--> Abstract: Episodic Advance of the Sigsbee Salt Canopy, Deepwater Gulf of Mexico, by Michael R. Hudec; #90078 (2008)

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Episodic Advance of the Sigsbee Salt Canopy, Deepwater Gulf of Mexico

Michael R. Hudec
Bureau of Economic Geology, The University of Texas at Austin, Austin, TX

Many areas along the Sigsbee Escarpment display two stages of salt-sheet advance: (1) an early stage fed from a deeper source layer via feeder diapirs, and (2) a later stage fed by expulsion of salt from beneath updip minibasins. The phases may be continuous if minibasins are already sinking into the updip part of the sheet at the time when the deep source layer is exhausted. However a hiatus between the two stages may occur, especially if the sheet is far from the sediment source, where minibasins are less common.

The end of Stage 1 is often triggered by ponding behind a bathymetric buttress. Buttresses can by formed by (a) rapid sedimentation in front of an advancing sheet, (b) a fold deforming the sea floor, (c) an imbricate wedge bulldozed by the salt, or (d) a minibasin rafted against the leading edge of the sheet.

Once pinned at the end of Stage 1, constant-thickness sediments bury the leading edge of a sheet. Later subsidence of minibasins further updip inflates the leading edge of the sheet, uplifting this roof. The inflated salt may quickly break out to the sea floor if the roof is thin. Thicker roofs require a longer phase of compressional folding and overthrusting before breakout is possible.

 

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas