Cargo Muchacho Mountains
| Cargo Muchacho Mountains | ||
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 The Cargo Muchacho Mountains from space, right above the Algodones dunes |
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| location | California (USA) | |
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| Coordinates | 32 ° 52 ′ N , 114 ° 47 ′ W | |
| surface | 100 km² | |
The Cargo Muchacho Mountains are an American mountain group in the extreme southeast of California . They are located in Imperial County and form part of the southeastern Colorado Desert not far from the lower reaches of the Colorado River and the borders with Arizona and Mexico . They reach a height of 676 meters above sea level . Compared to the Salton Sea , which is below sea level , there is a maximum difference in altitude of over 700 meters.
geography
The mountain group ( engl. Range ) of the cargo Muchacho Mountains extends about 14 km in a northwest-southeast direction approximately parallel to the south portion of the west passing San Andreas Fault (or sand Hills Algodones Fault ), which here from Dune field of the Algodones dunes is covered. Its width is about 7 kilometers. In the northeast and east it is bounded by the Imperial Valley and the Colorado River. The cities of Yuma and Winterhaven are in the southeast. The Chocolate Mountains join in the north and northwest . The All American Canal runs south of the chain .
geology
The geological features were described in detail by John T. Dillon in 1975.
The basement of the Cargo Muchacho Mountains consists of amphibolite facial metamorphites that were synkinematically penetrated by mesozonal granitoids . The granitoids are essentially composed of adamellites , but can cover the spectrum from gabbro to tonalite . The foliation , which characterizes both the metamorphic rocks and the granitoids, dips relatively flat to the south, with linear stretching lines lying in it pointing in the same direction. The metamorphic rocks - small to medium-grain quartz - feldspar - tectonites - are mainly assigned to the Tumco Formation . Due to the lack of stratification, their origin cannot be clearly determined; Possibly they are former arcoses , but they could also have emerged from granitoids.
In several places the basement is discordantly overlaid by barely solidified fanglomerates and breccias . The tilted sediments show an angle of incidence of 10 ° and a little more; they were in turn concordantly covered by olivine basalts and were thus preserved. In addition to locally occurring rock fragments of the basement, the fanglomerates also contain exotic volcanic rocks . The breccias are derived exclusively from autochthonous rocks that arose during the tectonically induced fragmentation of the Cargo Muchacho Mountains. This fragmentation goes back to several north-west-south-east trending, right-shifting, steep-lying faults , which can have a displacement amount of up to two kilometers.
A young Proterozoic age is assumed for the metamorphic rocks . According to Armstrong and Soup (1973), the granitoids are older than 62 million years and are therefore likely to date from the Mesozoic . The basalts were mined in the Neogene , they can be assigned the period 23 to 8 million years.
Natural resources
In the range of hills, gold was (and is) mined as soap deposits , for example in the American Girl Mine , the Golden Bee Mine , the Cargo Mine and the Tumco Mine .
Individual evidence
- ^ Dillon, John T. Geology of the Chocolate and Cargo Muchacho Mountains, Southernmost California , 1975 . University of California.
- ^ Henshaw, PC: Geology and mineral resources of the Cargo Muchacho Mountains, Imperial County, California . In: California Div. Mines rept. tape 38 , 1942, pp. 147-196 .
- ↑ Armstrong, J. and Soup, RL: Potassium-Argon geochronometry of Mesozoic rocks in Nevada, Utah and southern California . In: Geol. Soc. America Bull. Volume 84 , 1973, pp. 1375-1392 .
- ↑ Damon, PE et al .: Correlation and chronology of ore deposits and volcanic rocks . In: Ann. Prog. Rept. to US Atomic Energy Commission, no. C00-689-130 . 1970, p. 42 .