Highlights: Cambrian Cratonic Carbonates

What sediments are preserved during sea-level falls on cratonic passive margins? Raine and Smith explore the concept that on many carbonate platforms, sequence boundaries are represented by a zone of shallower facies and it is difficult to identify a single surface as a sequence boundary. To do so, they start by describing facies that provide evidence of a coastal sabkha, a sedimentary environment commonly not well preserved in Palaeozoic carbonates. At a larger scale, they document stacking patterns and physical features (e.g., karst, sandstone) that record a falling stage systems tract and a well-defined type 1 sequence boundary in a Cambrian succession in Scotland, interpreted to be consistent with the idea that the Sauk II-III boundary represents a major sea-level fall associated with progradation of sabkhas.

Sabkha facies and the preservation of a falling-stage systems tract at the Sauk II–III supersequence boundary in the Late Cambrian Eilean Dubh Formation, NW Scotland by Robert J. Raine and M. Paul Smith

Highlights: Seismic Expression of Fluvial Channels

Fluvial channels are inherently three-dimensional features; although challenging to study on two-dimensional outcrops, seismic data provide unique perspectives on their architecture. Alqahtani and others evaluate the geometry, dimensions, distribution and evolution of fluvial channel systems from a humid-tropical climatic setting through detailed analysis of high-resolution 3D seismic reflection data from the Malay Basin. The interpretations reveal eight depositional units that include systematic changes in six types of fluvial channels defined based on cross-sectional and planform geometries. The data provide input for reconstructions of the palaeo-hydrological conditions during Pleistocene sea-level cycles that affected the Sunda Shelf Sea. The manuscript further evaluates the roles that sea-level variations, climate, and sediment supply play on controlling the formation and evolution of fluvial systems, including incised valleys and associated tributary channels.

Controls on the geometry and evolution of humid-tropical fluvial systems: insights from 3D seismic geomorphological analysis of the Malay Basin, Sunda Shelf, Southeast Asia by Faisal A. Alqahtani, Christopher A.-L. Jackson, Howard D. Johnson, and M. Rapi B. Som