MDD法和裂变径迹法相结合模拟样品的低温热历史--以柴达木盆地北缘赛什腾山中新生代构造演化为例

MODELING THERMAL HISTORY DURING LOW TEMPERATURE BY K-FELDSPAR MDD AND FISSION TRACK:EXAMPLE FROM MESO-CENOZOIC TECTONIC EVOLUTION IN SAISHITENGSHAN IN THE NORTHERN MARGIN OF QAIDAM BASIN

MDD法和裂变径迹法是2种最常用的低温热年代学方法。通过对它们的测试结果的模拟,揭示出样品经历的热历史,可以有效地延伸这2种方法的研究范围。但是由于模拟的多解性,使得如何制约模拟过程,获得合理的模拟结果显得尤为重要。通过柴达木盆地北缘的模拟过程,展示了模拟中可能存在的问题及提高模拟结果的方法。同时揭示了柴达木盆地北缘中新生代可能存在的3次冷却事件,分别发生在距今约130～150、30～40和5～10Ma。

K-Feldspar MDD（Multiple Diffusion Domain）and fission track are two commonly-used methods in low closure temperature thermal chronometry.By modeling both the feldspar 39Ar/40Ar data and the fission track age and track-length data,the thermal history that sample underwent can be revealed and the effective temperature range of both feldspar 39Ar/40Ar method and fission track method is extended.Because of the multiple resolution of modeling,it is important to restrict the modeling process to gain a reasonable result,though it seems difficult.The possible problem in modeling thermal history is presented in this paper,and the helpful method that can be used to improve the result is illustrated by the sample collected along Saishitengshan in the northern margin of Qaidam Basin.Three rapid cooling events,occurring at 130～150Ma,30～40Ma and 5～10Ma respectively,in northern margin of Qaidam Basin are revealed by feldspar MDD method and fission track method.