本文選題：年代學(xué) + Sr-Nd-Hf同位素��； 參考：《中國(guó)科學(xué)技術(shù)大學(xué)》2017年博士論文

【摘要】：貴池地區(qū)金、銀、銅、鉬、硫等礦產(chǎn)資源豐富,系長(zhǎng)江中下游成礦帶七大銅金礦集區(qū)之一。區(qū)內(nèi)晚中生代巖漿巖極為發(fā)育,并與本區(qū)銅金礦產(chǎn)有著密切的成因關(guān)聯(lián)。晚中生代巖漿巖在該區(qū)分布廣泛,該區(qū)晚中生代巖漿巖研究積累豐富,但是成巖與成礦之間的系統(tǒng)性關(guān)聯(lián)仍有待進(jìn)一步探討。本文選擇貴池地區(qū)銅山、安子山、老山、銅鈴坡、寶樹尖、銅山排銅礦和朱家沖、查冊(cè)橋巖體金礦的含礦侵入巖和桂林鄭花崗斑巖、楊山花崗巖為研究對(duì)象,開展詳細(xì)的全巖地球化學(xué)、鋯石年代學(xué)和原位Lu-Hf同位素、Sr-Nd同位素、礦物原位研究,示蹤巖漿源區(qū),探討巖漿演化與成礦之間的關(guān)聯(lián),并為下一步礦產(chǎn)勘探提供指導(dǎo)性意見(jiàn)。鋯石U-Pb年代學(xué)數(shù)據(jù)顯示貴池地區(qū)晚中生代成礦相關(guān)巖漿活動(dòng)分別集中于148-136Ma及130-125Ma早晚兩個(gè)時(shí)期。早期成礦多為銅金礦床,晚期則以鉬(銅)礦床(化)為主,具有與長(zhǎng)江中下游地區(qū)其它礦集區(qū)相似的成礦特點(diǎn)。貴池地區(qū)第一階段含礦侵入巖巖石系列為花崗閃長(zhǎng)巖、閃長(zhǎng)巖、二長(zhǎng)花崗巖類,主要為高鉀鈣堿性系列,具有相對(duì)低的SiO2、高的Al2O3和MgO含量,強(qiáng)烈富集LREE和大離子親石元素LILE,虧損HREE和高場(chǎng)強(qiáng)元素HFSE,具較強(qiáng)的Nb、Ta、Ti負(fù)異常,無(wú)明顯Eu異常,大多數(shù)與俯沖洋殼型Adakite巖地球化學(xué)特征相近,起源于有限俯沖沉積物貢獻(xiàn)的俯沖洋殼部分熔融,在上升過(guò)程中與富集地幔發(fā)生相互作用,并混染了古老地殼物質(zhì)。貴池地區(qū)第二階段巖漿巖巖石地球化學(xué)特征顯示具有非常高的Si02,低的A1203,強(qiáng)烈的Eu負(fù)異常,富集Rb、Th、U、Nb、Ta等元素,強(qiáng)烈虧損Ba、Sr、P、Ti,具有典型的A型花崗巖特征,屬于伸展構(gòu)造體制下的產(chǎn)物。較年輕的 Nd 同位素模式年齡(1364～1490Ma),較高的 εNd(t)(-7.02～-5.47)、εHf(t)(7.5～5.9),說(shuō)明巖漿來(lái)源于中-新元古地殼物質(zhì)的部分熔融,并加入了新生地殼物質(zhì)。在巖漿演化過(guò)程中存在斜長(zhǎng)石、磷灰石、黑云母和Fe-Ti氧化物的結(jié)晶分異。通過(guò)鋯石中稀土微量元素特征,得出早期埃達(dá)克(質(zhì))巖的鋯石普遍具有較高的Ce4+/Ce3+值,反映了巖漿的高氧逸度;而晚期A型花崗巖的鋯石的Ce4+/Ce3+值普遍偏低,指示了巖漿具有較低的氧逸度,與之對(duì)應(yīng)的是早期的埃達(dá)克(質(zhì))巖更有利于銅金成礦。早期高氧逸度的巖漿巖形成于與俯沖有關(guān)的構(gòu)造環(huán)境,而晚期的低氧逸度巖漿反映了構(gòu)造體制的轉(zhuǎn)換,這一構(gòu)造環(huán)境的變化最可能是由俯沖板塊后撤引發(fā)巖石圈伸展減薄所致。因此,貴池地區(qū)的巖石組合,即從早期的成礦埃達(dá)克(質(zhì))巖至晚期A型花崗巖,其形成可能與俯沖的古太平洋板塊從下?lián)P子巖石圈下后撤而引發(fā)的陸內(nèi)巖漿過(guò)程有關(guān)。即古太平洋板塊后撤,引發(fā)熱的軟流圈物質(zhì)上涌,加熱中新元古地殼物質(zhì)并混合了新生地殼物質(zhì),從而導(dǎo)致了 了大量127Ma左右的A型花崗巖的形成。本區(qū)早期成礦作用與其巖漿活動(dòng)相關(guān),區(qū)內(nèi)主要為巖漿期后熱液成礦和接觸交代成礦作用,礦化類型包括矽卡巖型、斑巖型、沉積疊改型及熱液充填型等。晚期成巖成礦作用主要表現(xiàn)為由晚期巖漿侵入引起的中低溫?zé)嵋撼傻V作用和早期成礦基礎(chǔ)上的疊加成礦作用。本區(qū)主逆沖斷層以北屬長(zhǎng)江中下游成礦帶主帶,成礦主要與晚侏羅世中基性-中酸性高鉀鈣堿性巖漿侵入有關(guān),與銅陵地區(qū)具相近的成礦作用和相近的礦體賦存規(guī)律;墩上-張溪斷裂及其附近,成礦也主要與晚侏羅世中基性-中酸性高鉀鈣堿性巖漿侵入有關(guān),同時(shí)也受到早白堊世酸性、堿性巖漿侵入的影響,兩區(qū)成巖作用相近,且同受沿江構(gòu)造-巖漿巖帶控制。
[Abstract]:The Guichi area is rich in gold, silver, copper, molybdenum and sulfur. It is one of the seven major copper gold deposits in the middle and lower reaches of the Yangtze River. The late Mesozoic Magmatic Rocks in the region are extremely developed and closely related to the copper gold minerals in this area. Late Mesozoic Magmatic Rocks were widely distributed in this area, and the late Mesozoic Magmatic Rocks were rich in the area but formed in the area. The systematic association between rock and mineralization remains to be further discussed. In this paper, the Guichi area, Copper Mt., an Zi Shan, Laoshan, Tongling slope, Bao tree tip, Copper Mt. copper deposit and Zhu Jiachong, the ore bearing intrusive rock and Gui Linzheng granite porphyry and Yangshan granite in the jigqiao rock mass are selected as the research object, and the detailed whole geochemistry and zircon age are carried out in detail. The study and in situ Lu-Hf isotopes, Sr-Nd isotopes, mineral in situ studies, tracer magma source areas, explore the association between magma evolution and mineralization, and provide guidance for the next exploration of mineral exploration. The zircon U-Pb chronological data show that the late Mesozoic metallogenic related magma activities in the Guichi region were concentrated on two early and late 130-125Ma, 148-136Ma and 130-125Ma, respectively. The early mineralization was mostly copper gold deposits, and in the late stage the main mineralization was molybdenum (copper) deposit and similar to other ore deposits in the middle and lower reaches of the Yangtze River. The first stage of the Guichi area was granite