New Mexico Geological Society Annual Spring Meeting — Abstracts

The Monero coal field is in north-central New Mexico, on the northeastern side of the San Juan Basin. The field is defined by Mesaverde Group outcrops that form a narrow north-south band, cut by several northwest-trending faults in the northern part of the field. Where present, the coal-bearing sequence is considered to be the Menefee Formation.

Coals in the Monero field were first mined in the early 1880's to supply fuel to the Denver Rio Grande and Western Railroad, which was built through the area in 1881. Coal mining continued in the Monero field until 1970. Total production from at least 39 mines that operated during this 90-year interval totaled 1.4 million st. The total estimated coal resource for this area is 10 million st. Although the Monero coals are thin, they were valued for their high Btu values and coking properties. The average coal analyses for the Monero field indicate these coals are low moisture (3.6%), low ash (10.1%), and have a high volatile A bituminous rank.

Recent exploration in the Monero field has been minimal. In 1978 a small drilling program completed a few holes northeast of the town of Monero. The U.S. Geological Survey did a study for the Jicarilla Apache Indian Reservation in the mid-1980's. The New Mexico Bureau of Mines and Mineral Resources, through the New Mexico Research and Development Institute-funded coal quality project, drilled 7 holes in the northern Monero field. Data available from previous work and information from this study indicates these coals were deposited in a short-lived back barrier beach environment during a rapid retreat of the Late Cretaceous shoreline.