本文選題：西昆侖山　切入點：新生代　出處：《科學(xué)技術(shù)與工程》2017年33期 　論文類型：期刊論文

【摘要】：自新生代以來,西昆侖地區(qū)發(fā)生強(qiáng)烈的構(gòu)造變形和隆升,其初始隆升和末次快速隆升的時限仍是有待探討的重大問題。本文沿西昆侖北緣采集一系列砂巖樣品,利用裂變徑跡分析方法探討了西昆侖北緣新生代的冷卻歷史。結(jié)合裂變徑跡年齡和徑跡長度分布進(jìn)行分析,可以將6個磷灰石樣品分為2組。3個磷灰石樣品的徑跡年齡遠(yuǎn)小于所在地層的年齡。平均徑跡長度為(12.0±2.3)~(12.6±1.3)μm,呈不對稱單峰形態(tài),反映樣品緩慢地通過部分退火帶;另外3個磷灰石樣品徑跡年齡與各自地層的沉積年齡接近,平均徑跡長度介于(10.7±2.3)~(11.4±1.3)μm,呈現(xiàn)雙峰或混合分布的特征,表明沉積后發(fā)生部分退火。熱史模擬顯示,自晚白堊世以來,西昆侖山北緣共經(jīng)歷了3期抬升冷卻事件。晚始新世(40~30 Ma),受早期印度板塊向古亞洲大陸板塊俯沖碰撞的影響,西昆侖山北緣已經(jīng)開始隆升;晚漸新世 早中新世(25~15 Ma)是西昆侖乃至青藏高原重要的隆升時期;最后一輪強(qiáng)烈隆升則發(fā)生在距今5~3 Ma以來,冷卻速率最高達(dá)15℃/Ma,剝蝕速率相當(dāng)于600m/my。電子自旋共振測試揭示了早中新世(15 Ma)和晚上新世以來(2.6~0.63 Ma)兩期強(qiáng)烈的構(gòu)造變形和熱液活動,更進(jìn)一步限定了西昆侖最后一期強(qiáng)烈隆升在2.6 Ma以來。
[Abstract]:Since the Cenozoic, the tectonic deformation and uplift occurred strongly in the West Kunlun area, and the time limits of the initial uplift and the last rapid uplift are still important problems to be discussed. A series of sandstone samples were collected along the northern edge of the West Kunlun Mountains in this paper. The cooling history of the Cenozoic in the northern margin of West Kunlun is discussed by using the fission track analysis method, and the fission track age and track length distribution are analyzed. Six apatite samples can be divided into two groups. The track ages of 3 apatite samples are much smaller than that of the local layer. The average track length is 12.6 鹵1.3 渭 m, which shows that the sample passes slowly through part of the annealing zone. The track ages of the other three apatite samples are close to their sedimentary ages, and the average track length is between 10.7 鹵2.3 渭 m and 11.4 鹵1.3 渭 m, showing a bimodal or mixed distribution, indicating partial annealing after deposition. The northern margin of the West Kunlun Mountains experienced three uplift and cooling events. The northern margin of the West Kunlun Mountains began to uplift due to the subduction and collision of the early Indian plate to the Paleo-Asian continental plate in the late Eocene. The late Oligocene and early Miocene were important uplift periods in West Kunlun and even the Qinghai-Xizang Plateau, and the last strong uplift occurred since 5 ~ 3 Ma ago. The cooling rate is up to 15 鈩，

本文編號：1644471