Global distribution, hierarchical clustering classification, and significance of Holocene braid deltas

Abstract Braid deltas, environments that form where braided rivers meet base level, are more abundant on Holocene Earth than previously appreciated. A worldwide survey identified 786 braid deltas with feeder systems >500 m wide. Braid deltas occur at all latitudes north of the Antarctic Circle and are most abundant by land area in the 45°S–60°S and 60°N–90°N latitude bands. Marine-associated braid deltas compose 71% of the dataset, with the remainder in marginal lacustrine settings. Half of the observed braid deltas do not form radial terminal delta-plain geometry. Hierarchical clustering analysis separates braid deltas into nine clusters that define a classification scheme. Drivers of differentiation include basin type, embayment, sediment supply, and flow intermittence. The classified dataset provides analogues to ancient, nonvegetated deltaic environments and the essential framework for development of braid-delta facies models.