资源环境科技发展态势分析平台

Bedding-parallel veins of fibrous calcite (also called “beef”) occur in many sedimentary basins, especially those containing low-permeability strata with organic source material for petroleum. The formation of such veins is commonly linked with fluid overpressure in these source rocks. In this review, we demonstrate that beef veins are most commonly present in foreland basins worldwide or in basins that recorded a compressive tectonic period. The formation of beef veins is related to two main phases: (1) the initiation of bedding-parallel fracture and (2) the infilling of the fracture.

Previous structural studies have shown that formation of beef veins occurred during a period of compressive stress activity. This is especially the case for the Wessex Basin (United Kingdom) and the Neuquén Basin (Argentina). In this paper, we provide more observations for other basins: the Cordillera Oriental (Colombia), the Paris Basin (France), the northern Pyrenees (France), the Uinta Basin (United States), the Tian Shan Mountains (central Asia), and the Appalachian Mountains (United States). In the Paris Basin, beef vein formation is dated at 155 Ma (U/Pb calcite method) and is coeval with the compressional deformation in the eastern part of the basin.

Because of the timing of generation for such veins and even if the theory and the experiments of fracturing demonstrate that bedding-parallel fractures can be generated only with a distributed fluid overpressure, the formation of beef veins seems to be a consequence of both fluid overpressures and a compressional tectonic stress.