Fission track dating ppt
Etching of polished surfaces of these minerals reveals the "spontaneous fission tracks" for counting by optical microscopic means.The number of tracks correlates directly with the age of the sample and the uranium content.To determine the uranium content the sample is annealed by heating and exposed to a barrage of in the sample and the resulting new "induced tracks" are used to determine the uranium content of the sample as the U-235: U-238 ratio is well known.
The result shows that tectonically the Mabian area was relatively stable between 25 and 3 Ma, compared to the inner parts and other marginal areas of the Tibetan Plateau.
The studied area had little response to the rapid uplift events that occurred for several times in the Tibetan Plateau during 25–3 Ma.
The latest thermal event related to the activity of the Lidian fault zone (about 8 Ma) is later than that of the Ebian fault zone (18–15 Ma) to the west, indicating to some extent that the evolution of fault activity in the Mabian area has migrated from west to east.
The latest extensive tectonic uplift occurred since about 3 Ma.
As compared with the Xianshuihe fault zone, the Mabian area is closer to the eastern margin of the plateau, while the time of fast cooling event in this area is later than that in the southeast segment of the Xianshuihe fault zone (3.6–3.46 Ma).
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It appears to support the assumption of episodic uplift and stepwise outward extension of the eastern boundary of the Tibetan Plateau in late Cenozoic.