云南祥云寶興廠Cu、Mo礦區(qū)喜馬拉雅期巖漿演化及成因
發(fā)布時(shí)間：2018-09-07 07:52
【摘要】：寶興廠銅鉬多金屬礦床是金沙江-紅河新生代斑巖成礦帶中的重要礦區(qū)之一,礦區(qū)喜馬拉雅期構(gòu)造-巖漿活動(dòng)強(qiáng)烈,發(fā)育不同類型富堿斑巖。本文對(duì)寶興廠礦區(qū)開展了詳細(xì)的野外地質(zhì)調(diào)查及巖漿巖巖石學(xué)、巖石地球化學(xué)、成巖年代學(xué)及同位素地球化學(xué)等綜合研究,取得以下主要成果：(1)用宏觀地質(zhì)體穿切關(guān)系與微觀精確定年相結(jié)合的研究方法,重新厘定研究區(qū)巖漿侵位序列為正長(zhǎng)斑巖(Ⅰ階段)→斑狀花崗巖+煌斑巖(Ⅱ階段)→花崗斑巖+煌斑巖(Ⅲ階段)→堿長(zhǎng)花崗斑巖(Ⅳ階段),證實(shí)礦區(qū)喜馬拉雅斑巖體是同期多階段巖漿脈動(dòng)式活動(dòng)的產(chǎn)物。其中,第Ⅱ階段和第Ⅲ階段為巖漿主要侵位期,均伴有不同程度的基性巖漿活動(dòng)。(2)對(duì)已有可靠成巖年齡數(shù)據(jù)及本次新獲得的LA-ICP-MS鋯石U-Pb年齡數(shù)據(jù)的統(tǒng)計(jì)分析,確認(rèn)礦區(qū)喜馬拉雅期巖體形成年齡于38-33Ma之間,處在金沙江-紅河富堿斑巖帶的巖漿活動(dòng)高峰期(45～30 Ma)范圍內(nèi),但略滯后于其北段巖漿活動(dòng)高峰期。區(qū)域構(gòu)造-巖漿-成礦事件時(shí)空分布分析顯示,沿金沙江-紅河斷裂帶從北段的玉龍→中段北衙、寶興廠→南段銅廠等,巖漿活動(dòng)年齡和成礦年齡逐漸變新,反映青藏高原深部物質(zhì)流動(dòng)有向高原東南部遷移的趨勢(shì)。(3)礦區(qū)喜馬拉雅期花崗質(zhì)巖漿活動(dòng)由早階段至晚階段具有由中酸性→酸性,并向堿度增強(qiáng)和逐漸富鉀方向演化的特點(diǎn)。其中,由早階段巖體至晚階段巖體,Si02含量具有逐漸增高的趨勢(shì),A1203、CaO、Fe203、MgO和P205的含量有逐漸變低的趨勢(shì),分異指數(shù)(DI)有逐漸增大的趨勢(shì),固結(jié)指數(shù)(SI)有逐步降低的趨勢(shì)。暗色包體和煌斑巖的Si02含量在42.53%-54.98%之間,Si02、MgO、K20和全堿(K2O+Na2O)含量由早階段煌斑巖+暗色包體→晚階段煌斑巖依次升高,而A1203含量則依次降低。固結(jié)指數(shù)由暗色包體→早階段煌斑巖→晚階段煌斑巖逐漸增高,分異指數(shù)則相反且集中在40～50之間,暗示本區(qū)鐵鎂質(zhì)巖漿巖結(jié)晶分異作用不強(qiáng)。其中,暗色包體和早階段煌斑巖特征值相似或相近,揭示它們之間密切的演化關(guān)系。(4)不同階段花崗質(zhì)巖體、暗色包體和煌斑巖具相似的微量稀土元素特征：V、Co、Cu和Zn等過渡族元素輕微富集,Cr和Ni相對(duì)虧損,過渡族元素蛛網(wǎng)圖均呈大致相同的“W”型,明顯富集Rb、Ba、U、Th、Sr和La等大離子親石元素(LILE)以及Nb、Ta(或“TNT”)異常虧損的特點(diǎn)�？傮w具有輕稀土富集、重稀土虧損,存在微弱δEu負(fù)異常的特點(diǎn),其中花崗質(zhì)巖體和晚階段煌斑巖∑REE較低,暗色包體和早階段煌斑巖∑REE較高。(5)煌斑巖、暗色包體及花崗質(zhì)巖體具有相近的Sr、Nd、Hf同位素的組成：總體具有高Sr、低Nd的特征,但暗色包體和煌斑巖εNd(t)高于寄主花崗質(zhì)巖體,顯示幔源組分較高,具有向Ⅱ型富集地幔端元演化的趨勢(shì)；寄主花崗質(zhì)巖體的εHf(t)全部為正值,暗色包體和煌斑巖的εHf(t)均為負(fù)值,巖體高Hf和低Nd的特征,指示難熔的古老巖石圈地幔與俯沖的地殼物質(zhì)相互作用的結(jié)果；礦區(qū)巖體Pb同位素組成具造山帶鉛特點(diǎn),成因與殼-幔混合的巖漿作用有關(guān)；花崗質(zhì)巖體的鋯石的結(jié)晶標(biāo)型揭示巖體在低溫、偏堿環(huán)境下形成,且為以殼源為主的殼-�；旌铣梢�,具有富水、富堿的特征,是利于成礦的巖漿系統(tǒng)；鋯石總稀土含量很高,具有LREE強(qiáng)烈虧損、HREE富集的左傾配分型式,明顯的正Ce異常,中等到弱的負(fù)Eu異常；鋯石Hf同位素具有非常好的相似性,εHf(t)值散布于正值和負(fù)值(大部分為正值)之間,指示它們經(jīng)歷了比較顯著的殼幔巖漿混合過程。因此,源區(qū)有顯著的相關(guān)性又有區(qū)別,源區(qū)均具有俯沖板片流體交代富集地幔的特點(diǎn),其中鐵鎂質(zhì)巖漿主要起源于大陸巖石圈地幔,而花崗質(zhì)巖漿源區(qū)主要起源于殼�；旌蠀^(qū)。(6)寶興廠礦區(qū)富堿侵入體形成于后碰撞的板內(nèi)環(huán)境,構(gòu)造-巖漿活動(dòng)經(jīng)歷了以擠壓向伸展轉(zhuǎn)換過渡為主的減壓升溫過程,非常有利于發(fā)生基性到中酸性的巖漿演化以及大規(guī)模的巖漿-流體-成礦作用。礦區(qū)復(fù)式巖體經(jīng)歷源區(qū)部分熔融、殼�；旌弦约敖Y(jié)晶分異作用：花崗質(zhì)侵入體和晚階段煌斑巖為富集地幔源區(qū)相對(duì)高部分熔融(分別為15%和10%)的結(jié)果,暗色包體和早階段煌斑巖為富集地幔源區(qū)低部分熔融(-3%)的產(chǎn)物；花崗質(zhì)巖體地殼混染程度相對(duì)較高,煌斑巖混染程度相對(duì)較低；從花崗質(zhì)侵入體→暗色包體→早階段煌斑巖→晚階段煌斑巖結(jié)晶分異程度依次升高；殼�；旌媳壤�0.44～0.60之間,主要集中在0.5附近。(7)礦區(qū)經(jīng)歷了地殼縮短加厚、軟流圈上涌底侵、部分熔融和混合作用→熱流升高、地殼減薄、殼�；旌系纳畈縿�(dòng)力學(xué)作用過程,巖漿活動(dòng)過程中產(chǎn)生流動(dòng)分異和差異性上升,并沿紅河斷裂與程海斷裂交匯處的局部引張區(qū)發(fā)生脈動(dòng)式侵位,構(gòu)成一個(gè)完整的構(gòu)造-巖漿演化過程。據(jù)此,本文建立了陸內(nèi)走滑動(dòng)力學(xué)環(huán)境下巖漿脈動(dòng)式侵位模型。模型指出：第1階段巖漿巖的源區(qū)深度較大,源區(qū)的部分熔融程度較高,酸性組分和結(jié)晶分異程度較低,形成正長(zhǎng)斑巖墻：第Ⅱ-Ⅲ階段的巖漿的源區(qū)深度變淺,源區(qū)的部分熔融程度較低但規(guī)模大,有大量下地殼花崗質(zhì)組分參與,酸性組分和結(jié)晶分異程度較高,依次形成與成礦有關(guān)的斑狀花崗巖主巖體和含古老地殼基底物質(zhì)的花崗斑巖巖枝(脈)；第Ⅳ階段巖漿的源區(qū)深度與第Ⅱ-Ⅲ階段相似,但源區(qū)的部分熔融程度最低,巖漿熔融規(guī)模小,分異程度高,僅形成巖墻狀-脈狀堿長(zhǎng)花崗斑巖。巖漿主侵位階段,還伴隨有源區(qū)深度更大的小規(guī)模鐵鎂質(zhì)巖漿侵入,形成礦區(qū)兩階段煌斑巖脈。
[Abstract]:Baoxingchang copper-molybdenum polymetallic deposit is one of the important ore-forming areas in Jinshajiang-Honghe Cenozoic porphyry metallogenic belt. The Himalayan tectonic-magmatic activities in the deposit are intense, and different types of ALKALI-RICH PORPHYRIES are developed. The main achievements are as follows: (1) The magmatic emplacement sequence in the study area is redefined as syenite porphyry (stage I) porphyry granite + lamprophyre (stage II) granite porphyry + lamprophyre (stage III) alkali feldspar granite porphyry by means of the combination of macroscopic geological body transection and microscopic precise dating. The Himalayan porphyry in the mining area is the product of multi-stage magmatic pulsation. The second and third stages are the main emplacement stages of magma, accompanied by different degrees of basic magmatic activity. (2) Statistical analysis of the available reliable diagenetic age data and the newly obtained LA-ICP-MS zircon U-Pb age data. The formation age of the Himalayan intrusive bodies in the mining area is 38-33Ma, which is within the peak period of magmatic activity (45-30 Ma) of the Jinshajiang-Honghe alkali-rich porphyry belt, but slightly lags behind the peak period of magmatic activity in the northern part of the belt. The magmatic age and metallogenic age of the northern Ya, Baoxingchang and southern Tongchang in the middle part of the Qinghai-Tibet Plateau are gradually renewed, reflecting the migration of the deep-seated material flow to the southeastern part of the plateau. (3) The Himalayan granitic magmatic activity in the mining area has a tendency from intermediate-acidic to acidic from the early stage to the late stage, and to the direction of increasing alkalinity and gradually enriching potassium. The content of Si02 increases gradually from early stage to late stage, A1203, CaO, Fe203, MgO and P205 decreases gradually, DI increases gradually, and SI decreases gradually. The content of Si02 in dark xenoliths and lamprophyres ranges from 42.53% to 54.98%. The contents of Si02, MgO, K20 and total alkali (K2O+Na2O) increase in turn from early stage lamprophyre + dark xenolith to late stage lamprophyre, while A1203 decreases in turn. The consolidation index increases gradually from dark xenolith to early stage lamprophyre to late stage lamprophyre, while the differentiation index is opposite and concentrates between 40 and 50, suggesting that the ferromagnesian magmatic rocks in this area are consolidated. The characteristics of dark xenoliths and early lamprophyres are similar or similar, which reveals their close evolutionary relationship. (4) In granitic rocks of different stages, dark xenoliths and lamprophyres have similar trace REE characteristics: slight enrichment of V, Co, Cu and Zn, relative depletion of Cr and Ni, and transition elements. The cobweb maps are generally of the same "W" type and are obviously enriched with Rb, Ba, U, Th, Sr and La and Nb, Ta (or "TNT") anomalous depletion. The cobweb maps are characterized by light rare earth enrichment, heavy rare earth depletion, and weak Delta Eu negative anomalies, including low REE in granitic rocks and late lamprophyres, dark xenoliths and dark xenoliths. The lamprophyre_REE is higher in the early stage. (5) Lamprophyre, dark xenoliths and granitic rocks have similar Sr, Nd, Hf isotope compositions. The characteristics of high Sr and low Nd are generally high, but the dark xenoliths and lamprophyres are higher than the host granitic rocks, indicating that mantle-derived compositions are higher and have a tendency to evolve toward type II enriched mantle end-member. The epsilon Hf (t) values of the granitic rocks are all positive, the epsilon Hf (t) values of the dark xenoliths and lamprophyres are negative, and the high Hf and low Nd characteristics of the rocks indicate the interaction between the refractory ancient lithospheric mantle and the subducted crustal materials. The crystalline TYPOMORPHISM OF ZIRCON in granitic intrusions reveals that the intrusions are formed under low temperature and alkaline environment, and are of crust-mantle mixing origin mainly derived from crust, which is characterized by water-rich and alkali-rich, and is favorable to the mineralization of magmatic systems; the total rare earth content of zircon is high, with strong LREE deficit, HREE enriched left-dip distribution pattern, and obvious positive Ce anomaly, intermediate to moderate. Weak negative Eu anomalies; zircon Hf isotopes have very good similarities, and the values of epsilon Hf (t) are scattered between positive and negative values (mostly positive), indicating that they have undergone a relatively significant crust-mantle magmatic mixing process. Medium-Fe-Mg magma mainly originated from the continental lithospheric mantle, while the granitic magma source mainly originated from the crust-mantle mixing area. (6) The alkali-rich intrusions in Baoxingchang mining area were formed in the post-collision intraplate environment, and the tectono-magmatic activities underwent a decompression-heating process mainly from compression to extension, which is very conducive to the occurrence of basic to intermediate acid. The complex intrusions experienced partial melting in the source area, crust-mantle mixing and crystallization differentiation: granitic intrusions and late-stage lamprophyres were the result of relatively high partial melting (15% and 10% respectively) in the enriched mantle source area, and dark xenoliths and early-stage lamprophyres were enriched. The products of low partial melting (-3%) in the source area of the mantle; the crustal contamination degree of granitic rocks is relatively high, while the lamprophyre contamination degree is relatively low; the crystalline differentiation degree of the lamprophyres from granitic intrusions to dark xenoliths to early lamprophyres to late lamprophyres increases in turn; the crust-mantle mixing ratio is between 0.44 and 0.60, mainly concentrated in 0.5 attachment. (7) The mining area has undergone the deep dynamic processes of crustal shortening and thickening, asthenospheric upwelling and underwelling, partial melting and mixing heat flow increasing, crust thinning, crust-mantle mixing, flow differentiation and differential ascension in the process of magmatic activity, and pulsating intrusion along the local extensional area at the intersection of Honghe fault and Chenghai fault. Based on this, a magma-pulsating emplacement model under the condition of intracontinental strike-slip mechanics is established. It is pointed out that the source area of the first stage magma is deep, the partial melting degree of the source area is high, the acidic component and the crystalline differentiation degree are low, and the syenite porphyry wall is formed: the second-third stage. The source area of the magma in the section becomes shallow, the partial melting degree in the source area is low but the scale is large, a large number of lower crustal granitic components are involved, the acidic components and crystalline differentiation degree are high, and the porphyry main body related to mineralization and the granite porphyry branch (vein) containing ancient crustal basement material are formed in turn. The depth of the area is similar to that of stage II-III, but the source area has the lowest degree of partial melting, small scale of magma melting and high degree of differentiation, forming only dike-vein alkaline feldspar porphyry.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：P618.2
本文編號(hào)：2227659
