U–Pb and Re–Os Geochronology of the Tongcun Molybdenum Deposit and Zhilingtou Gold‐Silver Deposit in Zhejiang Province,Southeast China,and Its Geological Implications

Mesozoic ore deposits in Zhejiang Province, Southeast China, are divided into the northwestern and southeastern Zhejiang metallogenic belts along the Jiangshan–Shaoxing Fault. The metal ore deposits found in these belts are epithermal Au–Ag deposits, hydrothermal‐vein Ag–Pb–Zn deposits, porphyry–skarn Mo (Fe) deposits, and vein‐type Mo deposits. There is a close spatial–temporal relationship between the Mesozoic ore deposits and Mesozoic volcanic–intrusive complexes. Zircon U–Pb dating of the ore‐related intrusive rocks and molybdenite Re–Os dating from two typical deposits (Tongcun Mo deposit and Zhilingtou Au–Ag deposit) in the two metallogenic belts show the early and late Yanshanian ages for mineralization. SIMS U–Pb data of zircons from the Tongcun Mo deposit and Zhilingtou Au–Ag deposit indicate that the host granitoids crystallized at 169.7 ± 9.7 Ma (2σ) and 113.6 ± 1 Ma (2σ), respectively. Re–Os analysis of six molybdenite samples from the Tongcun Mo deposit yields an isochron age of 163.9 ± 1.9 Ma (2σ). Re–Os analyses of five molybdenite samples from the porphyry Mo orebodies of the Zhilingtou Au‐Ag deposit yield an isochron age of 110.1 ± 1.8 Ma (2σ). Our results suggest that the metal mineralization in the Zhejiang Province, southeast China formed during at least two stages, i.e., Middle Jurassic and Early Cretaceous, coeval with the granitic magmatism.     

冀东唐杖子、牛心山花岗岩体锆石SHRIMP U-Pb定年及其地质意义

冀东地区是一个金矿聚集区,但与国内外的矿集区相比,冀东地区却“只见星星不见月亮或少见月亮”,这可能是因为某些具有地区性特征的找矿标志尚未被人们所认识。本次工作采用SHRIMP锆石U-Pb法测得唐杖子金矿的花岗斑岩株的形成年龄为173Ma±2Ma,牛心山红色花岗岩的年龄为173Ma±2Ma,与峪耳崖岩体红色花岗岩的年龄174Ma±3Ma相吻合,同属中生代燕山早中期,应是同一岩浆活动的产物。如果金矿与该岩浆活动有关,那么这3个矿床就具有成因上的联系,即它们（也许包括更多的矿点）可能由一个热中心分异矿化形成,后经多次地壳活动形成目前的格局。     

Late Jurassic Cu-Mo Mineralization at the Zhashui-Shanyang District, South Qinling, China: Constraints from Re-Os Molybdenite and Laser Ablation-Inductively Coupled Plasma Mass Spectrometry U-Pb Zircon Dating

The Zhashui-Shanyang district is one of the most important sulfide deposits in the Qinling Orogen where the formation of porphyry-skarn Cu-Mo deposits has a close genetic link with the Yanshannian magmatism. Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb zircon dating of two granodiorite intrusions (Xiaohekou and Lengshuigou deposits) was investigated in the Zhashui-Shanyang district and the rock-forming ages obtained from 148.3±2.8?to 152.6±1.2?Ma, averaging 150.5 Ma, accompanied by a younger disturbance age of 144.3±1.7?Ma in the Lengshuigou intrusion, which is in excellent agreement with published sensitive high resolution ion micro-probe (SHRIMP) zircon date on the later monzodiorite porphyry phase in the Lenshuigou deposit. Two samples were selected for molybdenite ICP-MS Re-Os isotopic analyses from the Lengshuigou granodiorite porphyry, yielding Re-Os model ages from 149.2±2.7 Ma to 150.6±3.4 Ma, with a weighted mean age of 149.7±2.1 Ma. These mineralization ages overlap rock-forming ages of the host intrusions within the error range. This implies that the mineralization occurred in the Late Jurassic, which belongs to the tectonic phase B event of the Yanshan Movement, not Cretaceous as previously thought. Therefore, the Late Jurassic mineralization of the Zhashui-Shanyang district could be connected to the large-scale Yanshan molybdenum metallogenic period, the geodynamic regime of which is attributable to the far field response of convergence of surrounding plates, perhaps the approximately westward subduction of the Izanagi plate beneath the Eurasian continent.     

