摘要
研究了西藏泽当地区冈底斯逆冲断层（ＧＴ）和念青唐古拉山峰东侧两条山谷（ＮＴ）中８个钾长石样品的ＭＤＤ冷却历史，对钾长石低温阶段异常高年龄进行了Ｃ１校正，得到了两次明显的快速冷却事件。前者（ＧＴ）提供了网底斯逆冲断层的活动时间２７～２４Ｍａ、下限年龄约１８Ｍａ和最小滑动速率（１２±６）ｍｍ／ａ。后者（ＮＴ）表明在约８Ｍａ，即正断层运动开始时，西藏高原东南部地壳增厚和抬升可能已达到了近于现今的高度和水平。
n Ar-39Ar analyses and MDD(multiple diffusion domain) model cooling history were performed for 8 K-feldspar samples. They were colleted from Gangdese thrust (GT) in Zedang area and two valleyes of east Nian Qing Tang Gula mountain(NT). Two rapid cooling events at GT and NT were obtained after excess argon(4fArE) was released from K-feldspar at low temperatures(<800℃) during 4eAr-39Ar step-heating experiments corrected by 40Ar-Cl ratios. The first rapid cooling event suggested that active time of GT occurred between 27～24Ma. The lower age limit and slip rate were～18 Ma and (12±6)mm/a respetively. The second rapid cooling event at NT suggested that the crustal thickness and elevation may be close to their present level at ～8Ma on the southern Tibetan ploteau.
出处
《地震地质》
EI
CSCD
北大核心
1996年第2期109-115,共7页
Seismology and Geology
基金
国家自然科学基金
