
anoxic ghatana

mahasagariy anoxic ghatana kinwa anoxic ghatana (anoxia sthitee) asha kalkhandanche varnan karatat jyat pruthvichya mahasagarancha motha vistar vighatit auxigen (oo2) neey qamee jhaala hota, jyamule vishari, auxinic (anoxic aanee sulphidic) paanee tayar jhaale hote. jaree lakho varshanpasun anaxic ghatana ghadalya nasalya taree bhoogarbhiy nondi darshavtat qee tyaa bhootkalat anek vela ghadalya aahet. anaxic ghatana anek mothya pramanat vilupta honyashi julalya aanee tyanni tyat yogdan dile asave. yaa samoohik vilupta honyanmadhye kahee goshtincha samavesh aahe, jyacha vapar bhoo-jivashastradnya biostrategraphic dettingmadhe vel chinhak mhanoon karatat. dusarikade, madhya-cretatiuspasoon vyapak, vividh black-shale bedd aahet jeey anoxic ghatana darshavtat parantu mothya pramanat vilupta honyashi sambandhit naheet. anek bhoogarbhshastradnyanche asey mutt aahe qee mahasagariy anoxic ghatana mahasagarache paribhraman mandavane, havamanatil tapmanwadh aanee haritgruh vayunchya vadhiv patalishi drudhpane jodalelya aahet. sanshodhakanni yuksiniyasathi kendriya bahya trigger mhanoon vardhit jwalamukhi (carbon dioxideche prakashan) prastavit kele aahe."
british samudrashastradnya aanee vatavaraniy shastradnya, andreau watson yanni spasht kele qee, holocene yugat bhootkalatil anoxic ghatananmadhye yogdan denanya anek prakriyanchi aathvan karoon denanya anek prakriya disun aalya, tarr purn pramanat sagari anoxia vikasit honyas hajaro varshe lagtil."aadhunik hawaman badalamule asha ghatana ghadu shakatat yaa kalpanela kumpache gruhitak asehi mhanatat, tathapi, purave ajunahi gahal aahet.
parshvabhoomi.
sagari anoxic event (oae) chee sankalpana pratham 1976 madhye semore schlanger (1927-1990) aanee bhoogarbhshastradnya hyoog jenkins yanni prastavit kelee hotee aanee tee prashant mahasagaratil khol samudratil drilling prakalpane (dii. ess. dii. pii.) kelelya shodhanmadhun udbhavali hotee. panbudichya jwalamukhichya patharanvar jamaa jhalelya cretaceous galanmadhye kalya, karbanyukt shelscha shodh (udaa.jee. shatsky uday, manihiki pathar), tyanchya samaan vayasah, atlantic mahasagaratil korad sathe aanee europemadhil dnyat baher padananya bhagansah-visheshtah italitil chunkhadi-varchasva asalelya appenines sakhalichya bhoogarbhiy nondinmadhye-heey nirikshan jhaale qee yaa vyapak, ashach prakare bhinn staranni bhoogarbhiy kalachya anek swatantra kalkhandat pasarlelya jagatil mahasagaranmadhye atishay asamanya, auxigen-qamee jhalelya paristhitichi nond kelee.
aajahi suru asalelya yaa sendriya-samruddha galanchya galshastriy tapasanit samanyatah talashi rahana pranyandvare viina adthala sookshm starankachi upasthiti disun yete, jee samudraspativaril anoxic paristhiti darshavate jee hydrogen sulphide, etch2esachya khalchya vishari tharasobat julate asey manale jaate. yavyatirikt, tapshilvar sendriya bhoo-rasayanik abhyasanni alikadech jambhalya sulfurche jivanu aanee hiravya sulfurche jivanu yaa donhipasoon tayar jhalelya renunchi (tathakathit biomarkers) upasthiti ughad kelee aahe-jyaa jivanna prakash aanee mukt hydrogen sulphide (etch 2 ess) donhichi aavashyakta asate, heey darshavate qee photic varchya panyachya stambhat anoxic paristhiti jaast vistarli aahe.
