Dolomite-cemented fractures outcrop

Fig. 4. (A) Stratigraphy of Carboniferous rocks at Ballycastle, based on outcrop logging and data from Wilson Robbie (1966). Sandstones continue for approximately 200 m below the base of the log but are poorly exposed. (B) Sedimentary log of the study horizon labelled with sampling sites (1) cemented fractures and host sandstone (2) the Main Limestone (3) sandstone of similar facies but lacking dolomite-cemented fractures (4) dolomite beef vein. See text for description of facies associations.

Internally complex, ferroan dolomite-cemented fractures are a prominent feature within a fluvial sand body at Ballycastle, on the margins of the Rathlin basin in northeast Ireland. The cemented fractures display a tight modal orientation that is coincident with the dominant local normal faulting trend, and are interpreted to have formed in the same tectonic regime. However, there is no clear trend in the spatial distribution or width of the fractures with respect to a fault plane situated at one end of the outcrop. 

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