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Extensive Diagenetic Carbonate Cementation of Fluvial Successions, Upper Cretaceous, Previous HitBookNext Hit Cliffs, Utah: Implications for Subsurface Prediction


Taylor, Kevin G.1, Rob L. Gawthorpe2 (1) Manchester Metropolitan University, Manchester, United Kingdom (2) University of Manchester, Manchester, United Kingdom


Extensive diagenetic carbonate cementation of marine sandstones is a commonly documented process, as an internal supply of marine carbonate shell material is often available. Such cementation of fluvial sandstone successions is generally considered to be minimal. Here we document an example where carbonate cementation of fluvial successions is intensive (cement bodies over 100 m) and extensive (occurring over distances of 10s of kms) with implications for modelling of sub-surface reservoirs.


Carbonate cement bodies up to 100m long and 20m thick are present within the lowstand fluvial strata of the Desert Member and Castlegate Sandstones, Previous HitBookNext Hit Cliffs, Utah. These cement bodies are composed of early diagenetic ferroan dolomite (δ13C = +3.4 to -3.9o/oo VPDB; δ18O = -8.5 to -12.5o/oo VPDB). Additionally, whitecaps, up to 10m thick, are present beneath coals, formed from the early diagenetic leaching of detrital dolomite. Mapping reveals that cement bodies are present in two Previous HitstratigraphicNext Hit settings: amalgamated fluvial lowstand units; and amalgamated lowstand/highstand sand bodies, both restricted to units laterally down-dip from whitecaps.


The source for cements was detrital dolomite remobilised from updip whitecap units, as has also been shown for cements in marine shoreface sandstones in the Previous HitBookNext Hit Cliffs. δ18O data suggests that cements precipitated from meteoric fluid, although recrystallisation cannot be ruled out. The shape and distribution of the cement bodies, and their relationship to whitecaps and stratigraphy, supports an Previous HitinterpretationTop of detrital dolomite remobilisation by meteoric fluids from up-dip whitecaps, leading to extensive dolomite cementation in down-dip portions of the fluvial succession.


AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California