CAJ | 학술논문

采用LA-MC-ICP-MS测定技术，对怒江河流沉积物中的碎屑锆石进行了U-Pb和Lu-Hf同位素测定。结果显示，碎屑锆石U-Pb年龄可分为6个组段：50~74Ma、84~235Ma、275~413Ma、451~569Ma、657~1429Ma和1602~3436Ma，其中最主要的年龄组段为50~74Ma和84~235Ma。50~74Ma的年龄段为新特提斯洋从俯冲到碰撞闭合的阶段，约65Ma的年龄峰值可能是印度大陆与欧亚大陆主体碰撞的远程地质记录。84~235Ma年龄段代表了中特提斯洋演化阶段，年龄峰值约为110Ma，可能指示羌塘地块与拉萨地块的碰撞拼接此时已经完成，通过U-Pb年龄分布对比，羌塘地块几乎没有给怒江河流沉积物提供物质。怒江河流沉积物中碎屑锆石的εHf(t)值介于-18.7~+11.7之间，模式年龄分布于0.65~4.05Ga之间，其中中生代碎屑锆石的εHf (t)值分布于-16.4~+2.9之间，与中拉萨地块有密切的亲缘性，同时含有少量北拉萨地块的特征。因此，怒江河流沉积物代表了中拉萨地块与北拉萨地块的特征。
채용LA-MC-ICP-MS측정기술，대노강하류침적물중적쇄설고석진행료U-Pb화Lu-Hf동위소측정。결과현시，쇄설고석U-Pb년령가분위6개조단：50~74Ma、84~235Ma、275~413Ma、451~569Ma、657~1429Ma화1602~3436Ma，기중최주요적년령조단위50~74Ma화84~235Ma。50~74Ma적년령단위신특제사양종부충도팽당폐합적계단，약65Ma적년령봉치가능시인도대륙여구아대륙주체팽당적원정지질기록。84~235Ma년령단대표료중특제사양연화계단，년령봉치약위110Ma，가능지시강당지괴여랍살지괴적팽당병접차시이경완성，통과U-Pb년령분포대비，강당지괴궤호몰유급노강하류침적물제공물질。노강하류침적물중쇄설고석적εHf(t)치개우-18.7~+11.7지간，모식년령분포우0.65~4.05Ga지간，기중중생대쇄설고석적εHf (t)치분포우-16.4~+2.9지간，여중랍살지괴유밀절적친연성，동시함유소량북랍살지괴적특정。인차，노강하류침적물대표료중랍살지괴여북랍살지괴적특정。
In this paper, LA-ICP-MS technology was used to perform U-Pb dating and analyze Lu-Hf isotopic composition. U-Pb ages of the detrital zircons in the sediments of the Nujiang River can be divided into 6 groups: 50~74Ma, 84~235Ma, 275~413Ma, 451~569Ma, 657~1429Ma and 1602~3436Ma, with the most important age populations being 50~74Ma and 84~235Ma. The ages of 50~74Ma reflect the history of the subduction and the closure of the Neo-Tethys Ocean, and the age peak of ca.65Ma reveals the main collision stage between India and Eurasian continents. The 84~235Ma might reveal the evolution of the Meso-Teth?ys Ocean, and the age peak of ca.110Ma is the geological record of the post collisional stage between the Qiangtang block and the Lha?sa block. A comparison of the U-Pb ages distribution with that of the Qiangtang block suggests that sediments of the Nujiang River are not derived from the Qiangtang block. In addition, theεHf(t) values and the two-stage model ages of the detrital zircons from the Nujiang River range from-18.7 to+11.7 and from 0.65Ga to 4.05Ga, respectively. Meanwhile,εHf(t) values of the Mesozoic detrital zircons range from-16.4 to+2.9, which is consistent with the data from the Middle Lhasa block and the North Lhasa block.