川北青川地区下寒武统沥青质砾石的发现及其意义

    Discovery of bituminous gravels in the Lower Cambrian in Qingchuan, northern Sichuan, China and its geological significance

    • 摘要: 沥青质砾石被发现于四川省青川县白家镇一带的下寒武统碎屑岩中。黑色的沥青质砾石多呈次圆状或次棱角状,表面光滑但无光泽,与胶结物之间有明显的界线,直径最大可达5cm。推测这些砾石可能来自于被剥蚀的震旦系灯影组。沥青、碳酸盐岩和页岩以砾石的方式沉积于下寒武统,表明在早寒武世筇竹寺期之前川北青川地区已存在有古油藏,前寒武系中可能还有生烃的烃源岩。

       

      Abstract: Bituminous gravels are found in Lower Cambrian clastic deposits at Baijia Township, Qingchuan County, northern Sichuan Province. The black bituminous gravels are mostly subrounded or subangular, with a smooth surface by no luster, and have a maximum diameter of 5 cm, and there is distinct boundary between them and their cements. It is inferred that these gravels may have come from the denuded Dengying Formation. The deposition of bitumen, carbonate rocks and shale as gravels from the Lower Cambrian implies that a palaeo-petroleum-reservoir had existed in/near the Qingchuan area, northern Sichuan, before the Early Cambrian Qiongzhusian and that hydrocarbon source rocks may occur in the Precambrian in northern Sichuan.

       

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