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Objective Shallow-water deltas are widely observed in petroliferous basins and can form large-scale hydrocarbon reservoirs. Based on the relative proportions of mud and sand in their deposits， they can be classified into three types—sand-rich， sand-mud， and mud-rich deltas—whose geomorphological expression， depositional characteristics， sedimentary architecture， and sediment heterogeneity differ substantially. At present， systematic research on these three types of shallow-water deltas remains limited， which has severely constrained the efficient exploration and development of oil and gas resources. Methods This study employed sedimentary numerical simulation technology to reproduce the depositional evolution processes of the three types of deltas. Their sedimentary architecture and grain size models were reconstructed from the simulated depositional interfaces and grain size data. Subsequently， from a detailed analysis of the evolutionary processes， sedimentary architectural models for shallow-water deltas were established and the characteristics of sedimentary heterogeneity within this model framework were elucidated. ［Results and Conclusions ］ （1） The sediment supply ratio is a crucial influencing factor in deltaic depositional evolution， as it determines the sedimentation rate and erosion resistance of channel margins. On this basis， the evolution and ultimately the resultant architecture and heterogeneity are determined. （2） As the sand-to-mud ratio decreases， distributary channels exhibit reduced quantity， hierarchical complexity and areal proportion， as well as increased sinuosity， greater stability， diminished lateral migration capacity， and a transition from lateral migration-dominated filling to abandonment-dominated filling. （3） Sand-dominated deltas typically exhibit lobate or triangular shapes， with extensively developed distributary channels forming multistage， radial patterns. They frequently display lateral migration characteristics. Sand-mud deltas manifest as multi-fingered， branching forms with fewer distributary channels that are primarily controlled by trunk distributary channels with multi-directional bifurcations at their termini， creating multiple laterally amalgamated finger-like bar assemblages. Mud-rich deltas possess few distributary channels， being characterized by the development of narrow， sinuous， belt-like trunk distributary channels lacking lateral accretion features. These channels are predominantly infilled with muddy sediments following avulsion and abandonment. （4） Sand-rich deltas show near-continuous sand distribution with downstream fining. Coarsest grains occur in trunk channels， with finer grains in mouth bars， yielding weak planar heterogeneity but strong vertical heterogeneity due to multi-stage lateral/progradational fine-grained interbeds. Sand-mud deltas exhibit broad-banded sand bodies with coarse-grained reservoirs in trunk channels and mouth bars， weak planar heterogeneity， and strong vertical heterogeneity from muddy interbeds. Mud-rich deltas display strong planar heterogeneity， with reservoirs being restricted to mouth-bar cores that are laterally isolated by muddy channels， with weak vertical heterogeneity resulting from multi-stage muddy interbeds.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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