【摘要】 以鄂尔多斯盆地西南缘奥陶系马家沟组为例,应用碳酸盐岩碳氧同位素、有机碳含量及其同位素组成,结合地层、古生物特征,探讨相对海平面变化对海相碳酸盐岩有机质富集及烃源岩发育的影响。研究表明,桌子山地区受贺兰裂谷的强烈沉降,克里摩里期相对海平面上升幅度较大,引起一系列利于有机质富集和烃源岩发育的结果:①静水、缺氧环境;②有机质埋藏量增加和质量优化;③碳酸盐碳、氧同位素值偏重,而有机碳同位素值偏轻。在岐山地区,相对海平面波动较小,为浅水、氧化环境,不利于有机质保存。对一个地区或盆地而言,相对海平面变化是全球性海平面升降和区域性构造活动的综合效应,它通过改变古环境控制了有机质富集及烃源岩发育。因此,相对海平面变化的研究对海相烃源岩的发育程度及其分布预测具有重要意义。更多还原

【Abstract】 By taking Majiagou Formation of Ordovician in the southwest fringe of E’erduosi Basin as an example, according to the data on carbon isotope, oxygen isotope, organic carbon content and its isotopic com position, the influence of relative sea level variation on the organic matter e nrichment and hydrocarbon source rock development in marine carbonate rocks is d iscussed in the paper in combination with the stratigraphic and palaeontologic c haracteristics. The research results indicated that the relative sea level at Zh uozishan region had greatly risen because of the strong subsidence of Helan Rift in Kelimoli period, thus causing a series of results beneficial to the organic matter enrichment and hydrocarbon source rock development: ①an euxinic and an oxic environment; ②the quantitative increase and qualitative optimization of b uried organic materials; and ③the positive excursion of carbonate’s carbon an d oxygen isotopic ratios and the negative excursion of organic carbon isotopic r atio.The fluctuation of the relative sea level at Qishan region was small, whic h was unfavorable for the organic matters being preserved because of the shallow and oxic environment. In regard to a region or a basin, the relative sea level variation was a comprehensive effect of global sea level change and regional te ctonic activity. The organic matter enrichment and hydrocarbon source rock devel opment could be controlled by the change in palaeoenvironment.更多还原