本文選題：諸廣山南體 + 鐵質(zhì)花崗巖��； 參考：《南京大學》2015年碩士論文

【摘要】：諸廣山南體是南嶺鈾礦成礦帶的重要組成,該地區(qū)鈾礦主要產(chǎn)于中部和東部,均為花崗巖型鈾礦床,西部至今尚未發(fā)現(xiàn)鈾礦化。前人對諸廣山南體東部和西部的花崗巖開展了一些研究工作,而中北部的“三九”地區(qū)關注較少,研究程度相對薄弱。本文選擇“三九”地區(qū)桃金洞、東嶺、九龍和中棚四個花崗巖體作為研究對象,進行了成巖年代厘定,并綜合運用巖相學、元素地球化學和Sr-Nd同位素等研究手段,對四個花崗巖的巖石成因與構(gòu)造背景進行了探討,同時,在與諸廣山南體其他產(chǎn)鈾和非產(chǎn)鈾花崗巖對比的基礎上,初步評估了它們的產(chǎn)鈾潛力。LA-ICP-MS鋯石U-Pb定年結(jié)果顯示,桃金洞花崗巖的年齡為204±2.1 Ma,為印支晚期巖漿活動的產(chǎn)物。巖石地球化學組成上,桃金洞花崗巖為過鋁質(zhì)(除一個樣品的ASI=0.98,其余為1.02-1.12),鐵相對于鎂略富集的特征,屬于堿鈣性或鈣堿性-鐵質(zhì)花崗巖；稀土元素總量較高(∑REE=225.6～271.9×10-6),富集LREE(LREE/HREE=6.27～11.4,(La/Yb)N=4.01～15.0),Eu虧損較明顯(6Eu=0.15～0.42)；富集Rb.Th和U,虧損Ba、Sr、Ti和Eu,屬于典型的低Ba、Sr花崗巖。同位素組成上,桃金洞花崗巖(87Sr/86Sr)i值較高(0.71922～0.72040)εNd(t)值較低(-10.0～-10.2),兩階段Nd模式年齡為1.80～1.82 Ga。巖石地球化學特征表明,桃金洞花崗巖屬于典型的殼源型花崗巖,是在地殼伸展—減薄背景下,古元古代變質(zhì)雜砂巖經(jīng)過中低程度部分熔融形。東嶺、九龍和中棚三個花崗巖的成巖年齡分別為161.9±1.5 Ma、162.9±2.3Ma和148.2±1.9 Ma,為燕山早期巖漿作用的產(chǎn)物。它們均表現(xiàn)為富鐵、貧鎂和過鋁質(zhì)(ASI=1.00～1.12)的特征,屬于堿鈣性或鈣堿性—鐵質(zhì)花崗巖。東嶺、九龍和中棚三個花崗巖均具有較高的Si02(平均75.9%),高的Rb/Sr比值(平均22.2)以及明顯的Eu負異常(0.04～0.23),表明巖漿經(jīng)歷了強烈的結(jié)晶分異作用。對比東嶺、九龍花崗巖和長江花崗巖(圖2-4中的長江巖體)的地球化學特征,認為它們具有相似的巖石成因類型,它們的εNd(t)值較低(-9.6--10.8),兩階段Nd模式年齡較古老(1.73 Ga～1.83 Ga),兩者源區(qū)為砂質(zhì)巖和泥質(zhì)巖的混合。它們是在伸展構(gòu)造背景下,由古元古代變質(zhì)沉積巖部分熔融形成。中棚花崗巖的地球化學和同位素特征與粵北產(chǎn)鈾的帽峰花崗巖和南嶺產(chǎn)鎢花崗巖相似,具有較低的εNd(t)值(-9.6--10.4)和較古老的Nd模式年齡(1.70 Ga～1.80Ga)為古元古代變質(zhì)泥巖在伸展構(gòu)造背景下部分熔融形成。對比研究顯示,相對于諸廣山南體非產(chǎn)鈾花崗巖,該區(qū)典型的產(chǎn)鈾花崗巖蝕變作用較強；FeOT/(FeOT+MgO)比值變化較大,多為鐵質(zhì)花崗巖,反映相對還原的特征；并且CaO含量更低,Ba、Sr、Ti和Eu虧損更強烈；非產(chǎn)鈾花崗巖中的鈾主要賦存在鋯石、釷石等副礦物中,巖石后期熱液蝕變作用不明顯。因此,與非產(chǎn)鈾花崗巖特征相似的桃金洞花崗巖鈾成礦潛力有限,與產(chǎn)鈾花崗巖相似的東嶺、九龍和中棚花崗巖具有一定的鈾成礦潛力,其中,中棚花崗巖具有稀土元素四分組效應,可能具有較大的鈾成礦潛力。
[Abstract]:The Zhuguang Shannan body is an important component of the Nanling uranium metallogenic belt. The uranium deposit in this area is mainly produced in the middle and East, all of which are granite type uranium deposits. The uranium mineralization has not been found in the west to the present. The predecessors have carried out some research work on the granite in the eastern and western parts of the southern Shannan body, while the "39" area in the north and the North has paid less attention and the degree of research is less. It is relatively weak. This paper selects four granite bodies in "39" area, peach gold cave, Dongling, Kowloon and middle shed as research objects, and carried out diagenetic dating, and comprehensively applied petrography, elemental geochemistry and Sr-Nd isotopes to study the petrogenesis and tectonic setting of the four granites. On the basis of the comparison of other uranium producing and non uranium producing granites in Sannan body, the preliminary evaluation of their uranium potential.LA-ICP-MS zircon U-Pb dating shows that the age of the peach golden cave granite is 204 + 2.1 Ma, which is a product of late Indosinian magmatic activity. 