The role of volcanic ash in the formation of organic-rich source rock and its source identification

Volcanic ash promotes the formation of organic-rich source rocks by increasing the productivity of sedimentary basins and the formation of conducive preservation environment. In terms of productivity, volcanic ash provides Fe, Mn, Zn and other trace metal elements to sedimentary basins, and promotes the prosperity of water organisms and the improvement of primary productivity. The thickness of volcanic ash deposition is proportional to the concentration of nutrients released. Generally, the thickness of volcanic ash deposits around the crater is much thicker than far away, and more like to obtain the high concentration of nutrients, and make it easier to bloom. In terms of preservation environment, by increasing the salinity of sedimentary basins and participating in the biological sulfate reduction reaction (BSR), volcanic ash promote the formation of a reducing environment conducive to the preservation of organic matter. In addition, in order to deepen the research on the relationship between volcanic ash and the distribution of high-quality source rocks, this article discusses the sources and identification methods of volcanic ash, and proposes that lithium, as an effective geological tracer may have the ability to identify volcanic ash sources.