HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Al-Ramadan, K. Articles by Al-Aasm, I. Search for Related Content GeoRef GeoRef Citation

Distribution of Diagenetic Alterations in Siliciclastic Shoreface Deposits within a Sequence Stratigraphic Framework: Evidence from the Upper Jurassic, Boulonnais, NW France

¹ Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36, Uppsala, Sweden
² Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36, Uppsala, Sweden
³ Géosciences Rennes, UMR CNRS 6118-Université de Rennes I, Campus de Beaulieu, 263 Avenue du General Leclerc, 35042 Rennes Cedex, France
⁴ Department of Earth Sciences, University of Windsor, Windsor, Ontario N9B 3P4, Canada

The distribution of diagenetic alterations in Upper Jurassic, siliciclastic shoreface sediments from NW France has been linked to the sequence stratigraphic framework. Calcite cement in mudrocks and sandstones of the transgressive (TST) and lower part of the highstand (HST) systems tracts is microcrystalline and occurs as continuously cemented layers and stratabound concretions. The average ¹⁸O_V-PDB (–2.6) and ⁸⁷Sr/⁸⁶Sr (0.7078) compositions of microcrystalline calcite indicate precipitation from largely marine pore waters.

Calcite cement in sandstones of the forced regressive wedge (FRWST) and lowstand (LST) systems tracts is poikilotopic and occurs mainly as stratabound concretions. Complete dissolution of the carbonate grains and concomitant precipitation of poikilotopic calcite cement with low average ¹⁸O (–5.3) and radiogenic Sr-isotope (0.70882) signatures suggest incursion of meteoric waters into sandstones during relative sea-level lowstand. The poorly lithified sandstones interbedded with sandstones cemented by poikilotopic calcite concretions display evidence of diagenesis under episodes of arid to semiarid paleoclimate, including: (i) partial cementation by opal, chalcedony, gypsum, and minor vadose calcite cement, (ii) mechanically infiltrated clays and Fe-oxides, and (iii) secondary porosity owing to partial dissolution of carbonate grains. The integration of diagenesis into sequence stratigraphy allows better elucidation and prediction of the spatial and temporal distribution of diagenetic alterations and related reservoir-quality modifications in shoreface sediments.