简介:本文重点研究了大别山潜山,牌楼地区榴辉岩P-T-t轨迹,探讨了大别山地区榴辉岩成因,认为榴辉岩原岩主要是碱性玄武岩,少部分洋脊拉斑玄武岩岩浆早期结晶分异堆晶岩及部分钙质沉积岩。它们在华北与杨子板块碰撞时(260±30Ma),地壳向下俯冲到40-60km处,温度550°-830°C,压力1.1-2.1GPa的条件下形成的。在构造抬升过程中,榴辉岩产生了角闪岩相、绿片岩相退变质作用,角闪岩相温压条件:460°-570℃,0.4-0.7GPa。流体包裹体研究表明:流体包体成分主要为NaCl-H_2O,H_2O,NaCl-CO_2-H_2O体系,变质作用过程从早至晚由氧化向还原环境转化。熔融包体的发现表明:榴辉岩形成具有局部深熔作用。从榴辉岩产状、岩石化学、地球化学特征表明本地区榴辉岩不是一种成因,同时具有B类、C类榴辉岩特征。
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简介:WhileattendanceatpreviousIGC'swasremarkable,themorethan7,000earthscientists,exhibitorsandguestswhometinFlorenceforthe32^ndInternationalGeologicalCongresssetanall-timerecordasthehighestnumberofparticipants.Theycamefrom120countriesand75%werenotItalian.Thisproportionofforeignattendeeswasthelargestever;inlinewithatrendofincreasingnonlocalparticipation,ittestifiestothevitalityandinternationalcharacteroftheIGCs.
简介:为了解天山中新生代再造山过程的历史演化,沿横穿天山的乌鲁木齐—库尔勒公路采集了沉积岩、变质岩、花岗岩等7个样品,用作天山山体隆升和热历史演化研究.通过对样品中磷灰石裂变径迹的测年,获得7个样品的裂变径迹中心年龄,范围为(78.0±4.5)~(31.8±2.5)Ma;继之,在计算机上对磷灰石裂变径迹测定数据进行了热历史模拟,获得了隆升-冷却演化过程的新认识.裂变径迹的年龄数据和热模拟结果表明:天山造山带的中、新生代造山活动并非是整体统—抬升的过程.表现为中新世之前山体北侧先隆升、南侧后隆升的演化规律,山体隆升从北向南逐渐推进.到中新世晚期,才表现为整体抬升过程.通过磷灰石-锆石矿物对计算以及热模拟的结果,获得了各隆升阶段的视隆升速率,发现自晚白垩世晚期以来,视隆升速率有逐渐增加的趋势。
简介:ThereareobviousdifferencesinthemineralassemblageandmetamorphicP-TconditionsbetweentheeclogitesfromthenorthernandsouthernpartsoftheeasternDabieMountains.ThosefromthenorthernpartofthemountainsaredevelopedinAlpineperidotiteandgneiss.Theyhaveamineralassemblageofgarnet+diopsidewithnoquartz,andwereformedattemperaturesof600℃-740℃.Thosefromthesouthernpartaredevelopedingneissandmarble.Theyconsistofgarnet+omphacite+lessquartzandweremetamorphosedattemperaturesintherangeof650°-800℃.Thesedifferencessuggestthattheformermaybeformedduringthemetamorphismofthedeepsubductedoceaniccrust,whereasthelattermaybegeneticallyrelatedtothesubductionofthecontinentalcrustinthisarea.
简介:位于天山北部准噶尔盆地古尔班通古特沙漠西南部的艾比湖洼地。地理位置在北纬44°50′~45°05′,东经83°20′~84°07′。保护区地处塔城地区的乌苏市和博尔塔拉蒙古自治州的精河县境内,下设乌苏和精河两个管理站。保护区总面积546.6km~2。该保护
简介:TheTan-LufaultzonejoinstheDabieMountainsonitseasternmargin,andoffsetstheDabieandSuluorogenicbeltssinistrallyforabout500km.Onthebasisofcalculationoftemperatureandpressureexperiencedbythetwophasesofthefaultzoneaswellasthethermo-chronologicalinformationonmylonitefromtheearlierandlaterTan-LufaultzonesontheeasternmarginoftheDabieMountains,thispaperdiscussesthedelaminationhistoryandupliftingmagnitudesoftheDabieMountainsfromearlierJurassictoearlierCretaceous.Frommineralassemblages,mineraldeformationandmuscovite-chloritegeothermometrycalculation,itisknownthatthetemperatureexperiencedbythetwophasesofTan-Lufaultzonesarebetween400℃and450℃,andtheconfiningpressuresarebetween0.25Gpaand0.36GPafortheearliershearzonesand0.24-0.39GPaforthelateshearzones.AccordingtothegeobarometryofSi-in-phengiteandbyconsideringshearheatingandtectonicover-pressure,itisconcludedthatthemaximumformationdepthsforthetwophasesoftheductileshearzonesarenotmorethan12km.Differentialformationdepthsforthetwophasesofshearzonesare1-2kmatmost.Atabout190Maand128Ma,theTan-Lufaultzoneexperiencedtwophasesofcoolingevents.Duringthisperiod,theeasternmarginoftheDabieMountainsexperiencedatectoniccalmperiodandnouplifting.AccordingtoinformationfromtheTan-Lufaultzone,theupliftingmagnitudesoftheDabieorogenicbeltsarenotmorethan12kmduringtheearlierCretaceous.