A Point Source Depositional Model for Muleshoe Mound, a Mississippian (Osagean) Spar-Cemented Carbonate Buildup, Sacramento Mountains, New Mexico: ABSTRACT

Abstract

Three sections were measured, and oriented samples at 5-ft intervals were taken from the northwest cliff of Muleshoe Mound. Six microfacies were separated using hand samples and thin sections. These are: (1) crinozoan-bryozoan wackestones/packstones; (2) crinozoan-bryozoan wackestones/packstones with sheltered voids; (3) crinozoan-bryozoan packstones/grainstones with sheltered voids; (4) marine cemented bryozoan grainstones; (5) crinozoan wackestones/packstones; and (6) crinozoan packstones/grainstones. A sediment point source model, with gradational stages, was developed to interpret the vertical distribution of the microfacies in the measured sections. These stages are: (A) the basal wackestones/packstones sediment baffling stage; (B) the sparrich substrate modification stage; (C) the crinozoan-bryozoan diagenetic framestone stage; and (D) the clean, highly cemented, bryozoan diagenetic framestone stage. The bryozoan-radiaxial spar point sources developed from the quiet water stage (A) to the turbulent water stage (D). Grainstones and packstones on the flanks of adjacent point sources prograded laterally and eventually coalesced. This resulted in a complex carbonate buildup of spar-cemented crinoidal debris and localized bryozoan mounding facies. The progression from a quiet water to a turbulent water environment can be followed in three and possibly four cycles within the upper reef core of Muleshoe Mound. This indicates repeated, prolonged exposure to a turbulent environment throughout the history of the buildup. Confirmative studies are now underway at Little Suparloaf Mound, the southern sister buildup of Muleshoe Mound. End_of_Article - Last_Page 488------------