Late Jurassic adakitic ore-bearing granodiorite porphyry intrusions in the Xiaokele porphyry Cu(–Mo)deposit,Northeast China:implications for petrogenesis and tectonic setting

The Xiaokele Cu(–Mo)deposit is a recently discovered porphyry deposit in the northern Great Xing’an Range(GXR)of northeast China.The ore bodies in this deposit are mainly hosted within granodiorite porphyry intrusions.Potassic,phyllic,and propylitic alteration zones develop from center to edge.In this paper,we present zircon LA–ICP–MS U–Pb ages,zircon Hf isotopic compositions,and whole-rock geochemistry of the ore-bearing granodiorite porphyries from the Xiaokele Cu(–Mo)deposit.Zircon U–Pb dating suggests that the Xiaokele granodiorite porphyries were emplaced at 148.8±1.1 Ma(weighted-mean age;n=14).The Xiaokele granodiorite porphyries display high SiO2,Al2O3,Sr,and Sr/Y,low K2O/Na2O,MgO,Yb,and Y,belonging to high-SiO2 adakites produced by partial melting of the subducted oceanic slab.Marine sediments were involved in the magma source of the Xiaokele granodiorite porphyries,as indicated by enriched Sr–Nd isotopic compositions(eNd(-t)=-1.17–-0.27),low positive zircon eHf(t)values(0.4–2.2),and high Th contents(4.06–5.20).The adakitic magma subsequently interacted with the mantle peridotites during ascent through the mantle wedge.The Xiaokele granodiorite porphyries were derived from slab melting during the southward subduction of the Mongol–Okhotsk Ocean.

Application of high-frequency magnetotelluric method in porphyry copper deposit exploration：a case study of Duobaoshan deposit area

The Duobaoshan mine area in Heilongjiang is located in the northeast section of Xingmeng orogenic belt and is in the west side of Hegang Mountain-Heihe fault zone. There exist many deposits in this area,and its metallogenic conditions are superior,which has been one of the hotspots in geological prospecting and metallogenic research in Northeast China. On the basis of previous studies,the authors used the EH-4 electromagnetic imaging system to carry out the data acquisition of three survey lines in Woduhe Village,Duobaoshan Town,Nenjiang County. Through the analysis of apparent resistivity section under TE and TM polarization modes,integrating regional geological data,it is concluded that:(1) the electrical characteristics of the metal ore in this area show a relatively low resistance,and according to its resistivity difference with surrounding rocks,the geometrical structures and apparent resistivity parameters of the low resistivity bodies in the lower section of the survey line are defined,and the electrical anomalies can be identified;(2)faults F1 and F2 may have a good metallogenic environment,so they are recommended for further exploration;(3) low resistance metal ore bodies have good correlation with local small structures or faults,which may play an iconic role for the delineation of key target areas;(4) in the process of using apparent resistivity to define the geometric structures of ore bodies underground,comprehensive analysis integrating the advantages of TE and TM models should be carry out to achieve more reliable inversion results.

Porphyry Cu-Mo deposits in the eastern Xing’an-Mongolian Orogenic Belt: Mineralization ages and their geodynamic implications

东方 Xing “一 -- 蒙古(Xing-Meng ) Orogenic 带(XMOB ) 是斑岩铜(Cu ) 的重要区域之一在中国的铝(瞬间) 存款。然而，在矿化作用和他们的 geodynamic 意义的准确年龄的研究是很有限的。在这研究，从 Duobaoshan Cu 的 granodioritic 岩石扔， Daheishan 瞬间沉积物被选择做锆石虾 U-Pb 分析以便抑制他们的矿化作用年龄。Geochronological 数据显示矿化作用的二个事件发生在 Duobaoshan Cu 存款。与 Duobaoshan 斑岩 Cu 存款有关的 granodiorite 被形成在与 485 ± 8 妈的锆石 U-Pb 年龄早古生代，而与 Sankuanggou skarn 类型 Cu 存款有关的 granodiorites 是 emplaced 在里面，有锆石 U-Pb 的侏罗记 176 ± 3 和 177 ± 3 妈变老。在吉林省的 Daheishan 区域，与斑岩瞬间存款有关的 granodiorite 斑岩的炮兵阵地年龄在 178 ± 3 妈在 170 ± 3 妈，和 unmineralized monzogranite 被标明日期。因此， Cu 瞬间矿化作用的二个事件分别地在东方 XMOB 被开发，在 -485 妈和 -175 妈。基于地质的历史和 granitoids 的空间时间的分发在东北( NE )中国， Duobaoshan Cu 存款与 Xing 的碰撞有关，这被建议“and Erguna 堵住在早古生代，并且 Sankuanggou Cu 和 Daheishan 瞬间存款在侏罗记期间与Paleo和平的板的 subduction 有关。

大兴安岭南段内蒙古白音查干Sn多金属矿床石英斑岩的锆石U-Pb年龄、地球化学和Nd-Hf同位素特征及地质意义

白音查干矿床位于内蒙古自治区西乌珠穆沁旗,是大兴安岭南段新发现的一处大型Sn多金属矿床,也是该地区近些年来Sn矿找矿的重大突破。本文利用LA-ICP-MS锆石U-Pb法首次测得与成矿有关的石英斑岩成岩年龄为141.7±0.8Ma至140.2±1.1Ma。这一年龄与区内其他Sn多金属矿床成矿岩体的成岩年龄范围基本一致,说明大兴安岭南段与Sn成矿作用有关的花岗质岩石主要形成于早白垩世(140Ma左右)。全岩主量、微量和稀土元素地球化学特征显示,石英斑岩具有较高的SiO_2含量(70.99%~76.98%)、FeOT/(FeOT+MgO)值(0.90~0.97)、FeOT/MgO值(9.45~36.3)及10000×Ga/Al值(5.9~8.2)和较低的MgO(0.13%~0.18%)、TiO_2(0.10%~0.12%)及P2O5含量(0.02%~0.03%);稀土元素总量较低,配分模式呈轻稀土元素富集和明显负δEu异常的特点;微量元素富集Rb、U、Ta、Nd、Hf等元素,亏损Ba、K、Sr、P、Ti等元素。以上这些特征均说明,石英斑岩具备A型花岗岩的特点。微量元素、全岩Nd同位素和锆石Hf同位素结果显示,岩石具有较高的εNd(t)(+3.6^+3.8)和εHf(t)(+8.2^+11.6)值以及年轻的二阶段模式年龄(t_(NdDM2)为0.63~0.62Ga;t_(HfDM2)为0.67~0.45Ga),说明石英斑岩可能为幔源新生地壳物质部分熔融的产物,并在岩浆演化过程中经历了结晶分异作用。结合区域地质特征、成岩年代学、岩石地球化学和Nd-Hf同位素数据可知,大兴安岭南段晚中生代与Sn成矿作用有关的花岗岩以源区富含大量幔源新生地壳物质为特点,主要形成于晚中生代软流圈上涌所导致的岩石圈伸展的背景下。

兴蒙造山带中与古亚洲洋演化有关的成矿系统初步研究

古亚洲洋演化过程中在兴蒙造山带中形成了大量金属矿床。早古生代早期,古亚洲洋向北俯冲,形成了奥陶纪多宝山-铜山斑岩Cu-Au成矿系统;早古生代晚期,古亚洲洋向南俯冲并形成了晚奥陶世白乃庙Cu-Mo-Au成矿系统和志留纪别鲁乌图海底喷流块状硫化物成矿系统。古亚洲洋在晚古生代早期向北俯冲,形成了晚泥盆世欧玉陶勒盖Cu-Au成矿系统。基本同时,古亚洲洋向南俯冲,形成了晚泥盆世哈达门沟Mo成矿系统。早石炭世,研究区构造体制从岛弧环境逐渐转变为陆内伸展环境,并在此过程中形成了豆荚状铬铁矿成矿系统和小型斑岩Mo-Cu成矿系统。

内蒙古兴阿斑岩钼矿床地质特征、成岩时代与岩浆成因研究

兴阿钼矿床位于内蒙古自治区鄂伦春自治旗境内,是新近发现的一处超大型斑岩型钼矿床.矿体主要赋存于八道沟二长花岗斑岩体及其上的隐爆裂隙中,呈似层状分布,平均厚9.29 m,Mo平均品位0.118％.从岩体向外依次为钾化、硅化、绢英岩化、青磐岩化等斑岩型蚀变分带,围岩蚀变和物化探异常是重要的找矿标志.对矿区赋矿钾长花岗岩、成矿二长花岗斑岩和成矿后闪长玢岩开展了锆石LA-ICP-MS U-Pb定年,结果表明成矿作用发生于131-124 Ma,大约在129 Ma.3类侵入岩锆石Hf同位素研究显示,成矿相关岩浆源自新元古代末亏损地幔增生地壳物质的部分熔融.

内蒙古维拉斯托大型斑岩型锡多金属找矿勘查及启示

维拉斯托锡多金属矿床产于大兴安岭多金属成矿省南段,是近年来在中国北方发现的规模最大的以锡为主的斑岩型矿床。通过系统梳理和归纳维拉斯托锡多金属矿床区域构造背景、地质特征、矿床和矿脉展布特征,重点论证了锡多金属矿化与矿田范围内的时空格架,初步总结了找矿勘查模式。野外地质勘查及研究表明:锡多金属主要构成"地下室+楼阁"样式,即深部是以锡—锌—铷—铌—钽等成矿元素为主体的强云英岩化、天河石化石英斑岩型矿体;中部产出以锡—铜—锌成矿元素为主的隐爆角砾岩型矿(化)体;浅部为石英脉型锡—钨—锌—铜—钼—银脉型、网脉型矿体,具有叠加成矿的特征。根据找矿勘查经验,其构造—岩浆控矿明显,特征性的矿化蚀变和物化探异常是找矿的主要标志,也为在兴蒙造山带寻找同类型矿床提供了有益的启示。