pruthvivaril anek thikani sthanik patalivar anoxiachi vaishishtye disun yetat, jase qee shaiwal/jivanu phule aanee sthanik 'mrut kshetra'."amerikechya purv kinadhyalagatchya chesapik upasagarat tasech scandinavian samudradhuni, kaale samudra (joou sahasrabdipasun tyachya sarvat khol staravar anaxic asoo shakato), uttar adriaticmadhye tasech louisianachya kinadhyalagatchya mrut kshetrat mrut kshetre astitvat aahet. jagbharat jelifishchi sadhyachi vaadh hii kadhikadhi anoxic ghatanechi pahili halchal manali jaate. dakshin america, chean, japan aanee newzealandchya kinarpattichya panyat itar sagari mrut kshetre disu lagali aahet. 2008 salchya abhyasat jagbharatil 405 mrut kshetranche dastaivajikaran karnyat aale.
hii alikadachi samaj aahe, gelya teen dashakanmadhye heey kode haloohaloo ekatra kele gele aahe. mojkya dnyat aanee sanshayaspad anaxic ghatana bhuvaidnyanik nondinmadhye kalya shelchya jagbharatil bandmadhye jagatil teel sathyanchya mothya pramanat utpadanashi bhaugolikdrushtya jodalya gelya aahet.
euxinia.
euxynic (anoxic, sulphidic) paristhiti asalelya anoxic ghatana jwalamukhichya baherchya vayuchya tivra ghatananshi jodalya gelya aahet. jwalamukhimule vatavaranatil carbon dioxidechi nirmiti jhaali aanee jaagtik tapmanat vaadh jhaali, jyamule jalshastriy chakrat vaadh jhaali jyamule mahasagaranmadhye poshak tatvancha pravesh jhaala (planktonic utpadaktela uttejan). yaa prakriyanni pratibandhit khonyanmadhye yuksiniyasathi sambhavyapane eka prerak mhanoon kaam kele jethe jaal-stambh starikaran vikasit houu shakate. anoxic teey euxynic paristhitit, sagari phosphet galat tikavoon thewale jaat nahee aanee tyamule mukt kele jaau shakate aanee punarnavinikaran kele jaau shakate, jyamule satat uchch utpadaktela madat hote.
yantrana.
jurassic aanee cretaceous darmyanche tapman samanyatah tulanene ubdar asalyache manale jaate aanee parinami mahasagarat virghalaleli oxygenchi patali aajchya tulanet qamee hotee-jyamule anoxia sadhya karane sope hote. tathapi, alpakalin (daha laakh varshanpeksha qamee) sagari anoxic ghatananche spashtikaran denyasathi adhik vishisht paristhiti aavashyak aahet. done gruhitak aanee tyanvaril badal heey sarvat tikau siddha jhaale aahet.
eka gruhitak asey suchavate qee sendriya padarthanche visangati sanchay pratibandhit aanee kharab oxygenyukt paristhitit tyachya vadhiv sanrakshanashi sambandhit aahe, jeey swatach mahasagarachya khonyachya vishisht bhoomitiche karya hoteh asey gruhitak, jaree tarun aanee tulanene arund cretaceous atalantikala sahaj lagoo hote (jyachi tulana mothya pramanavaril kalya samudrashi kelee jaau shakate, jee keval jaagtik mahasagarashi kharabaritya jodaleli aahe), jagbharatil khulya mahasagaratil prashant patharanvar aanee shelf samudranvar saha-moolyankan kalya shelchya ghataneche spashtikaran denyat ayashasvi hote. punha atalantikmadhun asey suchavale jaate qee mahasagarachya parisancharanatil badal jababdar hota, jethe qamee akshanshavaril ubdar, kharat paanee atisardra jhaale aanee budun, kholivar, tapmanasah madhyavarti thurr tayar jhaala.
dusare gruhitak asey suchavate qee sagari anoxic ghatananmadhye mahasagaranchya supikatemadhye motha badal nondavala jaato, jyamule cocolith aanee foraminifera sarkhya calcorius planktonchya kimmatit sendriya-bhinti asalelya planktonmadhye (jivanunsah) vaadh hote. sendriya padarthanchya asha vegwan pravahane oxygenchya kiman kshetracha vistar keela asata aanee tivra kele asate, jyamule gaal nondinmadhye pravesh karananya sendriya carbonche praman aanakhi vadhale asate. moolatah hii yantrana mahasagaranchya prajjvalit tharanmadhye rahana phytoplankton loksankhyesathi nitrate, phosphet aanee bahudha loh yasarkhya virghalalelya poshak tattvanchya upalabdhatet mothee vaadh manate.
ashee vaadh honyasathi jaminitun milananya poshak tattvancha vegwan ogh aanee jordar vaadh aavashyak hotee, jyasathi jaagtik staravar mothya hawaman badalachi aavashyakta hotee. carbonate gaal aanee jivashmanmadhil auxigen-isotope gunottar aanee jivashmanmadhil magneshiyam/calcium gunottaratil bhoo-rasayanik mahitee asey soochit karate qee serve pramukh sagari anoxic ghatana aushnik kamalateshi sambandhit hotya, jyamule yaa antaradarmyan jaagtik hawaman darr aanee mahasagaranmadhye poshak dravyancha pravah vadhanyachi shakyata aahe. kharokhar, oxygenchi vidravyata qamee jhalyamule phosphateche prakashan hoil, jyamule samudrala aanakhi poshan milel aanee uchch utpadaktela chalana milel, tyamule oxygenchi uchch magani-sakaratmak pratisadachya madhyamatoon ghatana tikavoon raheel.
anoxic ghatananche spashtikaran denyacha aanakhi eka marg mhanje tivra jwalamukhichya kalavadhit pruthvi mothya pramanat carbon dye auxide sodate; haritgruh prabhavamule jaagtik tapmanat vaadh; jaagtik hawaman darr aanee pravahatil poshak pravahat vaadh; mahasagaranmadhye sendriya utpadakta vadhate; mahasagaranmadhye sendriya-carbon daphan vadhate (oae suru hote); sendriya padarth daphan jhalyamule aanee silicate khadakanche hawaman (ulat haritgruh parinam) yaa donhimule carbon dye auxide khalee odhala jaato; jaagtik tapmanat ghat hote aanee mahasagar-vatavaran pranali samatolakade (oae sampate) parat yete.
asha prakare, mahasagaratil anoxic ghatanekade vatavaran aanee jalkshetrat atirikt carbon dioxidechya injectionla pruthvicha pratisad mhanoon pahile jaau shakate. yaa kalpanechi eka chachani mhanje mothya agnimay prantanche (othanche) vay pahane, jyache baher kadhane bahudha carbon dioxidesarkhya mothya pramanat jwalamukhijanya vayunchya jalad utsarjanasah jhaale asave. teen othanche vay (karoo-ferrer flood besault, caribeancha motha agnikund prant, ontong jaava pathar) pramukh jurassic (prarambhik tarcian) aanee cretaceous (prarambhik aptian aanee senomanian-turonian) sagari anoxic ghatananshi changle sambandhit aahe, jeey soochit karate qee eka karanatmak sambandh vyavharya aahe.
ghatana.
mahasagaratil anoxic ghatana samanyatah atishay ubdar havamanachya kalat ghadatat, jyache vaishishtya carbon dioxidechi (see. oo. 2) uchch patali aanee prushthbhagache sarasari tapman bahudha tyapeksha jaast asate. sadhyacha kalavadhi, mhanje chaturthansh patali, fakt tulanene aahe. carbon dioxidemadhye ashee vaadh hii atyant jwalansheel naisargik vayoo (mithen) chya mothya vayoo baher padnyachya pratisadat jhaali asavi jyala kahijan "sagari burp" mhanatat. mithen hydratechya sanyugancha samavesh asalelya anek sathyanpaiki eka, barfapramane mithen aanee panyache ghan avkshepit sanyojan asalelya khandiy patharachya pruthvichya kavachat mothya pramanat mithen samanyatah bandist asato. thund tapman aanee uchch (khol) daab vagalata mithen hydrates asthir asalyamule, shastradnyanni vivartanik ghatananmule baheroon baher padnyachya chhotya ghatana pahilya aahet. naisargik vayuche prachand utsarjan heey havamanshastriy eka pramukh uddisht asoo shakate asey abhyas suchavatat, mithen haah swatah carbon dioxidepeksha kityek patine adhik shaktishali haritgruh vayoo aahe. tathapi, hirnantian (usheera ordovician) himayugadarmyan dekhil anoxia mothya pramanat hota.
sagari anoxic ghatana pramukhyane aadhich ubdar cretaceous aanee jurassic kalkhandatun olakhalya gelya aahet, jevha asankhya udaharane nondavali gelee aahet, parantu aadhichya udaharane tricic, permian, devonian (kelvasor ghatana), ordovician aanee cambrian yaa uttaradhat ghadalyache suchavale gele aahe.
