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2003年  14卷  第1期

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From Flysch to Molasse—Sedimentary and Tectonic Evolution of Late Caledonian~Early Hercynian Foreland Basin in North Qilian Mountains
Du Yuansheng, Wang Jiasheng, Han Xin, Shi G R
2003, 5(1).
摘要:
TheLateCaledoniantoEarlyHercynianNorthQilianorogenicbeltinnorthwesternChinaisanelongatetectonicunitsituatedbetweentheNorthChinaplateinthenorthandtheQaidamplateinthesouth.NorthQilianstartedinthelatestProterozoictoCambrianasariftbasinonthesouthernmarginofNorthChina,andevolvedlatertoanarchipelagicoceanandactivecontinentalmarginduringtheOrdovicianandaforelandbasinfromSiluriantotheEarlyandMiddleDevonian.TheEarlySilurianflyschandsubmarinealluvialfan,theMiddletoLateSilurianshallowmarinetotidalflatdepositsandtheEarlyandMiddleDevonianterrestrialmolassearedevelopedalongthecorridorNanshan.Theshallowing~upwardsuccessionfromsubabyssalflysch,shallowmarine,tidalflattoterrestrialmolasseanditsgraduallynarrowedregionaldistributiondemonstratethattheforelandbasinexperiencedthetransitionfromflyschstagetomolassestageduringtheSilurianandDevoniantime.
Characteristics of Bacillus cereus Spore Counts in Soils with Underlying Gold Mineralization in Northwestern Sichuan, China: Results from a Pilot Study
Wang Hongmei, Yang Fengqing, Qiao Shengying
2003, 5(1).
摘要:
A pilot survey on a microbial mineral exploration method based on soil Bacillus cereus spore counts was carried out across three different gold mining regions, which vary in soil type, climate condition and geological setting in northwestern Sichuan, China. B horizon soils from these sites were analyzed for B. cereus spores, Au, Ag, Cu, Pb and Zn. The results show that the numbers of B. cereus spores generally increased in soils overlying gold mineralization. Specifically, elevated spore counts were found in samples slightly offset from the outcrops of orebodies, whereas soils directly above the outcrops of orebodies usually contained low spore counts. However, the background counts of B. cereus spores varied from place to place and were complicated by environmental and pedological factors, but the relative ratios of spore counts still were indicative of the underlying gold mineralization.
Tectonic Affinity, T~t Path and Uplift Trajectory of Eclogites from Northern Dabie Mountains, Central~Eastern China
Liu Yican, Xu Shutong, Li Shuguang, Jiang Laili, Chen Guanbao, Wu Weiping
2003, 5(1).
摘要:
Petrologic geochemistry and isotopic chronology of the eclogites suggest that most of the eclogites in northern Dabie Mountains produced from the Triassic Yangtze subducted continental crust (lower crust and formed during the deep subduction) and the metamorphosed mafic~untramafic belt with eclogite, marble and meta~peridotite blocks around the Mozitan~Xiaotian fault zone may represent the meta~tectonic melange produced during the active subduction of an ancient oceanic slab and subsequent collision between the Yangtze and North China continental plates. The cooling history of the eclogites from ~900 ℃ to 300 ℃ can be subdivided into three stages: one isothermal stage and two rapid cooling stages. The initial stage between (230 ± 6) and 210 Ma was a near~isothermal or temperature rise process corresponding to the retrograded metamorphism of granulite~facies with a rapid uplift of 4 mm/a, then two fast cooling stages occurred with cooling rate of ~10 ℃/Ma during 210 Ma to (172 ± 3) Ma and ~4 ℃/Ma during (172 ± 3) Ma to 130 Ma. After the peak metamorphism of eclogite~facies, their initial isothermal stage with slower uplift rate and cooling rate and high~T overprinting of granulite~facies metamorphism is the major difference between the eclogites in northern Dabie Mountains from those in southern Dabie Mountains. This may be one of the most important reasons to preserve few evidences of earlier ultrahigh~pressure metamorphism.
K~ and Si~Metasomatism, Mineral Transformation and Formation of Granitoids from Basic Rocks in Qooshchi Area, NW Iran: A Mineralogical Context
Pouran Behnia, Lorence G Collins, Bahram A Samani
2003, 5(1).
摘要:
TheQooshchiarealiestonorthwestofOrumiehLakeinwesternAzerbaijan,NWIran.Abasementmetamorphiccomplex,consistingofPrecambrianschistsandgneisses,hasbeenintrudedbygabbrosanddiorites.Granitoidsaregroupedintofivesuitesaccordingtotheirmineralogy,textureandexposedfeatures.Themainbody,pinkQooshchigranite,andapophyse~like,myrmekite~bearinggranitoidsarediscussedinthispaper.Onthebasisoffieldobservationsandmicroscopicstudies,anintensivemetasomatismhasoverprintedthecountryrocks,especiallygabbros,transformingthemintoamorefelsiccomposition.Aprioreventofintensivedeformationandcataclasisprecededthemetasomatism,allowingtheintroductionofhydrothermalfluids.K~metasomatismconvertedplagioclaseintoK~feldspar(microcline),myrmekite,andsodicplagioclaseasSi~metasomatismreplacedtheferromagnesiansilicatesbyquartz.Apophyse~likebodieswithingabbros,calledleucometasomatites,areformedduringthisprocess.
