發(fā)布時間：2018-04-05 15:00

  本文選題：花崗巖　切入點：華北克拉通　出處：《成都理工大學(xué)》2015年碩士論文

【摘要】：本研究以冀北康保晚古生代花崗巖類為研究對象,識別出了8個具有不同類型花崗巖的巖體,并且進行了野外的地質(zhì)觀察、室內(nèi)的鏡下鑒定、電子探針測試以及鋯石U-Pb定年等方面的細致工作,取得了以下認識:(1)不同巖體的花崗巖礦物含量差別較大,西五福堂巖體、新村巖體、李生寶溝巖體、三老虎巖體和前孟家地巖體,花崗巖中暗色礦物依次逐漸減少,粒度由細粒到粗粒,巖石類型由花崗閃長巖-二長花崗巖-正長花崗巖。小西溝巖體、石柱梁巖體、大盤溝巖體,花崗巖中斜長石均較少,堿性長石含量依次逐漸增加,由正長花崗巖到堿長花崗巖,結(jié)構(gòu)由斑狀-含斑-似斑狀變化。礦物電子探針測試數(shù)據(jù)可以得西五福堂巖體的中細粒含角閃黑云花崗閃長巖中,斜長石(An=39.6~43.4)應(yīng)屬于中長石;新村巖體的中粒含角閃黑云二長花崗巖的斜長石中,斜長石(An=25.1~28.9)為更長石;李生寶溝巖體的中細粒二長花崗巖中的斜長石的特征相似,斜長石牌號應(yīng)均為更長石-鈉長石(An=2.9~16.8)。石柱梁和大盤溝巖體的花崗巖所含的斜長石為鈉長石(An=0~1.6)。西五福堂巖體花崗巖中黑云母為鎂鐵質(zhì)黑云母,顯示出殼�；烊镜膩碓春驮焐綆Щ◢弾r中黑云母的特征。其他巖體花崗巖均為鐵質(zhì)及富鐵黑云母,物質(zhì)來源于地殼,為堿性花崗巖中黑云母的特征。角閃石屬于鈣角閃石((Ca+Na)B≥1.00,NaB0.50)。進一步分別是淺閃石、鎂綠鈣閃石和綠鈣閃石,也顯示出了幔源物質(zhì)混染的特征。(2)花崗巖中鋯石Ti溫度計測算結(jié)果表明,康保晚古生代花崗質(zhì)巖漿的形成、結(jié)晶的平均溫度均大于750℃,這些花崗巖和花崗閃長巖均起源于地殼下部。鋯石Ti溫度與Zr/Hf、Th/U的相關(guān)性分析認為,巖漿冷凝時整個巖漿系統(tǒng)處于開放的系統(tǒng)下,而后期多期的流體或者巖漿以富U、Hf為特點(3)石柱梁巖體花崗巖LA-ICP-MS鋯石U-Pb年齡為260.6±1.6Ma、小西溝巖體花崗巖LA-ICP-MS鋯石U-Pb年齡為264.1±1.7Ma、前孟家地巖體花崗巖LA-ICP-MS鋯石U-Pb年齡為269.5±2.7Ma、三老虎巖體花崗巖LA-ICP-MS鋯石U-Pb年齡為276.3±1.9Ma、新村巖體花崗巖LA-ICP-MS鋯石U-Pb年齡為280.4±2.0Ma、西五福堂巖體花崗巖LA-ICP-MS鋯石U-Pb年齡為284.7±1.7Ma。西五福堂巖體的中細粒含角閃黑云花崗閃長巖和新村巖體的中粒含角閃黑云二長花崗巖形成于大陸邊緣弧環(huán)境向同碰撞轉(zhuǎn)換階段,其他巖石巖體的花崗巖巖性上為二長花崗巖和偏堿性花崗巖,應(yīng)是同碰撞后期到后碰撞環(huán)境下形成的。
[Abstract]:In this study, eight granites with different types of granites were identified from the late Paleozoic granites in Kangbao, northern Hebei Province, and field geological observations were carried out.The detailed work of electron probe test and zircon U-Pb dating has obtained the following understanding: the content of granite minerals in different rock masses is quite different, the West Wufutang, Xincun, Li Shengbaogou, etc.The dark minerals in the granites are gradually reduced from granulite to coarse-grained, and the rock types are from granodiorite to monzogranite to syenite.There are less plagioclase in Xiaoxigou rock body, Shizhouliang rock body, Dapanggou rock mass and granite, and the content of alkaline feldspar increases gradually, from syenite to alkali feldspar granite, and the structure changes from porphyry, porphyry to porphyry.From the mineral electron probe data, it can be concluded that the plagioclase of the medium and fine grained amphibole granodiorite of the West Wufutang rock body, the plagioclase of the plagioclase Anjiao 39.6n43.4) should belong to the plagioclase containing hornblende monzogranite in the Xincun rock mass.The plagioclase contained in the granite of Shizhulliang and Dapangou is albite.The biotite in the granites of the West Wufutang granite is magnesia-iron biotite, which shows the origin of crust and mantle mixing and the characteristics of biotite in the granites of the orogenic belt.The other granites are ferric and iron-rich biotite, derived from the crust and characterized by biotite in alkaline granites.Hornblende belongs to calcium hornblende (Ca Na)B 鈮，

本文編號：1715248