نتایج جستجو برای: travertine
تعداد نتایج: 197 فیلتر نتایج به سال:
Diatoms are a highly diversified group of algae that are widely distributed in aquatic ecosystems, and various species have different nutrient and temperature requirements for optimal growth. Here, we describe unusual psychrophilic diatoms of Cymbella in a travertine deposition environment in southwestern China in winter season.Travertine surfaces are colonized by these psychrophilic diatoms, w...
Petrographic and geochemical analyses of travertine-depositing hot springs at Angel Terrace, Mammoth Hot Springs, Yellowstone National Park, have been used to define five depositional facies along the spring drainage system. Spring waters are expelled in the vent facies at 71 to 73 degrees C and precipitate mounded travertine composed of aragonite needle botryoids. The apron and channel facies ...
We show that Zhang and Li's sedimentological model for the Chusang travertine neglects the three-dimensional information from multiple outcrops and that their optically stimulated luminescence (OSL) age of about 20,000 years for the human imprints is untenable. We highlight the robustness of our chronology and explore reasons why Zhang and Li's OSL age is a gross overestimation of the real depo...
We formulate and model the dynamics of spatial patterns arising during the precipitation of calcium carbonate from a supersaturated shallow water flow. The model describes the formation of travertine deposits at geothermal hot springs and rimstone dams of calcite in caves. We find explicit solutions for travertine domes at low flow rates, identify the linear instabilities which generate dam and...
A microstructural investigation by electron microscopy on a travertine specimen collected from Munigou National Park, Sichuan Province, China revealed evidence of a non-classical reversed crystal growth route previously only discovered in synthetic materials. Examination of the travertine specimen suggests that the presence of organic matter initiates the oriented aggregation of calcite nanocry...
A dynamical theory of geophysical precipitation pattern formation is presented and applied to irreversible calcium carbonate (travertine) deposition. Specific systems studied here are the terraces and domes observed at geothermal hot springs, such as those at Yellowstone National Park, and speleothems, particularly stalactites and stalagmites. The theory couples the precipitation front dynamics...
The Tazerj travertine deposits are located 25 km northwest of Haji Abad and 5 km northeast of Tazerj Village in Hormozgan Province, southern Iran. This area is part of the Folded Zagros Zone. The studied travertine deposits are located on Eocene deposits and were most likely formed through the dissolution and re-deposition of groundwater and atmospheric waters onto the Asmari limestone. The pet...
Substantial CO2 degassing occurs from geothermal waters in Turkey as evident from ongoing deposition of recent terrace travertines and emplacement of significant travertine vein and breccia deposits representing hydrothermal eruption products. Geochemical data indicate rapid ascent of CO2bearing fluids without significant interaction with basement and host rocks. High-precision U-series dates o...
1-Introduction Travertines are limestones that form where hot groundwaters rich in calcium and bicarbonate emerge at springs. Travertines cover a large area southwest of Azarshahr (East Azarbaijan province), in some parts of which active springs are currently settling travertine. One of the main questions about travertine springs is their origin, as well as the secondary processes that have ch...
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