Patterns of early post-depositional and burial cementation in distal shallow-marine sandstones: Upper Cretaceous Kenilworth Member, Book Cliffs, Utah, USA

Machent, Philip G., Taylor, Kevin G., MacQuaker, Joe H. S. and Marshall, Jim D. (2007) Patterns of early post-depositional and burial cementation in distal shallow-marine sandstones: Upper Cretaceous Kenilworth Member, Book Cliffs, Utah, USA. Sedimentary Geology, 198 (1-2). pp. 125-145. ISSN 0037-0738

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Abstract

There is a limited understanding of the spatial linkage between cementation processes in shoreface/coastal plain successions and those operating in distal offshore successions. To address this, an integrated sedimentological, sequence stratigraphic and diagenetic study was undertaken on a distal shallow-marine succession, the Upper Cretaceous Kenilworth Member Book, Cliffs, Utah, USA. Laterally extensive carbonate cement is the most volumetrically significant diagenetic feature. It constitutes up to 55 vol.% of the distal lower-shoreface sandstone and sandy siltstone units beneath major flooding surfaces. During rising relative sea-level major flooding events resulted in low sedimentation, which extended residence time of sediments in early diagenetic zones and promoted enhanced cementation beneath these boundaries. Carbonate for early calcite cements was probably derived from sulphate reduction, marine water and oxidation of organic matter. Stable-isotopic composition of later ankerite (δ18O − 11.9 to − 6.0‰ VDPB, δ13C − 4.5 to − 0.3‰ VDPB) suggests precipitation during progressive burial (c. 1.7 to 3.4 km, 72 to 122 °C) from evolved marine fluids. The carbonate and other mineralizing solutes were derived, increasingly with burial, from decarboxylation of organic matter and clay mineral transformations in adjacent siltstones and shales. These interbedded, overlying and underlying facies provided an important source of mineralizing solutes that influenced the extent of pervasive cementation during burial. The combination of stratigraphic and lithofacies control resulted in laterally extensive cements that differ to shoreface successions, although are similar in form to those described for many offshore mudstone-dominated successions. Limited early concretionary ferroan dolomite beneath the expression of the sequence boundary and some flooding surfaces, however, suggests cementation by meteoric fluids at times of relative sea-level lowstand. Similar processes have been demonstrated in more proximal successions in the Book Cliffs.