【摘要】 依据ODP204航次1250C站位钻井样品酸解烃数据结果,以及作者在南海西沙海槽研究区天然气水合物地球化学现场勘查中得到的多种烃类指标数据、异常点上微量甲烷碳同位素数值等资料,对海洋水合物地球化学勘探的依据和研究区气态烃异常特征、气体成因、天然气水合物成藏模式等相关问题进行了研究探讨。结果表明:气态烃指标地球化学异常主要分布在工区北部斜坡地带,并与BSR等地震标志及深部断裂关系密切;西沙海槽研究区海底沉积物气态烃甲烷以热解成因为主,但也有混合成因;推测该区天然气水合物为断层渗滤综合成藏模式。研究成果比较合理地解释了BSR分布和海底沉积物甲烷局部异常并非完全一致的原因;评价预测了该区天然气水合物有利勘探目标。成果为该区天然气水合物勘探、天然气水合物成因机制研究和天然气水合物远景预测,提供了地球化学方面的证据。更多还原

【Abstract】 The paper relies on the acidolysis hydrocarbon results of samples obtained from leg ODP 204,1250C site.We have analysed data from several sites and investigated the patterns of gas hydrate deposits in the area,and the origin of the gas hydrate. The results of this research show that the geochemical anomalies of gaseous hydrocarbon indicatrix are mainly distributed in the southern slope of the area studied. This is closely related to the seismic BSR marker and to the development of the ruptures; and that the cause of formation of submarine sedimentary gaseous hydrocarbon methane in the Xisha ocean trough is mainly ascribed to pyrolysis. We discuss the fault-filtering and comprehensive formation pattern of the gas hydrate, which reasonably explains the inconsistency of the BSR zone with the high value anomaly zone of seabed methane, and predicts some favorable prospecting areas. The results also provide the geochemical evidence for the exploration of the gas hydrate, and shed light on the cause of its formation.更多还原