资源描述:
《辽宁弓长岭含铁岩系的形成与演化.docx》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、辽宁弓长岭含铁岩系的形成与演化TheGongchanglingirondepositisLocatedintheAnshan-Benxiarea,Liaoningprovince,beingfamousforitsAnshan-typeironore(bandedironore),andspeciallyforitshigh-gradeironore.Theiron-bearingrockseries,occurringinthe"granitesea"inthefromofLargeresidualinclusions,showsageneralstructural
2、styleofanticlinoriumandhasamarginalmigmatizationcontactrelationshipwiththegraniteofc.2.5Ga.Thesyntheticsectionoftherockseries.withatotalthicknessof500-800m.givesthefollowingstratigraphicsequencefromoldtoyoung(inassendingorder):leucoleptyniticrockformation,hornblendicrockformation,andiron-bea
3、ringrockformationinthelowerpart,keybedconsistingofbiotiteleptyniteandgarnet-mica-quartzschistinthemiddle,iron-bearing,rockformation,andleucoleptyniticrockformationintheupper.Thereareaseriesofresidualsedimentarystructuresinthebiotitelephtyniteofthekeybed,includingthethininterbeddingofquartzma
4、gnetitepoorareandthebiotiteleptynite.Soitisclearthattheoriginalrocksoftheleptynitewereformedbysedimentation.Thebiotiteleptyniteandgarnet-mica-quartzschistoccurinthesamelayer,butgeochemicalandzirconresearchesindicatethattheiroriginalrockscamefromdifferentsources,theformerfromintermediate-acid
5、volcanicrockswithoutstronglyweathering,whilethelatterfromcontinentalcrustmaterialwithstronglyweathering.Therearetwokindsofplagioclaseintheiron-bearingrockseries,oneofthemisthelowerplagioclaseamphiboliteoccurringinthelowhornblendicrockformation,whichhasgenerallylayered,lamellarandbandedstruct
6、ures,withsomewhatlargechangeintheirmineralkindsandproportion.Somedetritalzirconsandmicrosopherulesarediscoveredinartificialheavyconcentrates.Henceitcanbeconcludedthattheoriginalrocksofthelowerplagioclaseamphibolitearemainlybasaltictuffs,taffiteandtuffaceoussedimentaryrocks.Geochemically,thel
7、owerplagioclaseamphiboliteisrelativelyhighinSiO2andlowinFeO,andexhibitsREEpatternsofslightenrichmentinLREEandnegativeEuanomaly,butwithoutthetrendoflineardistributionbetweeninactiveincompatibleelements.Thechemicalcharacteristicsareonthewh