中国科技信息
中國科技信息
중국과기신식
CHINA SCIENCE AND TECHNOLOGY INFORMATION
2010年
11期
25-30
,共6页
结扎群%晚三叠%同位素%构造环境
結扎群%晚三疊%同位素%構造環境
결찰군%만삼첩%동위소%구조배경
扎日根结扎群火山岩中基性岩以贫硅、钾,高钛、钙,中性岩类以低硅、中钾、钛、钙,酸性岩类以高硅、钾,中钛,低钙为特征.根据Fe*/MgO-TiO2图解上显示出本区火山岩绝大多数火山岩落在岛弧区.微量元素中Th/Nb=0.9>0.11,Nb/Zr>0.04显示出其构造背景为陆-陆碰撞形成的岛弧区.扎日根结扎群火山岩时代为晚三叠世,表面年龄分别是325±1.7Ma,345±15.9Ma,469±21.9Ma,229±3.3Ma,237±67.2Ma,318±90.4Ma,156±1.2Ma,162±13.1Ma,252±20.4Ma,207±0.9Ma,213±6.7Ma,288±9.2Ma其中207~237Ma年龄较多,与Rb-Sr等时线同位素给出的年龄相吻合,属晚三叠世.另外Sr同位素的初始比值Sr=0.70522±0.00023Ma,少于0.719,表明岩浆(原始)来源于上地幔,并且在上升的过程中受到地壳的混染.
扎日根結扎群火山巖中基性巖以貧硅、鉀,高鈦、鈣,中性巖類以低硅、中鉀、鈦、鈣,痠性巖類以高硅、鉀,中鈦,低鈣為特徵.根據Fe*/MgO-TiO2圖解上顯示齣本區火山巖絕大多數火山巖落在島弧區.微量元素中Th/Nb=0.9>0.11,Nb/Zr>0.04顯示齣其構造揹景為陸-陸踫撞形成的島弧區.扎日根結扎群火山巖時代為晚三疊世,錶麵年齡分彆是325±1.7Ma,345±15.9Ma,469±21.9Ma,229±3.3Ma,237±67.2Ma,318±90.4Ma,156±1.2Ma,162±13.1Ma,252±20.4Ma,207±0.9Ma,213±6.7Ma,288±9.2Ma其中207~237Ma年齡較多,與Rb-Sr等時線同位素給齣的年齡相吻閤,屬晚三疊世.另外Sr同位素的初始比值Sr=0.70522±0.00023Ma,少于0.719,錶明巖漿(原始)來源于上地幔,併且在上升的過程中受到地殼的混染.
찰일근결찰군화산암중기성암이빈규、갑,고태、개,중성암류이저규、중갑、태、개,산성암류이고규、갑,중태,저개위특정.근거Fe*/MgO-TiO2도해상현시출본구화산암절대다수화산암락재도호구.미량원소중Th/Nb=0.9>0.11,Nb/Zr>0.04현시출기구조배경위륙-륙팽당형성적도호구.찰일근결찰군화산암시대위만삼첩세,표면년령분별시325±1.7Ma,345±15.9Ma,469±21.9Ma,229±3.3Ma,237±67.2Ma,318±90.4Ma,156±1.2Ma,162±13.1Ma,252±20.4Ma,207±0.9Ma,213±6.7Ma,288±9.2Ma기중207~237Ma년령교다,여Rb-Sr등시선동위소급출적년령상문합,속만삼첩세.령외Sr동위소적초시비치Sr=0.70522±0.00023Ma,소우0.719,표명암장(원시)래원우상지만,병차재상승적과정중수도지각적혼염.
