Age dating fault gouge
Radioactivity causes negatively charged electrons to move from a ground state, the valence band, to a higher energy level at the conduction band.After a short time, electrons eventually recombine with the positively charged holes left in the valence band.
Direct dating of ductile shear zones and calculation of uplift/exhumation rates can be done using various radiometric dating techniques.strata in Himalaya are being continuously stressed due to an ongoing northward movement of the Indian plate.Such stresses are released periodically and induce earthquakes and neotectonic activity along the faults.A new isochrone method of electron spin resonance (ESR) dating has been proposed utilizing the different average dose rates of external radiation for different grain sizes due to the range of external α- and β-rays.Electron Spin Resonance Dating, or ESR dating, is a technique used to date newly formed materials, which Radiocarbon dating cannot, like carbonates, tooth enamel, or materials that have been previously heated like igneous rock.We examine fault gouge from the Lewis thrust of the southern Canadian Rockies, which we determine to be 52 Myr old.
This result requires the western North America stress regime to have changed from contraction to extension in only a few million years during the Eocene.
This correlation makes it clear that quartz-grain surface textures are an important clue to dating a relative age of faulting.
River patterns, striations, granular fracture surfaces, and dimple-like textures are observed to appear on less corroded surfaces of quartz grains from fault gouges.
Electron spin resonance dating was first introduced to the science community in 1975, when Motoji Ikeya dated a speleothem in Akiyoshi Cave, Japan.
ESR dating measures the amount of unpaired electrons in crystalline structures that were previously exposed to natural radiation.
The results indicate that neotectonic activity took place around 40 ka ago along Nainital and Sleepy Hollow fault, 70 ka ago along the MBT and 60 ka along the Mohand thrust.