简介:内蒙古边家大院银多金属矿床位于大兴安岭成矿带南段,是一个成因类型复杂的银多金属矿床.为了精确厘定该矿床的成岩时代,对区内与成矿关系密切的石英斑岩进行了LA-ICP-MS锆石U-Pb定年.结果表明,该斑岩的形成年龄为140±1.2Ma,为早白垩世岩浆活动的产物.岩石化学研究表明,边家大院石英斑岩的SiO2含量高(75.62%~75.80%),Al2O3含量较低(13.32%~13.33%),Alk质量分数较高(8.60%~8.71%),K2O/Na2O值为4.51~4.77.稀土配分曲线呈右倾轻稀土富集型,铕亏损强烈,δEu值为0.22.富集高场强元素Zr、Hf、Th和大离子亲石元素Rb、K,而亏损P、Ti、Sr、Ba、La.上述特征显示矿区石英斑岩与A1型非造山花岗岩一致,推断岩浆主要来源于地壳,形成于张性环境.结合矿床地质特征及前人在区域上的研究成果,认为燕山期是大兴安岭南段成矿和成岩高峰期之一,矿区石英斑岩形成的构造背景主要与古太平洋板块向西的大规模俯冲所引起的伸展作用有关.
简介:为厘清月亮湾斜长花岗岩的形成时代,用锆石LA-ICP-MSU-Pb法对其进行了研究,获得其成岩年龄为244.3±1.1Ma,即早三叠世,属印支期。其岩石学和地球化学研究表明,月亮湾岩体的SiO2含量为63.89%-67.03%,(Na2O+K2O)〈7.0%,K2O/Na2O为0.65-0.99,以钙碱性系列为主;铝饱和指数(ACNK)为0.95-0.98,为准铝质特征;其稀土总量为87.06×10^-6-201.89×10^-6,显示为轻稀土强烈富集的右倾式稀土配分型式。δEu为0.66-0.76,具有负铕异常,Rb/Sr特征反映出岩石具幔源岩浆的特点。构造环境判别图解显示月亮湾斜长花岗岩形成的大地构造背景为洋壳俯冲造山阶段的岛弧环境。
简介:为探讨西藏玉龙斑岩铜矿带南段斑岩的成因及其动力学机制,对该铜矿带南段日曲岩体开展了岩石学、同位素年代学和地球化学研究。结果显示,两件花岗闪长斑岩锆石U-Pb年龄分别为(38.2±0.2)Ma、(38.8±0.2)Ma,为喜马拉雅早期;花岗闪长斑岩富集大离子亲石元素,亏损高场强元素,属弱过铝质高钾钙碱性花岗岩;斑岩具有C型埃达克岩的地球化学特征,为加厚下地壳部分熔融的产物,未经明显的地壳混染;源区残留相主要由角闪石、石榴子石、金红石组成,并经历了较弱的壳幔混合作用。研究表明,日曲岩体的形成与印度板块与欧亚板块碰撞诱发妥坝-芒康左行走滑断裂活动有关,下地壳部分熔融及少量幔源物质的混入使斑岩具有壳幔混合的特征。
简介:GlobalabruptclimatechangefromMarinoansnowballEarthtogreenhouseEarth,recordedascapcar-bonateoverlainondiamictite,hadshedthefirstlightonCambrianbio-radiation.Themostdocumentedcapcar-bonatesectionsaretypicalwithcomprehensiveδ13Cneg-ativevaluesandubiquitoussedimentarystructures,suchastepee-like,sheet-cracketc.,whichareassociatedwithsuccessiveglacialeustaticvariationcausedbyisostaticreboundinshallow-waterfacies.Herewereportadeep-waterbasinalcapcarbonatesectionwithstrongnegativeδ13CvaluesinthesouthernmarginoftheQinlingOrogen,Heyu,ChengkouCounty,ChongqinginChina,whichconsistsofmassivedolostonewithabundantcarbonaceouslaminae.However,itlacksthesedimentarystructureasmentionedaboveandisoverlainbythin-beddedsiliciousshalesandcherts.AK-bentonitebedwasdiscoveredwithinthebaseofcapcarbonates,about0.7mabovethetopoftheMarinoandiamictite.Magmaticzirconsthatweresep-aratedfromtheK-bentonitebedyieldaSIMSconcordiaU-Pbageof634.14-1.9Ma(lσ,MSWDcE=0.31,ProbabilityCE=1.000,n-=20).TheageisingoodagreementwithpreviouslyreportedTIMSU-PbagesfortheterminationofMarinoanglaciationandprovidesageochronologicalconstraintfortheEdiacaransuccessionsintheQinlingOrogen.
