本文選題：成礦期次 + 成礦巖體��； 參考：《中國地質(zhì)大學(xué)(北京)》2017年碩士論文

【摘要】：哈海崗矽卡巖型W-Mo多金屬礦床位于西藏念青唐古拉成礦帶東段中部,岡底斯弧背斷隆帶南緣,受達(dá)龍區(qū)域斷裂帶控制。目前研究程度較低,僅限于礦床地質(zhì)與成礦、成巖年齡的研究,本文主要針對礦床地質(zhì)特征、成礦巖體厘定及其地球化學(xué)特征和成礦物質(zhì)來源的示蹤展開研究,有助于進(jìn)一步和岡底斯成礦帶其他礦床對比,探討成巖-成礦機(jī)制,總結(jié)區(qū)域成礦規(guī)律。結(jié)合野外地質(zhì)調(diào)查和顯微鏡下觀察,將哈海崗矽卡巖型成礦作用劃分為矽卡巖期和石英-硫化物期,包括干矽卡巖階段、濕矽卡巖階段、石英-輝鉬礦階段和石英-鐵銅鉛鋅硫化物階段。前人對礦區(qū)出露花崗閃長巖(56.1Ma)和二長花崗巖(57.02-58.66Ma)定年顯示晚于輝鉬礦成礦年齡(63.2Ma),而筆者通過野外采樣發(fā)現(xiàn)花崗閃長巖發(fā)育浸染狀白鎢礦和輝鉬礦化,二長花崗巖發(fā)育石英-輝鉬礦脈。因已有巖體年齡無法解釋該礦化現(xiàn)象,筆者對礦化巖體重新定年,發(fā)現(xiàn)花崗閃長巖發(fā)育侏羅紀(jì)和古新世兩期,鋯石U-Pb年齡分別為194.5±1.8Ma和63.82±0.7Ma,二長花崗巖年齡為64.63±0.8Ma。根據(jù)礦化現(xiàn)象、成巖年齡與礦床分帶特征,認(rèn)為成礦巖體很可能為古新世花崗閃長巖或二長花崗巖。古新世花崗閃長巖和二長花崗巖成巖年齡基本一致,均具有高的SiO2含量(69%-76%)、全堿含量(K2O+Na2O=6.5%-9.3%)和FeO*/MgO比值(3.3-7.7),表明它們經(jīng)歷了高程度結(jié)晶分異,且二長花崗巖結(jié)晶分異程度高于花崗閃長巖。通過主微量元素分析發(fā)現(xiàn),哈海崗古新世花崗閃長巖和二長花崗巖具有高分異I型花崗巖特征。通過哈海崗金屬硫化物和礦區(qū)巖體及旁那組沉積圍巖S-Pb同位素測試,發(fā)現(xiàn)其金屬硫化物δ34SCDT集中于2.7‰-5.4‰,平均值為4.08‰;研究認(rèn)為硫很可能來源于成礦巖體巖漿,且成礦熱液受到了圍巖地層的混染作用。鉛同位素比值相對穩(wěn)定,極差均小于0.1‰;構(gòu)造環(huán)境演化圖解中,金屬硫化物鉛同位素點落在上地殼演化線上,且集中均勻分布,指示礦物鉛主要來自于上地殼。綜合分析認(rèn)為,哈海崗成礦物質(zhì)主要來源于殼�；煸吹某傻V巖漿。
[Abstract]:The Hahaigang skarn type W-Mo polymetallic deposit is located in the middle of the eastern section of the Nianqingtang Gula metallogenic belt in Tibet and is controlled by the Dalong regional fault belt. The present study is limited to the study of ore deposit geology, mineralization and diagenetic age. This paper mainly focuses on the geological characteristics of the deposit, the determination of ore-forming rock mass, the geochemical characteristics and the trace of the source of the ore-forming material. It is helpful to further compare with other deposits in Gangdis metallogenic belt, discuss the diagenesis-metallogenic mechanism and summarize the regional metallogenic regularity. Based on the field geological survey and microscopic observation, the mineralization of the hahaigang skarn type is divided into skarn stage and quartz-sulfide stage, including dry skarn stage and wet skarn stage. Quartz-molybdenum stage and quartz-iron-copper-lead-zinc sulfide stage. The dating of protruding granodiorite (56.1 Maa) and monzomorphic granite (57.02-58.66 Ma) shows that the age of mineralization is 63.2 Mag later than that of molybdenum ore. However, the authors found that granodiorite developed disseminated scheelite and molybdenum mineralization through field sampling. The monzogranite developed quartz-molybdenum vein. Because the age of the existing rock mass can not explain the mineralization phenomenon, the author has redated the mineralized rock body and found that the U-Pb age of zircon is 194.5 鹵1.8Ma and 63.82 鹵0.7 Ma. the age of monzogranite is 64.63 鹵0.8 Ma. during the Jurassic and Paleocene stages of granodiorite. According to the mineralization phenomenon, diagenetic age and zonation characteristics of the deposit, it is considered that the ore-forming body is probably Paleocene granodiorite or monzomorphic granodiorite. Paleocene granodiorite and monzomorphic granodiorite have the same diagenetic age, both have high SiO2 content (69-76) and total alkali content (K _ 2O Na _ 2O _ 2O _ (6.5) -9.3%) and FeO*/MgO ratio (3.3-7.7), indicating that they have experienced high degree of crystallization differentiation. The degree of crystal differentiation of monzogranite is higher than that of granodiorite. Through the analysis of main trace elements, it is found that the hahaigang granodiorite and the monzomorphic granodiorite have the characteristics of high differentiation I type granite. Based on the S-Pb isotopic measurements of the Hahaigang metallic sulphide and the orebody and its surrounding rocks, it is found that the metal sulphide 未 34SCDT is concentrated in the range of 2.7 鈥，

本文編號：1900154