【作者】 崔培龙；

【导师】 孙景贵；

【作者基本信息】 吉林大学 ， 矿物学、岩石学、矿床学， 2014， 博士

【摘要】 鞍山-本溪地区位于华北克拉通北缘东段，以其广泛发育铁建造型（IF）铁矿倍受国内外学者的广泛关注和研究。为了进一步深入揭示区域内IF铁矿的成矿规律，本文在综合前人研究成果的基础上，开展了各类IF铁矿床的区域地质、矿床地质、成岩成矿年代学、矿床地球化学研究，结合地球物理特征，深入探讨成矿构造环境和成矿机制，建立成矿、找矿模式。取得的主要成果与进展如下。1.通过对区域地质、矿床地质以及地球物理特征的研究，将区内铁矿床分为鞍山矿集区、弓长岭矿集区、歪头山‐北台矿集区和南芬‐大台沟矿集区。鞍山矿集区主要铁矿床为西鞍山、齐大山、大孤山、胡家庙子、眼前山和小房身等，主要赋矿地层为鞍山群樱桃园组，控矿构造为以铁架山太古代花岗杂岩为核心的轴面近南北、西翼向南西倒伏、东翼近似直立的不对称穹形构造体系。南北两个矿带，南矿带呈东西走向，北矿带呈南北走向，主矿体均为单层，厚度>100m，上部矿石以假象赤铁石英岩、磁铁石英岩为主，下部矿石以磁铁石英岩、绿泥磁铁石英岩为主。地球物理特征为以铁架山负磁异常为中心，成环状高磁异常分布，南北矿带航磁异常呈南北向，北北西展布。值得注意的是鞍山矿集区还发育有赋存于南芬组紫色页岩中的赤铁石英岩型小房身富铁矿和赋存于早元古代千枚岩中的含菱铁矿型大孤山主矿体北侧铁矿体；弓长岭矿集区主要铁矿床为弓长岭一矿区、二矿区、三矿区、独木矿区，赋矿地层为鞍山群茨沟组，控矿构造为以混合花岗岩为核部，茨沟组和辽河群岩层为两翼的弓长岭背斜，北翼呈北西向，向北东倾斜，南翼走向近东西，向南倾斜。矿体同斜长角闪岩呈互层状产出，为多层薄层状，单层厚度<50m，矿石类型主要为磁铁石英岩。二矿区发育有富磁铁矿矿石，其围岩蚀变主要为绿泥石化、石榴石化、白云母化、电气石化、碳酸盐化、黄铁矿化。地球物理特征表现为磁异常南侧宽大，北侧呈细条状正异常，航磁总体走向为北西西向；歪头山‐北台矿集区主要铁矿床为歪头山、北台、棉花堡子、大河沿等，赋矿地层为鞍山群茨沟组和大峪沟组。控矿构造为近南北向往东倒卧复式背斜褶皱构造。多具有三层矿体，矿体均向西倾斜，呈NNE向延伸，紧闭同斜褶皱和石香肠构造发育，矿石类型主要为磁铁石英岩、含闪石磁铁石英岩。地球物理特征表现为具有多个椭圆状航磁正异常区，区内具有较高的剩余磁异常；南芬‐大台沟矿集区主要铁矿床为南芬、大台沟、思山岭、欢喜岭等，赋矿地层为鞍山群樱桃园组、茨沟组和大峪沟组。矿体主要受具有左行压扭性运动特征的偏岭断裂带控制，导致区内地层均轻微西倾。大台沟铁矿床为厚层板状单一矿体，而南芬铁矿床为多层薄层状矿体，矿石类型为赤铁石英岩、假象赤铁石英岩和磁铁石英岩。地球物理特征表现为航磁异常走向北北西向，北东侧梯度带较南西侧密集，显示矿层产状西倾的特征；2.对弓长岭二矿区、歪头山矿区鞍山群茨沟组同铁矿体呈互层状的中粗粒斜长角闪岩以及侵入至其中块状细粒斜长角闪岩进行锆石U‐Pb同位素定年，获得成岩年龄为2548±12Ma、2540±13Ma以及2523±12Ma，变质年龄为2475±15Ma、2476±8Ma以及2481±19Ma，表明鞍山‐本溪地区在晚太古代末期存在大规模基性火山岩喷发，随后发生基性脉岩的侵入，在早元古代初期经历强烈的构造变质作用。细粒斜长角闪岩中捕虏锆石内核207Pb/235U，206Pb/238U和207Pb/206Pb谐和年龄分别为4165±24Ma，4144±71Ma和4174±48Ma，但普通铅含量过高，多信号区间获得4100Ma左右的上交点年龄。弓长岭、歪头山地区浅粒岩中发现大量207Pb/206Pb年龄为3.3Ga、3.1Ga的早太古代末期‐中太古代具有岩浆成因的碎屑锆石，其中在弓长岭二矿区浅粒岩中发现具有早太古代早期的年龄信息的碎屑锆石，207Pb/206Pb年龄为3763±14Ma，表明鞍山‐本溪地区中‐始太古代锆石及岩石具有更大的分布范围。3.西鞍山铁矿床假象赤铁石英岩、大孤山铁矿床磁铁石英岩、齐大山铁矿床磁铁石英岩、弓长岭二矿区磁铁石英岩、歪头山铁矿床磁铁石英岩中具有岩浆成因的碎屑锆石中获得沉积下限年龄分别为2530±16Ma、2548±7.9Ma、2541±7.4Ma、2535.7±8.1Ma、2542±2.0Ma，变质年龄为2484±9Ma，从中还获得207Pb/206Pb年龄为2764±27Ma、2757±40Ma、2635±16Ma晚太古代中早期以及3563±14Ma，3498±14Ma早太古代中期碎屑锆石年龄信息。大孤山主矿体北侧含菱铁矿矿体中的假象赤铁石英岩沉积下限年龄为1872±18Ma，含有大量207Pb/206Pb加权平均年龄为2507±9.6Ma的晚太古代末期碎屑锆石；赋存于细河群南芬组紫色页岩中的小房身赤铁石英岩沉积下限年龄为820±13Ma，含有一粒207Pb/206Pb年龄为1564±66Ma的碎屑锆石。碎屑锆石年龄显示研究区内存在晚太古代末期、早元古代末期、新元古代中期三期铁建造成矿，在早太古代中期、晚太古代中早期以及中元古代早期存在岩浆构造事件。4.铁建造铁矿床主要矿石类型为磁铁石英岩、假象赤铁石英岩、富磁铁矿矿石、赤铁石英岩。主量元素显示不同类型铁矿石主要组分均为SiO2、Fe2O3、FeO，三者之和大于95%， SiO2含量同TFe2O3含量通常成反比关系，均含有较低的TiO2，暗示铁矿石中只有极少的陆源碎屑物质加入。原始地幔标准化微量元素配分模式对比图中，不同类型的铁矿石均具有Sr、Ta、Nb、Ti、Zr相对负异常，Rb、U、P、Y相对正异常，亏损高场强元素的特征。磁铁石英岩稀土总量（∑REE+Y）平均值为21.8×10‐6，轻重稀土明显分馏（La/YbPAAS=0.1～1.2），具有明显的La正异常（La/La*=1.0～4.1）、Eu正异常（Eu/Eu*=1.7～7.8）、Y正异常（Y/Y*=1.1～2.5）以及轻微的Ce负异常或无异常（Ce/Ce*=0.6‐1.5）。晚太古代末期假象赤铁石英岩稀土总量（∑REE+Y）平均值为15.3×10‐6，轻重稀土明显分馏（La/YbPAAS=0.19～0.84），具有明显的La正异常（La/La*=1.26～4.19）、Eu正异常（Eu/Eu*=1.97～4.27）、Y正异常（Y/Y*=1.42～2.37）以及轻微的Ce负异常或无异常Ce/Ce*=0.81～1.32）。早元古代末期假象赤铁石英岩稀土总量（∑REE+Y）平均值为20.19×10‐6，轻重稀土分馏现象更为明显，La/YbPAAS=0.31～0.54，具有较低的La正异常（La/La*=1.30～2.54）、 Eu正异常（Eu/Eu*=1.52～1.84）、Y正异常（Y/Y*=0.89～2.13）以及无Ce负异常（Ce/Ce*=0.78~1.19）。赤铁石英岩稀土总量（∑REE+Y）平均为117.8×10‐6，明显高于其它类型铁矿石，强烈富集重稀土元素（La/YbPAAS=0.12～0.22），具有La正异常（La/La*=1.24～1.38），轻微Eu正异常（Eu/Eu*=1.27～1.41）以及弱Ce正异常（Ce/Ce*=1.07‐1.24），Y异常不明显（Y/Y*=0.77～1.07）。富磁铁矿矿石稀土总量（∑REE+Y）平均为20.7×10‐6，重稀土元素富集，轻稀土元素亏损（La/YbPAAS=0.02～0.68），具有明显的La正异常（La/La*=0.73～5.42），强烈的Eu正异常（Eu/Eu*=1.2～5.3）、显著的Y正异常（Y/Y*=0.7～1.9）以及强烈的Ce正异常（Ce/Ce*=0.66～3.75）。5.元素地球化学特征表明晚太古代末期斜长角闪岩原岩为拉斑玄武岩，分为LREE平坦或略亏损TH1型和LREE富集TH2型两类拉斑玄武岩。TH1型拉斑玄武岩相对富集MgO、Al2O3、Ni，亏损SiO2、TiO2、P2O5以及不相容性元素和大离子亲石元素，无轻重稀土分馏特征（（La/Yb）N=0.85~1.10，（La/Sm）N=0.91~1.16，（Gd/Yb）N=0.72~1.05），具有较高的Zr/Hf、Zr/Sm比值， Nb/Th>8，。TH2型拉斑玄武岩明显轻稀土富集（（La/Yb）N=4.44～4.93，（La/Sm）N=2.28–2.41）,重稀土平坦（（Gd/Yb）N=1.33～1.4），无Eu异常，Nb、Ta、P、Ti等高场强元素同相邻稀土元素系统性亏损，Th、La相对Nb富集。Sr‐Nd同位素特征显示TH1型拉斑玄武岩具有较低的初始87Sr/86Sr比值（ISr=0.70066~0.70287），较高的147Sm/144Nd比值（147Sm/144Nd=0.1978~0.1988），εNd（t）=+4.5~+4.6，fSm/Nd=+0.01，单阶段模式年龄为2512~2523Ma，两阶段模式年龄为2540~2542Ma；TH2型拉斑玄武岩初始87Sr/86Sr比值较高（ISr=0.70849~0.70977），147Sm/144Nd比值为0.1387~0.1412，εNd（t）=+1.8~+2.4，fSm/Nd=‐0.28~‐0.29，单阶段模式年龄为2754~2822Ma，两阶段模式年龄为2706~2754Ma；地球化学特征表明TH1型拉斑玄武岩成岩岩浆起源于亏损地幔，未受地壳物质混染，具有深俯冲贫Th、U等大离子亲石元素以及轻稀土元素的洋壳板片进入软流圈地幔柱部分熔融特征，TH2型拉斑玄武岩成岩岩浆明显遭受地壳物质混染，为高温地幔柱岩浆熔融部分上地壳组分而成。6.区域构造演化显示：晚太古代末期IF铁矿形成的地球动力学背景为地幔柱‐岛弧构造体系，强烈的基性岩浆、火山热液活动为成矿提供大量的Si、Fe物质；中元古代末期IF铁矿形成于弧后伸展盆地构造环境中，大量的海底基性火山喷发为大孤山主矿体北侧沉积下限年龄为1.87Ga的铁建造形成提供了热液活动、硅铁来源以及成矿物理‐化学环境；新元古代中期IF铁矿形成于“雪球事件”时期的拉张构造环境中的海相沉积盆地。7.依据成矿地质特征、成矿年代学以及地球化学特征，将研究区内铁建造型铁矿分为Algoma型、Algoma型向Superior型过渡型、Superior型和Rapitan型。Algoma型IF铁矿主要分布于弓长岭矿集区、歪头山‐北台矿集区以及南芬铁矿床等，沉积环境为缺氧的深海盆地，同海底火山热液活动密切相关，成矿物质来源于高温热液同海水的混合。Algoma型向Superior型过渡型IF铁矿主要分布于下的鞍山矿集区，相对Algoma型IF铁矿，沉积环境更靠近浅海大陆架，具有硫同位素非质量分馏效应，成矿物质来源于高温热液同海水的混合，但含有更高的古海水组分。Superior型IF铁矿为沉积下限年龄为1.87Ga的大孤山主矿体北侧含菱铁矿矿体，成矿明显受海底火山热液活动的影响，为缺氧环境下高温热液和深部海水混合成因，但相对晚太古代末期铁建造其接受更多的陆源碎屑沉积，而热液组分相对减少。Rapitan型IF铁矿为赋存于南芬组紫色页岩中的小房身赤铁石英岩矿床，受新元古代中期“雪球事件”的影响，冰盖阻碍海洋微生物光合作用以及海洋同大气圈之间氧等物质的交换，使海水中的氧逐渐消耗缺氧，古风化环境中存在大规模的晚太古代铁建造，形成富铁的碎屑沉积、冰碛，使海水中溶解大量的Fe2+，后期随着海洋氧化程度的升高，就近沉积而成。富磁铁矿矿石均产出于贫矿体之中，同贫磁铁石英岩具有相同的PAAS标准化稀土元素配分模式，同蚀变岩关系密切，为高温变质热液淋滤贫磁铁矿，致使贫铁矿石脱硅、磁铁矿重结晶而成。8.将鞍山‐本溪地区航磁异常归纳为高大磁异常、复杂磁异常、低缓磁异常、深大磁异常、剩余磁异常五类。磁异常长轴方向反映矿体的走向，轴向越长矿体延长就越大，短轴方向反映矿体的厚度，短轴越宽矿体的厚度越大，梯度反映矿体的埋藏深度，梯度越陡矿体埋藏就越浅，反之越深，磁场强度反映矿体规模，强度越大矿体规模就更显著。更多还原

【Abstract】 The Anshan–Benxi greenstone belt is situated in the east segment of the northern margin of the North China Craton (NCC), concerned by domestic and foreign scholars due to the Widely distributed Iron‐formation(IF). In order to further reveal tectonic setting, metallogenic mechanism and establish metallogenic, exploration models for IF Mine, We carry out the study for the regional geology, deposit geology, diagenesis and metallogenic geochronology, ore deposit geochemistry and geophysical characteristics of the various types IF iron ore, on