【摘要】：青藏高原是歐亞板塊與印度板塊碰撞擠壓隆升而成,因此地質(zhì)構(gòu)造及巖漿活動復(fù)雜而強(qiáng)烈。又因青藏高原特殊的高海拔、高地應(yīng)力、高地?zé)岷透邥円箿夭钣绊?在巖漿活動強(qiáng)烈的區(qū)域,火成巖侵入圍巖時(shí)形成了特殊而復(fù)雜的火成巖蝕變帶。本文以西藏松宗～八宿地區(qū)的蝕變巖體為研究對象,針對蝕變巖的分布規(guī)律、組合特征、蝕變成因和力學(xué)性質(zhì)展開了系統(tǒng)的研究,取得了如下成果：(1)對研究區(qū)內(nèi)蝕變巖的資料進(jìn)行分析,總結(jié)出主要的蝕變巖種類和空間分布特征；通過現(xiàn)場的調(diào)查和室內(nèi)試驗(yàn)分析出蝕變巖的組合特征,得到調(diào)查區(qū)內(nèi)花崗巖的侵入大致是沿著區(qū)域性大斷裂發(fā)生,從平面上沿著斷裂帶走向呈帶狀分布。蝕變組合關(guān)系主要分為兩種：一、古新世(E1)花崗巖侵入早石炭世(C1)砂巖；二、早白堊世(K1)花崗巖侵入中晚侏羅世(J2-3)砂巖。(2)查明了蝕變帶內(nèi)巖體的蝕變成因,調(diào)查區(qū)蝕變巖的礦物蝕變主要包括黑云母綠泥石化,斜長石絹云母化,微斜長石白云母化和石英晶體的重結(jié)晶作用。其中綠泥石交代黑云母在黑云母花崗閃長巖中比較常見；絹云母交代斜長石在黑云母花崗閃長巖和侏羅系變質(zhì)砂巖中比較常見；白云母交代微斜長石主要發(fā)生在早白堊世的花崗巖中;石英的重結(jié)晶作用主要發(fā)生在熱液作用下的侏羅系細(xì)砂巖和長石石英砂巖中。(3)根據(jù)巖石中石英和長石的含量將侏羅系砂巖蝕變帶巖體中礦物間連接結(jié)構(gòu)分為三種：石英—石英—石英結(jié)構(gòu)(石英含量75%-90%,長石含量10%)；石英—長石—石英結(jié)構(gòu)(石英含量40%-50%,長石含量25%-40%)；長石—石英—長石結(jié)構(gòu)(石英含量400%,長石含量40%-60%)。(4)通過室內(nèi)單軸壓縮變形試驗(yàn),得到了蝕變帶內(nèi)各巖體的力學(xué)參數(shù)。認(rèn)為蝕變巖屬于高壓縮性、高強(qiáng)度的脆性變質(zhì)巖類,巖體內(nèi)部孔隙非常發(fā)育。采用巖塊單軸抗壓強(qiáng)度和割線模量兩個(gè)指標(biāo)將研究區(qū)內(nèi)蝕變巖體強(qiáng)度分為三個(gè)等級：高強(qiáng)度巖體,單軸抗壓強(qiáng)度100-200MPa,割線模量4.5～5.0×104MPa；中等強(qiáng)度巖體,單軸抗壓強(qiáng)度在50～100MPa,割線模量2.5～4.5×104MPa；低強(qiáng)度巖體,單軸抗壓強(qiáng)度在25-50MPa,割線模量1～2.5×104MPa。
[Abstract]:The Qinghai-Xizang Plateau is formed by collision and uplift of Eurasian plate and Indian plate, so geological structure and magmatic activity are complicated and strong. Because of the special high altitude, high ground stress, high geothermal and high diurnal temperature difference in the Qinghai-Tibet Plateau, the igneous rock formed a special and complex igneous rock alteration zone in the area with strong magmatic activity. In this paper, the altered rock mass in Songzong ~ Bashu area, Tibet is taken as the research object. The distribution law, assemblage characteristics, alteration cause and mechanical properties of the altered rock mass are systematically studied. The results are as follows: (1) the data of altered rocks in the study area are analyzed and the main types and spatial distribution characteristics of altered rocks are summarized. Based on the field investigation and laboratory tests, the authors analyze the assemblage characteristics of altered rocks. It is concluded that the granite intrusions in the investigation area occurred roughly along the large regional faults and distributed in a zonal pattern along the strike of the fault zone in the plane. Alteration assemblages are mainly divided into two types: first, the Paleocene (E1) granite intruded into the early Carboniferous (C1) sandstone; Second, the early Cretaceous (K1) granite intruded into the Middle and late Jurassic (J2-3) sandstone. (2) the causes of alteration of the altered rock mass in the altered zone were identified. The mineral alteration of the altered rocks in the investigation area mainly included biotite greenstone and plagioclase sericite. Microplagioclase Muscovite and recrystallization of quartz crystals. Chlorite metasomorphic biotite is common in biotite granodiorite, sericite metasomorphic plagioclase is common in biotite granodiorite and Jurassic metamorphic sandstone. Muscovite metasomorphic microplagioclase mainly occurred in early Cretaceous granite; The recrystallization of quartz mainly occurs in Jurassic fine sandstone and feldspar quartz sandstone under hydrothermal action. (3) according to the content of quartz and feldspar in the rock, the mineral connection structure in the Jurassic sandstone alteration zone is divided. There are three types: quartz-quartz structure (quartz content 75-90), Feldspar (10%); Quartz feldspar quartz structure (quartz content 40% -50%, feldspar 25% -40%); The mechanical parameters of each rock mass in the alteration zone were obtained by laboratory uniaxial compression deformation tests with feldspar quartz feldspar structure (quartz content 400 and feldspar content 40-60%). (4). It is considered that altered rocks belong to brittle metamorphic rocks with high compressibility and high strength, and the internal pores are very developed. According to the uniaxial compressive strength and Secant modulus of rock blocks, the strength of altered rock mass in the studied area is divided into three grades: high strength rock mass, uniaxial compressive strength 100-200MPa, Secant modulus 4.5mg 5.0 脳 104MPa; The uniaxial compressive strength of medium strength rock mass is 50 ~ 100MPa, the Secant modulus is 2.54.5 脳 104MPa, and the uniaxial compressive strength of low-strength rock mass is 25-50MPa, and the Secant modulus is 12.5 脳 104MPa.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P588.1;TU45

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