Ultramafic rocks of the western Idaho suture zone: Asbestos Peak and Misery Ridge

Conference · Thu Apr 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5126028

Godchaux, M M ^[1]; Bonnichsen, B ^[2]

---

1. Mount Holyoke Coll., South Hadley, MA (United States). Dept. of Geology
2. Univ. of Idaho, Moscow, ID (United States)

The Western Idaho Ultramafic Belt extends northward from the town of Weiser to the northern end of Dworshak Reservoir; in its northern portion most of the ultramafic bodies are localized along the suture zone where the Mesozoic oceanic accreted terranes meet the continental craton. Of the twenty bodies investigated, all are small, all are in fault contact with their metavolcanic and metasedimentary host rocks, all have been metamorphosed, and all display deformational fabrics in at least some portion of the outcrop area, suggesting that deformation continued after peak metamorphism. The degree of metamorphism ranges from incipient serpentinization to attainment of equilibrium in the upper amphibolite facies. Some bodies have been intruded by granitic dikes or pegmatite veins after emplacement, and have locally undergone contact metasomatism. Two particularly complex bodies, Asbestos Peak and Misery Ridge, were chosen for detailed petrographic and chemical study. Asbestos Peak is composed mostly of decussate anthophyllite-talc rock containing isolated patches of harzburgite protolith, and has blackwall border zones. Misery Ridge is composed mostly of coarse-grained sheared tremolite-talc schist without remnant protolith, and lacks true blackwall zones. Both bodies exhibit an unusual and enigmatic hornblende-poikiloblastic garnet-green spinel-skeletal ilmenite assemblage, present in some places as well-defined border zones and in other places as cross-cutting bodies.

• OSTI ID: 5126028
• Report Number(s): CONF-9305259--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
CHEMICAL COMPOSITION
CHEMISTRY
DEFORMATION
DEVELOPED COUNTRIES
EARTH CRUST
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC HISTORY
GEOLOGIC STRUCTURES
GEOLOGY
IDAHO
IGNEOUS ROCKS
METAMORPHIC ROCKS
METAMORPHISM
MINERALOGY
NORTH AMERICA
OCEANIC CRUST
PETROGRAPHY
PLATE TECTONICS
ROCKS
SCHISTS
SUBDUCTION ZONES
TECTONICS
USA
VOLCANIC ROCKS