the basis of previous research. The main advance achievements from this study are as followings.1. According to the research on g regional geology, deposit geology and geophysical characteristics, we further divide the study area into Anshan, Gongchangling, Waitoushan‐Beitai and Nanfen‐Dataigou ore concentration area.The main IF iron ores in Anshan ore concentration area are Xianshan, Qidashan, Dagushan, Hujiamiaozi, Yanqianshan, Xiaofangshen, and so on, hosted in the Yingtaoyuan Group of the Anshan complex. The ore‐controlling structure is the asymmetric domed structure system, as Tiejiashan Archean granitic complex as the core. The south ore zone is east‐west trend and the north ore zone is south‐north trend, which main orebody are single layer and thickness>100m. The upper part of the iron ore is consist by the martite quartzite and magnetite quartzite, the lower ore is composed by magnetite quartzite and chlorite magnetite quartzite. Geophysics is characterized by the Tiejiashan negative magnetic anomaly center, with a ring of high magnetic anomaly, north‐south trend and north‐west distribution aeromagnetic anomaly belt. It is noteworthy that Xiaofangshen hematite quartzites type is hosted in the purple shale of the Nanfen Group, and the Containing siderite ore type in the north side of the Dagushan main ore body is hosted in the early Proterozoic phyllite.The main IF iron ores in Gongchangling ore concentration area are First mine, Second mine, Third mine and Dumu mine, hosted in the Cigou Group of the Anshan complex. The ore‐controlling structure is Gongchangling anticline, with the mixed granite as the core and the Cigou Group and Liaohe Group stratum as the wings. Orebody with plagioclase amphibolite were interbedded output, multilayer thin‐bedded, single‐layer thickness of <50m, The main types of ore is magnetite quartzite. The Senond mine is known by lage scale rich iron ore, with the wall rock alteration of chlorite, garnet, muscovite, tourmaline, carbonate and pyrite. Geophysics is characterized by large magnetic anomaly on the south side, thin strip positive anomaly on the north side and the overall aeromagnetic NWW trend.The main IF iron ores in Waitoushan‐Beitai ore concentration area are Waitoushan, Beitai, Mianhuapuzi, Daheyan, hosted in the Cigou and Dayugou Group of the Anshan complex. The ore‐controlling structure is lying east and north‐south trend duplex anticlinal folds. The deposits Generally have westward tilt and NNE trending three‐layers orebodies, with magnetite quartzite and magnetite quartzite containing amphibole as the main ore types. Geophysics characterized by having a plurality of oval‐shaped aeromagnetic anomaly zone, with high residual magnetic anomaly.The main IF iron ores in Nanfen‐Dataigou ore