本文選題：蘇尼特左旗 + 中生代火山巖�。� 參考：《石家莊經(jīng)濟(jì)學(xué)院》2015年碩士論文

【摘要】：本文以“內(nèi)蒙古1:5萬準(zhǔn)和熱木音蘇木等六福區(qū)域地質(zhì)礦產(chǎn)調(diào)查”項目為依托,對內(nèi)蒙古蘇尼特左旗紅格爾地區(qū)中生代火山巖進(jìn)行研究。研究區(qū)大地構(gòu)造位置處于西伯利亞板塊東南大陸邊緣晚古生代陸緣增生帶,位于二連—賀根山板塊對接帶的西北側(cè)。該造山帶古生代屬古亞洲洋構(gòu)造域,中生代則處于濱太平洋構(gòu)造域。研究區(qū)構(gòu)造單元劃分屬于興蒙造山帶北方造山帶,位于內(nèi)蒙古北西部邊境地區(qū)。區(qū)內(nèi)巖漿巖活動頻繁,晚古生代及中生代有強烈的火山噴發(fā)及巖漿侵入活動。區(qū)域上中生代火山巖僅分布在1:5萬區(qū)域地質(zhì)調(diào)查圖準(zhǔn)和熱木音蘇木幅,呈條帶狀分布,在圖幅東北角延伸至測區(qū)鄰幅,與下伏石炭紀(jì)堿長花崗巖體呈火山噴發(fā)不整合接觸。紅格爾地區(qū)白音高老組火山巖處于NNE向斷裂帶,被白堊系大磨拐河組碎屑巖地層角度不整合覆蓋,火山巖發(fā)育近于直立劈理和褶皺構(gòu)造。巖性以流紋巖為主,夾凝灰?guī)r、熔結(jié)凝灰?guī)r、英安巖和黑曜巖薄層,南北兩端被石炭紀(jì)黑云母二長花崗巖侵入。本文中生代火山巖LA-ICA-MS鋯石測年所挑選的鋯石顆粒很少且為繼承性鋯石,其年齡結(jié)果代表了石炭紀(jì)堿長花崗巖的形成年齡,通過與鄰區(qū)已發(fā)表的白音高老組火山巖對比,發(fā)現(xiàn)具有一致的地球化學(xué)特征,顯示相同巖漿性質(zhì)進(jìn)而推斷二者為同期巖漿產(chǎn)物,因此參考鄰區(qū)準(zhǔn)和熱木音蘇木白音高老組火山巖的兩個LA-ICP-MS鋯石U-Pb同位素測年的加權(quán)平均年齡分別為135.1±5.6Ma和135.2±3.8Ma,說明本文研究區(qū)火山巖應(yīng)形成于早白堊世。在內(nèi)蒙古1:5萬準(zhǔn)和熱木音蘇木等六福區(qū)域地質(zhì)礦產(chǎn)調(diào)查報告中,前人將其厘定為寶力高廟組二段火山巖(Cb2),本文將其重新厘定為白音高老組火山巖(K1b).蘇尼特左旗紅格爾地區(qū)中生代火山巖Si O2含量介于69.52wt%-71.44wt%之間,富鉀且富鋁,含量分別為K2O=3.92wt%-4.72wt%和Al2O3=14.17wt%-14.7wt%。全堿(Na2O+K2O)含量為7.6wt%-8.78wt%,里特曼指數(shù)(δ)介于2.15-2.71之間,屬鈣堿性系列;A/CNK=0.99-1.10,A/NK=1.25-1.39,出現(xiàn)微量剛玉標(biāo)準(zhǔn)礦物,屬于準(zhǔn)鋁質(zhì)-弱過鋁質(zhì)巖石。稀土配分圖解顯示輕稀土富集,重稀土虧損,(La/Yb)N較高為23.31-39.98,說明其輕重稀土的分餾程度強,意味著巖漿源區(qū)出現(xiàn)殘余石榴石,表明造山后加厚巖石圈構(gòu)造背景。微量元素蛛網(wǎng)圖中,巖石顯示富集大離子親石元素(LILF)Rb、Ba、K,虧損高場強元素(HSFE)Nb、Ta和Ti,個別元素如Sr、P表現(xiàn)出明顯負(fù)異常,是巖漿由基性向酸性演化的結(jié)果,反映了本文研究區(qū)巖漿來自于造山后巖石圈地幔的演化巖漿,并非原生巖漿,是蒙古-鄂霍茨克大洋板塊向南俯沖遠(yuǎn)程效應(yīng)的產(chǎn)物。
[Abstract]:Based on the project of "investigation of regional geology and mineral resources in Liufu area of Inner Mongolia with 1: 50 000 Zhonghian and Thermoyengyumu", the Mesozoic volcanic rocks in Honggu area, Sunita, Inner Mongolia, are studied in this paper. The tectonic position of the study area is located in the late Paleozoic continental margin accretive zone of the southeastern continental margin of the Siberian plate, and is located in the northwestern side of the Erlian-Hegenshan plate docking zone. This orogenic belt belongs to the Paleozoic Asian oceanic tectonic domain and Mesozoic to the riparian Pacific tectonic domain. The tectonic units in the study area belong to the northern orogenic belt of Xingmeng orogenic belt and are located in the northern and western border areas of Inner Mongolia. Magmatic activities in the area are frequent, and there are strong volcanic eruptions and magmatic intrusions in late Paleozoic and Mesozoic. The Mesozoic volcanic rocks are only distributed in the 1: 50 000 regional geological survey map, which are banded and unconformable with the volcanic eruption of the lower Carboniferous alkali feldspar granite body in the northeast corner of the map, extending to the adjacent area of the survey area. The volcanic rocks of the BaiyinggaoLao formation in Honggu area are located in the NNE fault zone, covered by unconformity of clastic rocks of the Damoguahe formation, Cretaceous, and