Tertiary Volcanic Centers as Constraints on Oil and Gas Potential of Basin and Range Province: New Mexico Segment of Pedregosa Basin: ABSTRACT

Abstract

Stratigraphic similarities with the Permian basin and structural similarities with the Overthrust belt make the New Mexico segment of the Pedregosa basin an attractive target for petroleum exploration. Middle Tertiary volcanic cover and postvolcanic faults introduce constraints, as elsewhere in the Basin and Range province. Geologic mapping in southwesternmost New Mexico (Hidalgo County) has traced Oligocene ash-flow tuff sheets to at least nine major cauldrons, including Valles-type resurgent cauldrons 10 to 40 km wide (Apache Hills: Apache cauldron; southern Pyramid Mountains: Muir cauldron; southern Animas Mountains: Tullous, Juniper, Animas Peak, Cowboy Rim, San Luis cauldrons; southern Peloncillo Mountains: Rodeo and Geronimo Trail cauldrons). Faulted-off cauldron segments continue beneath the Playas, Animas-San Luis, and San Simon-San Bernadino Valleys. Composite batholiths probably underlie cauldron clusters, as in the San Juan and Mogollon-Datil volcanic fields. Exposed monzonitic plutons (Apache Hills, Pyramid Mountains, Animas Mountains) are apophyses, emplaced during resurgence. Other plutons, apparently unrelated to cauldrons, are present in the northern Pyramid and Little Hatchet Mountains. Distribution of cauldrons and plutons suggests that much of the Pyramid, Peloncillo, Little Hatchet, and Animas Mountains, Apache Hills, and adjacent valleys are unfavorable for petroleum accumulations. However, destructive thermal effects may be confined to aureoles extending only about 1,000 m from intrusive contacts, as in the KCM 1 Forest Federal wildcat. Cauldrons and thermal effects deleterious to petroleum potential are unknown in so theastern Hidalgo County (Dog, Alamo Hueco, Big Hatchet Mountains, southern Sierra Rica). End_of_Article - Last_Page 759------------