The impact of meteoric water on the diagenetic alterations in deep-water, marine siliciclastic turbidites

Meteoric-water flux and formation of kaolinite owing to the dissolution of detrital silicates are common features of continental and paralic sandstones. In deep-water marine sandstones, meteoric-water flux is commonly considered unlikely to occur. However, the study of deep-water, marine sandstones of the Shetland–Faroes Basin on the British continental shelf revealed widespread and extensive dissolution and kaolinitization of mica and feldspar grains, which are attributed to meteoric-water flux during a sea-level lowstand. We suggest that this apparently enigmatic meteoric-water flux mechanism is likely to have occurred by hyperpycnal flow. Hyperpycnal flow occurs when river effluent directly transfers into sediment gravity flow, and enters seawater as a mixture of sediment and fresh water. The likelihood for hyperpycnal flows increases at times when rivers and distributary channels reach the shelf edge, and their flows are delivered directly onto the deepwater slope.