地球学报
地毬學報
지구학보
ACTA GEOSCIENTIA SINICA
2014年
4期
415-424
,共10页
黄始琪%董树文%张福勤%苗来成%朱明帅
黃始琪%董樹文%張福勤%苗來成%硃明帥
황시기%동수문%장복근%묘래성%주명수
蒙古-鄂霍茨克构造带%韧性变形%脆性变形%古应力场%东亚多向汇聚%蒙古
矇古-鄂霍茨剋構造帶%韌性變形%脆性變形%古應力場%東亞多嚮彙聚%矇古
몽고-악곽자극구조대%인성변형%취성변형%고응력장%동아다향회취%몽고
Mongolia-Okhotsk collisional belt%ductile deformation%brittle deformation%stress field%East Asian multi-direction convergence%Mongolian
蒙古-鄂霍茨克构造带作为中亚造山带的重要组成部分,其构造变形和动力学特征一直是地质界关注的问题。沿着该构造带中段,对5个韧性变形点及1个脆性变形点进行详细解析,揭示了该构造带变形及动力学特征。B型褶皱、揉皱、A型褶皱、矿物拉伸线理、S-C组构都显示了该构造带明显的NW-SE剪切作用。剪切方向稳定而单一,未发现多方向变形叠加现象,可能指示了蒙古-鄂霍茨克构造带的形成过程为一期主要的俯冲碰撞或多期同向的俯冲碰撞。对蒙古-鄂霍茨克构造带形成时间和动力学背景进行了讨论,认为该构造带主要形成于中晚侏罗世-早白垩世东亚多向汇聚动力学背景之下。对构造带内地质点mg6脆性断层面上滑动矢量进行了统计和古应力场反演,得出两期古构造应力场,一期为NW-SE挤压,一期为近E-W挤压。NW-SE挤压应力场可能对应了中晚侏罗世-白垩纪古太平洋板块向西俯冲对中亚地区的远程影响;而近 E-W 向挤压可能反映了早新生代印度-欧亚板块碰撞对中亚地区的远程效应。
矇古-鄂霍茨剋構造帶作為中亞造山帶的重要組成部分,其構造變形和動力學特徵一直是地質界關註的問題。沿著該構造帶中段,對5箇韌性變形點及1箇脆性變形點進行詳細解析,揭示瞭該構造帶變形及動力學特徵。B型褶皺、揉皺、A型褶皺、礦物拉伸線理、S-C組構都顯示瞭該構造帶明顯的NW-SE剪切作用。剪切方嚮穩定而單一,未髮現多方嚮變形疊加現象,可能指示瞭矇古-鄂霍茨剋構造帶的形成過程為一期主要的俯遲踫撞或多期同嚮的俯遲踫撞。對矇古-鄂霍茨剋構造帶形成時間和動力學揹景進行瞭討論,認為該構造帶主要形成于中晚侏囉世-早白堊世東亞多嚮彙聚動力學揹景之下。對構造帶內地質點mg6脆性斷層麵上滑動矢量進行瞭統計和古應力場反縯,得齣兩期古構造應力場,一期為NW-SE擠壓,一期為近E-W擠壓。NW-SE擠壓應力場可能對應瞭中晚侏囉世-白堊紀古太平洋闆塊嚮西俯遲對中亞地區的遠程影響;而近 E-W 嚮擠壓可能反映瞭早新生代印度-歐亞闆塊踫撞對中亞地區的遠程效應。
몽고-악곽자극구조대작위중아조산대적중요조성부분,기구조변형화동역학특정일직시지질계관주적문제。연착해구조대중단,대5개인성변형점급1개취성변형점진행상세해석,게시료해구조대변형급동역학특정。B형습추、유추、A형습추、광물랍신선리、S-C조구도현시료해구조대명현적NW-SE전절작용。전절방향은정이단일,미발현다방향변형첩가현상,가능지시료몽고-악곽자극구조대적형성과정위일기주요적부충팽당혹다기동향적부충팽당。대몽고-악곽자극구조대형성시간화동역학배경진행료토론,인위해구조대주요형성우중만주라세-조백성세동아다향회취동역학배경지하。대구조대내지질점mg6취성단층면상활동시량진행료통계화고응력장반연,득출량기고구조응력장,일기위NW-SE제압,일기위근E-W제압。NW-SE제압응력장가능대응료중만주라세-백성기고태평양판괴향서부충대중아지구적원정영향;이근 E-W 향제압가능반영료조신생대인도-구아판괴팽당대중아지구적원정효응。
As an important part of the Central Asian Orogenic Belt, the Mongolia-Okhotsk collisional belt has attracted much attention for its tectonic deformation and dynamic characteristics. Along the middle part of the Mongolia-Okhotsk collisional belt, five ductile deformation sites and a brittle deformation site were analyzed to reveal its tectonic deformation and dynamic features. B style fold, crumple structure, A style fold, mineral stretching lineation and S-C fabric indicate NW-SE shearing. This information reveals that might have existed a large collision or multi-periodic collisions in the same direction, which resulted in the formation of the Mongolia-Okhotsk collisional belt. The forming time and global tectonic settings as well as the dynamic origin of the Mongolia-Okhotsk collisional belt were discussed. This tectonic belt was mainly formed during the middle Jurassic-early Cretaceous period under the tectonic setting of the East Asian multi-direction convergence. The brittle deformation of Site mg6 was analyzed and two paleo-stress fields were restored, i.e., the NW-SE compression stress field and the E-W compression stress field. The NW-SE compression stress field might have resulted from the distant effect of the westward subduction of the Paleo-Pacific plate during the Jurassic and Cretaceous, whereas the E-W compression stress field probably resulted from the distant effect of the India-Asia collision during the early Cenozoic.