concentration area are Nanfen, Dataigou, Sishanling, Huanxiling, hosted in the Cigou, Yingtaoyuan and Dayugou Group of the Anshan complex. The ore‐controlling structure is Pianling left–lateral displacement Fault，due to the slightly west‐dipping strata. The orebody is thickness single‐layer and multilayer thin‐bedded, with martite quartzite, magnetite quartzite and hematite quartzite as the main ore types. Geophysics have the performance of aeromagnetic anomalies towards NNW, north eastern side of the gradient zone over the southwest side of the dense, showing occurrence west‐dipping seam characteristics.2. Studies on diagenetic and metamorphic epoch show that the coarse‐grained amphibolites in the Gongchangling second mine and Waitoushan mine are occurred in2548±12Ma and2540±13Ma, with the metamorphic age of2475±15Ma and2476±8Ma. The massive fine‐grained amphibolites, intruded to those coarse‐grained, have a diagenetic age of2527±15Ma, and a metamorphic age of2476±19Ma. Those zircon U‐Pb ages indicate that Anshan‐Benxi areas exist large‐scale mafic volcanic eruption in the Late Archean, intrusive mafic dikes subsequently, and experienced strong tectonic metamorphism in the Early Paleoproterozoic. The xenocrystic core of zircon grain from the massive fine‐grained amphibolites exhibits a207Pb/206Pb age of4174±48Ma, corresponds to206Pb/238U and207Pb/235U ages within analytical uncertainty. The leptite in the Gongchangling second mine and Waitoushan mine have lots of Middle‐Early Archean zircons, with207Pb/206Pb ages of~3.1Ga,~3.3Ga, worthy noting that there is a initial Early Archean detrital zircon, with207Pb/206Pb age of3763±14Ma. Those ages indicate that the Middle‐Early Archean ancient earth materials have a wider distribution in the Anshan–Benxi greenstone belt.3. The martite quartzite form the Xianshan deposit and magnetite quartzites form Dagushan, Qidashan, Gongchangling and Waitoushan have magmatic detrital zircons U‐Pb weighted average age of2530±16Ma，2548±7.9Ma，2541±7.4Ma，2535.7±8.1Ma and2542±2.0Ma, with a metamorphic age of2484±9Ma, other Mid‐Late Archean detrital zircons age of2764±27Ma,2757±40Ma、2635±16Ma and Early Archean detrital zircons age of3563±14Ma，3498±14Ma. In addition, the Containing siderite ore type in the north side of the Dagushan main ore body has the detrital zircons U‐Pb207Pb/206Pb weighted average age of1872±18Ma and2507±9.6Ma. The hematite quartzites from Xiaofangshen deposit has the detrital zircons U‐Pb207Pb/206Pb weighted average age of820±13Ma, with a detrital zircon207Pb/206Pb age of1564±66Ma. The ages of detrital zircons indicate that there is final Late Archean, Late Paleoproterozoic and Middle Neoproterozoic metallogenic epoch for IF iron ore,, and middle Early Archean, middle‐early Late Archean and early