paleocene-eocene aushnik kamal (pii. eae. tii. emm.), jyache vaishishtya tapmanat jaagtik vaadh aanee kahee shelf samudranmadhye sendriya-samruddha shalesche sathavan hote, teey sagari anoxic ghatananshi anek samya darshavate.
samanyatah, sampoorn punarprapti honyapurvi sagari anoxic ghatana daha laakh varshanpeksha qamee kaal tikalya.
parinam.
sagari anoxic ghatananche anek mahattvache parinam jhaale aahet. asey manale jaate qee paleozoic aanee mesozoic yaa donhi prakarchya sagari jivanchya mothya pramanat vilupta honyasathi teey jababdar aahet. suruvatichya torsian aanee senomenian-turonian anoxic ghatana bahutek sagari jivanachya torsian aanee senomenian-turonian namshesh honyachya ghatananshi sambandhit aahet. sambhavya vatavaraniy parinamanvyatirikt, kholvar rahnare anek sagari jeev mahasagaranshi julavun gheu shakale naheet jithe auxigen keval prushthbhagachya tharanmadhye pravesh karat hota.
sagari anoxic ghatanancha aarthikdrushtya mahattvapoorn parinam mhanje anek mesozoic mahasagaranmadhil sadhyachya paristhitimule jagatil bahutek petroleum aanee naisargik vayoo sathyanche utpadan honyas madat jhaali aahe. sagari anoxic ghatanedarmyan, sendriya padarthanche sanchay aanee sanwardhan samanyapeksha barech jaast hote, jyamule jagbharatil anek vatavaranat sambhavya petroleum srot khadak tayar houu shakale. parinami, sumare 70 takke teel srot khadak heey junya kalatil mesozoic aahet aanee aanakhi 15 takke ubdar paleogenpasoonche aaheth keval kvachitach thund kalat sthanik pramanavyatirikt itar konatyahi srot khadakanchya utpadanasathi anukool paristhiti hotee.
vatavaraniy parinam.
2005 madhye lii kump, alekzandar pavlov aanee michael arther yanni mandalele eka model asey suchavate qee sagari anoxic ghatana atyant vishari hydrogen sulphide vayuyukt panyache vadhalele vaishishtya asoo shakate, jeey nantar vatavaranat sodale gele. yaa ghatanemule vanaspati aanee prani vishari jhaale asateel aanee mothya pramanat nasht jhaale asateel. yavyatirikt, asey prastavit kele gele aahe qee hydrogen sulphide varchya vatavaranaparyant chadhala aanee ozon tharavar hallah keela, joou samanyatah suryachya pranghatak atinil kiranotsargala avarodhit karato. yaa ozonchya avakshayamule jhalelya vadhiv yuu. vhee. kiranotsargamule vanaspati aanee pranyanchya jivanacha naash vadhala asata. permian-tricic namshesh honyachya ghatanechi nond karananya staratil jivashma bijkananmadhye yuu. vhee. kiranotsargashi susangat vikrutee disun yetat. heey purave, harit sulfur jivanunchya jivashma biomarkers ektritpane, asey soochit karatat qee yaa prakriyene tyaa mothya pramanat namshesh honyachya ghatanemadhye aanee kadachit itar namshesh honyachya ghatananmadhye bhoomika bajavali asatee. carbon dioxidechi patali prati dashalaksh sumare 1000 bhaganparyant vadhalyamule samudrache tapman vadhane heey yaa mothya pramanat vilupta honyache kaaran asalyache disate.
mahasagar rasayanshastrache parinam.
oxygenchi patali qamee jhalyamule redox-sanvedanshil dhatunchya samudrachya panyachya sandratet vaadh hone apekshit aahe. qamee oxygenchya paristhitit samudraspativaril galanmadhye loh-manganese oxyhydroxidesche qamee vighatan kelyas teey dhatoo aanee sambandhit trace dhatoo sodale jaatil. asha galanmadhye sulfetchi ghat jhalyane beriyamsarkhe itar dhatoo sodale jaau shakatat. jevha judd-dhatuyukt anoxic khol paanee khandiy almaryanmadhye pravesh karate aanee tyala oo2chya vadhalelya patalicha samna karava lagato, tevha kahee dhatuncha paus tasech sthanik biotamadhye vishbadha jhaali asatee. vilurian madhya-pridolichya uttaradhat, uthal-panyachya gaal aanee microplanktonmadhye phay, kyu, aii. ess., all, pii. bii., bii. aii., moow aanee emm. aine. patalimadhye vaadh disun yete; heey chitinozoan aanee itar microplankton prakaranmadhil vikrutichya daratil lakshaniy vadhishi sambandhit aahe, bahudha dhatuchya visharipanamule. madhya silurian irevican ghatanetil galanmadhye ashach prakarche dhatoo sanwardhan nondavale gele aahe.
