Quartz hydration dating
But when the rock is exposed to high enough levels of heat or light, that exposure causes vibrations in the mineral lattices and the trapped electrons are freed.
Luminescence dating is a collective term for dating methods that encompass thermoluminescence (TL) and optically stimulated luminescence (OSL) dating techniques.
Luminescence dating is good for between a few hundred to (at least) several hundred thousand years, making it much more useful than carbon dating.
Two forms of luminescence dating are used by archaeologists to date events in the past: thermoluminescence (TL) or thermally stimulated luminescence (TSL), which measures energy emitted after an object has been exposed to temperatures between 400 and 500°C; and optically stimulated luminescence (OSL), which measures energy emitted after an object has been exposed to daylight.
Dating Range: 100 - 1,000,000 yrs Materials: Indian artifacts, glacial materials, volcanic ash Example: Ken Pierce et al.
(1976) date Rocky Mountain glacial chronology SIMS Cosmic Rays: high-energy charged particles from outside solar system Solar Modulation: (flares produce) solar wind deflects Geological Modulation: magnetic field, Van Allen Belts, Geography Cosmogenic nuclide dating can be used to determine rates of ice-sheet thinning and recession, the ages of moraines, and the age of glacially eroded bedrock surfaces.
The age range of luminescence methods generally spans from a few decades to about 100,000 years, though ages exceeding several hundred thousand years have been reported in some studies.
High temperatures remove the tracks from the crystal, so when the ash leaves the hot volcano, its fission track ‘clock’ is at zero.
Tracks start building up after the crystals have cooled and settled in a layer on the ground or at the bottom of the sea. PRINCIPAL: establish hydration rate for each type of obsidian by examining pieces of known age, or with high pressure and temperature in lab.
Like C dating, thermoluminescence is related to radioactive decay.
Thermoluminescence is produced by radioactive decay particles (electrons), trapped in mineral grains.
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The number of tracks is proportional to the cooling age as well as to the U content of the apatite.