Systematic destruction of K-Feldspar in deeply buried rift and passive margin sandstones
Systematic patterns of detrital K-feldspar decline with increasing burial depth are revealed during deep burial (2.5-4.5km) of sandstones in diverse sedimentary basins from three rift and two passive margin setings in the North Sea and USA gulf coast. K-Feldspar destruction is predominantly by dissolution, though in-situ alteration to albite also occurs. Dissolution can remove up to 15% solid volume of the rock by 4.5km, so that primary arkosic snadstones become diagenetic quartzarenites at depth, with increased secondary:primary porosity ratios. Deeply buried sandstones are not reliable records of depositional composition.