简介:在结晶化以后沿着Yangtzecraton和他们的变形历史的西方边缘澄清变形侵入的关系,石油化学并且踪迹元素geochemical人物,标明日期的锆石虾U-Pb,和化学药品从在Kangding的Neoproterozoic变形侵入的共存的角闪石和斜长石的作文(),四川()省,和Yuanmou(),云南()省,被学习。与以前的出版数据结合了,在Yangtzecraton的西方边缘的Kangding花岗石的plutons和Yuanmou建筑群通常在一样的句号形成了,这被显示。在700妈的变形事件广泛地存在,至少在四川从Kangding区域盖住到Eshan()在中央云南的区域。而且,角闪岩外形可以代表山峰地区性的变形状况。
简介:Henglingguan和Beiyu变形granitoids,在Zhongtiaoshan前寒武纪的建筑群的西北分布式,包括trondhjemites和计算碱的monzogranites,与太古代的ZhaiziTTG片麻岩显示恼人的接触。并且Beiyumetamorphicgranitoids主要由trondhjemites组成,在Hujiayu背斜褶层的核心分布式。分别地,标明日期加权平均值~(207)Pb/~(206)Pb变老的数据表演的新虾锆石U-Pb是为Henglingguan变形计算碱的monzogranites和Beiyumetamorphictrondhjemites的2435.9Maand2477妈并且揭示600妈继承了的~2在magmatic锆石的核心。Whole-rockgeochemical数据显示那所有Henglingguan和Beiyu变形trondhjemitesandcalc碱的monzogranites属于遇见了铝土的中等钾、高钾的calc-alkalineseries。这些岩石被相对高的全部的碱内容描绘(Na_2O+K_2O,在to9.08%上面),弄空的Nb,Ta,P和Ti,和衰退权利的REE模式与对高LREEs/HREEsfractionation中等(吝啬的比率(La/Yb)_n=25)。在多元素蜘蛛图的Henglingguan和Beiyumetamorphictrondhjemites显示negativeRb,Th和K异例由原始披风使正常化。Sm-Nd同位素的数据表明这些granitoids有起始的ε_(Nd)到+2.4和Nd的(t)=-1.2弄空T_(MD)=的披风模型年龄2622马马。所有thesegeochemical特征显示这些granitoids在一条大陆边缘的弧被形成,并且trondhjemites主要从少年的部分融化发源玄武岩的材料并且然而,Henglingguan变形计算碱的monzogranites源于在一条大陆边缘的弧下面在古老的外壳中材料再循环。花岗石的岩浆在他们的形成期间经历了污染和分离结晶。
简介:Geza岛弧是一个著名矿化作用集中区域,在西藏的高原的东方边缘的Sanjiang领域的部分。在最近的年里,几迟了的Yanshanian花岗石的侵入和联系存款在这个区域被发现了,在桃花源,区域是其一最大Laba铝存款。以前的研究建议预定Laba矿化作用是85±2妈。然而,granodioritic斑岩的年龄仍然保持未知。在这研究,从忍受辉钼矿的granodioritic斑岩的三件样品锆石标明日期的LA-ICP-MSU-Pb与85.00±的产生日期一起被进行了0.23妈(MSWD=0.58),85.28±0.28妈(MSWD=1.12),并且84.83±0.26妈(MSWD=0.79)分别地,显示这些granodioritic斑岩在∼85附近在迟了的Yanshanian形成了妈。与矿化作用的地质的特征结合了,时间地,Laba存款遗传上空间地与granodioritic斑岩被联系。另外,Laba存款的年龄与另外的迟了的Yanshanian侵入和矿化作用一致,建议矿化作用可能在在迟了的白垩纪期间的intra板extensional环境下面被产生。
简介:TheYangshangolddepositisasuper-largefine-graineddisseminatedgolddepositlocatedinsouthernGansuProvince.ItsmetallogenicagehasbeendeterminedbyusingthecathodoluminescenceimageandionprobeU-Pbdatingtechniques.Itisfoundthatzirconsfromquartzveinletofthefine-graineddisseminatedgoldoreshowcharactersofmagmaticoriginwithprismidiomorphism,oscillatoryzoninganddominantTh/Uratiosof0.5-1.5.Threemainpopulationsofzirconsareobtained,givingaverage206pb/238Uagesof197.6±1.7Ma,126.9±3.2Maand51.2±l.3Marespectively.ThefirstagecorrespondstotheK-Arageoftheplagiogranitedike,whilethelattertwoagesindicatethatburiedCretaceousandTertiaryintrusivesexistintheorefield,suggestingthattheYangshangolddepositwasgeneticallyrelatedtothethreemagmatichydrothermalactivities.Bycontrast,zirconsfromcoarsegold-bearingquartzveinintheminingareaaremucholderthanthehostrock,indicatingthattheveinwasformedearlierandwasnotcontaminatedbylatermagmaticfluids.ItisconcludedthatthecouplingofmultiperiodichydrothermalactivitiesintheminingareahascontributedalottomineralizationoftheYangshangolddeposit.
简介:TheXishaBlockisaminoroneintheSouthChinaSeaandanimportanttectonicunitinthenorthwesternpartoftheregion.ZirconSHRIMPU-PbagesforthreevolcanicintrusivecoresamplesfromXike-1,anexploratorywellpenetratingthebiohermsoftheXishaIslands.ThecoresamplesarefromtheMiocenereefcarbonatebedrockandarerecognizedasdark-graybiotite-hornblendegabbro,grayfne-grainedbiotitediorite,andgrayfine-grainedgranite,respectively.Zirconcathodoluminescence(CL)imagesandtraceTh,UandPbcompositionsofthezirconsshowthattheserocksareofvolcanicintrusiveorigin.ZirconSHRIMPU-Pbdatingyieldedsixgroupsofages,rangingfrom2451-1857MatoearlyCretaceous,whichindicatethattheformationandevolutionoftheXishaBlockwasaffectedbytheevolutionandclosureofNeotethysOcean,probablywithinitseasternextensionintoSouthChinaSea.Bothold,deepsourcedmaterial,includingfragmentsfromRodinasupercontinent,andrecentmantle-derivedmagmaproductscontributedtotheemergenceandformationoftheXishablock.TheSHRIMPU-PbresultsalsoprovedthatthisprocessdifferedfromthatoftheKontummassif,theHainanBlock,andtheSouthChinaBlock,butissimilartothatoftheNanshaandZhongshablocks.TheprocesswasassociatedwiththeeffectsofYanshanianmagmatisminducedbysubductionmechanismsofthePaleo-PacificPlateorthereworkingofthemultiplemagmatismssincetheEarlytomid-Yanshanian,possiblyjointlyexperiencedbytheXisha-Zhongsha-NanshaBlock.