A Few Papers I’m Reading This Summer

Hey look at this, I’m posting on this blog again! The academic year has ended and I feel like I can take a breath. When people told me that being a tenure-track junior prof was going to keep me very busy they weren’t kidding, holey moley. But, it’s all exciting, fun, exhausting, challenging, and rewarding.

In an attempt to resuscitate this blog, I wanted to post about a few papers in sedimentary geoscience that I’m currently reading (or will read) this summer:

• From gullies to mountain belts: A review of sediment budgets at various scales — Matthias Hinderer, Sedimentary Geology, 2012 — This is a review paper taking a look at the importance of considering mass balance in Earth surface systems with an emphasis on methods for determining sediment budgets at geologic timescales. This is not about calculating sediment budgets in a hydrology/geomorphology sense — where flux can be monitored and measured in real time along different reaches of a stream, for example — this is about what we can (and, importantly, cannot) estimate or infer regarding paleo sediment budgets. For example, what tools are being used and what critical uncertainties exist for determining sediment budget in Quaternary (<2 million years old) systems? What about further back in time? The paper includes several case study examples that span a range of spatial and temporal scales.
• Scaling laws for aggradation, denudation, and progradation rates: The case for timescale invariance at sediment sources and sinks — Peter Sadler and Douglas Jerolmack, online-early contribution to upcoming GSL Special Publication “Strata and Time: Probing the Gaps in Our Understanding” — I predict this paper will be cited a lot by those of us interested in Earth surface dynamics, it’s a good one. I’ve written about Sadler’s contributions on this blog before (nearly seven years ago, time flies!), which deal with how unsteady depositional processes create a potentially misleading ‘artifact’ when comparing accumulation rates measured over different durations. Sadler & Jerolmack make the point that denudation (mass removal) rates rarely have this problem because methods like catchment-wide cosmogenics or thermochronology (for exhumation information) already sample the entire area of interest. Depositional (mass accumulation) rates, on the other hand, are typically measured in single locations, e.g., a borehole or outcrop section, which rarely are representative of the entire depositional area. This is perhaps an obvious point to make, but sometimes really important points are simple, and I think they articulate it very well. They then go on to make the case that cross-sectional area (a 2-D slice through a depositional volume) is potentially sufficient to approximate the true 3-D mass balance, which is difficult to impossible to constrain in ancient records.
• Mid-Cretaceous to Paleocene North American drainage reorganization from detrital zircons — Mike Blum and Mark Pecha, Geology, 2014 — I have not read this yet, I’m looking forward to diving in soon. This paper uses a database of >5,000 detrital zircon ages to reconstruct continent-scale drainage basin evolution of North American over 10s of millions of years of geologic history. The punchline is that during the Cretaceous much of North American drained north, toward the Arctic, and then in the Paleocene it switched towards the Gulf of Mexico (i.e., what has become the modern Mississippi drainage system).

Happy reading.