辽东大台沟沉积变质型铁矿床形成时代、地球化学特征及其地质意义
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摘要
辽东大台沟铁矿大地构造单元属中朝准地台胶辽台隆太子河-浑江台陷、辽阳-本溪凹陷,是近年来发现最大的"鞍山式铁矿"。利用LA-ICPMS将含铁层围岩中碎屑锆石年龄限制在2.52～2.56Ga,可推测大台沟铁矿床沉积时代约为2.54Ga左右。全岩分析结果显示Si O2、Fe2O3、FeO的含量占矿石组成的绝大部分,其它组分含量很低,说明矿石极少或者几乎没有受到陆源碎屑物质的混染。Na2O/K2O<1、ω(Sr)/ω(Ba)远远大于1,说明其为海水沉积物。Eu、Y、La具有强烈的正异常,说明形成时有热液参与。赤铁矿石中镜铁矿的发现也说明矿石为后期热液成因的产物。微量元素含量均较低,ΣREE含量较低,LREE亏损,HREE富集,稀土元素La、Eu、Y显示正异常、很高的Y/Ho比,这些特征与其它地区沉积变质型铁矿床非常相似。综合分析认为大台沟沉积变质型铁矿床成矿物质来源海底火山喷发和洋壳,火山活动活跃的部位不利于物质大量沉积,Si、Fe物质依次沉积的同时也陆续的被搬运至适合沉积成矿的位置,形成矿层,经后期区域变质变形作用、变质分异作用形成大台沟沉积变质型铁矿床。
Geotectonic unit of Liaodong Dataigou Iron Deposit belongs to Sino-Korean paraplatform, Jiaoliao platform uprise-Taizihe-hunjiang platform subside-Liaoyang-Benxi hollow.It is the largest Anshan-type iron deposit discovered in recent years. The age of clastic zircon in the surrounding rock of iron-bearing layer can be limited to 2.52～2.56 Ga by using LA-ICPMS. The results of whole rock analysis show that the content of SiO_2,Fe_2O_3 and FeO accounts for most of the ore composition,while the content of other components is very low. It shows that the ore is rarely or hardly contaminated by terrestrial clastic materials. The ratio of Na_2O/K_2O is less than 1 and the ratio of ω(Sr)/ω(Ba) is much greater than 1. It shows that it is a seawater sediment. Eu, Y and La has strong positive anomalies which shows that the hydrothermal solution is involved in the formation The discovery of specularite in hematite also shows that the ore is the product of hydrothermal origin in the later stage. The content of trace elements is low and the content of Σ REE is low. LREE is deficient and HREE is enriched. Rare earth element La,Eu and Y shows positive anomalies and a high ratio of Y/Ho. These characteristics are very similar to those of metamorphosed sedimentary iron deposit in other areas.Comprehensive analysis shows that the source of ore-forming materials of Dataigou metamorphosed sedimentary iron deposit is seafloor volcanic eruption and oceanic crust. The active part of volcanic activity is not conducive to the deposition of a large number of materials. Si and Fe material is deposited in turn and it is also transported one after another to a suitable position for sedimentary mineralization so as to form a ore layer.After the late regional metamorphism and metamorphic differentiation, it formed the Dataigou metamorphosed sedimentary iron deposit.
