CAJ | 학술논문

应用LA-ICP-MS分析了青海刚察大寺地区花岗闪长岩和花岗岩锆石U-Pb同位素年龄，获得了花岗闪长岩的2期侵入年龄，花岗闪长岩10CL008样品谐和曲线年龄为254.8Ma±2.0Ma（N=13，MSWD=0.87），属于二叠纪；花岗岩10CL003样品谐和曲线年龄为236.3Ma±2.4Ma（N=13，MSWD=0.48），属于三叠纪。地球化学特征表明，花岗闪长岩和花岗岩分别属于钙碱性和高钾钙碱性过铝质岩，原始岩浆结晶分异作用由弱到强；稀土元素方面，二者的（La/Yb）N值分别为2.23~10.38和4.52~14.98，分馏程度由弱到强；具有Nb、P、Ti负异常和Ba正异常，显示出岛弧岩浆或活动大陆边缘岩浆的特征。综合研究表明，刚察大寺古生代花岗岩具有岛弧或活动大陆边缘花岗岩的属性，与板块的俯冲作用有关；中生代花岗岩继承了古生代花岗闪长岩的地球化学特征，岩浆物质成分以中上地壳为主，形成于早期深部幔源物质，与能量向上侵入下地壳过程中的重熔作用密切相关。
응용LA-ICP-MS분석료청해강찰대사지구화강섬장암화화강암고석U-Pb동위소년령，획득료화강섬장암적2기침입년령，화강섬장암10CL008양품해화곡선년령위254.8Ma±2.0Ma（N=13，MSWD=0.87），속우이첩기；화강암10CL003양품해화곡선년령위236.3Ma±2.4Ma（N=13，MSWD=0.48），속우삼첩기。지구화학특정표명，화강섬장암화화강암분별속우개감성화고갑개감성과려질암，원시암장결정분이작용유약도강；희토원소방면，이자적（La/Yb）N치분별위2.23~10.38화4.52~14.98，분류정도유약도강；구유Nb、P、Ti부이상화Ba정이상，현시출도호암장혹활동대륙변연암장적특정。종합연구표명，강찰대사고생대화강암구유도호혹활동대륙변연화강암적속성，여판괴적부충작용유관；중생대화강암계승료고생대화강섬장암적지구화학특정，암장물질성분이중상지각위주，형성우조기심부만원물질，여능량향상침입하지각과정중적중용작용밀절상관。
Located in the southeast part of the South Qilian orogenic belt in Qinghai Province, the Gangchadasi area has well-devel-oped magmatic rocks, which intruded into Precambrian, Cambrian, and Silurian strata;nevertheless, their petrogenesis and petrogenic setting have not been reported by previous researchers. In this paper, in-situ zircon U-Pb geochronologic analysis of zircons was conducted in State Key Laboratory of Continental Dynamics by using LA-ICP-MS methods. The LA-ICP-MS zircon U-Pb dat-ing shows that the ages of the granodiorite(10CL008)in Gangchadasi area can be divided into two phases:the concordia curve age of granodiorite 10CL008 sample is 254.8Ma±2.0Ma(N=13, MSWD=0.87), belonging to Paleozoic Permian, whereas the other granite (10CL003)sample has an age of 236.3Ma ± 2.4Ma(N=13,MSWD=0.87), belonging to Mesozoic Triassic. Geochemical characteris-tics show that granodiorite and granite belong to calc-alkaline and high K calc-alkaline metaluminous rocks respectively, with the original magmatic differentiation being transition from weak to strong. In REE and trace elements aspects, (La/Yb)N values are in the range of 2.23~10.38 and 4.52~14.98 respectively, with obvious LREE and HREE fractionation as well as positive anomaly of Ba and negative anomalies of Nb, P and Ti, suggesting the tectonic setting of island arc or active continental margin. Comprehensive studies show that granites had island arc or active continental margin properties, and were closely related to plate subduction in Paleo- zoic. In contrast, the Mesozoic granite inherited the characteristics from Paleozoic granodiorite, the magma components mainly came from the upper crust and formed in the early deep mantle, which was closely related to the remelting process of middle-lower crust caused by energy intrusion.