Dimensions, texture-distribution, and geochemical heterogeneities of fracture-related dolomite geobodies hosted in Ediacaran limestones, northern Oman

摘要

Predicting spatial distribution, dimension, and geometry of diage-netic geobodies, as well as heterogeneities within these bodies, is challenging in subsurface applications, and can impact the results of reservoir modeling. In this outcrop-based study, we generated a data set of the dimensions of fracture-related dolomite geobodies hosted in Ediacaran (Khufai Formation) limestones of the Oman Mountains that are up to several hundreds of meters long and a few tens of meters wide. The dolomite formed under burial conditions by fluids that interacted with siliciclastic layers, as demonstrated by the enriched Fe (up to 4.4%) and Mn (up to 0.8%) contents and ~(87)Sr/~(86)Sr (~0.710) signatures. Dolomitization probably occurred during the Hercynian Orogeny (or pre-Permian) because dolomitization predates some folding and pre-Permian rocks have seen intense deformation related to the Carboniferous Hercynian Orogeny. Moreover, dolomitization occurred between the onset and termination of bedding-parallel stylolitization and thus most likely before deep burial related to the Alpine Orogeny. Hence, dolomitization most likely occurred before deep burial related to the Alpine Orogeny and during or following the intense deformation related to the Carboniferous Hercynian Orogeny had affected pre-Permian rocks.