Geotectonic unit of Liaodong Dataigou Iron Deposit belongs to Sino-Korean paraplatform, Jiaoliao platform uprise-Taizihe-hunjiang platform subside-Liaoyang-Benxi hollow.It is the largest Anshan-type iron deposit discovered in recent years. The age of clastic zircon in the surrounding rock of iron-bearing layer can be limited to 2.52～2.56 Ga by using LA-ICPMS. The results of whole rock analysis show that the content of SiO_2,Fe_2O_3 and FeO accounts for most of the ore composition,while the content of other components is very low. It shows that the ore is rarely or hardly contaminated by terrestrial clastic materials. The ratio of Na_2O/K_2O is less than 1 and the ratio of ω(Sr)/ω(Ba) is much greater than 1. It shows that it is a seawater sediment. Eu, Y and La has strong positive anomalies which shows that the hydrothermal solution is involved in the formation The discovery of specularite in hematite also shows that the ore is the product of hydrothermal origin in the later stage. The content of trace elements is low and the content of Σ REE is low. LREE is deficient and HREE is enriched. Rare earth element La,Eu and Y shows positive anomalies and a high ratio of Y/Ho. These characteristics are very similar to those of metamorphosed sedimentary iron deposit in other areas.Comprehensive analysis shows that the source of ore-forming materials of Dataigou metamorphosed sedimentary iron deposit is seafloor volcanic eruption and oceanic crust. The active part of volcanic activity is not conducive to the deposition of a large number of materials. Si and Fe material is deposited in turn and it is also transported one after another to a suitable position for sedimentary mineralization so as to form a ore layer.After the late regional metamorphism and metamorphic differentiation, it formed the Dataigou metamorphosed sedimentary iron deposit.
引文
1任广利,王核,刘建平,等.安徽繁昌地区桃冲铁矿床地球化学特征及矿床成因研究[J].地学前缘,2012(4):82-94
2沈宝丰.中国BIF型铁矿床地质特征和资源远景[J].地质学报,2012,86(9):1376-1395
3王庚亮.硫铁矿在中国硫资源中的地位分析[J].化工矿产地质,2018,40(1):55-61
4培慧.中国铁矿志[M].北京:冶金工业出版社,1993:1-662
5东野脉兴,栾俊霞,王莹.辽东-吉南地区下元古界硼矿床成因的商榷--兼论容矿大理岩及硼矿矿床的成因[J].化工矿产地质,2018,40(1):9-16.
6洪秀伟,庞宏伟,刘学文,等.辽宁本溪大台沟铁矿地质特征[J].中国地质,2010,37(5):1426-1433
7方如恒.辽宁铁矿类型与演化[J].辽宁地质,1995,(2):106-147
8张璟,邵军,鲍庆中,等.辽宁本溪大台沟铁矿地质特征及找矿标志[J].地质与资源,2014(4):343-356
9 Trendall A F.The significance of iron-formation in the Precambrian stratigraphic record[J].Special Publication International Association of Sedimentologists,2002,33(1):33-66
10王长乐,张连昌,刘利.国外前寒武纪铁建造的研究进展与有待深入探讨的问题[J].矿床地质,2012,31(6):1311-1325
11 Planavsky N,Bekker A,Rouxel OJ,etal.2010.Rare Earth Element and yttrium compositions of Archean and Paleoproterozoic Fe formations revisited:New perspectives on the significance and mechanisms of deposition[J].Geochimicaet Cosmochimica Acta,74(22):6387-6405
12李志红,朱祥坤,唐索寒.鞍山-本溪地区条带状铁建造的铁同位素与稀土元素特征及其对成矿物质来源的指示[J].岩石矿物学杂志,2010,27(4):285-290
13 Masuzawa T and Koyama M.1989.Settling particles with positive Ceanomalies from the Japan Sea[J].Geophysical Research Letter,16(6):503-506
14 Bau M.1993.Effects of syn-and post-depositional processes on the rare-earth element distribution in Precambrian iron-formations[J].European Journal of Mineralogy,5(2):257-267
15 Kato Y,Ohta I,Tsunematsu T,et al..1998.Rare earth element variations in Mid-Archean banded iron formations:Implications for the chemistry of ocean and plate tectonics[J].Geochimica et Cosmochimica Acta,62(21-22):3475-3497
16 Polat A and Frei R.2005.The origin of early Archean banded iron formations and of continental crust,Isua,southern West Greenland[J].Precambrian Research,138(1-2):151-175
17 Adekoya JA.1998.The geology and geochemistry of the Maru Banded Iron-Formation,northwestem Nigeria[J].Journal of African Earth Sciences,27(2):241-257