江西武山和永平铜矿含矿花岗质岩体锆石SIMSU—Pb年代学

江西武山和永平铜矿床是长江中下游金属成矿带中的两个重要矿床。对武山铜矿的花岗闪长斑岩和永平铜矿的花岗斑岩中锆石分别进行了,离子探针（SIMS）U—Pb定年研究,发现两个矿区的锆石年龄可分作两期,武山铜矿含矿岩体锆石^206Pb/^238U年龄分别为145±3．9Ma和121±2．5Ma,永平铜矿含矿岩体锆石^206Ph／^238U年龄分别为160±2．3Ma和135±7．4Ma。这两期不同的年龄可能反映了锆石在岩浆侵位时的结晶年龄和后期热液蚀变作用的年龄。因此确定武山铜矿花岗质岩体的侵位年龄为145Ma,永平铜矿花岗质岩体的侵位年龄为160Ma。该年龄可能也反映了这两个矿床中与燕山期岩浆侵入有关的矽卡岩型矿床和斑岩型矿床的形成时代。     

冀东峪耳崖金矿床辉钼矿Re-Os年龄及其地质意义

峪耳崖金矿床是冀东地区重要的金矿之一,位于华北板块燕山造山带东段,马兰峪复背斜北翼。金矿体赋存于峪耳崖花岗岩及其与灰质白云岩接触带中,矿化类型包括石英脉型和细脉浸染型,属中温热液型矿床。本次工作采用Re-Os同位素测年技术,对该矿床主成矿阶段的7件辉钼矿样品进行了精确定年,获得模式年龄为(168.4±2.5)Ma~(171.7±3.0)Ma,加权平均年龄为(169.84±0.95)Ma,等时线年龄为(171.9±2.7)Ma,表明矿床形成于中侏罗世,与成矿花岗岩侵位时间基本一致。辉钼矿的铼含量为50.63×10-6~116.1×10-6,平均84.61×10-6,指示成矿物质可能为壳幔混合来源。结合前人研究成果资料分析,峪耳崖金矿是冀东地区燕山早期区域性强烈构造-岩浆-成矿作用的产物。     

桂东北苗儿山-越城岭东北部界牌钨-铜矿区成矿岩体锆石U-Pb年龄及华南加里东期成矿分析

界牌W-Cu矿床产于苗儿山-越城岭复式岩体东北部斑状黑云母花岗岩与灰岩接触带的矽卡岩中,是苗儿山-越城岭复式岩体矿集区最大的矽卡岩型W-Cu矿床。矿区出露的主要岩体为斑状黑云母花岗岩及后期浅色花岗岩体,矿区外围则大面积出露斑状黑云母二长花岗岩。矿化产于斑状黑云母花岗岩与灰岩接触带矽卡岩,及斑状黑云母花岗岩中灰岩捕虏体矽卡岩化带中。黑云母花岗岩发育花岗岩型钨矿床成矿早期常见的钠长石化、云英岩化及从岩体至外接触带蚀变矿物组合显示形成温度逐渐降低。这些现象表明斑状黑云母花岗岩与矿床具有紧密成因联系。本文获得矿区斑状黑云母花岗岩、斑状黑云母二长花岗岩和浅色花岗岩体锆石LA-ICP-MS U-Pb年龄分别为:422±11 Ma,428±7 Ma,410±7 Ma,表明界牌W-矿床及区内主要岩体均形成于加里东期。本文的同位素年龄及前人报道的苗儿山-越城岭矿集区和华南加里东期与花岗岩有关矿床同位素年龄表明苗儿山-越城岭矿集区W-Mo-Cu矿床成矿主要发生在加里东期和印支期,U矿成矿主要发生在燕山期,华南在加里东期发生了分布广泛、成矿元素组合多样的与花岗岩有关的成矿事件,有很好的找矿前景,今后应加强华南加里东期矿床的找矿工作。     