pruthvichya itihasatil anaxic ghatana.
cretasius.
aaj talavanpasun teey kalya samudrasarkhya jaminibhovati asalelya bhoomadhya samudrasarkhya vividh jalsrotanmadhye astitvat asalelya sulphidic (kinwa euxynic) paristhiti visheshtah cretaceous atalantikmadhye prachalit hotya parantu jaagtik mahasagarachya itar bhaganmadhye dekhil tyaa prachalit hotya. yaa tathakathit atee haritgruh jagatatil barfmukt samudrat, kahee kalkhandat mahasagarache paanee titkech unch hote. prashnachinh asalelya kalmaryadet, khandiy plates changlya prakare vibhakt kelya gelya aahet asey manale jaate aanee aaj teey parvat (bahutek) bhavishyatil vivartanik ghatana hote-mhanje ekoon bhupradesh samanyatah khoopach qamee hote-aanee agadi ardhya atee-haritgruh havamanat dekhil jalakshayache yug atyant vegwan hote, jeey jaagtik mahasagaranmadhye mothya pramanat poshakdravye vahoon nett hote, jyamule sukshmajivanchya ekoon sphotak loksankhyela aanee oxygenyukt varchya tharanmadhil tyanchya shikari prajatinna indhan midale asate.
jagachya anek bhagantil cretaceous black shaleschya tapshilvar starikrut abhyasanni asey soochit kele aahe qee done mahasagariy anoxic ghatana (oaes) mahasagaranchya rasayanshastravar tyanchya prabhavachya drushtine visheshtah mahattvapoorn hotya, eka prarambhik aptianmadhye (~ 120 emae), jyala kadhikadhi selee event (kinwa oae 1aii) mhanatat, italian bhuvaidnyanik raimondo selee (1916-1983) nantar aanee dusare senomanian-turonian simevar (~ 93 emae), jyala kadhikadhi italian bhuvaidnyanik guido bonnerelli (1871-1951) nantar bonnerelli event (kinwa oae 2) mhanatat. oae1aii haah 1 teey 1 teey 3 mayarparyant tikala. chinmadhil dakshin tibetmadhil lakshaniyaritya vistarlelya oae2 madhyantaranchya uchch-resolution abhyasavar aadharit oae2 chaa kalavadhi andaje 820 qii. qii. aar. aahe.
cretatiusmadhil itar antaransathi (valanginian, houterivian, albian aanee coniatian-santonian tappyanmadhye) adhik kirkol sagari anoxic ghatana prastavit kelya gelya aahet, parantu sendriya-samruddha kalya shelsdware darshavilyapramane tyanchi gaal nond adhik sankuchit disate, atlantic aanee shejarchya bhagat pramukhyane darshavili jaate aanee kahee sanshodhak jaagtik badalamule baljabarine honadhyaivaji vishisht sthanik paristhitishi sambandhit aahet.
jurassic.
jyurasikmadhil dastaivajikaran keleli ekmev sagari anoxic ghatana torseanchya suruvatichya kalat (~ 183 maa) ghadali. konatyahi dii. ess. dii. pii. (khol samudratil khodkam prakalp) kinwa oo. dii. pii. (mahasagaratil khodkam karyakram) korne yaa kalatil kalya shelschee punarprapti kelee naslyamule-tethe qamee kinwa konatehi torsian mahasagar kavach shillak naslyamule-kalya shelche namune pramukhyane jaminivaril baherchya pikanmadhun yetat. kahee vyavsayik teel vihirinmadhil samagrisah heey baherche bhag serve pramukh khandanmadhye aadhaltat aanee hii ghatana done pramukh cretaceous udaharanansarkhich disate.
paleozoic.
cyberian sapalyanmadhun paloon jaanyamule suru jhaleli permian-tricic namshesh honyachi ghatana, mahasagaratil nirjantukikaranane chinhankit kelee gelee.