18 Kholodov VN and Butuzova GY.2001.Problems of iron and phosphorus geochemistry in the Precambrian[J].Lithology Mineral Resources,36(4):291-302
19 Bekker A,Slack JF,Planavsky N,et al.2010.Iron formation:The sedimentary product of a complex interplay among mantle,tectonic,oceanic,and biospheric processes.Economic Geology,105(3):467-508
20 Bau M.1993.Effects of syn-and post-depositional processes on the rare-earth element distribution in Precambrian iron-formations[J].European Journal of Mineralogy,5(2):257-267
21王长乐,张连昌,兰彩云,等.山西吕梁古元古代袁家村铁矿BIF稀土元素地球化学及其对大氧化事件的指示[J].中国科学(地球科学),2014,44(11):2389-2405
22张秋生.中国早前寒武纪地质及成矿作用[M].长春:吉林人民出版社,1984
23沈其韩,宋会侠,赵子然.山东韩旺新太古代条带状铁矿的稀土和微量元素特征[J].地球学报,2009,30(6):693-699
24沈其韩,宋会侠,杨崇辉,等.2011.山西五台山和冀东迁安地区条带状铁矿的岩石化学特征及其地质意义[J].岩石矿物学杂志,30(2):161-171
25 Danielson A,Moller P and Dulski P.1992.The europium anomalies inbanded iron formations and the thermal history of the oceanic crust[J].Chemical Geology,97(1-2):89-100
26 Bolhar R,Kamber BS,Moorbath S,et al.2004.Characterization of Early Archaean chemical sediments by trace element signatures[J].Earth and Planetary Science Letters,222(1):43-60
27 Bolhar R and Van Kranendonk MJ.2007.A non-marine depositional setting for the northern Fortescue Group,Pilbara Graton,inferred from trace element geochemistry of stromatolitic carbonates[J].Precambrian Research,155(3-4):229-250
28 Lee J H,Byrne R H.Complexation of trivalent rare earth elements(Ce,Eu,Gd,Tb,Yb)by carbonate ions[J].Geochim.cosmochim.acta,1993,57(2):295-302
29 Bau M,Dulski P.Comparing yttrium and rare earths in hydrothermal fluids from the Mid-Atlantic Ridge:implications for Yand REE behaviour during near-vent mixing and for the Y/Ho ratio of Proterozoic seawater[J].Chemical Geology,1999,155(1-2):77-90
30 Bolhar R,Kamber B S,Moorbath S,et al.Characterisation of early Archaean chemical sediments by trace element signatures[J].Earth&Planetary Science Letters,2004,222(1):43-60
31肖凡,班宜忠,孙建东,张翔,等.华东地区沉积变质型铁矿成矿规律[J].资源调查与环境.2015,36(3):179-189
32李厚民,王登红,李立兴,等.中国铁矿成矿规律及重点矿集区资源潜力分析[J].中国地质,2012,39(3):559-580
33洪秀伟,关玉波,王长峰,等.辽宁省本溪市大台沟铁矿普查报告[R].辽宁省地质矿产调查院,2015
34李志红,朱祥坤,唐索寒.鞍山-本溪地区条带状铁矿的Fe同位素特征及其对成矿机理和地球早期海洋环境的制约[J].岩石学报,2012,28(11):3545-58
35张东阳,苏慧敏,秦松,等.河南窑场铁矿地球化学特征及其地质意义[J].矿床地质,2009,28(3):321-335
36周世泰.鞍山、本溪地区鞍山群变质岩岩石化学研究及条带状铁矿的成矿条件[J].中国地质科学院院报.1987,(16):140-153
37程裕淇,赵一呜,陆松年.中国几组主要铁矿类型[J].地质学报,1978,52(4):253-268
38 Robert B,Kamber BS,Moorbath S,et al.2004.Characterisation of Early Archaean chemical sediments by trace element signatures[J].Earth Planet.Sci.Lett.,222(1):43-60
39 Frei R and Polat A.2007.Source heterogeneity for the major components of 3.7Ga banded iron formation(Isua Greenstone Belt,western Greenland):Tracing the nature of interacting water masses in BIF formation[J].Earth and Planetary Science Letters,253:266-281
40 Frei R,Dahl PS,Duke EF,etal.Trace element andisotopic characterization of Neoarchean and Paleoproterozoic Fe formations in the Black Hills(South Dakota,USA):Assessment of chemical change during 2.9-1.9Ga deposition bracketing the 2.4-2.2Ga first rise of atmospheric oxygen[J].Precambrian Res.2008,162(3-4):441-474
41 Byrne RH and Lee JH.1993.Comparative yttrium and rare earth elementchemistries in seawater[J].Marine Chemistry,44(2-4):121-130
42 Boynton WV.1984.Geochemistry of the rare earth elements:Meteorite studies.In:Henderson P(ed.).Rare Earth Element Geochemistry.Amsterdam:Elsevier,63-14
2沈宝丰.中国BIF型铁矿床地质特征和资源远景[J].地质学报,2012,86(9):1376-1395
3王庚亮.硫铁矿在中国硫资源中的地位分析[J].化工矿产地质,2018,40(1):55-61
4培慧.中国铁矿志[M].北京:冶金工业出版社,1993:1-662
5东野脉兴,栾俊霞,王莹.辽东-吉南地区下元古界硼矿床成因的商榷--兼论容矿大理岩及硼矿矿床的成因[J].化工矿产地质,2018,40(1):9-16.
