Organic geochemical characteristics and accumulation of the organic matterin the Jurassic to Cretaceous sediments of the Saihantala Sag, Erlian Basin,China
Organic geochemical characteristics and accumulation of the organic matterin the Jurassic to Cretaceous sediments of the Saihantala Sag, Erlian Basin,China
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二连盆地赛汉塔拉凹陷侏罗系至白垩系沉积物有机地球化学特征及有机质富集
DOI：
10.1016/j.marpetgeo.2018.01.002
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发表时间：
2018
影响因子：
4.2
通讯作者：
Liu Yan
中科院分区：
文献类型：
--
作者：
Luo Qingyong;Zhong Ningning;Liu Yan
对二连盆地赛罕塔拉凹陷侏罗系-白垩系烃源岩进行了有机岩石学和有机地球化学分析，确定了其地球化学特征、含油气性和有机质聚集。阿拉坦赫里组(J1+2al)、阿尔山组(K1ba)、腾格里下段(K1bt1)、腾格里上段(K1bt2)和塞罕塔拉组(K1bs)的泥岩具有不同的总有机碳含量和有机质类型。J1+2Al、K1ba、K1bt1和K1bt2泥岩中的显微组分按丰度顺序依次为腐泥岩(包括纹斑岩、矿物沥青基质和稀有的塔拉尔金组)、镜质组和惰质组，而K1bs泥岩中镜质组和惰质组是主要的显微组分。镜质组反射率低于0.7%，表明它们的有机成熟度较低，这与纹石和角晶石的强烈黄色荧光、低Tmax值、17β(H)、21β(H)和HOP-17(21)-烯的存在以及脂肪族和芳香族热成熟度参数相一致。研究样品主要沉积在缺氧盐湖环境中。生物标志物和显微组分表明，J1+2al、K1ba、K1bt1和K1bt2泥岩的主要生物源是细菌和藻类，而K1bs泥岩的生物标志物和显微组分含量表明，高等植物是更重要的生物源。J1+2Al泥岩、K1ba泥岩、K1bt1泥岩和K1bt2泥岩的生油能力主要强于天然气，而K1bs泥岩的生油能力主要强于天然气。尽管所研究的泥岩热成熟度较低，但在塞罕塔拉凹陷东南部发现了丰富的石油，具有成熟的烃源岩。其生成产物的性质是由于有机质积累的形成机制不同所致。J1+2Al、K1ba、K1bt1和K1bt2泥岩的有机质积累主要受高初级生产力和缺氧条件的控制，而K1bS富有机质沉积物的形成主要与高等植物的大量涌入有关。
The organic petrology and organic geochemistry of Jurassic to Cretaceous hydrocarbon source rocks from the Saihantala Sag, the Erlian Basin, have been analyzed to determine their geochemical characteristics, hydrocarbon potential and organic matter accumulation. The mudstones of the Alatanheli Formation (J1+2al), the Aershan Formation (K1ba), the lower Tengger member (K1bt1) and the upper Tengger member (K1bt2) and the Saihantala Formation (K1bs) contain variable total organic carbon concentrations and organic matter type. The observed macerals in the J1+2al, K1ba, K1bt1 and K1bt2 mudstones are sapropelinites (including lamalginites, mineral-bituminous groundmasses and rare telalginites), vitrinites and inertinites in order of abundance, whereas vitrinites and inertinites are the predominant macerals in the K1bs mudstones. The vitrinite reflectances are lower than 0.7% in the studied samples, suggestive of their low organic maturity, which is consistent with the strong yellow fluorescence of the lamalginites and telalginites, low Tmax values, the presence of 17β(H), 21β(H) hopanes and hop-17(21)-enes, and aliphatic and aromatic thermal maturity parameters. The studied samples were mainly deposited under anoxic saline lake environments. The major biological sources in the J1+2al, K1ba, K1bt1 and K1bt2 mudstones are bacteria and algae, whereas higher plants are the more important biological source in the K1bs mudstones as indicated by biomarkers and maceral contents. The J1+2al, K1ba, K1bt1 and K1bt2 mudstones mainly have more capacity to generate oil than gas, whereas the K1bs mudstones are mainly gas prone. Despite the low thermal maturity of the studied mudstones, abundant oil has been found in the southeast of the Saihantala Sag with mature source rocks. The nature of their generated products was due to their different formation mechanisms of organic matter accumulation. The organic matter accumulation in the J1+2al, K1ba, K1bt1 and K1bt2 mudstones was controlled by the high primary productivity and anoxic conditions, whereas the formation of the K1bs organic-rich sediments was mainly related with a high influx of higher plants.