Quartz Cementation History of Sandstones Revealed By High-Resolution Sims Oxygen Isotope Analysis

Abstract

Evaluating the timing and origin of quartz cement is central to understanding how porosity is lost in sandstones during burial. Kinetic models of quartz cementation have been calibrated using large-scale datasets but have never been tested at the microscopic level at which cement forms. Here, we use high-precision, in situ oxygen isotope analyses on sandstone from the Jurassic Ness Formation from the North Sea to reveal the growth history of single quartz overgrowths to a resolution of 2 mm. Measured d 18 O (cement) range from +28 to +20% V-SMOW in early to late cement and are consistent with quartz cementation models that propose the bulk of quartz precipitates as a continuous process beginning at 60-70 uC. Quantitative Xray Diffraction analyses and clay mineralogical analysis of interbedded shales are inconsistent with a silica source from shale, implying that silica for the cement is sourced internally to the sand. These isotope data are broadly consistent with predictive, conceptual quartz cementation models and provide a critical link from micron-scale measurements to basin-scale predictions and observations.

Insights into rates of fracture growth and sealing from a model for quartz cementation in fractured sandstones

“…Models that incorporate this kinetic approach together with the assumption of precipitation rate limitation have had impressive success at reproducing quartz cement abundances in sandstones from a broad range of geologic settings (i.e., Lander and Walderhaug, 1999;Walderhaug et al, 2000;Bloch et al, 2002;Taylor et al, 2004;Lander et al, 2008;Tobin et al, 2010;Taylor et al, 2010). Predictions made using this kinetic approach are consistent with high-resolution isotopic data from quartz overgrowths (Harwood et al, 2013).…”

“…Walderhaug (1994Walderhaug ( , 1996Walderhaug ( , 2000 postulated that in unfractured portions of most sandstones, the rate-limiting control on quartz overgrowth cementation is the crystal precipitation rate. While the crystal growth-rate limitation on quartz precipitation does not explicitly constrain the source or transport mode of the cement solutes, fl ow and mass balance calculations argue for mainly local sources (Bjørklykke and Egeberg, 1993;Giles et al, 2000;Harwood et al, 2013). Variations in quartz supersaturation state are likely to be of secondary concern for growth kinetics given that most formation fl uids have near-neutral pH values and are at or slightly above saturation with quartz (Livingstone, 1963).…”

The Carbonate Geochemistry of Enceladus' Ocean

“…The third assemblage is metastable, but could be present if the formation of quartz was kinetically inhibited (Drever, 1997). Yet instances of lowtemperature (<100°C) quartz formation on Earth have been reported (Harwood et al, 2013;Sharp et al, 2016;Streit et al, 2012).…”

Life and Liesegang: Outcrop-Scale Microbially Induced Diagenetic Structures and Geochemical Self-Organization Phenomena Produced by Oxidation of Reduced Iron

“…The interpretation of these patterned rocks as products of the Liesegang phenomenon does not, however, address the source of chemical components, the timing of pattern formation, or the fluid chemistry responsible for mineral precipitation at specific localities. (2) Mineral cements are archives in which records of fluid-mineral interaction are stored, a fact that has prompted considerable interest in the origin of carbonate and silicate mineral cements (e.g., Harwood et al, 2013;Tomkinson et al, 2013). IOCs have not, with recent exceptions (Chan et al, 2012, and references therein;Weber et al, 2012;Vasconcelos et al, 2013;Reiners et al, 2014), been subjected to the detailed study that is commonplace for carbonate or silicate cements.…”