Bulletin 3—Oil and Gas Possibilities of the Puertecito District, Socorro and Valencia (now Cibola) Counties, New Mexico

By E. H. Wells, 1919, 47 pp., 1 plate.

Mineral Resources Survey. This report represents an endeavor to supply locators, operators, and others who may be interested, with information regarding the geology and oil possibilities of an area near Puertecito, NM, in which a number of well-defined anticlines occur. Many placer oil locations were made in this district during the spring and summer of 1919.

The original intention of the Board of Regents of the NM State School of Mines, under whose direction the present investigations were concluded, was to have the report cover all of the known possible oil structures of Socorro County, and the writer spent several weeks during the first part of the field season in making preliminary examinations of several structures in the eastern part of the county. This work was discontinued on receiving notice that N. H. Darton of the USGS had made a detailed examination of the structures of eastern Socorro County and that his report on them would probably be available in a few months; it being thought inadvisable for the NM State School of Mines to prepare a report covering the same territory, which would be issued at a later date. The field work during the remainder of the season was confined to the Puertecito district. In addition to the work done in the mapped area, a reconnaissance examination of some of the surrounding country was made. An exceptionally severe rainy season which made the roads almost impassable much of the time, seriously interfered with some of the contemplated investigations.

Geological mapping was done largely with transit and stadia; distances were obtained from stadia readings, and elevations were computed with the aid for vertical angles. Some of the surveys were tied only to outlying section corners, which may not be exactly in their proper locations in all cases. The elevation datum is based on aneroid barometer readings carried to the district from an established bench mark at Socorro, NM, and it may be in error as much as 100 ft.

The area designated in this report as the Puertecito district is in Socorro and Valencia Counties, NM. Puertecito is a small settlement on the Alamosa Creek and is situated about 3 mi southwest of the southeast corner of the district. East of Puertecito this creek is known as the Rio Salado. It discharges into the Rio Grande near San Acacia.

Puertecito is 35 mi north-northwest from Magdalena, which is the terminus of a branch line of the Atchison, Topeka, and Santa Fe Railway connecting it with Socorro. The wagon and auto road from Magdalena to Puertecito is an unguarded road over rather rough country. Stretches of heavy sand are numerous, and the grades are steep in places. The Field and Payne anticlines are 6-10 mi northwest of Puertecito. Suwanee, on the main line of the Atchison, Topeka, and Santa Fe Railway, is connected with Puertecito by a road about 50 mi long, which is not as well traveled as the Magdalena road, but which has less objectionable grades. Transportation of drilling rigs and supplies to the district will be a relatively large item in the cost of drilling wells.

The central and eastern parts of the Puertecito district are included in the Puertecito Basin, a broad depression of roughly circular outline that is bounded on the north and west by a basalt-capped mesa, on the south by a line of cuesta escarpments separating it from the main Alamosa Creek valley, and on the east by a northward-trending range of hills with steep east slope, which is an effectual barrier to travel between it and the valley to the east. The basalt-capped mesa occupies a large area to the north of the district, but the part of which forms the western boundary of the basin is a narrow arm less than 2 miles in maximum width. This arm is separated into two parts by an erosional gap. The part of the district lying to the west of the mesa arm is included in the broad north-south Red Lake valley, one of the main tributary valleys of the Alamosa Creek. The surface water of the entire area discharges into the Alamosa Creek through arroyos, which are dry except during and shortly after heavy rains characteristic of the region in the summer months and during the melting of the light winter snows.