Geology topics

Research about Raft River Valley

Source-linked reports with geographic coverage including Raft River Valley.

3 recordsLinked to original sources

USGS2014

Geologic and geophysical data for wells drilled at Raft River Valley, Cassia County, Idaho, in 1977-1978 and data for wells drilled previously

In order to better define the size of the thermal anomaly in the Raft River Valley, Idaho, the U.S. Geological Survey drilled a series of intermediate-depth (nominal 500-ft depth) wells in 1977 and 1978. This report presents geologic, geophysical, and temperature data for these drill holes, along with data for five wells drilled by the Idaho National Engineering Laboratory with U.S. Department of Energy Funding. Data previously reported for other drill holes are also included in order to make them available as digital files. For purposes of defining the thermal anomaly for the geothermal system, temperature gradients are calculated over long depth intervals on the basis of the appearance of reasonable linear segments on a temperature versus plot depth. Temperature versus depth data for some drill holes can be represented by a single gradient, whereas others require multiple gradients to match the data. Data for some drill holes clearly reflect vertical flows of water in the formation surrounding the drill holes, and water velocities are calculated for these drill holes. Within The Narrows area, temperature versus depth data show reversals at different depth in different drill holes. In the main thermal area, temperatures in intermediate-depth drill holes vary approximately linearly but with very high values of temperature gradient. Temperature gradients on a map of the area can be reasonable divided into a large area of regional gradients and smaller areas defining the thermal anomalies.

Idaho↗

USGS1976

Geology and geophysics of the southern Raft River Valley geothermal area, Idaho, USA

The Raft River valley, near the boundary of the Snake River plain with the Basin and Range province, is a north-trending late Cenozoic downwarp bounded by faults on the west, south, and east. Pleistocene alluvium and Miocene-Pliocene tuffaceous sediments, conglomerate, and felsic volcanic rocks aggregate 2 km in thickness. Large gravity, magnetic, and total field resistivity highs probably indicate a buried igneous mass that is too old to serve as a heat source. Differing seismic velocities relate to known or inferred structures and to a suspected shallow zone of warm water. Resistivity anomalies reflect differences of both composition and degree of alteration of Cenozoic rocks. Resistivity soundings show a 2 to 5 ohm·m unit with a thickness of 1 km beneath a large part of the valley, and the unit may indicate partly hot water and partly clayey sediments. Observed self-potential anomalies are believed to indicate zones where warm water rises toward the surface. Boiling wells at Bridge, Idaho are near the intersection of north-northeast normal faults which have moved as recently as the late (?) Pleistocene, and an east-northeast structure, probably a right-lateral fault. Deep circulation of ground water in this region of relatively high heat flow and upwelling along faults is the probable cause of the thermal anomaly.

Idaho↗

USGS1975

Land subsidence and tectonism, Raft River Valley, Idaho

A comparison of 1974 leveling data with elevations established 40 years earlier reveals two types of vertical ground movement which have occurred in Raft River Valley, Idaho: (1) regional differential movement of about 0.22 ft (6.4 cm), apparently due to tectonism, and (2) extensive land subsidence of as much as 2.61 ft (0.80 m) caused by withdrawal of ground water. Data are too sparse to calculate the magnitude or areal extent of subsidence; however, tentative lines of equal subsidence suggest that the area affected by subsidence probably exceeds 100 mi 2 (260 km 2 ). In order to estimate historic subsidence or subsidence potential in Raft River Valley serious consideration should be given to a field program of basic-data collection. Leveling along a few carefully selected lines of existing control and the installation and operation of extensometer water-level recorders in areas of continuing water-level decline would provide useful data for evaluating past and estimating future subsidence.

Idaho↗