【摘要】：關(guān)于太古宙早期地殼演化構(gòu)造機(jī)制的爭(zhēng)論已經(jīng)持續(xù)了數(shù)十年,其焦點(diǎn)主要集中于水平構(gòu)造還是垂向構(gòu)造兩大經(jīng)典構(gòu)造模式的探討.對(duì)于早期地殼構(gòu)造演化方面的研究,將會(huì)有助于我們更好地理解早前寒武紀(jì)的地球動(dòng)力學(xué)機(jī)制.本文對(duì)華北克拉通東北部鞍山地區(qū)花崗-綠巖帶內(nèi)齊大山韌性剪切帶的構(gòu)造變形特征進(jìn)行了詳細(xì)的解析,揭示了該區(qū)新太古代垂向構(gòu)造作用樣式.研究結(jié)果表明,齊大山韌性剪切帶內(nèi)花崗質(zhì)巖石長(zhǎng)英質(zhì)礦物塑性拉長(zhǎng)特征明顯,條帶狀構(gòu)造發(fā)育,面理向NWW方向陡傾,不對(duì)稱組構(gòu)特征和礦物拉伸線理產(chǎn)狀指示向NWW的陡傾正滑移剪切作用.變形巖石中的長(zhǎng)英質(zhì)礦物均發(fā)育中低溫顯微變形特征,石英C軸電子背散射衍射(EBSD)組構(gòu)分析揭示石英以菱面a和底面a滑移系為主,巖石經(jīng)歷了中低溫非共軸變形.根據(jù)礦物的變形行為以及石英的結(jié)晶優(yōu)選方位推測(cè)變形溫度約為400~500℃,巖石變形特征以位錯(cuò)蠕變?yōu)橹?有限應(yīng)變分析結(jié)果表明,靠近鐵礦帶方向,構(gòu)造巖類型由L=S構(gòu)造巖過(guò)渡為L(zhǎng)S構(gòu)造巖,巖石應(yīng)變強(qiáng)度呈明顯增強(qiáng)趨勢(shì).運(yùn)動(dòng)學(xué)渦度測(cè)量結(jié)果顯示齊大山韌性剪切帶內(nèi)大多數(shù)巖石樣品的Wk值大于0.75,巖石形成于以簡(jiǎn)單剪切作用為主的一般剪切作用.對(duì)比花崗-綠巖帶西側(cè)的白家墳韌性剪切帶,顯示二者均具有相向的陡傾正滑移運(yùn)動(dòng)學(xué)特征,表明新太古代時(shí)期鞍山地區(qū)地殼構(gòu)造演化模式以垂向構(gòu)造作用為主.
[Abstract]:The debate on the tectonic mechanism of the early Archean crustal evolution has been going on for decades with the focus mainly on the discussion of the two classical tectonic models of horizontal or vertical tectonics. The study of early crustal tectonic evolution will help us to better understand the geodynamic mechanism of the early Precambrian. In this paper, the tectonic deformation characteristics of Qidashan ductile shear zone in the granite-greenstone belt in the Anshan area, northeast of North China Craton, are analyzed in detail, and the new Archean vertical tectonic patterns in this area are revealed. The results show that the feldspar minerals of granitic rocks in Qidashan ductile shear zone have obvious plastic elongation characteristics, strip-like structures are developed, and the plane is steeply inclined towards NWW. Asymmetric fabric characteristics and mineral tensile lineage indicate steep-dip normal slip shear to NWW. All the feldspathic minerals in the deformed rocks are microdeformed at moderate and low temperatures. The (EBSD) fabric analysis of quartz C-axis electron backscattering diffraction reveals that the quartz is dominated by rhombohedral a and bottom a slip systems, and the rocks have undergone moderate and low temperature non-coaxial deformation. According to the deformation behavior of minerals and the optimum orientation of quartz crystallization, the deformation temperature is about 400 ~ 500 鈩，

本文編號(hào)：2352027