深时源-汇系统古地理重建方法评述

源-汇系统根据侵蚀、搬运及沉积作用的显著程度可划分为物源区、过渡区和沉积区,根据研究的时间尺度可划分为现代系统、第四纪系统和深时系统。洋陆边缘源-汇系统根据地貌单元的空间配置可划分为"陡—短—深"、"宽—深"及"宽—浅"3种空间分布类型,这3种类型在沉积体积分布及沉积记录保存潜力上存在差异。完整的源-汇系统古地理重建包括沉积区古地理重建和物源区古地理重建。深时尺度下沉积区古地理重建方法随着岩相古地理、构造古地理、生物古地理及层序地层学的发展已趋完善,而物源区古地理重建则更具挑战性,尤其是在物源区遭受侵蚀而不复存在的情况下更具难度。在源-汇分析方法体系中,物源区古流域水系形态、面积范围、地貌地势等古地理要素可通过构造要素分析、碎屑矿物分析、沉积体积回填、地貌学参数比例关系、古水力学参数比例关系和河流沉积通量模型等方法获得。总之,深时源-汇系统古地理重建能够通过盆地沉积记录揭示出物源区古地理演化特征,为沉积盆地充填过程提供沉积供给的信息,对能源矿产勘探和深时古环境研究具有重要意义。

Review on palaeogeographic reconstruction of deep-time source-to-sink systems

The source-to-sink(S2S)system can be partitioned into the sediment source,the transition zone,and the sediment sink according to the significance of erosion,transportation or sedimentation in each zone. In terms of the time scale of the research,the S2S systems can be classified into modern systems,Quaternary systems,and deep-time systems. Based on spatial configuration of geomorphological units,the S2S systems can be subdivided into three end-member types,“steep-short-deep”,“wide-deep”,and “wide-shallow”,each of which has differences in sediment volume partition and preservation of sedimentary signals. The complete palaeogeography reconstruction in a S2S system includes reconstruction of the sink palaeogeography and the source palaeogeography. Methods for the sink palaeogeography reconstruction in deep-time scale are approaching their perfection with the development of lithofacies palaeogeography,tectono-palaeogeography,biological palaeogeography and sequence stratigraphy,while the understanding of the source palaeogeography remains challenged,especially when the sediments in the source areas are no longer preserved due to either later tectonic destruction or no deposition. In the S2S approach system,palaeogeography parameters like drainage patterns,areas,and relief in the source area can be acquired through analysis of tectonic elements,analysis of detrital minerals,sediment-volume backfilling,geomorphological scaling relationships,palaeohydraulic scaling relationships,and river sediment flux model. In conclusion,palaeogeography reconstruction of source-to-sink systems in deep-time can reveal the evolution of source palaeogeography from the sedimentary record in the sink,provide the information of sediment supply for basin fill processes,and is of great significance for the prospecting of energy resources and the understanding of palaeoenvironmental evolution in deep-time.