6洪秀伟,庞宏伟,刘学文,等.辽宁本溪大台沟铁矿地质特征[J].中国地质,2010,37(5):1426-1433
7方如恒.辽宁铁矿类型与演化[J].辽宁地质,1995,(2):106-147
8张璟,邵军,鲍庆中,等.辽宁本溪大台沟铁矿地质特征及找矿标志[J].地质与资源,2014(4):343-356
9 Trendall A F.The significance of iron-formation in the Precambrian stratigraphic record[J].Special Publication International Association of Sedimentologists,2002,33(1):33-66
10王长乐,张连昌,刘利.国外前寒武纪铁建造的研究进展与有待深入探讨的问题[J].矿床地质,2012,31(6):1311-1325
11 Planavsky N,Bekker A,Rouxel OJ,etal.2010.Rare Earth Element and yttrium compositions of Archean and Paleoproterozoic Fe formations revisited:New perspectives on the significance and mechanisms of deposition[J].Geochimicaet Cosmochimica Acta,74(22):6387-6405
12李志红,朱祥坤,唐索寒.鞍山-本溪地区条带状铁建造的铁同位素与稀土元素特征及其对成矿物质来源的指示[J].岩石矿物学杂志,2010,27(4):285-290
13 Masuzawa T and Koyama M.1989.Settling particles with positive Ceanomalies from the Japan Sea[J].Geophysical Research Letter,16(6):503-506
14 Bau M.1993.Effects of syn-and post-depositional processes on the rare-earth element distribution in Precambrian iron-formations[J].European Journal of Mineralogy,5(2):257-267
15 Kato Y,Ohta I,Tsunematsu T,et al..1998.Rare earth element variations in Mid-Archean banded iron formations:Implications for the chemistry of ocean and plate tectonics[J].Geochimica et Cosmochimica Acta,62(21-22):3475-3497
16 Polat A and Frei R.2005.The origin of early Archean banded iron formations and of continental crust,Isua,southern West Greenland[J].Precambrian Research,138(1-2):151-175
17 Adekoya JA.1998.The geology and geochemistry of the Maru Banded Iron-Formation,northwestem Nigeria[J].Journal of African Earth Sciences,27(2):241-257
18 Kholodov VN and Butuzova GY.2001.Problems of iron and phosphorus geochemistry in the Precambrian[J].Lithology Mineral Resources,36(4):291-302
19 Bekker A,Slack JF,Planavsky N,et al.2010.Iron formation:The sedimentary product of a complex interplay among mantle,tectonic,oceanic,and biospheric processes.Economic Geology,105(3):467-508
20 Bau M.1993.Effects of syn-and post-depositional processes on the rare-earth element distribution in Precambrian iron-formations[J].European Journal of Mineralogy,5(2):257-267
21王长乐,张连昌,兰彩云,等.山西吕梁古元古代袁家村铁矿BIF稀土元素地球化学及其对大氧化事件的指示[J].中国科学(地球科学),2014,44(11):2389-2405
22张秋生.中国早前寒武纪地质及成矿作用[M].长春:吉林人民出版社,1984
23沈其韩,宋会侠,赵子然.山东韩旺新太古代条带状铁矿的稀土和微量元素特征[J].地球学报,2009,30(6):693-699
24沈其韩,宋会侠,杨崇辉,等.2011.山西五台山和冀东迁安地区条带状铁矿的岩石化学特征及其地质意义[J].岩石矿物学杂志,30(2):161-171
25 Danielson A,Moller P and Dulski P.1992.The europium anomalies inbanded iron formations and the thermal history of the oceanic crust[J].Chemical Geology,97(1-2):89-100
