| 词条 | Bristol Lake | ||
| 释义 |
| name = Bristol Lake | image = Bristol Dry Lake.jpg | location = Mojave Desert San Bernardino County, California | coords = {{coord|34.4622|-115.6738|region:US-CA_type:waterbody_source:placeopedia | display=inline,title}} | lake_type = Endorheic basin | inflow = | outflow = Terminal (evaporation) | basin_countries = United States | length = {{convert|23|km|abbr=on}} | width = {{convert|20|km|abbr=on}} | area = | depth = | max-depth = | volume = | residence_time = | shore = {{convert|70|km|abbr=on}} | cities = Amboy, California Saltus, California | elevation = {{convert|183|m|ft|abbr=on}} | reference = {{gnis|239688}} }} Bristol Lake is a dry lake in the Mojave Desert of San Bernardino County, California, {{convert|42|km|abbr=on}} northeast of Twentynine Palms. Bristol Lake is located southeast of Amboy, California and U.S. Route 66, and is also south of Cadiz, California. Amboy Crater and the Bullion Mountains are to the west, and Old Woman Mountains to the east. The lake is approximately {{convert|23|km|abbr=on}} long and {{convert|20|km|abbr=on}} at its widest point.[1] Geological settingBristol Lake is located in San Bernardino County's Mojave Desert. It is a Playa Lake in the Basin and Range Province and is the northernmost member of a northwest-southeast trending playa lake system that includes Cadiz Lake and Danby Lake.[2] MineralogyBristol Lake's mineralogy is described as having a bullseye pattern of minerals with lithofacies consisting of halite at the center surrounded by mud, gypsum, and finally a sand flat playa margin. These minerals also have vertical lithofacies which resemble the horizontal facies stratification with gypsum occurring deeper in the playa followed by mud-halite and halite on top.[3] The mud lithofacies consists of thick detrital mud, and the halite lithofacies is defined by giant hopper shaped crystals.[2] Gypsum occurs in large lenticular crystals throughout the playa but is mostly concentrated around the mud lithofacies. Gypsum crystal sizes increase toward the center of the playa.[3] InterpretationGypsumPast studies have determined that the gypsum occurring in Bristol Lake precipitated displacively within the sediment where groundwater saturated with gypsum recharges around the mud lithofacies. This is supported by the geometry of the deposit and by chemical ldata, which suggests that water precipitating gypsum in the playa is more associated with groundwater than the brine at the basin center.[3] large size of the gypsum crystals may be due to several reasons; inflow waters containing low Ca/SO4 ratios may result in large lenticular crystals,[4] microorganisms have the potential to rework large lenticular crystals,[5] high concentrations of NaCl in inflow waters can decrease nucleation density of minerals resulting in larger crystal sizes [6](Cody 1988). It is likely that a combination of these processes was needed in order to form the gypsum crystals mentioned because gypsum crystals formed from low Ca/SO4 ratios or from microbial activity alone would not result in gypsum crystals large enough, and because gypsum size increases toward the center of the playa where NaCl concentrations are greatest.[3] HaliteThin crusts and hopper-shaped halite crystals that occur in the sediment are caused by evaporative growth from capillary brines discharging at the surface.[2] MudSediment mineral composition found in the desert saline sediments of southern California are predominantly influenced by the composition of the source rock, this is true for Bristol Lake as well.[7] Possible magma chamberThe brine chemistries at Bristol Lake are different from those predicted to form by the evaporative concentrations of the 2 inflow waters currently accounted for.
The basin center brines of BDL (saline mudflats and saline pan areas) are Na-Ca-Cl rich with lower concentrations of K and Mg and little SO4 and HCO3. Differing from their predicted chemical composition mostly by lacking SO4, CO3 and HCO3 and having high levels of Cl. Rosen 1991 attributed increased concentration of Cl to be from atmospheric precipitation, however the Ca-Cl concentrations present at Bristol Lake are not compatible with normal low temperature surface weathering and evaporative concentration processes. It is speculated that a magma chamber drives the formation of Ca-Cl brines at elevated temperatures and drives the transportation of these brines to the surface. Other evidence of a magma chamber in the area is the Amboy crater and its associated lava flows, which occur directly North of Bristol Lake.[8] IndustryA salt evaporator operation is situated on the dry lake bed just east of Amboy Road. See also
References1. ^U.S. Geological Survey Geographic Names Information System: Bristol Lake 2. ^1 2 HANDFORD, C. ROBERTSON. "Sedimentology and Evaporite Genesis in a Holocene Continental-sabkha Playa Basin-Bristol Dry Lake, California." Sedimentology, 29.2 (1982): 239–253. 3. ^1 2 3 ROSEN, MICHAEL R, and JOHN K WARREN. "The Origin and Significance of Groundwater-seepage Gypsum from Bristol Dry Lake, California, USA." Sedimentology, 37.6 (1990): 983–996. 4. ^Kushner J., “Effect of the Ca/SO4 Ratio on the Growth Rate and Crystal Habit of Gypsum.” [Abstract]. First Eur. Meeting Int. Ass. Sedimentologists, Bochum, 1980 pp. 239-241. 5. ^Cody, A.M., and Cody R.D. “Evidence for Microbiological Induction of {101} Montmartre Twinning of Gypsum (CaSO4*2H2O).” Journal of Crystal Growth, 98 (1989): 721-730 6. ^Cody R.D., and Cody A.M. “Gypsum Nucleation and Crystal Morphology in Analog Saline Terrestrial Environments.” Journal of Sedimentary Petrology, 58 (1988): 247-255. 7. ^DROSTE, JOHN B. "Clay Minerals in Sediments of Owens, China, Searles. Panamint, Bristol, Cadiz, and Danby Lake Basins, California." GSA Bulletin, 72.11 (1961): 1713–1721. 8. ^Lowenstein, Tim, and François Risacher. "Closed Basin Brine Evolution and the Influence of Ca–Cl Inflow Waters: Death Valley and Bristol Dry Lake California, Qaidam Basin, China, and Salar De Atacama, Chile." Aquatic Geochemistry, 15.1 (2009): 71–94.
External links
7 : Endorheic lakes of California|Salt flats of California|Lakes of the Mojave Desert|Lakes of San Bernardino County, California|Lakes of California|Landforms of San Bernardino County, California|Lakes of Southern California |
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