Geochronologic Constraints on the Magmatic Underplating of the Gangdise^ Belt in the India-Eurasia Collision： Evidence of SHRIMP II Zircon U-Pb Dating

Abstract  Abundant small mafic intrusions occur associated with granitoids along the Gangdisê magmatic belt. In addition to many discrete gabbro bodies within the granitoid plutons, a gabbro‐pyroxenite zone occurs along the southern margin of the Gangdisê belt to the north of the Yarlung Zangbo suture. The mafic intrusion zone spatially corresponds to a strong aeromagnetic anomaly, which extends ～1400 km. The mafic intrusions consist of intermittently distributed small bodies and dikes of gabbro and dolerite with accumulates of pyroxenite, olivine pyroxenite, pegmatitic pyroxenite and amphibolite. Much evidence indicates that the Gangdisê gabbro‐pyroxenite assemblage is most likely a result of underplating of mantle‐derived magma. Detailed field investigation and systematic sampling of the mafic rocks was conducted at six locations along the Lhasa‐Xigazê segment of the mafic intrusive zone, and was followed by zircon SHRIMP II U‐Pb dating. In addition to the ages of two samples previously published (47.0±1 Ma and 48.9±1.1 Ma), the isotopic ages of the remaining four gabbro samples are 51.6±1.3 Ma, 52.5±3.0 Ma, 50.2±4.2 Ma and 49.9±1.1 Ma. The range of these ages (47–52.5 Ma) provide geochronologic constraints on the Eocene timing of magma underplating beneath the Gangdisê belt at ca. 50 Ma. This underplating event post‐dated the initiation of the India‐Eurasia continental collision by 15 million years and was contemporaneous with a process of magma mixing. The SHRIMP II U‐Pb isotopic analysis also found several old ages from a few zircon grains, mostly in a range of 479–526 Ma (weighted average age 503±10 Ma), thus yielding information about the pre‐existing lower crust when underplating of mafic magma took place. It is believed that magma underplating was one of the major mechanisms for crustal growth during the Indian‐Eurasia collision, possibly corresponding in time to the formation of the 14–16 km‐thick “crust‐mantle transitional zone” characterized by Vp = 6.85–6.9 km/s.     

大兴安岭地区德尔布干断裂带北段构造年代学研究

德尔布干断裂带是大兴安岭隆起西侧NE向的重要断裂带,处在海拉尔-拉布达林-根河盆地西缘,是著名德尔布干成矿区东南边界断裂带.为了确定德尔布干断裂带运动性质、活动时间,深入探讨该断裂带与中生代海拉尔-拉布达林-根河盆地及大兴安岭盆山格局、认识德尔布干断裂带多金属矿床成因等问题,本文应用锆石SHRIMP和云母40Ar/39Ar定年技术,分别对断裂带内的细粒黑云母花岗岩侵入体、韧性变形的花岗闪长质片麻岩、白云母石英片岩,进行了同位素年代学研究.其中花岗闪长质片麻岩岩浆型锆石SHRIMP谐和年龄300.6±9.3Ma,为花岗闪长质片麻岩海西期的侵位年龄;而花岗闪长质片麻岩中黑云母40Ar/39Ar坪年龄是130.9±1.4Ma,白云母石英片岩的白云母40Ar/39Ar坪年龄是115.6±1.6Ma,代表早白垩世伸展构造变形年龄;细粒黑云母花岗岩侵入体岩浆型锆石SHRIMP谐和年龄130.1±1.4Ma,为同伸展构造变形侵位的岩浆事件.上述地质年代说明德尔布干断裂带是早白垩世(110～130Ma)该区最年轻的重大伸展构造变形产物.控制NE向大兴安岭隆起和中生代海拉尔-拉布达林-根河等火山沉积盆地的发育格局、以及中生代以来的地壳演化与成矿类型.     

哈萨克斯坦阿克斗卡特大型斑岩铜矿床成矿时代与剥露历史研究

哈萨克斯坦阿克斗卡特大型斑岩型铜矿床产在中亚成矿域巴尔喀什成矿带阿克斗卡矿田。本文根据花岗岩类岩石的锆石U-Pb、40Ar/39Ar和裂变径迹(FT)热年代学研究,结合前人研究成果,给出了阿克斗卡斑岩铜矿床从深成岩浆活动、成矿作用、区域冷却到剥露作用的全过程。阿克斗卡矿床及附近花岗岩类锆石SHRIMPU-Pb定年结果,给出科尔达尔岩体早期英云闪长岩的结晶年龄为335.7±1.3Ma;主成矿期的含矿二长花岗斑岩结晶年龄为327.5±1.9Ma,反映了阿克斗卡矿床斑岩型铜成矿作用的年龄。花岗岩类角闪石、黑云母、钾长石40Ar/39Ar热年代学分别给出矿物冷却年龄为310.6Ma、271.5Ma和274.9Ma,进一步限定了深成斑岩型铜成矿作用的时代和区域冷却的历史。磷灰石FT测年数据揭示,受区域构造作用的影响,阿克斗卡铜矿田在晚白垩世(91～68.0Ma)发生地块的差异隆升和剥露作用。     

苏-查萤石矿区钾长花岗岩锆石SHRIMP年龄 及其地质意义

内蒙古苏-查萤石矿区是全球范围内最大的单一萤石矿区。萤石矿体大多呈似层状和透镜体状在下二叠统火山-沉积岩地层内产出, 并且与显生宙花岗岩类侵入岩体具有密切时空分布关系, 其中部分矿体直接出现在敖包吐花岗岩株中。本次研究主要对敖包吐岩株钾长花岗岩进行了锆石SHRIMP铀-铅同位素年龄测定, 所获同位素年龄值为(138±4)Ma, MSWD值为2.3, 属中生代燕山期。根据上述同位素年代学数值, 同时结合其他地质与地球化学证据, 可以推测, 中生代时期, 受古板块内部构造应力调整作用影响, 苏-查萤石矿区及东西两侧曾发生过强烈构造-岩浆活动, 并且形成有敖包吐花岗岩株及相关的萤石矿床。中生代燕山期花岗岩类岩浆活动不仅为萤石矿床的形成提供了物质、动力和热力来源, 而且是成矿流体对流循环的“发动机”。对比分析结果表明, 敖包吐岩体的形成时间与华北陆台中东段许多含矿花岗岩体的成岩时代大体相似, 它们很可能是地壳演化特定阶段混源(壳、幔源)岩浆活动的产物。     

Neoarchean sanukitoid magmatism in the Kola region: Geological, petrochemical, geochronological, and isotopic-geochemical data

New geological, isotopic-geochronological, petrochemical, and isotopic geochemical data were obtained on the Porosozero and Kolmozero sanukitoid intrusions in the Kola region. The Porosozero differentiated intrusion was formed in four phases successively emplaced during approximately 60 Ma. Phase 1 consists of a gabbrodiorite-quartz monzodiorite-granodiorite-granite series. The zircon ages of granodiorite and quartz monzodiorite from the Porosozero are 2733 ± 6 and 2734 ± 4 Ma, respectively. Phase 2 of the intrusion comprises biotite leucogranites and aplite and leucoplagiogranite veins. The zircon age of the leucogranite is 2712 ± 6 Ma. Phase 3 consists of lamprophyre dikes of odinite-spessartite-vogesite composition. The emplacement age of the lamprophyres is constrained by the age of magmatic zircon from an odinite dike: 2680 ± 10 Ma. The age of the metasomatic zircon is 2629 ± 8 Ma. Phase 4 is composed of the youngest pegmatite veins. The Rb-Sr isochron age of the phase-1 rocks is 2724 ± 74 Ma. The zircon age of granitoids from the Kolmozero is 2736 ± 4 Ma. The rocks of the sanukitoid intrusions affiliate with the calc-alkaline series, have Mg# = 0.45?0.60, are enriched in Ba, Sr, K, P, and LREE, and contain elevated concentrations of Cr and Ni. Sm-Nd isotopic data on sanukitoids from both intrusions suggest that they were derived from a mantle source enriched in LILE and LREE and having ?_Nd(2740) from +1.02 to +0.36. It was melted approximately 140 Ma after its origin [T(DM) = 2.9?2.8 Ga]. The rocks of the Porosozero and Kolmozero are proved to be similar to magmatic sanukitoid series of Archean and Phanerozoic age whose genesis was controlled by mantle-crustal interaction in suprasubduction environments at active continental margins. Elevated concentrations of Ag and Au in rocks from the Porosozero make it metallogenically promising in terms of precious metals.     

松潘-甘孜地块南缘燕山早期矽卡岩型钨钼矿床 ——来自大牛场成岩成矿年代学及锆石Hf同位素证据

矽卡岩型矿床是钨、钼、锡等矿产的重要来源之一,中国的矽卡岩型矿床绝大多数分布于中国东部,成矿时代主要为燕山期.川西九龙大牛场是在松潘-甘孜地块新发现的矽卡岩型钨钼矿床,其成岩成矿时代尚未得到精确限定.大牛场地区铁厂河花岗岩体以二长花岗岩为主,少量正长花岗岩,而钨钼矿体主要产于矽卡岩中.文章对该矿床开展锆石U-Pb定年、...     

Laser Ablation ICP‐MS U‐Pb Zircon Geochronology of Granitoids and Quartz Veins in the Shihu Gold Mine,Taihang Orogen,North China: Timing of Gold‐mineralization and Tectonic Implications

The Shihu gold deposit, situated in the Taihang Mesozoic orogen of the North China Craton (NCC), is hosted by ductile-brittle faults within Archean metamorphic core complex. The deposit is characterized by gold-bearing quartz-polymetallic sulfides veins. The Mapeng granitoids stock and intermediate-basic dikes intruded the metamorphic basement rocks, and are spatially related to gold mineralization. Detailed laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) U-Pb zircon ages of the granitic rocks, dykes and mineralized quartz veins in the studied area reveal its magmatic and mineralized history. The mineralized quartz veins contain inherited zircons with ages of about 2.55 Ga and 1.84 Ga, probably coming from the basement. These two Precambrian events are coeval with those in other parts of the NCC. The Mapeng granitoid stock, the largest intrusion in the area, was emplaced at ca. 130 Ma, and is coeval with magmatic zircon populations from diorites and quartz diorite pophyrites in the same region. The ca. 130 Ma magmatism and gold mineralization were most likely related to an underplating event that took place in the Taihang orogen at Late Mesozoic. The timing of gold mineralization with respect to felsic magmatism in the area is similar to those observed in other major gold-producing provinces in the NCC. This episode is simultaneous with those in the eastern margin of NCC, indicative of a widespread late Yanshanian metallogenic event that was a response to the Early Cretaceous lithosphere in the eastern NCC, in which the mesothermal gold deposits were formed from similar tectono-magmatic environments.     

中亚萨亚克大型铜矿田矽卡岩型铜成矿作用的年代学制约

萨亚克铜矿田是中亚成矿域巴尔喀什成矿带唯一的以矽卡岩型铜矿化为主的大型铜矿床,产在哈萨克斯坦的萨亚克复向斜内。铜矿田包括了几个在空间上相对独立的矽卡岩型铜矿床、斑岩型铜钼网状脉矿床和一系列石英脉型矿脉,构成了斑岩型和矽卡岩型两个端元形成的成矿系列,但以矽卡岩型为主。铜矿田花岗岩类岩石的锆石SHRIMPU-Pb定年,给出了两期与矽卡岩型铜成矿作用有关的深成岩浆作用的时代,早期的闪长岩结晶年龄为335±2Ma,晚期的花岗闪长岩结晶年龄为308±10Ma,反映了两期矽卡岩型铜成矿作用的年龄。结合成矿元素分析,认为早期335±2Ma为主要成矿期年龄,而308±10Ma为次要成矿期年龄。区域成矿时代的分析表明,主矽卡岩型成矿期先于区域的斑岩型铜成矿作用而发生,次要的矽卡岩型成矿期略晚于区域斑岩铜成矿期。花岗岩类岩石中的角闪石、黑云母、钾长石40Ar/39Ar测年结果进一步限定了矽卡岩型铜成矿作用的时代,分别给出冷却年龄为286.6±6.7Ma、306.6±2.9Ma和257±11Ma。4个花岗岩类岩石中的磷灰石裂变径迹测年和热历史模拟给出年龄范围为85.4±4.5Ma至66.9±4.1Ma,说明了矽卡岩型萨亚克铜矿田的剥露作用主要发生在晚白垩世晚期。本文花岗岩类岩石的U-Pb、40Ar/39Ar和裂变径迹热年代学研究,揭示了萨亚克铜矿田从深成的岩浆侵入活动、成矿作用、区域冷却到剥露作用的全过程。     

SOVETSKAYA GEOLOGIYA (SOVIET GEOLOGY) IN COVER-TO-COVER TRANSLATION, 1960, NOS. 11 AND 12

The Río Negro-Juruena Province (RNJP) occupies a large portion of the western part of the Amazonian Craton and is a zone of complex granitization and migmatization. Regional metamorphism, in general, occurred in the upper amphibolite facies. The granites and gneisses of the RNJP yield Rb-Sr and Pb-Pb whole-rock isochron dates ranging from 1.8 Ga to 1.55 Ga, with initial ⁸⁷Sr/⁸⁶Sr ratios of ～ 0.703 and a single-stage model μ₁ value of ～ 8.1. In order to improve the geochronological control, SHRIMP U-Pb zircon ages, conventional U-Pb zircon ages, and additional Pb-Pb whole-rock isochron ages were determined for samples of granitoids and gneisses from the Papuri-Uaupés and Guaviare-Orinoco rivers areas (northern part of the province) and Jamari-Machado rivers and Pontes de Lacerda areas (southern part). The granitoids from the northern part of the province yield conventional U-Pb zircon ages of 1709 ± 17 Ma and 1521 ± 31 Ma, and SHRIMP U-Pb concordant zircon results of 1800 ± 18 Ma. Samples of gneissic rocks from the southern part of the RNJP yielded SHRIMP U-Pb concordant ages of 1750 ± 24 Ma and 1570 ± 17 Ma and a Pb-Pb whole-rock isochron age of 1717 ± 120 Ma. These new U-Pb and Pb-Pb results confirm the previous Rb-Sr and Pb-Pb geochronological evidence that the main magmatic episodes within the RNJP occurred between 1.8 and 1.55 Ga, and suggest that this crustal province constitutes a segment of continental crust newly added to the Amazonian Craton at the end of the Early Proterozoic. In the area of the RNJP, there are several anorogenic rapakivi-type granite plutons. Because of the absence of recognized Archean material within the basement rocks, it is reasonable to consider the Early to Middle Proterozoic continental crust as the magmatic source for the rapakivi granite intrusions.     

Zircon Dating and Geological Implications of Granitic Gneiss in the Metamorphic Zone of Gaoligong Mountains in Western Yunnan, China

The general classification of intermediate-acid intrusive rocks in the metamorphic zone of Gaoligong Mountains as one of the metamorphic terranes of Proterozoic Gaoligong Mountains is problematic regarding the intrusion stage and age, as well as the subsequent metamorphism and deformation. In this study, we investigated granitic gneiss in the metamorphic zone of Gaoligong Mountains based on the 1:50,000 regional geological survey of Qushi Street (2011-2013) and SHRIMP U-Pb zircon geochronology. Results showed that the SHRIMP U-Pb zircon dating of granitic gneiss ranged from 163.5±5.7 Ma to 74.0±2.0 Ma. Thus, the granitic gneiss was grouped into orthometamorphic rocks (metamorphic intrusions). The dating data of granite rocks associated with intense metamorphism and deformation were divided into three groups, 163.5±5.7 to 162.3±3.1 Ma, 132.2-101.0 Ma and 99.4±3.5-74.0±2.0 Ma, which respectively represented three independent geologic events including an important magma intrusion with superimposed metamorphic effects in the late Middle Jurassic, regional dynamic metamorphism and superimposed reformation of fluid action in the early Cretaceous, and dynamic metamorphism dominated by ductile shear and metamorphism starting from the late Cretaceous.     

Re–Os and U–Pb Geochronology of Porphyry and Skarn Types Copper Deposits in Jilin Province,NE China

Jilin Province in NE China lies on the eastern edge of the Xing–Meng Orogenic Belt. Mineral exploration in this area has resulted in the discovery of numerous large, medium, and small sized Cu, Mo, Au, and Co deposits. To better understand the formation and distribution of both the porphyry and skarn types Cu deposits of the region, we examined the geological characteristics of the deposits and applied zircon U–Pb and molybdenite Re–Os isotope dating to constrain the age of the mineralization. The Binghugou Cu deposit yields a zircon U–Pb age for quartz diorite of 128.1 ± 1.6 Ma; the Chang'anpu Cu deposit yields a zircon U–Pb age for granite porphyry of 117.0 ± 1.4 Ma; the Ermi Cu deposit yields a zircon U–Pb age for granite porphyry of 96.8 ± 1.1 Ma; the Tongshan Cu deposit yields molybdenite Re–Os model ages of 128.7 to 130.2 Ma, an isochron age of 129.0 ± 1.6 Ma, and a weighted mean model age of 129.2 ± 0.7 Ma; and the Tianhexing Cu deposit yields molybdenite Re–Os model ages of 113.9 to 115.2 Ma, an isochron age of 114.7 ± 1.2 Ma, and a weighted mean model age of 114.7 ± 0.7 Ma. The new ages, combined with existing geochronology data, show that intense porphyry and skarn types Cu mineralization was coeval with Cretaceous magmatism. The geotectonic processes responsible for the genesis of the Cu mineralization were probably related to lithospheric thinning. By analyzing the accumulated molybdenite Re–Os, zircon U–Pb, and Ar–Ar ages for NE China, it is concluded that the Cu deposits formed during multiple events coinciding with periods of magmatic activity. We have identified five phases of mineralization: early Paleozoic (~476 Ma), late Paleozoic (286.5–273.6 Ma), early Mesozoic (~228.7 Ma), Jurassic (194.8–137.1 Ma), and Cretaceous (131.2–96.8 Ma). Although Cu deposits formed during each phase, most of the Cu mineralization occurred during the Cretaceous.     

Geochronological and geochemical constraints on formation of the Tongling metal deposits,middle Yangtze metallogenic belt,east‐central China

The Tongling district is one of the most important non‐ferrous metal producers in China. The origin of Cu–Au deposits in the region is closely related to Late Mesozoic intermediate intrusions, which are mainly high‐K calc‐alkaline and shoshonitic series. Geochemical characteristics indicate that these granitic rocks are mixtures of more than two compositional end‐members, i.e. mantle‐derived melts and crust components incorporated through assimilation. Three important magmatic intrusions related to the Cu–Au deposits in the Tongling region – the Jiguanshi quartz monzodiorite, the Xishizishan quartz diorite and the Miaojia diorite porphyry – were selected for this study. Zircon U–Pb dating by LA ICP‐MS yielded two groups of ages (～130–132 and 138–140 Ma) for these intrusions. Pyrite Re–Os age for the Xinqiao Cu–Fe–S deposit in the Tongling region is 126±11 Ma. Trace elements of zircon grains show that the earlier Cu–Au mineralization event was associated with adakitic rocks characterized by high positive Ce anomalies, produced at an elevated oxygen fugacity range. In contrast, later iron‐sulphur mineralization was closely related to low positive Ce anomalies, reflecting low oxygen fugacities. Considering that Pacific lithospheric subduction was the dominant factor that controlled major tectonic evolution in eastern China during the Early Cretaceous, the geochemical characteristics of these coeval ore‐forming intermediate intrusive rocks in the Tongling district were likely the result of Pacific plate underflow.     

U–Pb SHRIMP data constraints on calc-alkaline granitoids with 1.3–1.6 Ga Nd TDM model ages from the central domain of the Borborema province,NE Brazil

The Tabira, Itapetim and Timbaúba granitoids are intruded into metasedimentary sequences and Cariris Velhos (Tonian) orthogneisses from the Central Domain of the Borborema Province, NE Brazil. They have U–Pb SHRIMP ages of 593 ± 7 Ma; 615 ± 9 Ma and 616 ± 5 Ma respectively. The studied granitoids have zircon cores inherited from the protholith, with a large number of analyses showing ²⁰⁶Pb/²³⁸U ages ranging from 950 to 1200 Ma. Oscillatory zoning typical of magmatic zircon is common, although it is faint in some inherited cores.The studied granitoids are calc-alkaline and show Nd T_DM model ages ranging from 1.30 to 1.56 Ga and ?Nd (600 Ma) ranging from ?2.40 to ?5.34. These values are similar to those recorded in the country rocks. The lowest values of ?Nd (600 Ma) were recorded in enclaves of dioritic composition. Nd and U–Pb SHRIMP data suggest a significant participation of the metasedimentary rocks in the protholith of these granitoids. The Mesoproterozoic Nd T_DM model ages recorded in the studied granitoids are interpreted as the result of a hybrid source involving melting of metagraywackes, metamafic rocks of Tonian ages and/or biotite – bearing orthogneisses (Cariris Velhos Orthogneisses). The resulted melting was modified by mingling with juvenile Brasiliano melts, diorite in composition.The Timbaúba granitoids intrusions are coeval with high-T metamorphism and flat-lying foliation forming event in an intracontinental setting, during the Brasiliano convergence and contractional deformation. The Itapetim Pluton was emplaced in the convergence - lateral escape setting and the Tabira granitoids were intruded after the flat-lying foliation event, representing sin transcurrent intrusions.Our data show that within the Central Domain of the Borborema Province, granitoids with similar petrographic and geochemical compositions can have distinct ages and be intruded in distinct tectonic regimes.     

赣南矽卡岩型钨矿成岩成矿年代学及地质意义——以焦里和宝山矿床为例

矽卡岩型钨矿是赣南地区的一种重要钨矿床类型。本文以焦里和宝山两个典型的矽卡岩型钨多金属矿床为例,开展了系统的成岩成矿年代学和岩石地球化学研究,结合区域钨锡矿床最新年代学研究成果,探讨了赣南地区钨矿的成岩成矿时代及形成构造环境。结果表明,焦里矽卡岩型钨多金属矿区斑状花岗闪长岩SHRIMP锆石U-Pb年龄为164.4±1.1Ma,辉钼矿Re-Os等时线年龄为170.6±4.6Ma;宝山矽卡岩型钨矿区花岗岩SHRIMP锆石U-Pb年龄为156.6±3.9Ma,辉钼矿Re-Os模式年龄加权平均值为161.0±1.9Ma,厘定了它们的成岩成矿年龄为中-晚侏罗世,同一矿区的成岩和成矿年龄在误差范围内基本一致。结合赣南崇(义)-(大)余-(上)犹钨锡矿集区已有的年代学资料,指出本区的成岩成矿年龄介于170～150Ma,集中在160～150Ma,认为赣南钨矿形成于华南中生代岩石圈伸展-减薄时期的侏罗纪板内拉张的地球动力学背景,系同一成岩成矿系统的产物。