普通地质学(英文)课件.ppt

1、SEDIMENTARY ARCHIVESSedimentary StructuresCross-bedding or Cross-stratificationSEDIMENTARY ARCHIVESSedimentary StructuresCross-bedding or Cross-stratificationBeds in which one set is inclined to othersAdvance of delta or dunesCurrent dominated environmentWind or waterSlope of cross-bed can indicates

2、 current or prevailing wind direction SEDIMENTARY ARCHIVESSedimentary StructuresCross-bedding or Cross-stratificationTabularorPlanarSEDIMENTARY ARCHIVESSedimentary StructuresSole marksSEDIMENTARY ARCHIVESSedimentary StructuresFlute castsSEDIMENTARY ARCHIVESSedimentary StructuresTool marksSEDIMENTARY

3、 ARCHIVESSedimentary StructuresFlame StructuresSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Which Way is UP?Load structuresSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Which Way is UP?MudcracksSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Wh

4、ich Way is UP?Planar Cross-bedsSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Which Way is UP?Trough Cross-bedsSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Which Way is UP?Oscillation ripplesSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Which

5、Way is UP?Tool marksSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Which Way is UP?FossilsSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Which Way is UP?FossilsSEDIMENTARY ARCHIVESSedimentary StructuresGeopetal Structures or Which Way is UP?Raindrop ImpressionsSED

6、IMENTARY ARCHIVESInterpretation of Sedimentary RocksProvide information about conditions in and near the site of depositionSuch as:source area from compositionamount of transport erosionQtz vs.Feldspar(clay and ironcompounds)vs FerromagnesiansImmature vs matureSEDIMENTARY ARCHIVESClassification of S

7、edimentary RocksSystems of classification are not hatracks,objectively presented to us by nature.They are dynamic theories developed to express particular views.Stephen Jay GouldSEDIMENTARY ARCHIVESClassification of Sedimentary RocksSEDIMENTARY ARCHIVESClassification of Sedimentary RocksSEDIMENTARY

8、ARCHIVESClassification of Sedimentary RocksTEXTURESEDIMENTARY ARCHIVESClassification of Sedimentary RocksSEDIMENTARY ARCHIVESClassification of Sedimentary RocksQuartz Arenite 90%Quartz Cement:silica calciteSEDIMENTARY ARCHIVESClassification of Sedimentary RocksFeldspathic AreniteArkose 25%Feldspar G

9、ranitic source Remainder is quartz Cement:clay calcite iron oxidesSEDIMENTARY ARCHIVESClassification of Sedimentary RocksLithic AreniteGreywacke 33%rock fragments Immature sandstone Poorly sorted,angular Remainder is quartz,feldspar Cement:very little mostly claysSEDIMENTARY ARCHIVESClassification o

10、f Sedimentary RocksCompositionCarbonate rocks consist of limestone and dolostone.The minerals present in each are:Limestone Calcite Aragonite Dolostone Dolomite SEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonatesSEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonatesMost of m

11、arine originDirectly or indirectly related to biological processesSkeletal remains may be visibleCan be evaporitesChanges in water temp.,alkalinity,CO2 conc.Clear,shallow tropical watersSEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonatesCharacteristics of most marine carbonate environm

12、ents:Warm water Tropical climate(30 N-30 S of equator)Shallow water(less than 200 m deep)Clear water(low to no terrigenous input)Sunlight required for photosynthesis by algaeSEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonatesSEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbon

13、atesOrigin of carbonate sedimentsMuch lime mud forms from the disintegration of calcareous algae(such as Halimeda and Penicillus).When the calcareous algae die,their skeletons break down and disintegrate producing aragonite needle muds.These lime muds lithify to form fine-grained limestone.SEDIMENTA

14、RY ARCHIVESSEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonatesFossiliferous limestoneBiomicriteBiospariteSEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonatesOolitic limestoneOomicriteOospariteSEDIMENTARY ARCHIVESClassification of Sedimentary RocksCarbonatesDolostoneCompose

15、d of dolomite(CaMg(CO3)2)The Dolomite“Problem”Dolomite is believed to form when magnesium that has been concentrated in sea water replaces calcium carbonate in a previously deposited limestone.Today,dolomite only forms in a few areas of the world where intense evaporation of seawater concentrates th

16、e magnesium.Extensive areas of carbonate rocks of Precambrian,Paleozoic,and Mesozoic age have been altered to dolomite.Dolomitization may be related to times of high sea level worldwide,under favorable climatic conditions.SEDIMENTARY ARCHIVESClassification of Sedimentary RocksClays,Mudrocks and Shal

17、esMudrocks are a very fine-grained Composed of clay and silt-sized particlesIf the mudrock is fissile it is a-shale Typically form in low energy environmentsSEDIMENTARY ARCHIVESSea Level ChangesEustatic Sea Level ChangeGlobal change in sea level positionCaused by:Glacial advance and retreatChange in

18、 spreading ratesEffect lowland areasSEDIMENTARY ARCHIVESSea Level ChangesSequence StratigraphyEpeiric seasSeas covered continentsProduced packages called sequencesLed to sequence stratigraphySEDIMENTARY ARCHIVESSea Level ChangesSequence StratigraphySequence StratigraphyA group of relatively conforma

19、ble strata that represents a cycle of deposition and is bounded by unconformities or correlative conformities.Sequences are the fundamental unit of interpretation in sequence stratigraphy.Sequences comprise systems tracts.SEDIMENTARY ARCHIVESSea Level ChangesSEDIMENTARY ARCHIVESSea Level ChangesVail

20、 CurveSequence StratigraphySEDIMENTARY ARCHIVESSea Level Changeshttp:/strata.geol.sc.edu/clastic-movie.htmlSEDIMENTARY ARCHIVESSea Level ChangesSequence StratigraphyTHE FOSSIL RECORDPaleontologyAttempts to understand all aspects of the successionof plants and animals over time.Based on study of foss

21、ilsArchaeopteryxTHE FOSSIL RECORDPaleontologyFossil PreservationCover this aspect in laboratoryFossilization fortuitousChances enhanced byHard partsRapid burialEnvironments Oceans,lakes and streamsTHE FOSSIL RECORDTaphonomyWhat happens to an organism from time of death to preservation as a fossilSof

22、t parts usually lostTHE FOSSIL RECORDThe Rank and Order of LifeBinomial nomenclatureA system of binomial nomenclature is used to name organisms.The first of the two names is the genus and the second name is the species.The genus and species names are underlined or italicized.The name of the genus is capitalized,but the name of the species is not.Examples:Felis domesticus,the house catFelis leo,the African lionFelis onca,the jaguarCanis familiaris,the dogHomo sapiens,the human