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Slope Sedimentation Associated with a Vertically Building Shelf, Bone Spring Formation, Mescalero Escarpe Field, Southeast New Mexico

A. H. Saller, J. W. Barton, R. E. Barton

Mescalero Escarpe field contains slope strata in the Bone Spring formation which provide insight into development of the Northwestern shelf to the north and the Delaware basin to the south. During the Leonardian (Permian), the Northwestern shelf grew vertically due to regional subsidence and cyclic sedimentation. Slope facies include (1) dolomitized peloid-bioclast packstone, (2) dolomite megabreccia, (3) laminated dolomitic mudstone, and (4) very fine-grained sandstone. Oil is produced from peloid-bioclast packstones and megabreccias. Stratigraphic relationships indicate carbonate sedimentation in slope and basinal environments contemporaneous with carbonate sedimentation on the shelf. Peloid-bioclast packstones overlain by megabreccias are present at the toe-of-slope, a d dolomitic mudstones occur higher on the slope and deeper in the basin. Basinal sandstones are present between those carbonate strata. Seismic data show erosion and backstepping of the shelf margin correlative with megabreccia deposition at the toe-of-slope. Lithologic and stable isotope data suggest that erosion of the shelf took place in seawater.

Depositional cycles are related to sea level cycles. (1) During rapid sea level rises, the shelf was flooded and carbonate sedimentation initiated. Sediment swept off the shelf formed peloid-bioclast packstones at the toe-of-slope and dolomitic mudstones in other slope and basinal environments. (2) As sea level rise slowed or stopped, the shelf approached sea level. The shelf margin was eroded, and debris flows transported eroded detritus to the toe-of-slope, and megabreccias formed. Deposition of carbonate mud continued in adjacent environments. (3) When sea level stayed still or dropped, the shelf was at sea level or emergent, and terrigenous sand was transported into the basin.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.