diorite, diorite and two granitoid, mainly of high potassium calc alkaline series, with relatively low SiO2 and high level. The content of Al2O3 and MgO, strong enrichment of LREE and large ion stone element LILE, loss HREE and high field strong element HFSE, has strong Nb, Ta, Ti negative anomalies, and no obvious Eu anomalies, most of which are similar to those of subducted oceanic Adakite rocks. The subduction of subducted oceanic crust, which was derived from the contribution of the limited subduction sediments, was rich in the rising process. The second stage magmatic rock geochemical characteristics of the second stage magmatic rocks in Guichi region show that they have very high Si02, low A1203, strong negative Eu anomalies, enriched Rb, Th, U, Nb, Ta and so on, and have a strong loss of Ba, Sr, P, Ti, and are characteristic of typical granite type granites, which belong to the extensional tectonic system. The younger Nd isotopic age (1364 ~ 1490Ma), higher epsilon Nd (T) (-7.02 to -5.47) and epsilon Hf (T) (7.5 ~ 5.9) indicate that magma originated from partial melting of meso Neoproterozoic crustal materials and added to the new crustal substance. In the process of magma evolution, the crystallization of plagioclase, apatite, biotite and Fe-Ti oxide was different. The trace elements of the rare earth elements in the zircon show that the early age of the zircon of the early DAC (Qualitative) rock has a high Ce4+/Ce3+ value, reflecting the high oxygen fugacity of the magma, while the Ce4+/Ce3+ value of the zircons of the late A type granites is generally low, indicating that the magma has a lower oxygen fugacity. The early high oxygen fugacity of the magmatic rocks formed in the tectonic environment related to subduction, and the late low oxygen fugacity magma reflects the transformation of the tectonic system. This tectonic environment is most likely due to the extension and thinning of the lithosphere caused by the withdrawal of subducted plates. Therefore, the rock assemblage in the Guichi region is from the early metallogenic EDA. The formation of the late A type granites may be related to the intracontinental magma process caused by the subduction of the subducted paleo Pacific plate under the lower Yangtze lithosphere. That is, the paleo Pacific plate withdrew and the heating soft flow circle was upwelling, heating the Neoproterozoic crustal material and mixing the new crust material, resulting in a large amount of 127Ma. The formation of the left and right A type granites. The early mineralization in this area is related to its magmatic activity. The main areas are post magmatic hydrothermal mineralization and contact metasomatism. The mineralization types include skarn type, porphyry type, depositional superimposition and hydrothermal filling type. The late diagenesis and mineralization are mainly manifested in the middle stage of magma intrusion. The main thrust fault of the main thrust fault in this area is the main belt of the middle and lower Yangtze River metallogenic belt in the north of the region, and the mineralization is mainly related to the middle base intermediate acid high potassium calcium alkaline magma intrusion in the late Jurassic, which is similar to the Tongling area and the similar ore body occurrence law, and the pier Chang Zhang Xi fault. The mineralization is mainly related to the middle base intermediate acid high potassium calcium alkaline magma intrusion in the late Jurassic, and is also affected by the early Cretaceous acid and alkaline magma intrusion, and the diagenesis of the two region is similar, and is controlled by the tectonic magmatic belt along the river.

【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：P618.2;P588.11
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本文編號(hào)：1790937