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1、内蒙古苏尼特左旗地区岩脉群的地球动力学意义ABSTRACTSonidzuoqiinthenorth-centralofInnerMongolia,itbelongstotheInnerMongolia-DaHingganMountainsorogenicbeltoftheeasternsegmentofthecentralAsianorogenicbelt.Thestudyareaislocatedintheerlian-hegenshanarcaccretionarybelt.ThisbeltextendstoNEE,itssouthernborderiser
2、lian-hegenshanfaultzoneanditsnorthernborderischaganaobao-arongqifaultzone.IntensivedikeswarmsdevelopinginthisareaintrudeinthesandstoneandconglomerateofniqiuhegroupofDevonianandthelatePaleozoicmagmaticrocks,likethevolcanicrockofboligaomiaogroupofcarboniferous,carboniferousgranodiorite
3、,carboniferousmonzoniticgranite.Dikeswarmstypesaremainlyacidicgraniteporphyrydikeandrhyoliticdike,andincludeasmallamountofdioriteporphyrydikes.Becauseofitssmallnumberandlittleresearchsignificance,wewillnotresearchitinthispaper.ThroughtheLA-ICP-MSmethodmeasuredthezirconsofgraniteporph
4、yryU-Pbharmonicagewas289.2±2.8Ma,zirconofrhyoliteU-Pbharmonicagewas282.4±7.4Ma,whichcandeterminethatthedikesinteudedinthiserainearlyPermian.Theseagesconformtothethegeologicalfacts.Dikeswarmsparalleltoeachother,theirdirectionsisconsistentwithregionaltectoniclineasNNE.Onthelandscape,mo
5、stofthedikes’typeisans,partofthedikesarecutbytheNNEfaults.Becauseofhavingstrongweatheringresistance,theyhaveobviousdifferenceofweatheringwithsurroundingrocks,theybecameridgeandremotesensingimagedisplaysasdenseribbons.Theintervalofadjacentdikeismainlyconcentratedin70-100meters,themini
6、mumconcentrationareasisabout10-20meters.Asingledikeexposeduptoseveralkilometersinlength,20-30metersinwidth,theirdirectionsbetween75°-90°andtheiroccurrenceisnearlyvertical.Bothofthegraniteporphyrydikeandrhyoliticdikeareporphyriticstructure.Graniteporphyry’phenocrystsaremainlypotassium
7、feldsparandquartzandlittleplagioclase.Rhyolitic’phenocrystarequartzandasmallamountoffeldspar,anditdevelopesflowlinesstructureandspheroliticstructure.Thegraniteporphyrydikeandtherhyoliticdikehavethesimilarrockgeochemistrycharacteristics.Theyhaverichsilicon,richalkali,highaluminumandlo
8、wcalcium,att
