Boom and Bust with the Latest 2m Temperature Surveys: Dead Horse Wells, Hawthorne Army Depot, Terraced Hills, and Other Areas in Nevada

Abstract

New examples of the use of two-meter temperature (2m) surveys to quickly and inexpensively reveal blind geothermal systems were documented at Dead Horse Wells, the Hawthorne Army Depot, and Emerson Pass, all located in Nevada. In addition, more than 100 new 2m measurements at Astor Pass, Nevada resolved additional details of near-surface thermal outflow in this blind geothermal system. And at Columbus Salt Marsh, Nevada, additional 2m measurements better defined the shape of a blind, shallow thermal anomaly; also at this location deeper temperature measurements were used to develop a near-surface temperature gradient. 2m surveys in three other basins south of Hawthorne, NV in the Walker Lane Belt did not identify thermal anomalies. At Dead Horse Wells, Mineral County, Nevada, 2m temperatures greater than 37ºC (99ºF) were measured over a distance of more than 1.5 km, and lower level anomalous temperatures extend for a distance of 5.5 km. The long axis of this thermal anomaly is oriented in an east-northeast direction and is at least 2 km wide. Near Hawthorne, Mineral County, Nevada, 2m surveys delineated three separate temperature anomalies. Most significantly, the surveys identified a previously unknown, 1.8-km-long, highertemperature extension (possibly the primary upwelling zone) of a 10-km-long 2m anomaly originally discovered in the early 1980s along the northwestern margin of the Garfield Hills. The surveys also improved the delineation of a 6.5-km-long shallow thermal outflow zone previously identified from shallow well drilling west of the town of Hawthorne. A third 2m anomaly at the Hawthorne Army Depot envelopes a north-northeast-trending, 4-km-long zone of carbonate tufa towers in the southeastern portion of the Walker Lake Valley. A new geothermal system was identified from 2m measurements at Emerson Pass on the Pyramid Lake Paiute Reservation in Washoe County, Nevada. This narrow NNW-trending valley contains several faults that appear to transfer dextral strain from NW-striking faults in the northern Walker Lane to N-NNWstriking normal faults in the Smoke Creek Desert. The thermal anomaly extends for at least 3 km parallel to the range-front fault that defines the east side of the Emerson Pass valley. A maximum temperature of 35º C was recorded near several large tufa mounds on the valley floor down-gradient from a NNW-striking, westdipping normal fault. Similar to Astor Pass, located 11 km to the southwest, carbonate tufa mounds provided the initial clue as to the presence of thermal groundwater Further south in Mineral and Esmeralda Counties, Nevada, 2m measurements were conducted in Huntoon Valley, Garfield Flat, and Monte Cristo Valley. These valleys occur in extensional tectonic settings and/or show evidence of recent faulting. Over twenty 2m measurements were completed at each of these locations, with individual measurements spaced approximately 1 km apart, but no thermal anomalies were found.