摘要
本论文研究以现代成矿作用、成矿预测理论为指导,对焦冲金硫矿矿区地层、构造、岩浆岩及焦冲金硫矿成矿流体特征等与成矿有关的信息进行综合分析,结合野外实地调查,开展焦冲金硫矿成矿规律及成矿预测工作,圈定预测远景区,为该区找矿工作的部署提供依据。
对焦冲金硫矿成矿规律研究表明,焦冲金硫矿矿床多与燕山期造山运动有关。该区的金硫矿矿床,明显地受断裂构造控制,含矿断裂为北东向和北北东向。焦冲金硫矿成矿流体的来源为岩浆热液并从岩石中萃取成矿物质,形成成矿溶液,最后形成矿床,通过对矿物包裹体研究表明,该矿床的三个成矿阶段的成矿温度区间分别为410℃～440℃、320℃～350℃和260℃～320℃,即从早期的石英-硫化物阶段到晚期的方解石热液阶段成矿温度呈现逐渐减低的趋势。焦冲金硫矿成矿深度为1.5Km,成矿压力400×105 Pa。焦冲金硫矿床含金矿物主要为硫化物,硫化物的δ~(34)S平均值相当于热液的总δ~(34)S值,为4.16‰,该值反映了矿石中的硫总体具有深源硫的特征,即硫主要来源于深源岩浆,极少量可能来自于地层中的海水硫酸盐。矿石铅的μ值(9.38～9.49)未出现大幅度的波动,可以指示其壳源特征且与岩浆活动关系密切,反应出该种铅来自下部地壳或者上地幔,铅同位素演化基本处于封闭体系,且在成矿过程中基本未受地壳物质的混染。
矿区侵入的辉石二长闪长岩、花岗闪长斑岩具有陆壳沉积岩重熔派生的花岗岩类岩石特征。结合矿区地质作用背景及成矿年代学研究,认为可能燕山中晚期中国东部大陆壳大面积减薄,导致深部幔源熔融岩浆上升,直接底侵到陆壳沉积岩下,使得陆壳沉积岩发生部分熔融,进而派生出本区中酸性的花岗闪长斑岩岩浆。同时,幔源岩浆进一步分异,向过碱性方向演化,形成了本区辉石二长闪长岩岩浆。根据焦冲矿区侵入岩LA—ICP—MS锆石U—Pb年龄分析结果和解释,辉石二长闪长岩结晶年龄206Pb/238U加权平均年龄为122±1Ma,比花岗闪长斑岩结晶年龄206Pb/238U加权平均年龄128±2 Ma要晚。该区岩浆岩形成顺序应为花岗闪长斑岩-辉石二长闪长岩。
综合研究认为焦冲金硫矿是青山背斜与岩浆活动共同作用形成的中高温热液充填～交代型矿床,成矿深度为中深成,矿体形成以充填为主,交代次之。
This article, guided by modern theories of mineralization and metallogenic prognosis, makes a comprehensive analysis on the information about the stratum, structure, magmatic rocks and characteristics of fluorite mineralization fluid of the the Jiaochong Au-S ore deposit area. Combined with field investigation and the results of work on metallogenic regularity and metallogenic prognosis of the Jiaochong Au-S ore deposit, it enloses a prospect forecast area and provides guidance for the arrangement of the exploration in this area.
Studies on the metallogenic regularity of the Jiaochong Au-s ore deposit show that Au-s ore deposit has a lot to do with Yanshanian orogenic movement. Obviously controlled by fault structure, the ore-bearing faults in this area run in E-W and N-S direction. The Jiaochong Au-S ore deposit mineralization liquid comes from the magmatic thermal fluid, extracting mineralizing substance from the rocks, and eventually produces the deposit. Research on the mineral fluid inclusions indicate that the temperature is divided by 3 ranges: 410℃～440℃、320℃～350℃和260℃～320℃,showing a decreasing trend of the temperature from the Quartz-sulfide stage earlier to calcite thermal fluid stage. The depth of the mineralization of Jiaochong Au-S ore deposit is 1.5 Km, and the mineralization pressure is 0.4 Gpa. The S-containing minerals including in the Jiaochong Au-S ore deposit are mostly sulfide. The averagement value of theδ~(34)S of the sulfide which equates the sum value of theδ~(34)S of the thermal fluid is 4.16‰, The value indicates that the sulfur of the ores has the characteristics of the deep-resource sulfur, which means that the sulfur mostly comes from the deep magma and little may come from the marine sulfate in the stratum. Theμvalue of the lead in the ores never shows the wave in big scales, indicating their crustal characteristics and the close association with the magmatic activity. The value also shows this kind of lead comes from the lower crust or the upper mantle, lead isotope basically evolved in the enclosed system and hasn’t been contaminated by the crustal substance.
The intrusive pyroxene monzodiorite and granodiorite porphyry have the characteristics of granite deriving from the crustal sedimentary rocks remelting. Combing with the ore-geological function background and ore-forming chronological study, it’s considered that in the mid-late stage of the Yanshan the continental crust in the East China thinned, causing the up-raising of deep mantle-derived magma and directly intrude beneath the crustal sedimentary rocks which makes the crustal sedimentary rocks partly melting and derives to the mid-acid granodiorite porphyry magma. Meanwhile, mantle-derived magma differentiates to the alkaline direction, producing the pyroxene monzodiorite magma in this section. According to the analysis and interpreter of the LA-ICP-MS zircon U-Pb dating of the intrusive rocks, the 206Pb/238U average age of the pyroxene monzodiorite’s crystalization is 122±1Ma, which is latter than that of the granodiorite porphyry, exactly 128±2 Ma.This dating is controversial to the primitive petrogenetic age in this district. The sequence of the magmatic rocks’crystaliztion should be granodiorite poryphyry-pyroxene monzodiorite.
After the comprehensive study, it’s considered that Jiaochong Au-S ore deposit is the moderate-to-high temperature thermal filled-alteration ore deposit affected by both Qinggshan anticline and the magma activity. The ore-forming depth is mesogenetic, and the type of the ores are filled primarily and alteration secondarily.
引文
1. Potter R W I, Clynne.M A, Brown.D L. Freezing point depression of aqueous sodium chloride solutions [J]. Economic geology, 1978, 73: 284-285.
2. Ames L, Zhou G. Xiong B. 1996. Geochronology and isotopic character of ultrahigh-pressure metamorphism with implications for collision of the Sino-Korean cratons, central China . Tectonics. 15: 472~489.
3. Chen J F, Jahn B M. 1998. Crustal evolution of Southeastern China: Nd and Sr isotopic evidence. Tectonophysics. 284: 101-133
4. Deng J F, Luo Z H, Zhao H L, et al. 1998. Trachyte and syenite: Petrogenesis constrained by the petrological phase equilibrium. Proceeding Interna Symp 100th Annivers Beijing Univ. 745-757.
5. DENG Jun, FANG Yun, YANG Liqiang et al. 2001. Numerical Modelling of Ore-forming Dynamics of Fractal Dispersive Fluid Systems. Acta Geologica Sinica. 25(2).
6. Deng Jun, Wang Qingfei, Wei Yanguang et al. 2004,The Metallogenic Effect of the Transition of Tectonic Dynamic System. Journal of China University of Geosciences, 15
7. Du Yangsong, Tian Shihong & Li Xuejun. 2003.Contrast in fluid metallogeny between Tianmashan and Datuanshan ore deposits, Tongling, Anhui. Acta Geologica Sinica. 77(1): 116– 124.
8. Huang Dinghua,Deng Jun,Yao Lingqing et al. 2004. Surplus Space Method: A new Numerical model for prediction of shallow concealed magmatic bodies. Acta Geologica Sinica. 78(1).
9. LüQ T, Hou Z Q, Zhao J H, et al.. 2003. Deep seismic reflection profiling reveals complex crustal structure of Tongling ore district. Science in China (Series D) 33(5): 442-449.
10. Mao Jingwen, Zhang Zhaochong, Zhang Zuoheng, Du Andao. 1999. Rhenium– osmium isotopic dating of molybdenite in the Xiaoliugou W(Mo) deposit in North Qilian Mountains and its geological significance [J] . Geochemica Cosmochemica Acta. 63:1815~1818.
11. Pan Y, and Dong P. 1999. The Lower Changjiang (Yangzi/Yangtze River) metallogenic belt, east China: intrusion- and wall rock-hosted Cu-Fe-Au, Mo, Zn, Pb, Ag deposits . Ore Geology Reviews. 15:177~242.
12. Wu Cailai, Wang Fusheng, Hao Meiying et al.. 2000a. Geochronology of Intermediate-Acid Intrusive Rocks from Tongling, Anhui. Continental Dynamics. 5(1):15-23.
13. Wu Cailai, Wang Zhihong, Qiao Dewu, et al.. 2000b. Types of Enclaves and theirFeatures and origins in intermedite-acid intrusive rocks from Tongling Distract, Anhui, China. Acta Geologica Sinica. 74 (1):54-67.
14. WU Ganguo, ZHANG Da, ZANG Wenshuan. 2003. Study of tectonic layering motion and layering mineralization in the Tongling metallogenic cluster. Science in China(Series D). 46(8): 852-863.
15. Xu G, Zhou J. 2001. The Xinqiao Cu-S-Fe-Au deposit in the Tongling mineral district,China: synorogenic remobilization of a stratiform sulfide deposit [J]. Ore geology reviews. 18:77-94.
16. Zhai Y.S., Xiong Y.Y., Yao S.Z., Liu X.D. 1996. Metallogeny of copper and iron deposits in the Eastern Yangtze Craton, east-central China. Ore Geology Review. 11:229~248.
17. Zhai Yusheng, Peng Runmin, Deng Jun. 2000. Analysis of Mineralization System and Prediction of New-Type Ore Deposits. Journal of China University of Geosciences. 11(2):107-112.
18. Zhang Qi, Jian Ping, Liu Dunyi et al. 2003. SHRIMP dating of volcanic rocks from Ningwu area and its geological implications.Science in China,Ser.D. 46(8):830-837.
19. Zhou Taofa, Yuan Feng,Zhao Yong. 2000.Two series of copper-gold deposits in the Middle and Lower Reaches of Yangtze River area(MlRYA)and the hydrogen,oxygen,sulfur and lead isotopes of their ore-foring hydrothermal systems. Science in China (Series D).43(Supp):209~218.
20. Collins P L F. Gas hydrates in CO2-bearing fluid inclusions and the use of freezing data for estimation of sality [J]. Economic Geology, 1979, 74 : 1435-1444.
21. Doe B R, Stacey J S. The application of lead isotope of the problem of ore genesis and ore prospect evolution. Economic Geology, 1974, 69: 724~789
22. Ohmoto H and Rye R O. Isotopes of sulfur and carbon. In Barnes H L, ed. Geochemistry of hydrothermal ore deposits. New York: John Wiley & Sons. 1979: 509~567
23. Zartman R E and Doe B R. Plumbtectonics: The model .Tectonophysics, 1981. 75 (1-2): 135~162
24. Pan Y, and Dong P. 1999. The Lower Changjiang (Yangzi/Yangtze River) metallogenic belt, east China: intrusion- and wall rock-hosted Cu-Fe-Au, Mo, Zn, Pb, Ag deposits . Ore Geology Reviews. 15:177~242.
25. Reynolds S J, Lister G S. 1989.滑脱断层带内流体与岩石相互作用的构造样式.世界地质. 8(1): 25-31.
26.常印佛,刘湘培,吴言昌. 1991.长江中下游铜铁成矿带.北京:地质出版社. 1-379.
27.常印佛,唐永成,邢凤鸣等. 1997.安徽沿江地区铜金多金属成矿预测研究(简介).安徽地质科技. 40(1):1~11.
28.陈沪生. 1988.扬子准地台下扬子盆地HQ-13线地球物理-地质解释纲要.见:陈沪生主编.中国南方油气勘查新领域探索论文集(第二辑).北京:地质出版社.
29.储国正. 1992.铜陵狮子山矿田构造及其控岩控矿作用的研究.安徽地质. 2(2):1~14.
30.邓晋福,莫宣学,赵海玲,等. 1999.中国东部燕山期岩石圈—软流圈系统大灾变与成矿环境.矿床地质. 18(4):309~315.
31.邓晋福,吴宗絮. 2001.下扬子克拉通岩石圈减薄事件与长江中下游Cu、Fe成矿带.安徽地质. 11(2): 86-91
32.邓晋福,叶德隆,赵海玲,等,1992,下扬子地区火山作用深部过程盆地形成.武汉:中国地质大学出版社.
33.狄永军,赵海玲,张贻全,等. 2003.安徽铜陵地区花岗岩类岩石中的岩浆混合结构.北京地质. 15(1): 12-17
34.狄永军. 2003.铜陵矿集区燕山期岩浆作用及深部过程.北京:中国地质大学博士学位论文
35.杜杨松,李学军. 1997.安徽铜陵典型矿区岩石包体及其岩浆-成矿作用过程探讨.高校地质学报. 3(2): 171-182
36.富士谷. 1977.长江中下游成矿带中石炭纪海底火山喷发-沉积黄铁矿型铜矿地质特征[J] .南京大学学报(自然科学版).5(1):110~112.
37.顾连兴,徐克勤. 1986.论长江中下游中石炭世海底块状硫化物矿床.地质学报. 66 (2):176~188.
38.黄许陈,储国正. 1993.铜陵狮子山矿田多位一体(多层楼)模式.矿床地质. 12(3):221~230.
39.凌其聪,刘丛强,鲍征宇. 2002.地质流体的输运—化学反应与成矿作用微观机制研究—以安徽冬瓜山层控夕卡岩型铜矿床为例.大地构造与成矿学. 26(1):56~62.
40.刘文灿,高德臻,储国正. 1996.安徽铜陵地区构造变形分析及成矿预测.北京:地质出版社.
41.刘文灿. 1994.遥感图像在铜陵地区断裂构造分析中的应用.勘查地球物理勘查地球化学文集^c第18集^d遥感地质应用专辑.. 101～109
42.吕庆田,侯增谦,赵金华,等. 2003.深地震反射剖面揭示的铜陵矿集区复杂地壳结构形态.中国科学(D辑). 33(5): 442-449.
43.毛建仁,苏郁香,陈三元,等. 1990.长江中下游中酸性侵入岩与成矿.北京:地质出版社. 1-191
44.毛景文, Stein H.J,周涛发,等. 2004.长江中下游地区铜金(钼)矿Re-Os年龄精测及其对成矿作用的指示.地质学报. 78(1)
45.毛景文,华仁民,李晓波. 1999.浅议大规模成矿作用与大型矿集区.矿床地质. 18(4):291~299.
46.梅燕雄,毛景文,李进文,等. 2003.安徽铜陵大团山铜矿床层状夕卡岩矿体中辉钼矿Re-Os年龄测定及其地质意义.
47.唐永成,吴言昌,储国正,等. 1998.安徽沿江地区铜多金属矿床地质.北京:地质出版社.
48.田世洪,杜杨松,秦新龙,等. 2001.安徽铜陵地区中酸性侵入岩及其岩石包体中的矿物包裹体研究.地学前缘. 8(4): 422-428
49.王强,许继峰,赵振华,等. 2003.安徽铜陵地区燕山期侵入岩的成因及其对深部动力学过程的约束.中国科学(D辑). 33(4): 323-334.
50.吴才来,周珣若,黄许陈,等. 1996.铜陵地区中酸性侵入岩年代学研究.岩石矿物学杂质. 15(4): 299～306.
51.吴淦国,张达,臧文拴. 2003.铜陵矿集区构造滑脱与分层成矿特征研究.中国科学(D辑). 33(4): 300-308.
52.吴淦国. 1998.矿田构造与成矿预测.地质力学学报. 4(2):1-4.
53.吴言昌,曹奋扬,常印佛. 1999.初论安徽沿江地区成矿系统的深部构造—岩浆控制.地学前缘. 6(2):285-296.
54.夏元法. 1999.铜陵地区层控矽卡岩型矿床地质特征和成矿条件.矿产与地质. 13(6): 338-342.
55.肖新建,顾连兴,倪培等. 2002.铜陵地区海底喷流沉积(SEDEX)块状硫化物矿床成矿流体研究.矿床地质. 21(增刊): 491~494.
56.邢风鸣,徐祥. 1996.铜陵地区高钾钙碱系列侵入岩.地球化学. 25(1):29—38.
57.邢风鸣,赵斌,徐祥,等. 1997.安徽省铜陵地区侵入岩成因的实验研究.中国区域地质. 16(3):267～274.
58.邢凤鸣,徐详. 1996. AFC混合与铜陵地区侵入岩的成因.岩石矿物学杂志. 15(1):10-20.
59.邢凤鸣. 1998.扬子江岩浆带东段基性岩地球化学.地球化学. 27(3):258~268.
60.杨学明,林文通. 1988.铜官山火成杂岩体成岩机理研究.地质论评. 34(1): 25-35
61.杨学明,杨晓勇,王奎仁,等. 1997.安徽铜陵老鸦岭层状铜矿床的成矿地球化学研究.大地构造与成矿学. 21(4):347-361.
62.岳文浙,业治铮. 1993.长江中下游威宁期沉积地质与块状硫化物矿床.北京:地质出版社. 9~126.
63.曾普胜,裴荣富,侯增谦,等. 2002.安徽铜陵地块沉积—喷流块状硫化物矿床.矿床地质. 21(增刊): 532~535.
64.翟裕生,姚书振,林新多,等. 1992.长江中下游地区铁铜(金)成矿规律.北京:地质出版社.
65.张达,吴淦国,臧文拴,等. 2002.火山成因块状硫化物矿床及其古构造环境研究现状综述.矿床地质. 21(增刊).
66.张达,吴淦国,李东旭. 2001.铜陵凤凰山岩体接触带构造变形特征.地学前缘. 8(3):223~229.
67.张理刚,邢风鸣. 1993.安徽中生代花岗岩铅同位素组成与铅同位素省划分.岩石学报. 9:105~114.
68.周涛发,岳书仓,袁峰,等. 2000.长江中下游两个系列铜、金矿床及其成矿流体系统的氢、氧、铅同位素研究.中国科学(D辑). 30(增刊):122~128.
69.周涛发,岳书仓. 2001.长江中下游成矿带铜、金(多金属)矿床形成的动力学背景.大陆动力学与成矿作用—教育部高级研讨班论文集. 252~259.
70.周涛发,岳书仓,刘晓东. 1999.长江中下游铜、金矿床密集形成条件及矿床成因综述.地质科技情报. 18(3):51~54.
71.周涛发,岳书仓. 2000.长江中下游铜、金矿床成矿流体系统的形成条件及机理.北京大学学报(自然科学版). 36(5):697~707.
72.周珣若,任进. 1990.长江中下游中生代花岗岩.北京:地质出版社. 1~119.
73.周珣若,吴才来,黄许陈,等. 1993.铜陵中酸性侵入岩同源包体特征及岩浆动力学.岩石矿物学杂志. 12(1):20～31.
74.周真. 1984.铜陵马山金矿床的研究.地质论评. 30(5): 467~475
75.吴开兴,胡瑞忠,毕献武,等.矿石铅同位素示踪成矿物质来源综述.地质地球化学,2002,30(3):73～82
76.张理刚.稳定同位素在地质科学中的应用.西安:陕西科学技术出版社,1985:60～90
77.郑永飞,陈江峰.稳定同位素地球化学.北京:科学出版社,2000
78.刘斌,段光贤. NaCl-H2O溶液包裹体的密度式和等容式及其应用[J]..矿物学报, 1987, 7 (4) : 345-351.
79.张文淮,张志坚,伍刚.成矿流体及成矿机制[J].地学前缘,1996, 3 (3, 4) : 245-252.
80.朱永峰.液态不混溶作用:成矿机制之一—以太行山地区的金矿为例[J]..矿物岩石地球化学通报, 1999, 18 (1) : 206-209.
81.索书田.大陆岩石圈的流动特征.当代地质科学前沿—我国今后值得重视的前沿研究领域.武汉:中国地质大学出版社,1993.136-141
