--> ABSTRACT: Carbonate Cementation in Distal Marine Sequences: Upper Cretaceous Panther Tongue and Kenilworth Members, Book Cliffs, Utah, USA, by Philip G. Machent, Kevin G. Taylor, and Joe H. S. Macquaker; #90906(2001)

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Philip G. Machent1, Kevin G. Taylor1, Joe H.S. Macquaker2

(1) Manchester Metropolitan University, Manchester, United Kingdom
(2) University of Manchester, Manchester, United Kingdom

ABSTRACT: Carbonate Cementation in Distal Marine Sequences: Upper Cretaceous Panther Tongue and Kenilworth Members, Book Cliffs, Utah, USA

An understanding of the processes controlling carbonate cementation in distal siltstone sequences is key, so as to enable the linkage of sandstone diagenetic processes to those of distal marine mudstone successions in sedimentary basins. To this aim, we present data from two contrasting marine siltsone sequences from the Cretaceous Western Interior Seaway.

Prodelta siltstones of the Panther Tongue regressive wedge contain carbonate concretions up to 8 metres in length. These are rare in proximal facies, increasing in abundance down-dip. The diagenetic component of these concretions is an early, pre-compactional ferroan dolomite (av.4 mol% Fe, up to 40% by volume). In contrast, carbonate cementation in the distal sandy siltstone of the aggradational to progradational Kenilworth Member is characterised by laterally extensive cement below marine flooding surfaces, with only minor concretionary bodies. These cement zones can be traced for several kilometres, vary in thickness from 0.6 to 4 metres and are cemented by early to intermediate ferroan calcite (av.2 mol% Fe) and later ankerite (av.17 mol% Fe).

Based on field and petrographic relationships, we propose that the dolomite cements in the Panther Tongue were sourced from the remobilisation of detrital dolomite by meteoric fluids that entered the Panther Tongue as a result of relative sea-level fall. In contrast, the lateral cements within the Kenilworth Member were initiated beneath marine flooding surfaces at times of depositional hiatus, with cement precipitation continuing through burial. These results highlight the spatial and temporal variability of diagenetic processes in sedimentary basins.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado