 cm时，Ro基本保持不变，而当样品距岩体的距离小于180 cm时，Ro开始明显增高，且增高幅度很大；W008和W009号样品的H/C原子比相对较小，分别是0.385和0.404，而W011～W015五块样品的H/C原子比在0.5左右，而且基本保持一致；O/C原子比的变化范围相对较小，集中在0.1左右，W008和W009号样品的O/C比相邻样品（W010、W011）略小一些；W008号样品的总烃和氯仿沥青“A”略高于W009～W012号样品；从有机质饱和烃参数来看，W008、W009和W010三个样品的CPI值相对较小，与W012和W014两块样品存在明显的差别。通过以上分析说明该烃源岩整体成熟度较高，同时靠近岩体1~1.8 m距离范围内，有机质的各项成熟度指标具有异常增高的趋势，说明侵入岩体与直接接触的烃源岩的烘烤作用的范围相对较小，大约在1.8 m以内。
Abstract:
In order to probe into abnormal geothermal's influence on hydrocarbongeneration, we collected eight source rock samples (W008W015) from the black mudstone series of strata of Carboniferous upper Haerjiawu group on the south side of the diabase intrusion of the East Daheishan Profile in the Santanghu Basin, whose distance to the diabase rock is 20 cm, 50 cm, 100 cm, 180 cm, 300 cm, 500 cm, 1 000 cm, and 1 700 cm, respectively. Through analysis of the basic geochemical characteristics such as the atomic ratios of Ro to H/C and to O/C, the change of the chloroform bitumen "A" and total hydrocarbon of the eight samples, along with selective analysis of the chromatographic characteristics of the saturated hydrocarbon of five of them, we found that with the distance to the diabase rock greater than 180 cm, the content of Ro remains almost unchanged, however, the content of Ro significantly increases with the distance less than 180 cm; the atomic ratio of H/C in W008 and W009 is relatively small, which is 0.385 and 0.404, while from W011 to W015, the atomic ratio of H/C is about 0.5, which remains the same on the whole; the range of variation in the atomic ratio of O/C is relatively small concentrating around 0.1, and the atomic ratio of O/C in W008 and W009 is slightly smaller than adjacent samples (W010, W011); the chloroform bitumen "A" and total hydrocarbon of W008 is slightly higher than that of W009 ~ W012; from the pespective of organic saturated hydrocarbon parameters, CPI in W008, W009 and W010 is relatively small, which is obviously different from that of in W012, and W014. From the above analysis, we can conclude that the overall maturity of this source rock is rather high, and near the diabase intrusion with the distance range of 1~1.8 m, its maturity index has the trend of exceptional increase which shows the source rocks directly exposed to the intrusive rocks has a relative smaller scope of baking effect which is less than about 1.8 m.
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