Sediment Accumulation Rates and the Completeness of Stratigraphic Sections

TLDR

Sediment accumulation is primarily driven by unsteady, discontinuous sedimentation, with fluctuations that increase with longer recurrence intervals, and measurement error and compaction only partially explain observed regressions. The study aims to use ratios of median long‑to‑short‑term accumulation rates to assess the expected completeness of sedimentary stratigraphic sections at short‑term timescales. The authors calculate these ratios of median long‑to‑short‑term accumulation rates to quantify expected stratigraphic completeness. Sediment accumulation rates span 11 orders of magnitude, decline systematically with longer time spans, vary across depositional environments, and show that expected stratigraphic completeness deteriorates at finer temporal scales.

Abstract

A compilation of nearly 25,000 rates of sediment accumulation shows that they are extremely variable, spanning at least 11 orders of magnitude. Much of this variation results from compiling rates determined for different time spans: there is a systematic trend of falling mean rate with increasing time span. The gradients of such trends vary with environment of deposition. Although measurement error and compaction contribute to these regressions, they are primarily the consequence of unsteady, discontinuous sedimentation. The essential character of the unsteadiness may be cyclic or random, but net accumulation is characterized by fluctuations whose magnitudes increase with increasing recurrence interval. Ratios of median long- to short-term accumulation rates provide a measure of the expected completeness of sedimentary stratigraphic sections, at the time scale of the short-term rate. Expected completeness deteriorates as finer time scales are considered.