Mesoproterozoic magmatic tectonic events.4. The main ore types of IF iron deposits are magnetite quartzite, martite quartzite, hematite quartzite and rich magnetite ore. The major elements show that the sum of SiO2, Fe2O3and FeO is more than95%, low content of TiO2, with the inverse relationship between SiO2and TFe2O3, demonstrated little terrigenous material in the ore. In the primitive mantle‐normalized trace element distribution patterns comparison chart, different types of iron ores are characterized by Sr, Ta, Nb, Ti, Zr relatively negative anomaly, Rb, U, P, Y relatively positive anomalies, loss on of high field strength elements. Magnetite quartzite shows low REE+Y average contents with∑REE+Y of21.8×10‐6. Post Archean Australian Shale (PAAS) normalized REE patterns for Magnetite quartzite show that HREE are strongly enriched with La/YbPAAS of0.1～1.2. Magnetite quartzite displays significantly La, Eu and Y positive anomalies with La/La*PAAS, Eu/Eu*PAAS and Y/Y*PAAS of1.0～4.1,1.7～7.8and1.1～2.5, slight Ce negative anomalies or no anomalies with Ce/Ce*PAAS of0.60～1.5. Final Late Archean martite quartzite shows low REE+Y average contents with∑REE+Y of15.3×10‐6. PAAS normalized REE patterns for martite quartzite show that HREE are strongly enriched with La/YbPAAS of0.19～0.84. Martite quartzite displays significantly La, Eu and Y positive anomalies with La/La*PAAS, Eu/Eu*PAAS and Y/Y*PAAS of1.26～4.19,1.97～4.27and1.42～2.37, slight Ce negative anomalies or no anomalies with Ce/Ce*PAAS of0.81～1.32. Late Paleoproterozoic martite quartzite shows low REE+Y average contents with∑REE+Y of20.19×10‐6. PAAS normalized REE patterns for Late Paleoproterozoic martite quartzite show that HREE are strongly enriched with La/YbPAAS of0.31～0.54. Late Paleoproterozoic martite quartzite displays relatively lower La, Eu and Y positive anomalies with La/La*PAAS, Eu/Eu*PAAS and Y/Y*PAAS of1.3～2.54,1.52～1.84and0.89～2.13, slight Ce negative anomalies or no anomalies with Ce/Ce*PAAS of0.78～1.19. Middle Neoproterozoic hematite quartzite shows obviously higher than other iron ores REE+Y average contents with∑REE+Y of117.8×10‐6. PAAS normalized REE patterns for hematite quartzite show that HREE are very strongly enriched with La/YbPAAS of0.12～0.22. Hematite quartzite displays slight La and Eu positive anomalies with La/La*PAAS and Eu/Eu*PAAS of1.24～1.38and1.27～1.41, slight Ce positive anomalies and no Y anomalies with Ce/Ce*PAAS and Y/Y*PAAS of1.07～1.24and0.77～1.07. Rich magnetite ore shows similar to magnetite quartzite REE+Y average contents with∑REE+Y of20.7×10‐6. Post Archean Australian Shale (PAAS) normalized REE patterns for rich magnetite ore show that HREE are very strongly enriched with La/YbPAAS of0.02～0.68. Rich magnetite ore displays significantly La, Eu and Y