Department of Geosciences, University of Arkansas, Fayetteville, AR, 72701, USA.
Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, 78758, USA.
Sci Rep. 2019 Mar 11;9(1):4115. doi: 10.1038/s41598-019-39754-6.
Understanding how environmental forcings (e.g., tectonics, climate) are transformed by erosional landscapes into sedimentary signals is a critical component of inverting the stratigraphic record. Previous research has largely focused on sediment supply (Q) and grain size as the de facto sedimentary signals of changing forcing mechanisms. We use a numerical model to consider the paired response of sediment provenance (P), expressed as fractional sediment load, and Q to demonstrate that the same change in environmental forcing may have a different expression in the sedimentary record. While Q reflects integrated denudation across an erosional catchment, P is controlled by spatially variable erosion that occurs in transient landscapes. P from proximal sediment sources increases during upstream knickpoint migration, whereas P from distal sediment sources increases when bedrock channels incise to produce lower gradient profiles. Differences between the Q and P signals relate to distinct geomorphic processes that operate on different time scales and allow for a refined differentiation of the timing and mechanism of forcings than possible via analysis of either signal alone. Future efforts to integrate multiple sedimentary signals may thus yield a richer picture of underlying forcing mechanisms, facilitating efforts to invert the stratigraphic record.
理解环境强迫（例如构造、气候）如何通过侵蚀地貌转化为沉积信号，是反演地层记录的关键组成部分。先前的研究主要集中在沉积物供给（Q）和粒径作为变化的强迫机制的实际沉积信号上。我们使用数值模型来考虑物源（P）和 Q 的配对响应，以证明相同的环境强迫变化可能在沉积记录中有不同的表现。虽然 Q 反映了侵蚀性流域的整体剥蚀，但 P 则受到瞬态地貌中空间变化的侵蚀控制。当上游的节点迁移时，来自近端物源的 P 会增加，而当基岩河道切入产生较低梯度剖面时，来自远端物源的 P 会增加。Q 和 P 信号之间的差异与不同的地貌过程有关，这些过程在不同的时间尺度上运行，允许比仅通过分析任一信号更精细地区分强迫的时间和机制。因此，未来整合多个沉积信号的努力可能会更好地反映潜在的强迫机制，从而有助于反演地层记录。
