Lower Paleozoic hydrocarbon-generation history in the mid-south of North China Basin
Lower Paleozoic hydrocarbon-generation history in the mid-south of North China Basin
复制标题
DOI：
--
复制
发表时间：
2005
影响因子：
1.8
通讯作者：
Xu Hua-zheng
中科院分区：
文献类型：
--
作者：
Xu Hua-zheng
中国盆地北部下古生界海相碳酸盐岩总体上具有有机质丰度低、成熟度高的特点。有机质丰度低是由沉积环境造成的。岩性、岩石结构和沉积构造证明，下古生界中国盆地北部主要分布在浅海和泻湖，水体不平静，盐度较高。蒸发速率高，沉积环境不利于低级生物生长和保存。高成熟度是中新生代产生的深部变质作用所致。特别是当中生界被厚度2000~2500米的中、下三叠统盖盖时，下古生界烃源岩埋藏深度超过3000米，早期生烃充分。根据1500个样品的数据，很少有样品的有机质丰度超过0.5%，其平均值不到0.2%。氯仿沥青“A”含量低于0.012%。S 1+S 2的平均浓度低于0.2 mg/g，均达不到有效油源岩的标准。利用Tti、、Ro换算和地层对比恢复了中、下三叠统碳酸盐岩盆地的沉积环境。计算的三叠纪末下古生界热变质程度大于1.2%，与目前中国盆地北部热变质程度的分布相吻合。
The lower-paleozoic marine carbonate rocks in North China Basin were generally characterized by low abundance of organic matter and high maturity. The low abundance of organic matter was caused by the sedimentary environment. Lithology, rock texture and sedimentary structure proved that the North China Basin in the Lower Paleozoic was mainly in the shallow inland sea and lagoon, where water was unquiet and salty. The evaporation rate was high, and the sedimentary environment was unfavorable for low-grade living beings to grow and be preserved. The high maturity was caused by the deep-seated metamorphism produced in the Mesozoic-Cenozoic period. Especially, when the Mesozoic was covered by the low-middle Triassic Formations with the thickness ranged from 2000 meters to 2500 meters, the buried depth of the Lower Palaeozoic source rocks was over 3000 meters, which resulted in the early-hydrocarbon-generation fully. According to the data of 1500 samples, the organic matter abundance of few samples exceed 0.5 percent, and their average value is less than 0.2 percent. The content of chloroform bitumen “A” is lower than 0.012 percent. The average concentration of S 1+S 2 is lower than 0.2mg/g. All these indications are inaccessible to the standard of effective oil source rock. The TTI R o conversion and strata correlation were used to recover the sedimentary environment of the low-middle Triassic carton basin. The calculated thermal metamorphic grade of the Lower Paleozoic at the end of Triassic is higher than 1.2 percent, which accords well with the present distribution of thermal metamorphic grade in North China Basin.