Sedimentology and Organic Matter Dynamics in Fine-Grained Sedimentary Rocks

Fine-grained sedimentary rocks, including mudstones and shales, archive processes of sediment delivery, organic matter accumulation and early diagenesis in a variety of marine and lacustrine settings. Their depositional fabrics, often expressed as laminae or microfacies, result from fluctuations in energy, supply of siliciclastic and biogenic material, redox conditions and relative sea-level change. Organic matter dynamics in these rocks encompass kerogen deposition, preservation under suboxic to anoxic bottom waters and subsequent transformation during burial. Mineralogy, pore networks and fracture fabric interact to control porosity, fluid storage and migration pathways. Advances in geochemical proxies, high-resolution imaging and laboratory simulation techniques have refined models of organic carbon accumulation, reservoir quality and basin-scale resource evaluation, with implications for hydrocarbon exploration, carbon sequestration and palaeoclimate reconstruction.

Research from Nature Portfolio

Recent studies have used sequential high-pressure water pyrolysis to simulate in situ petroleum generation and expulsion in uplifted onshore basins. This method reproduces gas yields and dry gas compositions consistent with actual shales, demonstrating that low porosity (circa 1%) is sufficient to accommodate generated gas. Extrapolation to regional scales refines estimates of maximum gas-in-place and highlights the importance of realistic laboratory protocols for resource assessment and exploration strategy.

Sedimentology and Organic Matter Dynamics in Fine-Grained Sedimentary Rocks publication trend

The graph below shows the total number of articles in sedimentology and organic matter dynamics in fine-grained sedimentary rocks across all publications each year (not limited to Nature Index journals).

Technical terms

Laminae: Thin layers or seams in sedimentary rocks, varying in composition and grain size, which record changes in depositional conditions.

Kerogen: Insoluble organic matter in sedimentary rocks that generates hydrocarbons upon thermal maturation.

Diagenesis: Physical, chemical and biological changes occurring in sediments after deposition, affecting porosity and organic matter preservation.

Porosity: The proportion of void space in a rock, governing fluid storage capacity and gas migration.

Pyrolysis: Thermal decomposition of organic matter under controlled laboratory conditions to assess hydrocarbon generation potential.

Microfacies: Small-scale sedimentary units characterised by texture, composition and fossil content, used to infer depositional environments.

References

1. Shale gas reserve evaluation by laboratory pyrolysis and gas holding capacity consistent with field data. Nature Communications (2019).
2. Heterogeneity and Sedimentary Characteristics of Shale Laminae of Fine-Grained Sediments in Alkaline Lacustrine Strata in the Permian Fengcheng Formation, Mahu Sag, NW China. Energies (2024).
3. From marine bands to hybrid flows: Sedimentology of a Mississippian black shale. Sedimentology (2019).
4. Depositional Structures and Their Reservoir Characteristics in the Wufeng–Longmaxi Shale in Southern Sichuan Basin, China. Energies (2022).