[Abstract]:Baoxingchang copper-molybdenum polymetallic deposit is one of the important ore-forming areas in Jinshajiang-Honghe Cenozoic porphyry metallogenic belt. The Himalayan tectonic-magmatic activities in the deposit are intense, and different types of ALKALI-RICH PORPHYRIES are developed. The main achievements are as follows: (1) The magmatic emplacement sequence in the study area is redefined as syenite porphyry (stage I) porphyry granite + lamprophyre (stage II) granite porphyry + lamprophyre (stage III) alkali feldspar granite porphyry by means of the combination of macroscopic geological body transection and microscopic precise dating. The Himalayan porphyry in the mining area is the product of multi-stage magmatic pulsation. The second and third stages are the main emplacement stages of magma, accompanied by different degrees of basic magmatic activity. (2) Statistical analysis of the available reliable diagenetic age data and the newly obtained LA-ICP-MS zircon U-Pb age data. The formation age of the Himalayan intrusive bodies in the mining area is 38-33Ma, which is within the peak period of magmatic activity (45-30 Ma) of the Jinshajiang-Honghe alkali-rich porphyry belt, but slightly lags behind the peak period of magmatic activity in the northern part of the belt. The magmatic age and metallogenic age of the northern Ya, Baoxingchang and southern Tongchang in the middle part of the Qinghai-Tibet Plateau are gradually renewed, reflecting the migration of the deep-seated material flow to the southeastern part of the plateau. (3) The Himalayan granitic magmatic activity in the mining area has a tendency from intermediate-acidic to acidic from the early stage to the late stage, and to the direction of increasing alkalinity and gradually enriching potassium. The content of Si02 increases gradually from early stage to late stage, A1203, CaO, Fe203, MgO and P205 decreases gradually, DI increases gradually, and SI decreases gradually. The content of Si02 in dark xenoliths and lamprophyres ranges from 42.53% to 54.98%. The contents of Si02, MgO, K20 and total alkali (K2O+Na2O) increase in turn from early stage lamprophyre + dark xenolith to late stage lamprophyre, while A1203 decreases in turn. The consolidation index increases gradually from dark xenolith to early stage lamprophyre to late stage lamprophyre, while the differentiation index is opposite and concentrates between 40 and 50, suggesting that the ferromagnesian magmatic rocks in this area are consolidated. The characteristics of dark xenoliths and early lamprophyres are similar or similar, which reveals their close evolutionary relationship. (4) In granitic rocks of different stages, dark xenoliths and lamprophyres have similar trace REE characteristics: slight enrichment of V, Co, Cu and Zn, relative depletion of Cr and Ni, and transition elements. The cobweb maps are generally of the same "W" type and are obviously enriched with Rb, Ba, U, Th, Sr and La and Nb, Ta (or "TNT") anomalous depletion. The cobweb maps are characterized by light rare earth enrichment, heavy rare earth depletion, and weak Delta Eu negative anomalies, including low REE in granitic rocks and late lamprophyres, dark xenoliths and dark xenoliths. The lamprophyre_REE is higher in the early stage. (5) Lamprophyre, dark xenoliths and granitic rocks have similar Sr, Nd, Hf isotope compositions. The characteristics of high Sr and low Nd are generally high, but the dark xenoliths and lamprophyres are higher than the host granitic rocks, indicating that mantle-derived compositions are higher and have a tendency to evolve toward type II enriched mantle end-member. The epsilon Hf (t) values of the granitic rocks are all positive, the epsilon Hf (t) values of the dark xenoliths and lamprophyres are negative, and the high Hf and low Nd characteristics of the rocks indicate the interaction between the refractory ancient lithospheric mantle and the subducted crustal materials. The crystalline TYPOMORPHISM OF ZIRCON in granitic