positive anomalies with La/La*PAAS, Eu/Eu*PAAS and Y/Y*PAAS of0.73～5.42,1.2～5.3and0.7～1.9, obviously Ce positive anomalies or no anomalies with Ce/Ce*PAAS of0.66～3.75.5. Elements geochemistry indicate that the protolith of final Late Archean amphibolites is tholeiite, and divided into TH1tholeiite with depleted LREE and TH2tholeiite with enriched LREE. TH1tholeiite relatively enrich MgO, Al2O3, Ni, and deplete SiO2, TiO2, P2O5, incompatible elements and LILE, without fractionation of REE ((La/Yb)N=0.85~1.10,(La/Sm)N=0.91~1.16,(Gd/Yb)N=0.72~1.05), and high the ratio of Zr/Hf、Zr/Sm and Nb/Th. TH2tholeiite is characterized by the obviously enrichment of LREE ((La/Yb)N=4.44～4.93,(La/Sm)N=2.28–2.41), without Eu anomaly, Nb, Ta, P, Ti high field strength elements with adjacent REE systematic loss, and hight the ratio of Th/Nb and La/Nb. Sr‐Nd isotope show that: TH1tholeiite have low initial87Sr/86Sr ratio (ISr=0.70066~0.70287), high147Sm/144Nd ratio (147Sm/144Nd=0.1978~0.1988), εNd(t)=+4.5~+4.6, fSm/Nd=+0.01, the single‐stage model ages of2512~2523Ma，the two‐stage model ages of2540~2542Ma；TH2tholeiite is characterized by high initial87Sr/86Sr ratio (ISr=0.70849~0.70977), low147Sm/144Nd ratio (147Sm/144Nd=0.1387~0.1412), εNd(t)=+1.8~+2.4, fSm/Nd=‐0.28~‐0.29, the single‐stage model ages of2754~2822Ma Ma，the two‐stage model ages of2706~2754Ma；The protolith magma of TH1tholeiite was derived from a long–term depleted mantle that evolved as LREE–depleted sources, without crustally contaminated. Positive anomalies at Nb (Nb/Th>8) have been interpreted to be the recycling of ocean slab into a mantle plume. The protolith magma of TH2tholeiite were formed by melts from a depleted mantle source that were contaminated with15%–20%of upper crustal materials before eruption.6. Regional tectonic evolution Show: final Late Archean IF iron deposits were formed in the plume‐arc tectonic setting, where strongly mafic magma erupted and volcanic hydrothermal activity brought lots of Si and Fe; Late Paleoproterozoic IF iron deposit was formed in the back‐arc extensional basin tectonic environment, where strongly mafic magma erupted and volcanic hydrothermal activity brought lots of Si and Fe for the Containing siderite ore type in the north side of the Dagushan main ore body; Middle Neoproterozoic IF iron deposit was formed in the marine sedimentary basins in extensional the tectonic environment in the “Snowball” event.7. According to the deposit geology, metallogenic chronology and geochemical characteristics, we divide the IF iron deposit in the Anshan‐Benxi area into Algoma‐type IF、Algoma transition to Superior‐type IF、Superior‐type IF and Rapitan‐type IF. The Algoma‐type IF are mainly distributed in Gongchangling ore concentration area, Waitoushan‐Beitai ore concentration district and Nanfen iron ore deposit etc. Algoma‐type IF deposited in the environment of the deep anoxic basin, with closely related to submarine volcanic hydrothermal activity, and formed in the hydrothermal mixed with seawater. Algoma transition to Superior‐type IF are mainly distributed in Anshan ore concentration area, relative to Algoma‐type IF, deposited closer to the shallow shelf, with sulfur isotope Mass independent fractionation effects, and derived from high‐temperature hydrothermal minerals mixed with seawater, But contains a higher component of ancient seawater. Superior‐type IF is the containing siderite ore body on the north side of the Dagushan main ore body,1.87Ga age limit for the deposition. Superior‐type IF mineralization is significantly affected by submarine volcanic hydrothermal activity, has the causes of hydrothermal and deep anoxic seawater mixed, but accept more terrigenous clastic sediments, and decrease the hydrothermal component, relative to Late Archean IF. Rapitan type IF is hosted in purple shale of Nanfen group in the Xiaofangshen hematite quartzite deposits. Due to the impact of Mid‐Neoproterozoic “snowball” event, ice hinder marine microbial photosynthesis and the exchange between atmosphere and ocean with oxygen and other substances, so that the gradual depletion of oxygen in the water make the ocean anoxia. Because of the massive presence of the late Archean IF in the ancient weathering environment, the formation of iron‐rich clastic sediments and moraines result in the large‐scale dissolution of Fe2+in the seawater. The degree of oxidation of the oceans rise as the ice melts, the Fe2+deposit in the near. Rich magnetite ore are produced with lean ore body, and has the similar PAAS normalized REE distribution patterns to magnetite quartzite, with close relation to altered rock. High temperature metamorphic hydrothermal leach the magnetite quartzite, and make it desilication and the recrystallization to form rich magnetite ore.8. Aeromagnetic anomalies in the Anshan‐Benxi area are summarized as tall magnetic anomalies, complex magnetic anomaly, low and gentle magnetic anomaly, deep and enormous magnetic anomalies and residual magnetic anomaly. The long axis of magnetic anomalies reflect the orebody trend, the ore bodis have greater extension as the longer of the long axis. Short axis direction reflects the thickness of the ore body, the greater the thickness of the ore bodies as the wider short axis direction. Gradient of the magnetic anomalies reflects the depth of burial ore body, the steeper the gradient, the more shallow buried ore bodies, whereas the deeper. Field strength of the magnetic anomalies reflects the size of the ore body, the larger size of field strength with more remarkable ore body.更多还原