the volcanic rocks are developed near vertical cleavage and fold structure. The lithology is dominated by rhyolite, intercalated tuff, fused tuff, dolomite and obsidian thin layer, and the north and south ends are intruded by Carboniferous biotite monzogranite. The LA-ICA-MS zircon dating of the Mesozoic volcanic rocks selected in this paper has very few zircon grains and is inherited zircon. Its age represents the age of formation of Carboniferous alkali feldspathic granites, and is compared with the volcanic rocks of the Baiyingao formation published in the adjacent area. It is found that there are consistent geochemical characteristics, indicating the same magmatic properties and inferring that they are contemporaneous magmatic products. Therefore, with reference to the weighted mean ages of two LA-ICP-MS zircon U-Pb isotopic dating for the volcanic rocks of the Quasi-and Thermo-Sappa Baiyingao formation in the adjacent area, respectively, the weighted mean ages are 135.1 鹵5.6Ma and 135.2 鹵3.8 Ma, respectively, indicating that the volcanic rocks in this study area should have been formed in the early Cretaceous. In the investigation report of the regional geology and mineral resources of Liufu region, such as 1: 50, 000 in Inner Mongolia, and thermosone, the former people determined it as the volcanic rock of the second stage of the Baoligaomiao formation, and the volcanic rock of the Baiyingao formation was reclassified as the volcanic rock of Baiyingao formation in this paper. The Sio _ 2 content of Mesozoic volcanic rocks in Hongger area, Sunita Zuo Qi is between 69.52 wt- 71.44 wt%, K _ 2O -3.92 wt-4.72 wt% and Al _ 2O _ 3 14.17 wt-14.7 wtbatt. The content of Na2O K _ 2O is 7.6 wt- 8.78 wt. the Ritman index (未) is between 2.15-2.71, belonging to the calc-alkaline series A / CNK _ (0.99-1.10) A / N ~ (K) 1.25-1.39. There are trace corundum standard minerals, which belong to quasi-aluminite-weakly peraluminous rocks. The REE partition diagram shows that LREE is enriched and the heavy REE depleted La- / Ybnn is higher than 23.31-39.98, indicating that the fractionation degree of REE is strong, which means the residual garnet appears in the magmatic source area, indicating the tectonic setting of the thickening lithosphere after orogeny. In the trace element cobweb diagram, the rocks show the enrichment of the large ion lithophile elements LILFFN RbPBA K, and the depletion of the high field strength elements HSFEN, NB, Ta and Ti. Some elements, such as Srnp, show obvious negative anomalies, which are the result of the evolution of magma from the basic to the acidic. It is shown that the magma in this study area is derived from the evolution magma of the lithospheric mantle after orogeny and is not primary magma but the product of the remote subduction effect of the Mongolia-Okhotsk oceanic plate towards the south.
【學(xué)位授予單位】：石家莊經(jīng)濟(jì)學(xué)院
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P588.14

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