『Abstract
The interactions among climate, erosion, and tectonics have long
been of interest to geologists, but have not yet been united into
a single theoretical framework. In this study, representations
of orographic precipitation and fluvial erosion are combined with
the concept of a critical wedge orogen. The idealized framework
captures the basic system dynamics. It also allows for a formal
analysis of the precipitation and tectonic interactions in terms
of feedback factors and gains, and so permits a quantitative comparison
of their relative strengths. The constraint of self-similar growth
in a critical wedge orogen acts as a tectonic governor, whereby
changes in orogen size are strongly damped. We determine that
this negative tectonic feedback is stronger than the precipitation
feedback, which may be negative or positive depending on whether
precipitation increases or decreases with orogen size. For an
extreme positive feedback unconstrained runaway growth is possible,
ultimately leading to plateau formation. When orographic precipitation
leads to a significant rain shadow, there is a strong partitioning
of rock uplift rates that favors the wet, windward flank of the
orogen. This flank also dominates the response of the whole orogen
to changes in climate or tectonic forcing, except in the case
where a large fraction of the eroded material is recycled into
the wedge. Finally, it is demonstrated that the response time
of the orogen depends on the feedbacks, and is proportional to
the gain of the system.』
1. Introduction
2. Feedback basics
2.1. A precipitation feedback
2.2. Definitions of grains and feedback factors
3. Orographic precipitation
3.1. Precipitation as a function of orogen size
3.2. Discussion of precipitation model
4. The case of a one-sided critical wedge orogen
4.1. Results of coupling one-sided critical wedge orogen
to orographic precipitation model
4.2. Runaway growth
5. Response of rock uplift rates to the precipitation feedback
6. The case of a two-sided critical wedge orogen
6.1. Partitioning of rock uplift rates
6.2. Response of two-sided orogen to a climate feedback
6.3. The effect of sediment recycling
7. The relative strength of the tectonic and precipitation feedbacks
8. The connection between feedback strength and the orogen response
time
9. Summary
10. Discussion
Acknowledgments
Appendix A Feedback analysis for two-sided critical wedge
References