简介:AccordingtoVeningMeinesz-Moritz(VMM)globalinverseisostaticproblem,eithertheMohodensitycontrast(crust-mantledensitycontrast)ortheMohogeometrycanbeestimatedbysolvinganon-linearFredholmintegralequationofthefirstkind.HeresolutionstothetwoMohoparametersarepresentedbycombiningtheglobalgeopotentialmodel(GOCO-03S),topography(DTM2006)andaseismiccrustmodel,thelatterbeingtherecentdigitalglobalcrustalmodel(CRUST1.0)witharesolutionof1o×1o.ThenumericalresultsshowthattheestimatedMohodensitycontrastvariesfrom21to637kg/m3,withaglobalaverageof321kg/m3,andtheestimatedMohodepthvariesfrom6to86kmwithaglobalaverageof24km.ComparingtheMohodensitycontrastsestimatedusingourleastsquaresmethodandthosederivedbytheCRUST1.0,CRUST2.0,andPREMmodelsshowsthatourestimateagreesfairlywellwithCRUST1.0modelandratherpoorwithothermodels.TheestimatedMohodepthsbyourleast-squaresmethodandtheCRUST1.0modelagreeto4.8kminRMSandwiththeGEMMA1.0basedmodelto6.3km.
简介:KarstrocksfromtheHuanglongFormationexposedatthemarginoftheEasternSichuanBasincanbedividedintofourtypes:slightlycorroded,moderatelycorrodedporous,intenselycorrodedbrecciatedandintenselycorrodedandreplacedsecondarycalcickarsticrocks.Thecarbon,oxygenandstrontiumisotopecompositionsofthevariouskarstrocksareanalyzedsystematicallyandcomparedtorockswithoutkarstcorrosion.Theresultsindicatethat(1)theHuanglongFormationintheeasternSichuanBasinwasarestrictedbaysuppliedandcontrolledbyfreshwaterinwhichmudmicriteandmud-dolomicriteexhibitlowδ13Candδ18Ovaluesandhigh87Sr/86Srratios;(2)alltypesofkarsticrocksinthepaleokarstreservoirsoftheHuanglongFormationintheresearchareaareaffectedbyatmosphericfreshwaterwiththeδ13Candδ18Ovaluesand87Sr/86Srratiosintheoriginalformationapproachingthoseofatmosphericfreshwater,whichreflectsancienthydrologicalconditions,fluidproperties,isotopicsourceandthefractionationeffect;(3)theintenselycorrodedandreplacedsecondarylimestoneisaffectedbyavarietyofdiageneticfluids,oftenreflectedbyδ13Candδ18Ovalues,whilethe87Sr/86Srratiosexhibitthestrongdegreeofthecorrosion;(4)aftercomparingthe87Sr/86Srratiosofeachtypeofkarstrock,thediageneticfluidsaredeterminedtobemainlyatmosphericfreshwater,anddependingonthestrengthofcorrosion,andthelow87Sr/86Srratiofluidsinthelayerwillparticipateinthekarstprocess.Thecarbon,oxygen,andstrontiumisotopesofdifferentkarsticreservoirscanprovidemeaningfulgeochemicalinformationforforecastingandevaluatingthedevelopmentanddistributionrulesoftheHuanglongFormationatthemarginoftheeasternSichuanBasinintimeandspace.更多还原
简介:<正>1IntroductionTheundergroundbrineresourcesdistributingwidelyinSichuanBasin,Chinahavedrawnworldwideattentionduetotheirunusualelementabundanceandexcellentquality.