【摘要】：哀牢山-紅河剪切帶剪切時間的厘定至今存在較多的爭議,爭議的本質(zhì)更確切地說是對于剪切帶內(nèi)及其附近剪切作用與巖漿作用認(rèn)識的差異。點(diǎn)蒼山雜巖是位于哀牢山-紅河剪切帶北端的一個雜巖體,由西部的深變質(zhì)巖、東部的疊加退變質(zhì)帶和不同時代的花崗質(zhì)巖石組成。為了正確厘定剪切前、剪切期(包括剪切前期和剪切后期)、剪切后花崗質(zhì)巖脈,剪切作用過程中構(gòu)造變形與巖漿作用之間的關(guān)系,同時對哀牢山-紅河剪切帶剪切時間進(jìn)行新的約束,本文圍繞點(diǎn)蒼山雜巖開展詳細(xì)的宏觀構(gòu)造解析、顯微構(gòu)造觀察和組構(gòu)分析,以查明巖體(脈)巖漿流動構(gòu)造和晶質(zhì)塑性變形構(gòu)造,同時對同剪切巖脈開展鋯石U-Pb學(xué)分析。結(jié)果顯示,剪切不同階段就位的花崗質(zhì)巖石具有不同的宏觀構(gòu)造、顯微構(gòu)造與組構(gòu)特征�，F(xiàn)今所見巖石變形構(gòu)造、顯微構(gòu)造和組構(gòu)特點(diǎn)一方面取決于遞進(jìn)剪切變形作用過程中的時間早晚,另一方面還與它們在遞進(jìn)剪切變形作用過程中的構(gòu)造位置有密切聯(lián)系。獲得兩組同剪切年齡為28.54±0.15Ma和27.31±0.23Ma,其中前者為剪切早期階段同就位的花崗巖脈,后者為剪切稍晚階段同就位的花崗巖。研究揭示出就位較晚的巖脈(即后者)因其位于遞進(jìn)剪切變形的高應(yīng)變帶而具有較為復(fù)雜的變形構(gòu)造、顯微構(gòu)造和組構(gòu)型式,就位較早的巖脈(前者)因在遞進(jìn)剪切變形作用過程中位于低應(yīng)變帶而具有簡單的變形構(gòu)造、顯微構(gòu)造和組構(gòu)型式,并仍然保留有巖漿結(jié)晶組構(gòu)特點(diǎn)。哀牢山-紅河剪切帶在28.54~27.31Ma間持續(xù)發(fā)生著從早期階段較高溫(~700℃),向中期階段中高溫(550~600℃)和晚期階段低溫(低于400℃)環(huán)境的遞進(jìn)剪切變形作用。
[Abstract]:The determination of shear time in the Ailaoshan-Honghe shear zone is controversial up to now. The essence of the controversy is the difference between shear and magmatism in and around the shear zone. The Dancangshan complex is a complex at the northern end of the Ailaoshan-Honghe shear zone, which is composed of the western deep metamorphic rocks, the eastern superimposed retrograde metamorphic zone and the granitic rocks of different ages. In order to correctly determine the relationship between tectonic deformation and magmatism during shearing, shearing (including pre-shear and post-shear), post-shear granitic veins, At the same time, the shear time of the Ailaoshan-Honghe shear zone is restricted. The detailed macroscopic structural analysis, microscopic structure observation and fabric analysis are carried out around the point Cangshan complex. In order to find out the magmatic flow structure and the grain plastic deformation structure of the rock mass (vein), zircon U-Pb analysis was carried out for the same shearing vein at the same time. The results show that the granitic rocks in different stages of shear have different macroscopic structure, microstructure and fabric characteristics. On the one hand, the microstructure and fabric characteristics of rock deformation are determined by the time of progressive shear deformation, on the other hand, they are closely related to their tectonic position in the process of progressive shear deformation. The same shear age is 28.54 鹵0.15Ma and 27.31 鹵0.23 Ma.The former is the same in the early stage of shearing, and the latter is in the same position in the later stage of shear. The study reveals that the late vein (that is, the latter) has complex deformation structures, microstructures and fabric patterns due to its location in the high strain zone of progressive shear deformation. The early emplaced veins (the former) have simple deformation structures, microstructures and fabric patterns because they are located in low strain zones during progressive shear deformation, and still retain the characteristics of magmatic crystallization fabric. In the Ailaoshan-Honghe shear zone, progressive shear deformation occurred between the early stage (700 鈩，

本文編號：2151781