Tuesday, June 30, 2015

Highlights—Clinoform Geometries and Sediment

Clinoforms are fundamental sequence and seismic stratigraphic elements, reflecting information on sediment distribution in space and time to and across shelf margins. In this contribution, Gong et al. quantitatively explore relationships between clinoform-growth styles and sand- and sediment-budget partitioning across shelf margins of late Miocene-Quaternary clinoforms of the northwestern South China Sea. The results illustrate that clinoform-growth styles represent distinct stratal stacking patterns and sediment distribution. For example, downward-prograding shelf-margin clinoforms with low angles of growth trajectories (Gct) and low clinoform height (Hc) favor partitioning volumes of sediment into deep-water areas, thus are fronted by sand-rich submarine fan systems. In contrast, steeply upward aggrading shelf-margin clinoforms with high Gct and high Hc favor storage of volumes of sediment on shelf margins, and hence include mud-dominated mass-transport systems downdip of shelf breaks. Gct and Hc therefore increase linearly with sediment budget stored on shelf margins, but decrease linearly with sand- and sediment-budget partitioning into deep-water areas, provided similar sediment-supply conditions through time. The results suggest that clinoform-growth styles are thus good predictors of sand- and sediment-volume partitioning across shelf margins.

Growth styles of shelf-margin clinoforms: prediction of sand- and sediment-budget partitioning into and across the shelf by Chenglin Gong, Yingmin Wang, Ronald J. Steel, Cornel Olariu, Qiang Xu, Xiangnan Liu, and Qianhui Zhao

Monday, June 8, 2015

Highlights—Dueling pore systems from bioturbation

Bioturbation is an important post-depositional process that can alter sedimentary textures, porosity, and permeability. Here, Baniak et al. examine the influence of burrow geometry and connectivity on porosity and permeability within the Upper Jurassic Ula Formation of the Norwegian Central Graben. Spot permeametry data and numerical modeling of this shoreface succession illuminate relationships among burrow morphology, bioturbated volume, and burrow connectivity. These data provide insights for a conceptual framework for assigning bulk permeability to reservoir media, useful to better characterize hydrocarbon deliverance through bioturbated sandstone reservoirs with dual porosity and dual permeabeability systems.