Umkhathi wokuqala womhlaba ungesinye sezihloko ezithakazelisayo neziyinkimbinkimbi lapho sihlola umsuka weplanethi yethu nempilo ngokwayo. Ukuqonda ukuthi yavela kanjani, zaziyini izingxenye zayo zokuqala, nokuthi ishintshe kanjani ngokuhamba kwesikhathi akusisizi nje kuphela ukuthi siqonde okwedlule, kodwa futhi kusinikeza imikhondo mayelana neminye imihlaba okuhlalwa kuyo.
Esikhathini eside ngaphambi kokuba umoya wakhiwe umoya-mpilo ne-nitrogen njengoba siwazi namuhla, usongwe ngongqimba oluyisivikelo emisebeni yelanga, umkhathi wawuyindawo enenzondo., egcwele amagesi anobuthi futhi engenawo nomkhondo wokuphila ngendlela esikuqonda ngayo. Ngezinqubo eziyinkimbinkimbi kakhulu ze-geological, amakhemikhali, kanye ne-biological, leyo nguqulo yakudala yashintsha indawo ezungezile eyenza ukuguquguquka kwezinto eziphilayo kwenzeka.
Uyini umkhathi futhi kungani uyisihluthulelo sokuphila?
Umkhathi ungqimba lwegesi oluzungeza umzimba wasezulwini, kulokhu, uMhlaba. Ingaphezulu kakhulu kwengxube elula yamagesi: isebenza njengesivikelo sokuvikela kanye nokulawula izinga lokushisa., futhi ibalulekile ekuthuthukisweni nasekulondolozeni impilo.
Njengamanje, umkhathi woMhlaba wakhiwe ikakhulukazi i-nitrogen (78%), umoya-mpilo (21%) kanye nengxube yamagesi asalayo njenge-carbon dioxide, i-argon, umhwamuko wamanzi kanye ne-ozone.. Kodwa lokhu kwakheka akuzange kube ngale ndlela ngaso sonke isikhathi, futhi ukuziphendukela kwayo kuye kwaphawulwa ngezinguquko ezinkulu phakathi nezinkulungwane zezigidi zeminyaka.
Iminyaka Eyizigidi Zokuqala: Izinxushunxushu ZaseHadean
Cishe eminyakeni eyizigidi eziyizinkulungwane ezingu-4.500 edlule, uMhlaba wakhiwa ifu lothuli lwe-cosmic kanye negesi eyadala i-Solar System.. Eminyakeni eyizigidi ezimbalwa zokuqala, eyaziwa ngokuthi i-Hadean eon, ubuso beplanethi babuwulwandle lwe-magma encibilikisiwe, futhi umkhathi ngaleso sikhathi wawungazinzile kakhulu futhi uhlala isikhathi esifushane.
Ngalesi sikhathi sokuqala, iplanethi yahlaselwa kakhulu ama-meteorite emcimbini owaziwa ngokuthi i-Late Heavy Bombardment., phakathi kweminyaka eyizigidi eziyizinkulungwane ezingu-4.100 nezingu-3.800 edlule. Le mithelela ilethe izinhlanganisela eziguquguqukayo ezifana namanzi, i-ammonia, ne-methane, okunomthelela ekwakhekeni komkhathi wokuqala nolwandle.
Isici esibalulekile esihambisana nalesi siphithiphithi sokuqala kwaba ukudalwa kweNyanga. Into elingana neplanethi eyaziwa ngokuthi i-Theia kukholakala ukuthi ishayisane noMhlaba, yakhipha izingcezwana ezidale isathelayithi yethu. Lesi senzakalo siphinde saba nomthelela omkhulu ekumisweni kokuqala komkhathi ngenxa yamandla akhishiwe.
Umkhathi wokuqala womhlaba: izingxenye nezici
Ngemuva kwezehlakalo ezinodlame kakhulu zeHadean, uMhlaba waqala ukupholisa kancane, okuvumela ukwakheka koqweqwe oluqinile.. Kulo mongo, esikwaziyo njengomkhathi ozinzile noma isimo sakudala kwavela.
Yayingenawo umoya-mpilo wamahhala, kodwa yayakhiwe kakhulu ngamagesi entaba-mlilo: i-carbon dioxide (CO2), umhwamuko wamanzi (H2O), i-methane (CH4ammonia (NH3), isulfure (SO2) kanye ne-nitrogen (N2). Le cocktail ene-gaseous yakha umkhathi onciphisayo, okusho ukuthi ithanda ukusabela kwamakhemikhali okuzuza i-electron, okuphambene nalokho okwenzeka lapho kukhona umoya-mpilo.
Ukugxila okuphezulu kwe-methane ne-carbon dioxide kwasebenza njengamagesi abamba ukushisa anamandla., okwavumela iplanethi ukuthi igcine ukushisa okwanele ukuze igcine amanzi awuketshezi, nakuba iLanga elincane lalikhipha kuphela u-70% wokushisa eliwukhiphayo njengamanje.
Indida yelanga ebuthakathaka: kwenzeka kanjani ukuthi umhlaba uhlale ufudumele?
Omunye wemibuzo ethakazelisa kakhulu mayelana nokuvela kweplanethi kwasekuqaleni ukuthi amanzi awuketshezi abengagcinwa kanjani ebusweni bomhlaba ukube iLanga belingakhanyi kangako.. Lesi simo saziwa ngokuthi i-Sun paradox encane.
Incazelo eyamukelwa kakhulu yale mpicabadala ilele ekwakhekeni komkhathi wakudala.. Ngaphandle kwesikhutha, i-methane, esebenza ngokuphindwe izikhathi ezingu-20 kuya kwezingu-25 njengegesi ebamba ukushisa, yaba nendima ebalulekile ekugcineni amazinga okushisa embulunga yonke ephezulu.