Crust~Mantle Structure and Coupling Effects on Mineralization: An Example from Jiaodong Gold Ore Deposits Concentrating Area, China
Yang Liqiang, Deng Jun, Zhang Zhongjie, Wang Guangjie, Wang Jianping
2003, 5(1).
摘要:
Based on the results of two~dimension velocity structure, 1 ∶ 100 000 aeromagnetic anomaly, 1 : 200 000 bouguer gravity anomaly and seismic anisotropy of Jiaodong and neighboring region in Shandong, China, the information of geophysical field was divided into two parts: deep~ and shallow~focus fields. And then, the information of two different fields was combined with that of deep~seated geology and ore deposit features. The synthetic result was adopted to analyze three~dimension structure, to probe into crust~mantle coupling effects of mineralization and dynamics of ore formation system.
Improved Geological Interpretation Using Landsat TM Data in Lancang Jinghong Area, Yunnan Province, China
Bassam F Al Bassam
2003, 5(1).
摘要:
LandsatTMdigitalspectraldataofLancang~Jinghongarea(YunnanProvince)hasbeenusedforthepurposeofgeologicalinterpretation.Tomeetthisobject,differentimageprocessingtechniquesincludingselectedbandcolorcomposites,principalcomponentanalysisandIHSdecorrelationstretchingareusedtoimprovethediscriminationofdifferentlithologicalandstructuralfeaturesinthearea.ItwasfoundthatIHSdecorrelationstretchingimagesobtainedfromthetransformationoffalsecolorcomposite741(inred,greenandblue)providedthebestresultsbasedontheoriginaldata.Bycombiningthecharacteristicsofimagesproducedbydifferentapproachesandothercanonicallytransformedimageswithavailablegeologicaldataandsurfaceobservations,thegeologicalinterpretationcouldbedonewithsatisfactorydegreeofaccuracy.
Evaluation of Sand Dunes Stabilization Techniques in Baiji District, Iraq
Ayad Mohammed Fadhil
2003, 5(1).
摘要:
ThisresearchwasconductedatthesanddunesstabilizationresearchstationinBaijidistrict,Iraq.Threetechniquesforsanddunesstabilizationareselected:thefirstmethodisstabilizationbyclayeyblockbarriers;thesecondmethodisstabilizationbydryplantingoftamarix(tamarixarticulata)cuttingsandthethirdisstabilizationbyusingcanebranchbarriers.Randomizedsamplesweretakenfromthesurfaceandsubsurfacelayersofthestabilizedandshiftingsanddunestoevaluatetheeffectofthethreetechniquesonwinderosionparameters.Theresultsindicatehighsignificantdifferencesbetweenthewinderosionparametersinthesurfaceandsubsurfacelayersinthestabilizedsanddunes,whilethereareinsignificantdifferencesbetweenthesubsurfacelayerofthestabilizeddunesandthesurfaceandsubsurfacelayersintheactivesanddunes.Theresultsclarifythefactthatthereisanincreaseinthepercentageofclay,silt,organicmatter,meanweightdiameterandthepercentageofthedryaggregates(>0.84mm).Adecreaseisfoundintherateofdisaggregationforthedryaggregatesinthesamplesofthesurfacelayerofstabilizedduneswhencomparedwiththesubsurfacelayerofstabilizeddunesandthesurfacelayeroftheshiftingsanddunes.Thereisapositivehighsignificantcorrelationamongtheaggregatestabilityparametersandthepercentageofclayandsilt,andthecontentoforganicmatterinthestudiedlayers.
Regional Fault Systems of Qaidam Basin and Adjacent Orogenic Belts
Tang Liangjie, Jin Zhijun, Dai Junsheng, Zhang Mingli, Zhang Bingshan
2003, 5(1).
摘要:
ThepurposeofthispaperistoanalyzetheregionalfaultsystemsofQaidambasinandadjacentorogenicbelts.FieldinvestigationandseismicinterpretationindicatethatfiveregionalfaultsystemsoccurredintheQaidamandadjacentmountainbelts,controllingthedevelopmentandevolutionoftheQaidambasin.Thesefaultsystemsare:(1)northQaidam~QilianMountainfaultsystem;(2)southQaidam~EastKunlunMountainfaultsystem;(3)Altunstrike~slipfaultsystem;(4)Elashanstrike~slipfaultsystem,and(5)Gansen~Xiaochaidanfaultsystem.ItisindicatedthatthefaultsystemscontrolledtheorientationoftheQaidambasin,theformationanddistributionofsecondaryfaultswithinthebasin,themigrationofdepocentersandthedistributionofhydrocarbonaccumulationbelt.
Technology and Its Application: MIS with Geographical Information
Chen Wenming, Qi Huan
2003, 5(1).
摘要:
DespitetheconstantexpansionoftheapplicationofGIS,inrecentyears,thedataprocessingabilityoftheapplicationsystemdevelopedwithGIS_Toolisquitelimited.Managementinformationsystemwiththegeographicalinformationcannotonlybeusedtodealwithdatacommonly,butalsodealwithdigitizedmapsasGIS_Tooldoes.Thusitcanhelptheuserdevelopanapplicationsystemhighqualifiedbothinmapsandtraditionaldata.Thispaper,bytakingthemethodofintegratedMapInfointheapplicationofVisualBasicasanexample,mainlyillustratestwotechnologicalproblems~integratedmaptechnologyandthemultiuserizationofMapInfogeographicalinformation.Andalsotheconcretesolutionstotheproblemsareprovided.