Hydrothermal systems in two areas of the Jemez volcanic field: Sulphur Springs and the Cochiti mining district

Technical Report · Wed Mar 01 04:00:00 EST 1989

DOI:https://doi.org/10.2172/6513705· OSTI ID:6513705

WoldeGabriel, G

K/Ar dates and oxygen isotope data were obtained on 13 clay separates (<2 ..mu..m) of thermally altered mafic and silicic rocks from the Cochiti mining district (SE Jemez Mountains) and Continental Scientific Drilling Project (CSDP) core hole VC-2A (Sulphur Springs, Valles caldera). Illite with K/sub 2/O contents of 6.68%--10.04% is the dominant clay in the silicic rocks, whereas interstratified illite/smectites containing 1.4%--5.74% K/sub 2/O constitute the altered andesites. Two hydrothermal alteration events are recognized at the Cochiti area (8.07 m.y., n = 1, and 6.5--5.6 m.y., n = 6). The older event correlates with the waning stages of Paliza Canyon Formation andesite volcanism (greater than or equal to13 to less than or equal to8.5 m.y.), whereas the younger event correlates with intrusions and gold- and silver-bearing quartz veins associated with the Bearhead Rhyolite (7.54--5.8 m.y.). The majority of K/Ar dates in the hydrothermally altered, caldera-fill rocks of core hole VC-2A (0.83--0.66 m.y., n = 4) indicate that hydrothermal alteration developed contemporaneously with resurgence and ring fracture Valles Rhyolite domes (0.89--0.54 m.y.). One date of 0 +- 0.10 m.y. in acid-altered landslide debris of postcaldera tuffs from the upper 13 m of the core hole probably correlates with Holocene hydrothermal activity possibly associated with the final phases of the Valles Rhyolite (0.13 m.y.).

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6513705
• Report Number(s): LA-11509-OBES; ON: DE89007556
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
150201* -- Geology &amp; Hydrology of Geothermal Systems-- USA-- (-1989)
CALDERAS
ENERGY SYSTEMS
EVALUATION
FEDERAL REGION VI
FLUID FLOW
GEOLOGY
GEOTHERMAL SYSTEMS
GEOTHERMAL WELLS
Geothermal Legacy
HEAT FLOW
HYDROTHERMAL SYSTEMS
JEMEZ MOUNTAINS
MOUNTAINS
NEW MEXICO
NORTH AMERICA
USA
WELLS