intrusions reveals that the intrusions are formed under low temperature and alkaline environment, and are of crust-mantle mixing origin mainly derived from crust, which is characterized by water-rich and alkali-rich, and is favorable to the mineralization of magmatic systems; the total rare earth content of zircon is high, with strong LREE deficit, HREE enriched left-dip distribution pattern, and obvious positive Ce anomaly, intermediate to moderate. Weak negative Eu anomalies; zircon Hf isotopes have very good similarities, and the values of epsilon Hf (t) are scattered between positive and negative values (mostly positive), indicating that they have undergone a relatively significant crust-mantle magmatic mixing process. Medium-Fe-Mg magma mainly originated from the continental lithospheric mantle, while the granitic magma source mainly originated from the crust-mantle mixing area. (6) The alkali-rich intrusions in Baoxingchang mining area were formed in the post-collision intraplate environment, and the tectono-magmatic activities underwent a decompression-heating process mainly from compression to extension, which is very conducive to the occurrence of basic to intermediate acid. The complex intrusions experienced partial melting in the source area, crust-mantle mixing and crystallization differentiation: granitic intrusions and late-stage lamprophyres were the result of relatively high partial melting (15% and 10% respectively) in the enriched mantle source area, and dark xenoliths and early-stage lamprophyres were enriched. The products of low partial melting (-3%) in the source area of the mantle; the crustal contamination degree of granitic rocks is relatively high, while the lamprophyre contamination degree is relatively low; the crystalline differentiation degree of the lamprophyres from granitic intrusions to dark xenoliths to early lamprophyres to late lamprophyres increases in turn; the crust-mantle mixing ratio is between 0.44 and 0.60, mainly concentrated in 0.5 attachment. (7) The mining area has undergone the deep dynamic processes of crustal shortening and thickening, asthenospheric upwelling and underwelling, partial melting and mixing heat flow increasing, crust thinning, crust-mantle mixing, flow differentiation and differential ascension in the process of magmatic activity, and pulsating intrusion along the local extensional area at the intersection of Honghe fault and Chenghai fault. Based on this, a magma-pulsating emplacement model under the condition of intracontinental strike-slip mechanics is established. It is pointed out that the source area of the first stage magma is deep, the partial melting degree of the source area is high, the acidic component and the crystalline differentiation degree are low, and the syenite porphyry wall is formed: the second-third stage. The source area of the magma in the section becomes shallow, the partial melting degree in the source area is low but the scale is large, a large number of lower crustal granitic components are involved, the acidic components and crystalline differentiation degree are high, and the porphyry main body related to mineralization and the granite porphyry branch (vein) containing ancient crustal basement material are formed in turn. The depth of the area is similar to that of stage II-III, but the source area has the lowest degree of partial melting, small scale of magma melting and high degree of differentiation, forming only dike-vein alkaline feldspar porphyry.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：P618.2
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相關(guān)期刊論文 前10條
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