--> Abstract: Modeling Near-surface Porosity Evolution in Isolated Carbonate Platforms: a New Diagenetic Scheme for the CARB3D+ Forward Simulation Model; #90063 (2007)
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Modeling Near-surface Porosity Evolution in Isolated Previous HitCarbonateNext Hit Platforms: a New Diagenetic Scheme for the CARB3D+ Forward Simulation Model

 

Smart, Peter L.1, Fiona Whitaker2, Richard Paterson3, David Oldham1 (1) University of Bristol, Bristol, England (2) University of Bristol, Bristol, United Kingdom (3) Bristol University, Bristol, United Kingdom

 

We have developed a 3-dimensional forward model for the sedimentology of Previous HitcarbonateNext Hit platforms (CARB3D+) which incorporates near-surface Previous HitdiagenesisNext Hit (Patterson et al, Journ. Sed. Res. 76). This provides a useful tool to aid understanding of the complex relationships between sequence stratigraphy and the extent of diagenetic modification. A depth-averaged freshwater lens model is used to predict the distribution of vadose, freshwater, mixing and saline zones in exposed Previous HitcarbonateNext Hit sediments. Processes and uniform rates of Previous HitdiagenesisNext Hit are than defined for these zones, allowing the progressive changes in fabric selective porosity, cement volume and mineralogy to be tracked through time. Secondary porosity is used to up-scale to island-scale permeability, permitting critical feedbacks between the evolving poro-perm characteristics and distribution of the hydrological-zones to be included. A revised diagenetic scheme is currently under development which reduces the extent of user-defined model parameterisation, being based on the nature of the regional climate (temperature, rainfall and potential evapotranspiration) and nature and thickness of the soil cover. It is conceptually based on hydrological flow paths, and considers the progressive changes which occur in the geochemistry of waters along these paths. It is therefore incorporates 2 key aspects of Previous HitdiagenesisNext Hit recognised from hydrochemical and geological studies of modern Previous HitcarbonateNext Hit platforms; the strong depth dependence of both dissolution and cementation in any specific hydro-zone, and the dependence of Previous HitdiagenesisNext Hit rates on the extent of Previous HitdiagenesisTop in the overlying hydro-zone. Preliminary 1D modelling results will be presented to explore the implications of different model schemes for meteoric dissolution and cementation.

 

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