8, the rest is 1.02-1.12, which is characterized by the slightly enriched iron, which belongs to the alkali calcium or calc alkaline iron granites; the total amount of rare earth elements is higher (REE=225.6 ~ 271.9 * 10-6), enriching LREE (LREE/HREE=6.27 to 11.4, (La/Yb) N=4.01 15), Eu loss is obvious (6Eu=0.15 to 0.42), Rb.Th and U, Ba in the loss, Sr, Sr, U, etc. Low Ba, Sr granite. On the isotope composition, the I value of peach golden cave granite (87Sr/86Sr) is higher (0.71922 ~ 0.72040), Nd (T) is lower (-10.0 to -10.2), and the two stage Nd mode age is 1.80 ~ 1.82 Ga. rock geochemical characteristics, and the peach golden cave granite is a typical crust source granite, which is in the background of crust extension and thinning, Gu Yuangu The generation of metamorphic complex sandstone is partially melted in middle and low degree. The age of three granites in Dongling, Kowloon and middle shed are 161.9 + 1.5 Ma, 162.9 + 2.3Ma and 148.2 + 1.9 Ma, which are the products of early magmatism in Yanshan. They are all characterized by iron rich, poor magnesium and peraluminous (ASI=1.00 to 1.12), belonging to alkali calcium or calc alkaline iron. Three granites in Dongling, Kowloon and middle shed have high Si02 (average 75.9%), high Rb/Sr ratio (average 22.2) and obvious negative Eu anomaly (0.04 ~ 0.23), indicating that the magma experienced a strong crystallization differentiation. They have similar petrogenesis types, their Nd (T) values are lower (-9.6--10.8), the two stage Nd model age is older (1.73 Ga to 1.83 Ga), and the source region is a mixture of Sandy and argillaceous rocks. They are formed by the melting of Paleoproterozoic metamorphic rocks under the extensional tectonic setting. The characteristics of the position are similar to the Gufeng granite and Nanling wolfram granites in North Guangdong, with lower epsilon Nd (T) value (-9.6--10.4) and older Nd mode age (1.70 Ga to 1.80Ga) as Paleoproterozoic metamorphic mudstones formed partially by the extensional tectonic setting. The typical uranium granites have strong alteration, FeOT/ (FeOT+MgO) ratio varies greatly, most of which are iron granites, reflecting the characteristics of relative reduction; and CaO content is lower, Ba, Sr, Ti and Eu are more strongly depleted; the uranium in the non uranium granites mainly exists in the secondary minerals such as zircon and thorium, and the late hydrothermal alteration of the rocks is not obvious. The mineralization potential of the Tao Jin Dong granite, which is similar to the non uranium bearing granite, is limited. The Dongling, similar to the uranium bearing granite, has a certain uranium metallogenic potential in the Dongling, the Kowloon and the middle shed granites, of which the medium shelf granite has the four grouping effect of rare earth elements, which may have large uranium metallogenic potential.
【學位授予單位】：南京大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P619.14;P588.121

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