本文選題：膠東半島 + 構(gòu)造演化��； 參考：《中國(guó)地質(zhì)大學(xué)(北京)》2016年博士論文

【摘要】：膠東半島晚中生代花崗質(zhì)巖漿活動(dòng)可分為-160 Ma,～130 Ma,～115 Ma三期。三期侵入巖極端負(fù)的全巖εNd(t)和鋯石εHf(t)及非常老的鋯石鉿TDM2年齡表明其母巖漿源區(qū)主要為古老下地殼。元素和同位素地球化學(xué)特征說明三期侵入巖母巖漿形成深度逐漸變淺,形成于伸展構(gòu)造環(huán)境,可能是受太平洋板塊俯沖控制。通過對(duì)花崗質(zhì)巖石繼承鋯石的研究,認(rèn)為三疊紀(jì)碰撞時(shí)揚(yáng)子下地殼俯沖到膠北地體之下至少～40 km的深度,形成類似鱷魚嘴式構(gòu)造；俯沖的揚(yáng)子下地殼是膠北地體和蘇魯造山帶內(nèi)晚中生代花崗巖母巖漿的主要源區(qū)。膠萊盆地沉積巖碎屑鋯石U-Pb年齡顯示出-2500 Ma,～1850 Ma,～770 Ma,～230 Ma和～120 Ma五個(gè)主要峰值,反映區(qū)域五期主要構(gòu)造-熱事件�！�120 Ma的峰值年齡與膠東半島金成礦的年代一致。盆地頂?shù)撞砍练e物源區(qū)存在差別,從底到頂白堊紀(jì)年齡越來越多,而白堊紀(jì)之前的越來越少,且白堊紀(jì)峰值年齡逐漸變年輕。膠萊盆地中新元古代碎屑鋯石具巖漿成因特征,源自蘇魯造山帶,其年齡頻譜與揚(yáng)子克拉通西緣和北緣巖漿活動(dòng)時(shí)限一致,推測(cè)沿?fù)P子克拉通西緣和北緣的俯沖活動(dòng)可能向東延伸到蘇魯?shù)貐^(qū)。三疊紀(jì)或以前形成的交代地慢和俯沖的揚(yáng)子板塊為區(qū)域金成礦提供流體、揮發(fā)份及成礦物質(zhì)。鋯石、磷灰石裂變徑跡研究表明在～30-80 Ma膠東地殼經(jīng)歷明顯隆升,隆升時(shí)間段與周緣盆地最大沉降及華北克拉通東部玄武巖形成時(shí)間吻合,說明華北克拉通東部在晚白堊世-古近紀(jì)經(jīng)歷顯著地殼隆升,形成地塹-地壘構(gòu)造系統(tǒng)。膠東半島金礦主要賦存于晚中生代花崗巖中,通過花崗巖鋯石和磷灰石裂變徑跡數(shù)據(jù)約束的地殼隆升剝蝕量估算出該區(qū)域金礦化深度為～6-11 km。膠東金礦省蝕變巖型金礦床的蝕變包括鉀長(zhǎng)石化、絹云母化、碳酸鹽化,不同蝕變之間具有成因上的聯(lián)系,前一階段蝕變能誘發(fā)下一期次蝕變,同一期次蝕變不同反應(yīng)相互促進(jìn),各種蝕變、礦化如同多米諾鏈,起始于富K+、H+和Au流體與含斜長(zhǎng)石的花崗巖相遇。從鉀長(zhǎng)石化到碳酸鹽化階段,不同熱液蝕變導(dǎo)致蝕變巖石、礦石樣品具有不同礦物組合及地球化學(xué)特征。蝕變類型和強(qiáng)度控制元素在空間的分布,斷裂、節(jié)理等構(gòu)造也控制元素遷移富集,構(gòu)造發(fā)育部位,蝕變礦化強(qiáng)烈,成礦元素含量呈現(xiàn)峰值,金礦體亦在此部位產(chǎn)出。
[Abstract]:The late Mesozoic granitic magmatism in Jiaodong Peninsula can be divided into three phases of -160 Majiao 130 Majiao 115 Ma. The TDM2 age of zircon and very old zircon hafnium indicates that the parent magmatic source region is mainly of the ancient lower crust. The geochemical characteristics of elements and isotopes indicate that the formation depth of the intrusive mother magma gradually shallowes in the extensional tectonic environment and may be controlled by the subduction of the Pacific plate. Based on the study of inherited zircon from granitic rocks, it is considered that the lower crust of Yangtze subducted to a depth of at least 40 km below the Jiaobei terrain during the Triassic collision, forming a similar crocodile beak structure. The subducted lower crust of Yangtze is the main source of late Mesozoic granitic mother magma in Jiaobei terrane and Sulu orogenic belt. The zircon U-Pb age of depositional rocks in Jiaolai Basin shows five main peaks of -2500 Ma / 1850 Ma / 770 Ma / 230Ma and / or 120Ma respectively, which reflect that the peak age of the five major tectonic-thermal events (120Ma) is consistent with the age of gold mineralization in Jiaodong Peninsula. There are differences in the source regions of the sediments at the top and bottom of the basin. The age of Cretaceous is increasing from bottom to top, but less and less before Cretaceous, and the peak age of Cretaceous becomes younger and younger. The MesoNeoproterozoic clastic zircon in the Jiaolai Basin is of magmatic origin and originated from the Sulu orogenic belt. The age spectrum of the zircon is consistent with the time limit of magmatic activity in the western margin of the Yangtze craton and the northern margin of the Yangtze craton. It is inferred that the subduction along the western and northern margin of the Yangtze craton may extend eastward to the Sulu area. The Yangtze plate formed during the Triassic or before the metasomatism and subduction provides fluids, volatiles and ore-forming materials for regional gold mineralization. The study of fission track of zircon and apatite shows that the crust of Jiaodong experienced obvious uplift at 30-80 Ma, and the uplift time coincided with the maximum subsidence of the peripheral basin and the formation time of basalt in the eastern part of the North China Craton. It is concluded that the eastern North China Craton experienced a significant crustal uplift during the late Cretaceous to Paleogene and formed a graben-barrier tectonic system. The gold deposits in Jiaodong Peninsula are mainly located in late Mesozoic granites. The depth of gold mineralization in this area is estimated to be 6-11 km by crustal uplift and denudation restricted by fission track data of zircon and apatite. The alteration of the altered rock type gold deposit in Jiaodong gold deposit includes potassium feldspar, sericite, carbonization, and there is a genetic relationship among the different alterations. The alteration in the previous stage can induce the next secondary alteration. In the same period, different reactions promote each other, and all kinds of alteration and mineralization are like dominoes, which originated from the encounter of K-rich H and au fluids with plagioclase bearing granite. Different hydrothermal alteration results in altered rocks, and the ore samples have different mineral assemblages and geochemical characteristics. The distribution of alteration type and strength control elements in space, faults, joints and other structures also control the migration and enrichment of elements, structural development site, strong alteration mineralization, metallogenic elements content of peak value, gold orebody also occurred in this area.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：P618.51;P548
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本文編號(hào)：1957290