--> ABSTRACT: Aptian-Albian Coral-Rudist Patch Reefs, Southwestern New Mexico, by R. J. Schuster, R. E. Clemons, and W. B. Kolins; #91026 (2010)

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Aptian-Albian Coral-Rudist Patch Reefs, Southwestern New Mexico

R. J. Schuster, R. E. Clemons, W. B. Kolins

The U-Bar Formation in southwestern New Mexico contains five informal members. In ascending order they are the brown limestone, oyster limestone, limestone-shale, reef, and suprareef members. The U-Bar is correlative with the Mural Limestone of southeastern Arizona. The upper member of the Mural contains coral-rudist patch reefs analogous to the subsurface buildups in Albian rocks of Texas. Previous to our studies, only brief mention was made to corals and colonial corals as minor constituents of the limestone-shale and reef members of the U-Bar. Recently, we have found small (1-3 m high, 5-20 m long) coral and coral-rudist patch reefs in the central Animas Mountains, Sierra Rica, and Eagle Nest hill in southwestern New Mexico. These small reefs are in the upper part of t e limestone-shale member of the U-Bar Formation. About 70 m of shale, sandstone, and silty limestone separate the patch reefs from the overlying reef member of the U-Bar. This occurrence of coral-rudist patch reefs is similar to the massive carbonates reported in the lower member of the Mural Limestone at Guadalupe Canyon in southeastern Arizona. The lower part of the coral-rudist patch reef at Eagle Nest contains abundant flat laminar corals (Microsolena?) and less common branching corals (Calamophyllia?). A few more massive corals resembling Actinastrea? are also present. Most of the corals appear to be in growth position. The upper part of the reef is dominated by caprinid and requienid rudists. Patch reefs in the central Animas Mountains are mostly bushes of branching corals. The Sie ra Rica patch reefs contain branching corals in the lower parts with caprinid and requienid rudists in the upper parts.

AAPG Search and Discovery Article #91026©1989 AAPG Southwest Section, March 19-21, 1989, San Angelo, Texas.