--> Abstract: Hydrothermal Dolomitization in Paleozoic Carbonates - Enhanced Fluid Flow and Foreland Basin Processes; #90063 (2007)

Datapages, Inc.Print this page

Hydrothermal Dolomitization in Paleozoic Carbonates - Enhanced Fluid Flow and Foreland Basin Processes

 

Lavoie, Denis1, Guoxiang Chi2 (1) Geological Survey of Canada, Quebec City, QC (2) University of Regina, Regina

 

In North America, world-class reservoirs are hosted by Paleozoic hydrothermal dolomites. These fields are found in successions affected by tectono-magmatic processes linked to foreland basins. In eastern North America, Taconian (Middle-Upper Ordovician) and Acadian (Upper Silurian-Lower Devonian) foreland basins generated tectono-magmatic conditions favourable for the formation of hydrothermal dolomites (HTD).

 

The Ordovician HTD cases occur in passive margin to foreland basin carbonates. Hot saline fluids moved along Taconian extensional faults commonly rooted in crystalline basement; these fluids were laterally forced into carbonate units when reaching an effective seal. Coeval K-bentonite deposits testify to major volcanic centres and hence high geothermal gradients critical for enhancing deep-seated fluid convection. The Lower Silurian peritidal ramp facies is dissected by older faults that were reactivated at the late Early Silurian onset of the Acadian foreland basin. The major reef complexes and pinnacles of Upper Silurian to lowermost Devonian were positioned on the paleotopographic highs of tilted extensional tectonic blocks. Lower Devonian outer shelf carbonate facies were deposited in a faulted depositional setting; these faults were in late Early Devonian, reactivated as dextral strike slip. These faults were conduits for episodic high pressure migration of high temperature saline fluids that resulted in local to regional hydrothermal dolomitization. Enhanced fluid convection was generated by high geothermal gradients that resulted from active volcanism episodically recorded from the Early Silurian to the Early Devonian.

 

Lower Paleozoic tectono-magmatic events created conditions for the hydrothermal alteration of carbonates. The Ordovician and Devonian reservoirs host economic accumulations of hydrocarbons.

 

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