Microcrystalline quartz generation and the preservation of porosity in sandstones: evidence from the Upper Cretaceous of the Subhercynian basin, Germany by Marsha W. French, Richard H. Worden, Elisabetta Mariani, Richard E. Larese, Russell R. Mueller, and Chris E. Kliewer
Friday, July 13, 2012
Diagenetic processes can either destroy or create porosity; in some cases early events can markedly influence later processes. French et al. describe scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) observations from a Cretaceous succession in Germany and relate these observations to porosity. The data reveal nanofilms of amorphous silica between the detrital quartz grains and a subsequent microcrystalline quartz cement with c axes randomly oriented relative to the grain. These observations lead to a conceptual model for one means of preservation of porosity in deep sandstone reservoirs, wherein the amorphous silica nanofilm inhibits growth of systematically growing quartz that could fill the pores.