ordovician aanee silurian kalkhandanmadhil seema, samanya, vishari paristhitisaha, anoxiachya punaravrutti kalavadhidvare chinhankit kelee jaate. yavyatirikt, silurian darmyan anoxic masik paalee aadhaltat. heey anoxic kalkhand himanadyadarmyan, qamee jaagtik tapman (jaree patali jaast hotee) asatana ghadale.
jepson (1990) yanni eka yantrana prastavit kelee aahe, jyadvare dhruviy panyache tapman khalchya bhagat rahana panyachya nirmitiche thikan tharavate. jarr uchch akshanshatil paanee khalee asel tarr teey budnyaitke daat asateel; kaaran teey thund aahet, tyanchya panyat auxigen atyant virghalato aanee khol mahasagar oxygenyukt hoil. jarr uchch akshanshavaril paanee tyapeksha jaast ushna asel tarr tyanchi ghanata itaki qamee aahe qee teey thund khol panyachya khalee budnar naheet. tyamule, thermohalline parisancharan keval meeth-vadhalelya ghanatedvare chalavale jaau shakate, jeey jethe bashpibhavan jaast aahe asha ubdar panyat tayar hote. heey ubdar paanee qamee auxigen virghalu shakate aanee qamee pramanat tayar hote, jyamule qamee khol panyachya oxygens mand parisancharan tayar hote. yaa ubdar panyacha prabhav samudratoon pasarato aanee mahasagar dravanat dharan karoo shakatat tyache praman qamee karate, jyamule mahasagar bhoogarbhiyadrushtya qamee velet (daha kinwa hajaro varshe) mothya pramanat vatavarnamadhye sodatat. ubdar panyamule clathratesche prakashan dekhil suru hote, jyamule vatavaraniy tapman aanee khoyatil anoxia aanakhi vadhato. sheet-dhruv prakarananmadhye samaan sakaratmak pratisad karya karatat, jyamule tyanche shitalan parinam vadhatat.
thund dhruv asalelya kalkhandanna 'pii-episodes' ('primo' sathee lahan) mhanatat aanee teey jaiv-ashant khol mahasagar, damat bhoomadhyaresha aanee uchch hawaman daradvare darshavile jaatat aanee namshesh honyachya ghatanandware samapt hotat-udaharanarth, irevicane aanee laau ghatana. ulate heey ubdar, vishari "ess-episodes" ("sekando") sathee kharey aahe, jethe khol mahasagaratil gaal samanyatah graptolytic black shale asatat.
sekando-primo" bhaganche eka vaishishtyapurn chakr aanee tyanantarchi "ghatana" samanyatah sumare 3 emm. aii. paryant chalate.
ghatanancha kalavadhi tyanchya suruvatichya tulanet itka lamb asato kaaran sakaratmak pratisadancha bhaar uchalala gela pahije. hawaman daratil badalanmule mahasagar-vatavaran pranalitil carbonche praman prabhavit hote, jeey tyaa badalyat pramukhyane pavsadvare niyantrit kele jaate. kaaran heey silurian kalatil tapmanashi ulat sambandhit aahe, ubdar (uchch) ess-episodes darmyan carbon haloohaloo khalee kadhala jaato, tarr pii-episodes darmyan ulat kharey aahe. yaa haloohaloo honanya pravruttichya varr milankovic chakranchya sanketanche atimudran kele jaate, jeey shevati pii-aanee ess-bhaganmadhil badalas chalana dete.
devonian kalat yaa ghatana dirgh hotat; vadhana jaminivaril vanaspati biota kadachit carbon dioxidechya sandratesathi eka motha snrakshak mhanoon kaam karat hota.
antim-ordovician hirnantian ghatana paryayipane shaiwal fulancha parinam asoo shakate, jee vavyamule vadhana panyamule poshak tattvancha achanak puravatha jhalyamule kinwa vitalananya himanadyanmadhun poshak tatvanni samruddha vitalalelya panyachya pravahamule houu shakate, jeey tyachya tajya swabhavamule sagari parisancharan dekhil mandavel.
archaean aanee proterozoic.
asey manale jaate qee pruthvichya bahutansh itihasat mahasagaranmadhye mothya pramanat oxygenchi kamatarata hotee. archaean kalat, mahasagaranmadhye sulfetchi upalabdhata qamee asalyamule euxinia mothya pramanat anupasthit hota, parantu proterozoic kalat, too adhik samanya jhaala.