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Geologic map of the Valjean Hills 7.5' quadrangle, San Bernardino County, California
| Content Provider | Semantic Scholar |
|---|---|
| Author | Calzia, James P. Troxel, Bennie W. Raumann, Christian G. |
| Copyright Year | 2003 |
| Abstract | SURROUNDING 7.5' QUADRANGLES Tkq China Ranch beds of Mason (1948) (Miocene)-Conglomerate, lacustrine deposits, and tuffs in the Alexander Hills and southern Death Valley region. The conglomerate includes interbeds of monolithologic breccia of Proterozoic sedimentary rocks and Tertiary magmatic rocks; lacustrine deposits include interbeds of marly limestone and tuff. Sanidine from an altered tuff at the base of the China Ranch beds yields a K-Ar age of 10.3 Ma (Scott, 1985); tuff beds near the top of this formation yield an 40Ar/39Ar age of 8.36±0.24 Ma (Scott and others, 1986). China Ranch beds within the map area include Fanglomerate deposits-Partially consolidated fanglomerate interbedded with sandstone and lacustrine deposits. The fanglomerate is several tens to 500 m thick and consists of rounded to subangular cobbles and boulders of Proterozoic sedimentary rocks and Tertiary magmatic rocks, including the granite of Kingston Peak, porphyritic andesite, and latite, in a matrix of silt, brown fineto medium-grained sand, and gravel. Beds are poorly defined and several meters thick. Clast composition varies with location. Along the northern boundary of the quadrangle and the west side of the Kingston Range, the fanglomerate is characterized by boulders, up to 5 m across, of the granite of Kingston Peak; subangular to rounded cobbles and boulders of the volcanic rocks are more abundant than clasts of the Proterozoic rocks. Clasts of Proterozoic rocks, however, are more common than clasts of Tertiary rocks in a large slump block of the fanglomerate north of the Valjean Hills. Interbeds of rounded boulders and cobbles of diabase and gneiss (Tcfd) and landslides of the fanglomerate (Tcfl) are common in the northwest corner of the quadrangle Interbeds of sandstone and lacustrine deposits consist of fineto coarse-grained sandstone and pebble conglomerate with a matrix of mediumto coarse-grained sand. These interbeds are laterally discontinuous and fine upwards into lacustrine deposits and finegrained cross-bedded sandstone. The lacustrine deposits consist of alternating beds of resistant light brown pea gravel, brown siltstone, and punky white tuffaceous siltstone. The pea gravel consists of rounded to subrounded clasts of quartzite, volcanic rocks, and brown shale in a matrix of brown siltstone Lapilli tuff-Pumice lapilli tuff consisting of biotite, hornblende, lithic fragments, and altered glass shards. This tuff is correlated by tephrochronology with a biotite-bearing tuff that yields K-Ar ages of 7.6 to 8.4 Ma (A.M. Sarna-Wojcicki, written commun, 1986) Quartz porphyry facies of the granite of Kingston Peak (Miocene)-Very fine-grained biotite+hornblende granite porphyry characterized by quartz phenocrysts up to 3 cm across, 6-8 percent mafic minerals, and miarolitic cavities. Stoped blocks of gray monzogranite from the granite of Rabbit Holes Spring are common. The quartz porphyry facies forms gradational contacts with the 12.4 Ma feldspar porphyry facies of the granite of Kingston Peak in the Kingston Range (Calzia, 1990) Volcanic rocks (Miocene)-Small round outcrops of trachytic andesite and basalt that intrude the carbonate breccia along the east side of the Valjean Hills. The andesite consists of lath-shaped phenocrysts of plagioclase, 1-5 mm long, and anhedral biotite in a matrix of plagioclase microlites. The basalt consists of plagioclase phenocrysts, 0.5-1.0 mm long, orthoand clinopyroxene, and minor olivine. These volcanic rocks resemble 13.4 Ma (Fowler, 1992) volcanic rocks in the Resting Springs Formation in the southern Kingston Range Granite of Rabbit Holes Spring (Cretaceous?)-Medium-grained monzogranite that is modally and texturally similar to plutons in the Cretaceous Teutonia Batholith. Divided into gray monzogranite and tan monzogranite Gray monzogranite-Medium-grained biotite monzogranite with rare subhedral potassium feldspar phenocrysts up to 6 mm long Tan monzogranite-Mediumto coarse-grained monzogranite; generally equigranular but locally porphyritic. Pegmatite dikes and autoliths of gray monzogranites are common Bonanza King Formation (Cambrian)-Banded gray and black dolomite and limestone overlain by massive dark gray mottled dolomitic limestone. The banded unit contains occasional chert nodules and oolitic dolomite; the massive unit includes thin clayey and sandy limestone beds. The base of this formation is marked by thin-bedded grayish orange silty limestone, dolomite, and shale Carrara Formation (Cambrian)-Silty or calcareous shale interbedded with thinto medium-bedded limestone and limy mudstone. The shale included micaceous sand or silt lenses and minor quartzite; the limestone is generally laminated and locally oolitic Zabriskie Quartzite (Cambrian)-Cross-bedded, pale-red to gray fineto medium-grained quartz arenite with granules and rounded cobbles of red chert and white quartz. These rocks are overlain by gray fineto medium-grained quartz sandstone with poorly developed ripple marks and trough cross beds Wood Canyon Formation (Cambrian and Late Proterozoic)-Massive and cross-bedded mediumto fine-grained feldspathic or micaceous sandstone, mediumto finely-crystalline dolomite, cross-bedded arkosic quartz pebble conglomerate, and purplish-red siltstone. Micaceous siltstone and sandy dolomite lenses in micaceous sandstone become more common up section Stirling Quartzite (Late Proterozoic)-White to brownish red coarseto fine-grained quartzose, feldspathic, and arkosic sandstone locally overlain by fining upward cycles of purple, gray, and yellow brown micaceous siltstone and medium-grained feldspathic sandstone. These rocks are overlain by gray and pink mediumand coarse-grained quartz sandstone with thin interbeds of pinkish to greenish siltstone and shale. Rounded to subrounded quartz pebbles are common near the base and top of this formation. Sandstone beds are characterized by planar and truncated cross beds Johnnie Formation (Late Proterozoic)-Siltstone, sandstone, and carbonate rocks informally divided into upper, middle, and lower members Upper member-Purple siltstone with interbeds of gray mediumto coarse-grained quartz arenite, orange oolitic dolomite, and fineto medium-grained quartz arenite. Red-brown dolomite and sandy dolomite mark the base of this member. The oolite is locally separated into two beds by purple siltstone; the lower quartz arenite is locally graded from pebble sandstone to sandstone Tct |
| File Format | PDF HTM / HTML |
| DOI | 10.3133/ofr0396 |
| Alternate Webpage(s) | https://pubs.usgs.gov/of/2003/0096/pdf/valjean_geomap.pdf |
| Alternate Webpage(s) | https://doi.org/10.3133/ofr0396 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
