CAJ | 학술논문

　　西藏冈底斯岩浆岩带西段北侧的林子宗群火山岩含有从板块俯冲机制向大陆碰撞机制转变的丰富信息。将措勤地区典中组火山岩与冈底斯岩浆岩带东段林周盆地的典中组火山岩在同位素地球化学、演化特征方面进行对比,探讨冈底斯岩浆岩带西段与东段在演化过程中的异同性。结果表明，措勤地区典中组火山岩的87Sr/86Sr初始比值变化范围为0.710352~0.713423，具较高的87Sr/86Sr比值；143Nd/144Nd初始比值为0.512293~0.512407，具较低的143Nd/144Nd比值；林周盆地典中组火山岩的87Sr/86Sr初始比值为0.7057~0.7063之间，143Nd/144Nd初始比值范围为0.5125~0.5126。同位素特征显示措勤地区典中组源区物质可能来自于富集Ⅱ型地幔，即源区为俯冲和再循环的大陆地壳物质与地幔岩发生了混合作用的产物，源区受控于冈底斯地壳基底。林周盆地典中组火山岩源区物质可能与富集Ⅰ型地幔有关。
　　서장강저사암장암대서단북측적림자종군화산암함유종판괴부충궤제향대륙팽당궤제전변적봉부신식。장조근지구전중조화산암여강저사암장암대동단림주분지적전중조화산암재동위소지구화학、연화특정방면진행대비,탐토강저사암장암대서단여동단재연화과정중적이동성。결과표명，조근지구전중조화산암적87Sr/86Sr초시비치변화범위위0.710352~0.713423，구교고적87Sr/86Sr비치；143Nd/144Nd초시비치위0.512293~0.512407，구교저적143Nd/144Nd비치；림주분지전중조화산암적87Sr/86Sr초시비치위0.7057~0.7063지간，143Nd/144Nd초시비치범위위0.5125~0.5126。동위소특정현시조근지구전중조원구물질가능래자우부집Ⅱ형지만，즉원구위부충화재순배적대륙지각물질여지만암발생료혼합작용적산물，원구수공우강저사지각기저。림주분지전중조화산암원구물질가능여부집Ⅰ형지만유관。
Cuoqin volcanic basin is located on north of the western part of Gangdese magmatic belt,its petrological and geochemical characteristics of which indicate that they contains abandant information of the transition from the subduction mechanism to continental collision mechanism. This paper that were compared to the Dianzhong formation in Lin-zhou basin,and to that distributed in other different of regions Gandese blet,explorethe similarities and differencesbe-ween western and the eastern section the Gangdese magmatic belt of the of in the evolution process.The results show that Isotopic characteristics of Dianzhong volcanic rocks 87Sr/86Sr the ratio of initial changes in 0.710 352 to 0.713 423, have higher 87Sr/86Sr ratios;the 143Nd/144Nd the ratio of initial changes in 0.522 293~0.512 407, have low 143Nd/144Nd ratios;Linzhou volcanic rocks 87Sr/86Sr the ratio of initial changes in 0.705 7 to 0.706 3,have higher 87Sr/86Sr ratios;the 143Nd/144Nd the ratio of initial changes in 0.512 5 to 0.512 6, have low 143Nd/144Nd ratios.Its Shows that source material from the enriched II type mantle, the source region are subduction and recycling of continental crust mixed with pyrolite, the source region is controlled in the Gangdese crustal basement.Materials from the source rock in Linzhou basin may relat-ed to enrichdeⅠtype mantle.