Petrography and geochemistry of precambrian rocks from GT-2 and EE-1
During the drilling of GT-2 and EE-1, 27 cores totaling about 35 m were collected from the Precambrian section. Samples of each different lithology in each core were taken for petrographic and whole-rock major- and trace-element analyses. Whole-rock analyses are now completed on 37 samples. From these data four major Precambrian units were identified at the Fenton Hill site. Geophysical logs and cuttings were used to extrapolate between cores. The most abundant rock type is an extremely variable gneissic unit comprising about 75% of the rock penetrated. This rock is strongly foliated and may range compositionally from syenogranitic to tonalitic over a few centimeters. The bulk of the unit falls within the monzogranite field. Interlayered with the gneiss is a ferrohastingsite-biotite schist which compositionally resembles a basaltic andesite. A fault contact between the schist and gneiss was observed in one core. Intrusive into this metamorphic complex are two igneous rocks. A leucocratic monzogranite occurs as at least two 15-m-thick dikes, and a biotite-granodiorite body was intercepted by 338 m of drill hole. Both rocks are unfoliated and equigranular. The biotite granodiorite is very homogeneous and is characterized by high modal contents of biotite and sphene and by high K/sub 2/O, TiO/sub 2/, and P/sub 2/O/sub 5/ contents. Although all of the cores examined show fractures, most of these are tightly sealed or healed. Calcite is the most abundant fracture filling mineral, but epidote, quartz, chlorite, clays or sulfides have also been observed. The degree of alteration of the essential minerals normally increases as these fractures are approached. The homogeneity of the biotite granodiorite at the bottom of GT-2 and the high degree of fracture filling ensure an ideal setting for the Hot Dry Rock Experiment.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 7080705
- Report Number(s):
- LA-6930-MS
- Country of Publication:
- United States
- Language:
- English
Similar Records
Rb--Sr, K--Ar, and fission-track geochronological studies of samples from LASL drill holes GT-1, GT-2, and EE-1
Geology and geochemistry of samples from Los Alamos National Laboratory HDR Well EE-2, Fenton Hill, New Mexico
Related Subjects
JEMEZ MOUNTAINS
GEOCHEMICAL SURVEYS
GEOLOGICAL SURVEYS
PETROLOGY
ROCKS
CHEMICAL COMPOSITION
ALUMINIUM OXIDES
BIOTITE
BOREHOLES
CALCITE
CALCIUM OXIDES
CALDERAS
CARBON DIOXIDE
CHLORITE MINERALS
CLAYS
DRILL CORES
EPIDOTES
GEOLOGIC FAULTS
GEOTHERMAL EXPLORATION
GRANITES
GRANODIORITES
IGNEOUS ROCKS
IRON OXIDES
MAGNESIUM OXIDES
MANGANESE OXIDES
NEW MEXICO
PHOSPHORUS OXIDES
POTASSIUM OXIDES
PRECAMBRIAN ERA
QUARTZ
ROCK DRILLING
SILICA
SODIUM OXIDES
STRONTIUM OXIDES
SULFIDES
TITANIUM OXIDES
TRACE AMOUNTS
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CALCIUM SILICATES
CARBON COMPOUNDS
CARBON OXIDES
CARBONATES
CAVITIES
CHALCOGENIDES
DRILLING
EXPLORATION
GEOLOGIC AGES
GEOLOGIC STRUCTURES
GEOLOGY
IRON COMPOUNDS
IRON SILICATES
MAGNESIUM COMPOUNDS
MANGANESE COMPOUNDS
MICA
MINERALS
MOUNTAINS
NORTH AMERICA
OXIDES
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
POTASSIUM COMPOUNDS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
SODIUM COMPOUNDS
STRONTIUM COMPOUNDS
SULFUR COMPOUNDS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
USA
Geothermal Legacy
150201* - Geology & Hydrology of Geothermal Systems- USA- (-1989)
150302 - Geothermal Exploration & Exploration Technology- Geochemical Techniques & Surveys