Detailed structure and stratigraphy of the eastern Marble Mountain terrane, Klamath Mountains, CA
Abstract
Amphibolite-grade rocks in the eastern Marble Mountains (MM), N. California, consist of several fault-bounded, SSE-dipping lithotectonic units. Each unit is ca. 2 km thick and is characterized by differences in rock type, metamorphism, and structural style. The lowermost unit composed of well-foliated and lineated epidote amphibolite grading upward into clinopyroxene-bearing amphibolite with a consistent NE-SW lineation. Structurally overlying these rocks are andalusite- and staurolite-bearing, epidote-amphibolite facies rocks (Wright Lake assemblage (WLa)) that have variable foliation and lineation orientations. The WLa consists of meta-supracrustal rocks with well-preserved relict textures, and massive, meta-ultramafic rock. Supracrustal rocks include polymict conglomerate and breccia, fine- to medium-grained clastic rocks, alkalic pillow basalt, chert, and carbonate. Conglomerate clasts include partially recrystallized granitoids and quartzite. Previous studies have interpreted the WLa to represent a fragment of oceanic crust, but coeval coarse-grained sedimentation and alkalic volcanism, small volume of mafic volcanics, conglomerate composition, and lack of oceanic plutonic and hypabyssal rocks suggest deposition in an arc-related rift or transtensional basin. Previous studies have also described the terrane as melange, but recognition of local pseudostratigraphy allows mapping of multiply folded, isoclinal, nappe-like structures. Small-scale nappes are generally 100+ m thick and are imbricated with massive meta-ultramafic rocks along gentlymore »
- Authors:
-
- Stanford Univ., CA (United States). Dept. of Geology
- Publication Date:
- OSTI Identifier:
- 5129483
- Report Number(s):
- CONF-9305259-
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
- Resource Type:
- Conference
- Journal Name:
- Geological Society of America, Abstracts with Programs; (United States)
- Additional Journal Information:
- Journal Volume: 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; Journal ID: ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 58 GEOSCIENCES; AMPHIBOLITES; ISOTOPE DATING; PETROLOGY; STRATIGRAPHY; CALIFORNIA; GEOLOGIC FORMATIONS; ARGON ISOTOPES; GEOLOGIC FAULTS; GEOLOGIC HISTORY; GEOLOGIC STRUCTURES; GEOLOGY; METAMORPHISM; PETROGENESIS; AGE ESTIMATION; DEVELOPED COUNTRIES; GEOLOGIC FRACTURES; ISOTOPES; METAMORPHIC ROCKS; NORTH AMERICA; ROCKS; USA; 580000* - Geosciences
Citation Formats
Miller, D E, and Hacker, B R. Detailed structure and stratigraphy of the eastern Marble Mountain terrane, Klamath Mountains, CA. United States: N. p., 1993.
Web.
Miller, D E, & Hacker, B R. Detailed structure and stratigraphy of the eastern Marble Mountain terrane, Klamath Mountains, CA. United States.
Miller, D E, and Hacker, B R. 1993.
"Detailed structure and stratigraphy of the eastern Marble Mountain terrane, Klamath Mountains, CA". United States.
@article{osti_5129483,
title = {Detailed structure and stratigraphy of the eastern Marble Mountain terrane, Klamath Mountains, CA},
author = {Miller, D E and Hacker, B R},
abstractNote = {Amphibolite-grade rocks in the eastern Marble Mountains (MM), N. California, consist of several fault-bounded, SSE-dipping lithotectonic units. Each unit is ca. 2 km thick and is characterized by differences in rock type, metamorphism, and structural style. The lowermost unit composed of well-foliated and lineated epidote amphibolite grading upward into clinopyroxene-bearing amphibolite with a consistent NE-SW lineation. Structurally overlying these rocks are andalusite- and staurolite-bearing, epidote-amphibolite facies rocks (Wright Lake assemblage (WLa)) that have variable foliation and lineation orientations. The WLa consists of meta-supracrustal rocks with well-preserved relict textures, and massive, meta-ultramafic rock. Supracrustal rocks include polymict conglomerate and breccia, fine- to medium-grained clastic rocks, alkalic pillow basalt, chert, and carbonate. Conglomerate clasts include partially recrystallized granitoids and quartzite. Previous studies have interpreted the WLa to represent a fragment of oceanic crust, but coeval coarse-grained sedimentation and alkalic volcanism, small volume of mafic volcanics, conglomerate composition, and lack of oceanic plutonic and hypabyssal rocks suggest deposition in an arc-related rift or transtensional basin. Previous studies have also described the terrane as melange, but recognition of local pseudostratigraphy allows mapping of multiply folded, isoclinal, nappe-like structures. Small-scale nappes are generally 100+ m thick and are imbricated with massive meta-ultramafic rocks along gently to steeply east-dipping shear zones. Shear zones are characterized by metamorphosed ultramafic fault rocks that suggest a range of brittle to ductile behavior. Regionally distributed, Ar/Ar hornblende ages of 149.9[+-]0.4, 150.3[+-]0.6, 152.1[+-]4.7, 152.5[+-]2.5 Ma and Ar/Ar biotite ages of 148.8[+-]2.6 and 149.9[+-]0.4 Ma indicate the MM terrane cooled rapidly through ca. 500--300 C in the Late Jurassic.},
doi = {},
url = {https://www.osti.gov/biblio/5129483},
journal = {Geological Society of America, Abstracts with Programs; (United States)},
issn = {0016-7592},
number = ,
volume = 25:5,
place = {United States},
year = {Thu Apr 01 00:00:00 EST 1993},
month = {Thu Apr 01 00:00:00 EST 1993}
}