Application On Mineral Luminescence Technology In Active Orogenic Process

The luminescence dating technology has been successfully applied to the dating of Quaternary sediments after more than 20 years development.Depositional age of sediments can be obtained by measuring the accumulated luminescence signals of buried sediments.Mineral luminescence signals have great potential in the uplift and exhumation of orogenic belts and in the process of strong earthquake orogeny.The current luminescence thermochronology technology can reconstruct the history of rock temperature changes caused by tectonic uplift and surface denudation.However,there is a potential problem.Before measurement,the process of trapping electrons under the high temperature is the same as the room temperature,which has not yet been tested.On the other hand,the application of luminescence technology to the age determination of seismic events in the process of strong earthquake orogeny also faces a series of problems,including:（a）the quartz luminescence signal is not sensitive to irradiation;（b）the short-term transport process of minerals before deposition is insufficient,which makes the mineral luminescence signal fail to return to zero before deposition,resulting in overestimation of the final age.To solve the above problems,this paper aims to make the mineral luminescence signals more accurately applied to the study of orogenic belts exhumation and strong earthquake orogeny through a series of validation experiments in methodology.The main research contents include:（1）temperature effect of electron trapping process in potassium feldspar;（2）the reliability of luminescence dating of sediments related with seismic events.The main conclusions are as follows:（1）Using potassium feldspar separated from Gongger Mountain granite in Pamir as material,we tested whether the given laboratory radiation temperature or temperature change can be obtained by measuring the IRSL signal of potassium feldspar,to verify the similarities and differences of trapping electron process in mineral crystals under high temperature conditions and room temperature conditions.The results show that the process of trapping electrons at high temperature is consistent with that at room temperature.Therefore,it is feasible to restrict the cooling rate and erosion rate of rock mass during active orogeny by measuring the luminescence signals of minerals.（2）In order to verify the reliability of the luminescence dating of sediments related with seismic events,11 samples from the trench in the Xorkol Basin of the Altyn Tagh Fault have been tested the age of luminescence,and then compared with the known ¹⁴C age.The results show that the signal response ratio of quartz minerals in this area is poor but the K-feldspar is strong,which can be used of luminescence dating.The post-IR IRSL₁₇₀ signal of potassium feldspar has not been fully exposed before deposition,and still has a large residual.We used the single particle technique and the minimum age model to select particles that have experienced full exposure,and then measured the deposition age.The results are basically consistent with the ¹⁴C age.It shows that it is reliable to apply the luminescence technique to determine the age of sediments related seismic events in the process of strong earthquake orogeny.