Federico F. Krause¹
(1) University of Calgary, Calgary, AB

Abstract: Clathrate hydrate frost heave structures in a carbonate mud-mound: Meiklejohn Peak, Nevada, U.S.A

On the west face of Meiklejohn Peak, Nevada is located a large, wedge-shaped, light-grey carbonate mud-mound with a steep north flank and a gentle south flank. Over and underlying lithologies which encase the mud-mound accumulated below storm and swell wave-base, in a slope or toe-of slope location.

Light-grey stromatactis and zebra limemudstones and wackestones are common to the mound's core and flanks and are often interbedded with dark grey, nodular, bioclastic limewackestones and limepackstones. Most striking along the mound's northern flank are breccia beds with angular clasts (typically boulder to pebble size) with abundant zebra and stromatactis lithologies. Encasing the breccia deposits are dark grey nodular beds that slump into them. Disposition of these two deposits suggests that failure occured subcutaneously. Spar and sediment filled neptunian dykes, as well as injection pipes and sills containing dark grey nodular beds are present along the base and south flank. All of these lithologies are indicative of early submarine cementation and failure associated with excess pore pressure during early compaction. In addition, zebra lithologies display classical frost heave sheet cracks and small folds and thrusts. These structues are indicative of early jacking of sediment, plastic flow and brittle failure. The large and small scale structures noted point to early submarine cementation, deformation, reorganization and differential compaction of sediments. All of these fabrics appear to be responses to incongruent freezing, thawing and cementation during and shortly after sedimentation, as are observed with the consolidation and dissociation of clathrate hydrate deposits in modern ocean basins.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana