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1.
东昆仑祁漫塔格地区白干湖钨锡矿田是认识中国西北地区钨锡矿床成矿规律的重要窗口。作者对采自含矿石英脉的2个白云母样品进行40Ar/39Ar定年,获得其坪年龄分别为(422.7±4.5)Ma和(421.8±2.7)Ma。2个样品的等时线年龄与反等时线年龄也在误差范围内一致,分别为(424±15)Ma和(418±24)Ma,表明分析数据可信。获得的白云母40Ar/39Ar坪年龄指示成矿作用发生在晚志留世,与原特提斯洋闭合事件密切相关,闭合后的陆陆碰撞使富含成矿物质的变质沉积物重熔而形成花岗岩浆;花岗岩浆侵入并析出含矿热液,导致钨锡成矿。 相似文献
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阳储岭斑岩型钨钼矿床同位素地质年代学研究 总被引：4，自引：0，他引：4
阳储岭斑岩钨矿床的花岗闪长岩体Rb-Sr等时线年龄 (140.5±0.6Ma) ,代表阳储岭杂岩体成岩年龄;~(40)Ar~(36)Ar—~(40)K~(36)Ar等时线年龄(134.0±4.7Ma)代表杂岩体的冷却年龄,其经历了6Ma的冷却史。蚀变矿物K—Ar表面年龄分散值(37—124Ma) 与冷却年龄相近,反映出本区的隐爆、热液蚀变和矿化作用是在成岩后期相伴产生的,并具多阶段成矿特点。依据锶初始比值。阳储岭杂岩体的岩石成因属于混源型花岗岩,成岩成矿物质是多来源的。 相似文献
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赣南大吉山花岗岩成岩与钨矿成矿年龄的研究 总被引：45，自引：9，他引：36
大吉山是赣南著名的钨—铌钽矿床,多年以来,由于受测试技术的限制,对该矿床的成矿年龄以及与成矿有关的大吉山花岗岩的成岩年龄缺乏系统和精确的研究。本文利用单颗粒锆石U-Pb同位素方法对大吉山补体花岗岩(铌—钽矿体的母岩)进行了成岩年龄测定,获得其侵位年龄为151.7±1.6Ma;利用快中子活化法对大吉山钨矿主矿脉中的云母进行了40Ar/39Ar地质年龄测定,获得了大吉山钨矿主矿脉的成矿年龄为144Ma和147Ma。根据这套数据,结合钨矿主矿脉、铌钽矿化和大吉山主体、补体花岗岩的空间产状,对它们的形成顺序进行了讨论。大吉山的花岗岩成岩与钨矿成矿年龄数据表明,它们是华南燕山中期陆壳重熔型花岗岩岩浆活动及相关的中生代第二次大规模成矿作用的产物。 相似文献
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《大地构造与成矿学》2015,(6)
锡田矿床是近年来新发现的一个大型钨锡多金属矿床。为了探讨锡石直接定年的可能性,拓宽流体包裹体~(40)Ar/~(39)Ar定年对象,本文对锡田钨锡矿床一块矿石的共生白云母和锡石进行了~(40)Ar/~(39)Ar定年对比研究。白云母采用激光阶段加热分析,锡石采用真空击碎法提取流体包裹体进行定年,两者获得了非常一致的~(40)Ar/~(39)Ar年龄。白云母形成平坦的年龄谱,坪年龄为155.6±1.7 Ma(2σ)。锡石真空击碎分析形成了下降型阶梯状年龄谱,最初7个阶段表观年龄明显偏老且迅速下降,表明锡石中次生包裹体含有过剩氩;第8~18阶段形成了年龄坪,对应的~(39)Ar释放量占83.8%,坪年龄为154.3±3.0 Ma。锡石年龄坪数据点构成高度线性相关的等时线,等时年龄为155.1±7.0 Ma,代表了原生包裹体的年龄。锡石原生包裹体年龄与共生白云母年龄一致,代表了锡田矿床的成矿年龄,成矿作用发生在~155 Ma,属华南晚侏罗世大规模钨锡多金属成矿高峰期。在K-Cl-40Ar相关图解上,次生、原生包裹体数据点截然分开,表明次生、原生包裹体的流体性质完全不同,且根据这些图解可以获得锡石次生包裹体年龄约为104 Ma。 相似文献
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闪锌矿流体包裹体^40Ar-^39Ar法定年探讨——以广东凡口铅锌矿为例 总被引：7，自引：0，他引：7
本文首次把流体包裹体~(40)Ar-~(39)Ar 测年技术应用于闪锌矿,对凡口铅锌矿的闪锌矿进行了直接定年分析,获得了可靠的等时线年龄和坪年龄。闪锌矿中次生包襄体沿裂隙分布而易于提取,真空击碎的开始5个阶段以次生包裹体释气为主,其数据点在~(36)Ar/~(40)Ar-~(39)Ar/~(40)Ar 图上构成等时线,年龄为(233.6±7.4)Ma(1σ),对应的~(40)Ar/~(36)Ar 初始比值为703±27,表明次生包裹体含有过剩氩,其等时线年龄可能代表了成矿后的一期热液活动的时间。真空击碎第7至17阶段(末阶段)以原生包襄体释气为主,这些阶段构成了平坦的年龄坪,对应的数据点在~(36)Ar/~(40)Ar-~(39)Ar/~(40)Ar 图上构成线性关系很好的等时线,等时线年龄(265.8±10)Ma 与坪年龄(264.4±0.7)Ma 非常一致,代表了闪锌矿的成矿年代,它表明凡口铅锌矿的一期矿化作用发生在二叠纪中期:等时线截距对应的~(40)Ar/~(36)Ar 初始比值为291±2,表明原生包裹体不含过剩氩。闪锌矿流体包裹体~(40)Ar-~(39)Ar定年的成功将为金属硫化物矿床直接定年开辟一条有效的新途径。 相似文献
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特提斯喜马拉雅是继华南和新疆阿尔泰之后又一条新发现的大型稀有金属成矿带,其成矿时代受到广泛的关注。本文以代表性矿床错那洞铍稀有多金属矿床为研究对象,挑选出矽卡岩型矿化体中的热液白云母,利用Ar-Ar同位素定年的方式测定热液活动时间,以此限制成矿时代。结果显示错那洞穹窿矽卡岩型矿体中白云母Ar-Ar同位素坪年龄为14.21±0.22Ma,对应的~(40)Ar/~(36)Ar-~(39)Ar/~(36)Ar的等时线年龄为14.21±0.27Ma,与错那洞穹窿中具有高分异特征的白云母花岗岩浆侵位时间(～14Ma)一致,表明错那洞矽卡岩型铍稀有多金属矿床的成矿年龄为～14Ma,而与穹窿内高分异白云母花岗岩一致的年龄暗示了该高分异花岗岩为该期矽卡岩型稀有金属矿化的成矿母岩浆。 相似文献
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江西大吉山钨矿成矿年代学研究 总被引：25，自引：0，他引：25
大吉山钨矿床是一个大型的石英脉型钨矿床。矿床在空间上与燕山早期复式花岗岩相伴。利用云母单矿物的K Ar同位素年龄测试方法,测定了矿床有关的花岗岩及矿脉的同位素年龄。结果表明,黑云母花岗岩中黑云母K Ar年龄为(160 3±3 03)Ma和(164 2±3 5)Ma,二云母花岗岩中白云母K Ar年龄为(160 6±2 8)Ma,含钨石英脉中白云母K Ar年龄为(152 6±2 35)Ma和(158 1±2 8)Ma。钨成矿与花岗岩的成岩基本不存在时差,推测含钨石英脉的形成可能与岩浆分异出的富含矿化剂和成矿元素的流体有关。 相似文献
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曹四夭斑岩钼矿床位于内蒙古兴和县,是华北克拉通北缘最大的钼矿床。该矿床中部发育斑岩型钼矿体,外围和上部产出热液脉型铅锌金矿体。文章选取1件与斑岩钼矿化共生的绢云母样品进行了40Ar-39Ar定年,获得40Ar-39Ar坪年龄为(144.4±1.2)Ma,相应的39Ar/36Ar-40Ar/39Ar等时线年龄为(146.4±2.2)Ma(MSWD=0.31),将等时线年龄认作绢云母的Ar封闭年龄,表明曹四夭斑岩钼矿化发生在约146 Ma前。选取14件脉型铅锌矿石中的闪锌矿、黄铁矿和磁黄铁矿样品开展了Rb-Sr定年,获得4件闪锌矿的Rb-Sr等时线年龄为(145.1±3.0)Ma(MSWD=0.63);5件黄铁矿的Rb-Sr等时线年龄为(145.2±1.3)Ma(MSWD=0.53);4件闪锌矿、5件黄铁矿和1件磁黄铁矿的Rb-Sr等时线年龄为(145.3±1.0)Ma(MSWD=0.43)。硫化物Rb-Sr定年结果表明曹四夭矿床脉型铅锌矿化形成于约145 Ma前。本次绢云母40Ar-39Ar和硫化物Rb-Sr定年结果表明,曹四夭矿床斑岩型钼矿化和脉型铅锌金矿化为同期产物,两者均形成于晚侏罗世末期,属于同一个斑岩成矿系统。曹四夭矿床硫化物的w(Rb)和w(Sr)分别为0.1867×10~(-6)~1.305×10~(-6)和0.3175×10~(-6)~6.935×10~(-6),Sr同位素初始比值(87Sr/86Sr)i介于0.709 919~0.711 951之间,平均值0.710 952,结合前人获得的辉钼矿Re含量,认为曹四夭矿床的成矿物质主要来源于地壳。 相似文献
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浙东南某些中生代侵入岩体的^40Ar—^39Ar年龄测定 总被引：13，自引：3，他引：13
采用~(40)Ar~(39)Ar定年技术测定了浙东南几个侵入于磨石山群中的燕山期中酸性岩侵入体的年龄。梁弄岩体的石英闪长岩和二长花岗岩的年龄为101Ma,龙王堂岩体的花岗岩和钾长花岗岩的年龄均为110Ma,山头郑石英闪长岩年龄为108Ma,洪公石英正长岩的年龄为124Ma。此年龄范围与早白垩世太平洋洋底快速扩张期相当。 相似文献
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西藏谢通门县雄村铜金矿主要地质体的40Ar/39Ar年龄及地质意义 总被引：5，自引：3，他引：2
雄村铜金矿Ⅱ号矿体在2007-2008年取得了重大的找矿突破,详细的地质编录成果表明,矿体同样受含眼球状石英斑晶的角闪石英闪长玢岩和角闪石英闪长玢岩控制.含眼球状石英斑晶的角闪石英闪长玢岩和角闪石英闪长玢岩的锆石U-Pb年龄已经确定(164～177 Ma),因此,雄村铜金矿不同地质体的云母类、长石类矿物Ar-Ar同位素年龄的测定显得尤为关键.文章通过对穿切I号矿体的黑云母花岗闪长岩、云煌岩脉的黑云母Ar-Ar同位素测年,结合其他研究者的成果,得到一组十分重要的年龄数据.穿插矿体的黑云母花岗闪长岩中的黑云母(样号6187-335)坪年龄(46.96±0.42)Ma,穿插矿体的无矿化的云煌岩(5053-324.4)(Cu含量0.0551%,Au含量0.034 g/t,Ag0.6 g/t)中的黑云母给出了一个较好的似坪年龄,加权平均年龄为(49.59±0.58)Ma.结合其他研究者测定的中侏罗世侵位的角闪石英闪长玢岩(不含矿)[锆石U-Pb年龄为(177.1±2.0)Ma]中黑云母的At-At同位素年龄为(48.57±0.31)Ma;含矿凝灰岩围岩[锆石U-Pb年龄为(176±5)Ma,MS3VD=0.63}的蚀变绢云母Ar-Ar年龄为(47.07±0.30)Ma;似伟晶岩中长石的At-At年龄为(47.62±0.7)Ma,认为不同形成时代、不同产出空间、不同矿化程度的地质体的云母类、长石类矿物的Ar-Ar同位素年龄的一致性,反映了后期岩浆热事件对中侏罗世早期形成的地质体和矿体的黑云母氩同位素体系产生了较强的扰动或置换.谢通门大岩基黑云母花岗闪长岩的侵位致使各地质体发生显著的退变质,形成典型的角岩化带,这种退变质的时限在46-48 Ma之间的始新世lutetian期,进而认为各地质体中云母类矿物的~(40)Ar/~(39)Ar同位素年龄不能作为成矿年龄. 相似文献
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Jesús Solé Michael Cosca Zachary Sharp Pere Enrique 《International Journal of Earth Sciences》2002,91(5):865-881
The cooling history of Hercynian calc-alkalic, post-kinematic plutonic intrusions of the Montnegre massif (NE Spain) has been determined by 40Ar/39Ar analysis of two hornblendes, four biotites and eight K-feldspars (Kfs). The hornblendes have 40Ar/39Ar total fusion ages of 291Dž Ma and define the magmatic cooling of the basic and oldest structural intrusions. The biotites from the acid and intermediate rocks have 40Ar/39Ar plateau ages of 285Dž Ma, which date cooling of the intrusions through argon closure in biotite. The 40Ar/39Ar ages of the K-feldspars vary widely, ranging from 276-191 Ma. A correlation between K-feldspar 40Ar/39Ar total fusion age and several other features such as structural state, microstructures indicated by obliquity and, to some degree, optically visible perthites, is consistent with post-crystallisation partial argon loss in the K-feldspars. The 'D values of the biotites also correlate with age and chlorite contents, but this is not so for the '18O values of either feldspar or quartz. We infer that most microtextural changes occurred during cooling of the batholith, but a possibly Mesozoic, late disturbing hydrothermal event of weak intensity and with only minor fluid circulation must have occurred. This event provoked significant argon loss in the most structurally complex K-feldspars and is recorded in the hydrogen, but not oxygen, isotope data. 相似文献
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长英质浅色体广泛出露于柴北缘造山带中段锡铁山地体花岗质片麻岩中,多呈脉状、不规则透镜状顺区域片麻理走向产出,主要由钾长石、斜长石、角闪石、石英以及少量黑云母组成,是黑云母花岗质片麻岩深融作用的产物。温压估算获得其形成条件为P=(6.5~9.6)′102 MPa,T=640~690℃,达麻粒岩相。选取浅色体角闪石和钾长石单矿物进行激光阶段加热~(40)Ar/~(39)Ar定年。角闪石共进行了17个阶段,其中3~17阶段数据形成平坦年龄谱,坪年龄为442.5±4.0 Ma;构成年龄坪的数据对应的等时线年龄为441.6±3.9 Ma,相应初始捕获氩比值为303±4,暗示该角闪石样品不含过剩~(40)Ar。坪年龄~442.5 Ma解释为角闪石初始结晶年龄,代表了锡铁山地区黑云母片麻岩发生深融(混合岩化)的时代。共生钾长石阶段加热获得一个低温和一个高温坪,坪年龄分别为307.5±2.9 Ma和323.3±3.0 Ma;等时线图谱暗示该钾长石样品未受过剩~(40)Ar干扰。坪年龄分别代表浅色体冷却到钾长石封闭温度~200℃和~250℃的时间。~(40)Ar/~(39)Ar定年结果显示锡铁山黑云母片麻岩深熔作用后经历了低速抬升(0.1~0.2 km/Ma)和缓慢冷却(3~3.6℃/Ma)的演化历史。 相似文献
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北大巴山超基性、基性岩墙和碱质火山杂岩形成时代的新证据及其地质意义 总被引：4，自引：0，他引：4
北大巴山早古生代地层广泛出露一套超基性、基性岩墙和碱质火山杂岩(包括碱性玄武岩和粗面岩),为研究北大巴山早古生代构造演化提供了重要的载体。本文通过利用锆石U-Pb定年和金云母~(40)Ar/~(39)Ar同位素定年方法对它们的形成时代进行了系统研究,结合地球化学特征探讨它们的成因及构造意义。通过对岚皋县和镇坪县的两个辉绿岩墙开展锆石U-Pb定年,分别获得它们的年龄为399±1Ma和451±4 Ma,是研究区目前已报道的有关超基性、基性岩墙最年轻和最老的就位时代。地球化学分析结果表明,它们的主量元素与区内其他基性岩墙位于同一演化趋势线上,微量和稀土元素地球化学特征相似,类似于OIB的特征,表明它们来自相同的地幔源区。因此,研究区内基性岩墙侵入事件最早开始于晚奥陶世中期(约450Ma),结束于早泥盆世晚期(约400 Ma),期间经历了多次岩浆侵入活动。对与碱性玄武岩共生的火山碎屑岩中金云母晶屑进行~(40)Ar/~(39)Ar同位素定年,获得年龄446±3Ma,代表了火山喷发时间,表明碱性玄武质岩浆喷发活动与基性岩浆侵入事件大致同时发生。对粗面岩进行SHRIMP锆石U-Pb定年虽未获得准确的岩浆结晶年龄,但较年轻锆石年龄(165±3Ma和229±2Ma)的存在,暗示其形成时代可能属于中生代。系统的年代学研究表明,北大巴山地区早古生代地层中的超基性、基性岩墙和碱性玄武质火山杂岩为同期岩浆活动的产物,最早开始于450Ma,经历了多期火山喷发和岩浆侵入活动(450~400 Ma),结束于早泥盆世晚期(~400Ma)。而粗面岩与上述岩石不是同一期岩浆活动产物,研究区不存在双峰式火成岩组合,它们可能形成于中生代,属于南秦岭中生代岩浆活动的产物,为南秦岭、北大巴山中生代成矿作用提供物源。 相似文献
16.
赣北阳储岭大型斑岩型钨钼矿床地处江南造山带东部九岭-障公山隆起带,是江南钨矿带典型的斑岩型白钨矿矿床。钨钼矿体主要发育于二长花岗斑岩内,少量发育于花岗闪长岩和爆破角砾岩中。矿体以脉状、网脉状、似层状、透镜状、星点状产出。前人针对阳储岭矿床已开展全岩Rb-Sr法、全岩K-Ar法、锆石U-Pb法、辉钼矿Re-Os法等诸多定年工作,但因“过剩Ar”的存在、后期热事件扰动和高U花岗岩中锆石发生蜕晶化等原因,导致成岩年龄结果及解释仍存在争议。文章选取与成矿相关的二长花岗斑岩开展了独居石和金红石原位LA-ICPMS U-Pb同位素定年分析,以精确厘定成矿岩体的侵位年龄。研究表明,独居石年龄为（146.06±0.61）Ma(MSWD=10.2),金红石年龄为（150.20±2.60）Ma(MSWD=1.13)。此外,独居石是开展高U成钨岩体定年的有力对象,独居石年龄与前人发表的高精度辉钼矿Re-Os年龄在误差范围内相一致,独居石年龄可更准确地代表矿床的成矿岩体年龄。阳储岭矿床所处的江南钨矿带内的矿床形成时代主要可分为中侏罗世（约162 Ma）、晚侏罗世（150～135 Ma）和早白垩世（135～12... 相似文献
17.
INTRODUCTIONEasternShandongProvincerepresentsthelargestgoldconcentrationregioninChina ,withannualproduc tion >5 5 - 6 0tgoldandpresentreserveofmorethan90 0tgold ,accountingforaquarterofthetotalgoldproductioninthecountry .Amajorityofthegoldde positsishostedintheJurassic Cretaceousgranitoidin trusions .TimingofgoldmineralizationineasternShan donghasbeenamajorfocusofmanypreviousstudies .K Ar,Rb SrandconventionalU Pbisotopicdatinginthelasttwodecadeshaveyieldedawiderangeofminer alizationag… 相似文献
18.
Paleomagnetic data from lavas and dikes of the Unkar igneous suite (16 sites) and sedimentary rocks of the Nankoweap Formation (7 sites), Grand Canyon Supergroup (GCSG), Arizona, provide two primary paleomagnetic poles for Laurentia for the latest Middle Proterozoic (ca. 1090 Ma) at 32°N, 185°E (dp=6.8°, DM=9.3°) and early Late Proterozoic (ca. 850–900 Ma) at 10°S, 163°E (dp=3.5°, DM=7.0°). A new 40Ar/39Ar age determination from an Unkar dike gives an interpreted intrusion age of about 1090 Ma, similar to previously reported geochronologic data for the Cardenas Basalts and associated intrusions. The paleomagnetic data show no evidence of any younger, middle Late Proterozoic tectonothermal event such as has been revealed in previous geochronologic studies of the Unkar igneous suite. The pole position for the Unkar Group Cardenas Basalts and related intrusions is in good agreement with other ca. 1100 Ma paleomagnetic poles from the Keweenawan midcontinent rift deposits and other SW Laurentia diabase intrusions. The close agreement in age and position of the Unkar intrusion (UI) pole with poles derived from rift related rocks from elsewhere in Laurentia indicates that mafic magmatism was essentially synchronous and widespread throughout Laurentia at ca. 1100 Ma, suggesting a large-scale continental magmatic event. The pole position for the Nankoweap Formation, which plots south of the Unkar mafic rocks, is consistent with a younger age of deposition, at about 900 to 850 Ma, than had previously been proposed. Consequently, the inferred 200 Ma difference in age between the Cardenas Basalts and overlying Nankoweap Formation provides evidence for a third major unconformity within the Grand Canyon sequence. 相似文献
19.
《地学前缘(英文版)》2016,(5)
The Halasu area is located in the southeastern margin of the Chinese Altai in Xinjiang, China. It is part of the Altaid orogenic collage where a number of porphyry-type Cue Moe Au deposits have been discovered in recent years. Geological mapping and drilling indicate the presence of various mineralized porphyritic intrusions in the Halasu Cue Au deposit, which is currently under exploration. Ue Pb dating of zircon crystals from four different mineralized porphyries reveals three significantly different ages of magmatic intrusion, i.e., ca. 372e382 Ma granodioritic porphyry and porphyritic granite, ca. 266 Ma quartz monzonitic porphyry, and ca. 216 Ma quartz dioritic porphyry. Ree Os dating of molybdenite from veinletdissemination ores in the granodioritic porphyry yields an age of mineralization of ca. 377 Ma, and Ar e Ar dating of K-feldspar from K-feldsparequartzechalcopyrite veins produces ages of ca. 269 and ca.198 Ma. The mineralization(and alteration) ages correspond broadly to the three episodes of magmatic intrusion, suggesting three overprinting porphyry mineralization events that are significantly separated in time. The first episode of porphyry intrusion and mineralization may be related to the magmatic arc being above a plate subduction zone, and the second was formed in a late-collisional environment during the closing of the Junggar Ocean, whereas the third episode of mineralization took place in the postcollisional stage. This case study suggests that in orogens where major porphyry deposits have been found in magmatic arc environments, the potential of discovering late- to post-collisional porphyry deposits cannot be neglected; conversely, in orogens where most porphyry deposits have late- to postcollisional ages, more attention should be paid to porphyries that were formed earlier in magmatic arc environments. 相似文献
20.
Geochronology and Significance of Granites Associated with Gold Deposits in the Jidong Area, China 总被引：1，自引：0，他引：1
The Jidong area is located on the north margin of the North China craton. It is a nucleus composed of the oldest rocks in China. Precambrian metamorphic rocks with various Phanerozoic granitoids invaded are widespread. Gold deposits here have close spatial relations to granitoids. Some deposits occur within them and others in the outer zone of the contact belt of the intrusion, extending thousands of metres. There have been controversial views in regard to the relations of the deposits to the intrusions although traditional techniques have been used to date the intrusions. In order to solve such a problem, the SHRIMP technique was adopted to date the U-Pb ages of zircon collected from the Yuerya intrusion which hosts the large-sized Yuerya Au deposit and Qingshankou intrusion 2 km away from the Jinchangyu (larger-sized) Au deposit. Analysis shows that the ages of 175±1 Ma and 174±3 Ma for Yuerya intrusion and the age of 199±2 Ma for Qingshankou granite indicate the Early Yanshanian stage of the Meso- 相似文献