简介：BasedontheJointTyphoonWarningCenter(JTWC)best-trackdatasetbetween1965and2009andthecharacteristicparametersincludingtropicalcyclone(TC)position,intensity,pathlengthanddirection,amethodforobjectiveclassificationoftheNorthwesternPacifictropicalcyclonetracksisestablishedbyusingk-meansClustering.TheTClifespan,energy,activeseasonandlandfallprobabilityofsevenclustersoftropicalcyclonetracksarecomparativelyanalyzed.Thecharacteristicsoftheseparametersarequitedifferentamongdifferenttropicalcyclonetrackclusters.Fromthetrendofthepasttwodecades,thefrequencyofthewesternrecurvingcluster(accountingfor21.3%ofthetotal)increased,andthelifespanelongatedslightly,whichdiffersfromtheotherclusters.TheannualvariationofthePowerDissipationIndex(PDI)ofmostclustersmainlydependedontheTCintensityandfrequency.However,theannualvariationofthePDIinthenorthwesternmovingthenrecurvingclusterandthepelagicwest-northwestmovingclustermainlydependedonthefrequency.

简介：通过分析珠江口盆地惠州凹陷新近系珠江组NE—SW向平行于古岸线展布的K22条带状砂体外部地震反射特征、内部反射结构及平面展布规律,并运用层序地层学方法和理论,结合海平面变化特点,对K22条带状砂脊沉积成因进行了研究。结果显示：K22条带状砂脊为发育在陆架区古构造高带、受控于强制性海退过程的再沉积产物,其物源来自于早期的三角洲,沉积水动力条件多样,主要为海退过程中的潮汐流和波浪作用;同时,沿岸流也对砂脊形态的形成起到了关键作用,这些砂脊后期得益于快速的海侵而保留下来。留存下来的沙脊沉积被包裹在海相泥岩背景中,可形成良好的岩性圈闭。

简介：ThisstudyreportszirconU-PbandHfisotopesandwhole-rockelementaldataforgranodioritesfromtheEastKunlunorogen.ThezirconU-Pbdatingdefinestheircrystallizationageof235Ma.Therocksarecharacterizedbyhigh-Kcalc-alkaline,magnesianandmetaluminouswith（K2O+Na2O）=6.38wt.%–7.01wt.%,Mg#=42–50[Mg#=100×molarMg/（Mg+FeOT）],A/CNK=0.92–0.98,coupledwithhighεHf（t）valuesfrom-0.65to-1.80.Therockswerederivedfrompartialmeltingofajuvenilemaficcrustalsourcewithinnormalcrustthickness.Thejuvenilelowercrustwasgeneratedbymixinglithosphericmantle-derivedmelt（55%–60%）andsupracrustalmelt（40%–45%）duringtheseafloorsubduction.TogetherwithavailabledatafromtheEastKunlun,itisproposedthatthestudiedMiddleTriassicgranodioriteswereformedinpost-collisionalextensionsetting,inwhichmeltingofthejuvenilelowercrustinresponsetothebasalticmagmaunderplatingresultedintheproductionofhigh-Kgranodioriticmelts.