26 Bolhar R,Kamber BS,Moorbath S,et al.2004.Characterization of Early Archaean chemical sediments by trace element signatures[J].Earth and Planetary Science Letters,222(1):43-60
27 Bolhar R and Van Kranendonk MJ.2007.A non-marine depositional setting for the northern Fortescue Group,Pilbara Graton,inferred from trace element geochemistry of stromatolitic carbonates[J].Precambrian Research,155(3-4):229-250
28 Lee J H,Byrne R H.Complexation of trivalent rare earth elements(Ce,Eu,Gd,Tb,Yb)by carbonate ions[J].Geochim.cosmochim.acta,1993,57(2):295-302
29 Bau M,Dulski P.Comparing yttrium and rare earths in hydrothermal fluids from the Mid-Atlantic Ridge:implications for Yand REE behaviour during near-vent mixing and for the Y/Ho ratio of Proterozoic seawater[J].Chemical Geology,1999,155(1-2):77-90
30 Bolhar R,Kamber B S,Moorbath S,et al.Characterisation of early Archaean chemical sediments by trace element signatures[J].Earth&Planetary Science Letters,2004,222(1):43-60
31肖凡,班宜忠,孙建东,张翔,等.华东地区沉积变质型铁矿成矿规律[J].资源调查与环境.2015,36(3):179-189
32李厚民,王登红,李立兴,等.中国铁矿成矿规律及重点矿集区资源潜力分析[J].中国地质,2012,39(3):559-580
33洪秀伟,关玉波,王长峰,等.辽宁省本溪市大台沟铁矿普查报告[R].辽宁省地质矿产调查院,2015
34李志红,朱祥坤,唐索寒.鞍山-本溪地区条带状铁矿的Fe同位素特征及其对成矿机理和地球早期海洋环境的制约[J].岩石学报,2012,28(11):3545-58
35张东阳,苏慧敏,秦松,等.河南窑场铁矿地球化学特征及其地质意义[J].矿床地质,2009,28(3):321-335
36周世泰.鞍山、本溪地区鞍山群变质岩岩石化学研究及条带状铁矿的成矿条件[J].中国地质科学院院报.1987,(16):140-153
37程裕淇,赵一呜,陆松年.中国几组主要铁矿类型[J].地质学报,1978,52(4):253-268
38 Robert B,Kamber BS,Moorbath S,et al.2004.Characterisation of Early Archaean chemical sediments by trace element signatures[J].Earth Planet.Sci.Lett.,222(1):43-60
39 Frei R and Polat A.2007.Source heterogeneity for the major components of 3.7Ga banded iron formation(Isua Greenstone Belt,western Greenland):Tracing the nature of interacting water masses in BIF formation[J].Earth and Planetary Science Letters,253:266-281
40 Frei R,Dahl PS,Duke EF,etal.Trace element andisotopic characterization of Neoarchean and Paleoproterozoic Fe formations in the Black Hills(South Dakota,USA):Assessment of chemical change during 2.9-1.9Ga deposition bracketing the 2.4-2.2Ga first rise of atmospheric oxygen[J].Precambrian Res.2008,162(3-4):441-474
41 Byrne RH and Lee JH.1993.Comparative yttrium and rare earth elementchemistries in seawater[J].Marine Chemistry,44(2-4):121-130
42 Boynton WV.1984.Geochemistry of the rare earth elements:Meteorite studies.In:Henderson P(ed.).Rare Earth Element Geochemistry.Amsterdam:Elsevier,63-14