Geodiversitas | |
The contribution of calcareous green algae to the production of limestones: a review | |
Bruno Granier1  | |
关键词: Dasycladales; Bryopsidales; Halimeda; bioherm; euphotic zone; phylloid; aragonite; calcite; porosity; epigenesis; cementation; Dasycladales; Bryopsidales; Halimeda; bioherme; zone euphotique; phylloïde; aragonite; calcite; porosité; épigenèse; cimentation; | |
DOI : 10.5252/g2012n1a3 | |
学科分类:生物科学(综合) | |
来源: Museum National d Histoire Naturelle | |
【 摘 要 】
Calcareousgreenalgae(CGA)areanartificiallyunitedbuthighlyheterogeneousgroupoflargeunicellularbenthicalgaewithonecharacterincommon:allhavethecapabilityofsecretingacalcareouscoatingontheoutersideofthecytoplasmicenvelope.Today,theyareamajorcontributortocarbonatesedimentationatallscalesfromclay-sizedparticles(aragoniticneedles)tocoarsergrains(sandandgravel)andeventoplurimetricsedimentarystructures.Therearefossilanaloguestothefeatureslistedabove.PhycologistsknowbestHalimeda,Penicillus,AcetabulariaandCymopolia;micropaleontologistsandcarbonatesedimentologistsaremostknowledgeableaboutAcicularia,Clypeina,Neoteutloporella,Salpingoporella,Anthracoporella,Boueina,andEugonophyllum.TheCaCO3precipitatedtoformthecoatingisgenerallyaragonite(theorthorhombicform)butthereareshortperiodsinthegeologicrecordduringwhichitscalcitevariant(therhombohedricform)existedcontemporaneouslyindiscretespecies.RecentstudiesonHalimedahaveshownthatsomeoftheBryopsidaleshavethecapabilitytocalcifystronglyinthelowerportionoftheeuphoticzone(whererespirationbecomesmoreimportantthanphotosynthesisintheprocessofmineralization)andtoproducepositivesedimentaryreliefs(bioherms)insitubelowthefair-weatherwavebase.PreviousmodelsofpaleoenvironmentsconsideredthepresenceofDasycladalesorBryopsidalestoindicateshallow-water,thatistheuppereuphoticzone(fromtheseasurfacedownto-25m),andpredominantlylow-energy,protected,lagoonalenvironments.Whenthealgalremainswerefoundingrain-supportedfacies,theyweretakentohavebeensubjectedtodynamictransportandthereforeindicativeofhigh-energyenvironmentsofdeposition.Thenewdeeper-waterfindshavechangedinterpretationsoftheenvironmentsascribedfossilalgae.AcurrentconceptionisthatancestralinarticulatedBryopsidalescouldhavegrownatdepthsasgreatas-120m(nearthebaseofthelowereuphoticzone).Thispreliminaryreviewconcludeswithsuggestionsaboutfieldsforcontinuinginvestigations.
【 授权许可】
Unknown
【 预 览 】
Files | Size | Format | View |
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RO201912090770075ZK.pdf | 157KB | download |