An unusual paleokarst sedimentary rock in the Bohemian Karst (Czech Republic), and its regional tectonic and geomorphologic relationships

Bulletin of geosciences

Bosák P¹  Žák K¹  Å lechta S¹  Pruner P¹  Svobodová M¹ 

关键词: Prague Synform;    paleokarst sedimentary rocks;    Triassic;    paleomagnetic study;    C and O stable isotopes;    plant microfossils;   

DOI  :  

来源: Czech Geological Survey

【 摘 要 】

AnunusualtypeofpaleokarstcarbonatesedimentaryrockhasbeenfoundintheBohemianKarst,CzechRepublic.Thiswell-layeredcoarse-crystallinelimestoneisreddishincolorandoccursashorizontalorslightlyinclinedlayersfillingdeeppaleokarstcavitieswithinkarstifiedfaultsinEarlyDevonianmarine-limestonehostrocks.FieldobservationsconfirmthatthesesedimentaryrocksareundoubtedlyyoungerthanthepolyphasedVariscanfolding.PetrographicandgeochemicalstudiesindicatethatthestudiedpaleokarstlimestoneisquitedifferentfromtheSilurianandDevonianlimestones,fromcommoncavespeleothems,aswellasfromthetypicalclasticLateCretaceousandCenozoickarstsedimentsoftheBohemianKarst.Carbonatedelta;13Canddelta;18Ostableisotopicratiosofthepaleokarstlimestone(delta;13Cfrom-4.0to-6.2‰,delta;18Ofrom-6.2to-8.4‰PDB),differingbothfrommarineSilurianandDevonianlimestonesandCenozoicsecondarycavecarbonatesofthearea,correspondtoanon-marinedepositionalenvironment.ThepaleomagneticdatasuggestthatmagneticpropertiesofthestudiedrockswereacquiredduringtheEarlytoMiddleTriassic,althoughtheseageshavenotyetbeenconfirmedbyfindsofcontemporaneousmicrofossils.TheonlymicrofossilsthatwereextractedusingdissolutionmethodsconsistofseveralyoungerplantandfaunalremainsincludingangiospermpollengrainspecimensbelongingtothefamilyMyricaceae,likelyTertiaryinage.Theirsporadicoccurrenceisinterpretedastheresultofsecondaryinfiltrationsintothemillimeter-widecracksandcavities,incorrespondencewiththethin-sectiondataondiageneticsuccessions.

【 授权许可】

Unknown