Ngaphezu kwalokho, ezinye izici ezifana nokushisisa kwamagagasi ngenxa yokuba seduze kweNyanga noma inani elikhulu lama-elementi akhipha imisebe engaphakathi leplanethi nakho kunikele ngokushisa.. Ukuhlanganiswa kwazo zonke lezi zakhi kwavumela ulwandle ukuba luhlale lusesimweni esiwuketshezi, isimo esiyinhloko sokuvela kokuphila.
Ubufakazi bokuqala bokwakheka komhlaba: Sazi kanjani ukuthi umkhathi wawunjani?
Ulwazi lwethu oluningi mayelana nomkhathi wokuqala luvela ekuhlaziyeni amatshe amadala kakhulu.. Lokhu kufaka phakathi ukwakheka kwe-sedimentary, ukufakwa koketshezi, ama-stromatolites nokuhlaziywa kwe-isotopic.
Isibonelo esicacile ama-BIF noma ama-banded iron formations, ezibonisa izingqimba ezishintshanayo zama-iron oxides ne-silica. Lezi zakhiwe ngesikhathi i-ayoni eyinsimbi (Fe2+) olwandle lwaqala ukwenza i-oxidize kanye nemvula ngokusabela komoya-mpilo okhiqizwa izinhlobo zokuphila ze-photosynthetic zakuqala.
Ngakolunye uhlangothi, amaminerali afana ne-pyrite (FeS2) ekhona emadwaleni asendulo e-sedimentary ibonisa ukuthi indawo ezungezile yayine-anoxic, njengoba le mineral ayikwazi ukwakha lapho kukhona umoya-mpilo wamahhala.
Ukufakwa kwamagesi abanjiwe kuye kwatholakala kumakristalu asendulo., okuvumela ukwakheka komkhathi wezikhathi ezithile ukuthi kwakhiwe kabusha ngezinga elifanelekile lokunemba. Ngokuhlanganisa yonke le mikhondo, kube nokwenzeka ukulandelela inguquko eqhubekayo ukusuka emkhathini ongenawo umoya-mpilo kuya kokucebile ku-O.2.
I-biological Revolution: i-cyanobacteria kanye ne-Great Oxidation Event
Ukuvela kwe-cyanobacteria kuphawula esinye sezikhathi ezibaluleke kakhulu emlandweni womkhathi.. La magciwane e-photosynthetic, asekhona nanamuhla, aqala ukusebenzisa ukukhanya kwelanga nesikhutha ukuze akhiqize amandla, akhiqize umoya-mpilo njengomkhiqizo.
Emakhulwini ezigidi zeminyaka, umoya-mpilo owawukhiqizwa wawumuncwa ulwandle namadwala. Ikakhulukazi, iphendule ngensimbi encibilikile, yabangela ukuna kwama-iron oxide kanye nokwakheka kwama-BIF ashiwo ngenhla. Kwaze kwaba yilapho lezi zimiso sezigcwele lapho umoya-mpilo waqala ukunqwabelana emkhathini.
Lesi senzakalo, esaziwa ngokuthi i-Great Oxidation, senzeka cishe eminyakeni eyizigidi eziyizinkulungwane ezingu-2.400 edlule futhi saba nemiphumela elimazayo neguquguqukayo ngesikhathi esifanayo.. Izinhlobo eziningi ze-anaerobic azikwazanga ukuphila endaweni entsha ye-oxidizing, kuyilapho ezinye zakha izindlela zokusebenzisa umoya-mpilo, njengokuphefumula kwamangqamuzana e-aerobic.
Ukushintsha kwesimo sezulu kanye namaqhwa okuqala
Umthelela oseceleni we-Great Oxidation Event kwaba ukuncishiswa kwe-methane yasemkhathini, isabela nomoya-mpilo ukuze kwakhe isikhutha namanzi. Njengoba i-methane yayiyigesi ebamba ukushisa enamandla, ukwehla kwayo kwabangela ukwehla okukhulu kwezinga lokushisa emhlabeni.
Lokhu kwaholela kulokho okubhekwa njengeqhwa lokuqala elikhulu eMhlabeni: i-Huronian glaciation.. Abanye ososayensi bakholelwa ukuthi lo mcimbi wawungaba ngokwedlulele kangangokuthi uMhlaba waba "ibhola leqhwa" eliqandisiwe, into okusaphikiswana ngayo kodwa ezwakalayo.
Ngesikhathi se-Proterozoic eon, okungenani amanye amaqhwa amathathu abalulekile enzeka, ubude bayo nobubanzi bayo kusacwaningwa. Umhlaba wanyakaza phakathi kwezikhathi ezifudumele nezibandayo, ngokuvamile ngenxa yokungalingani okuncane kwamagesi abamba ukushisa, umsebenzi wentaba-mlilo, ama-plate tectonics, kanye nokuzungeza kweplanethi.
Umkhathi kanye nokuvela kwezinto eziphilayo eziyinkimbinkimbi
Ngamazinga aphezulu oksijini, ukugxuma kokuziphendukela kwemvelo okuya ezintweni eziphilayo ze-eukaryotic kwaba nokwenzeka.. Lawa ane-nucleus nama-organelle achaziwe njenge-mitochondria nama-chloroplast, asebenzisa umoya-mpilo ukukhiqiza amandla ngendlela ephumelela kakhulu kunokuvutshelwa kwe-anaerobic.
Le ntuthuko yamangqamuzana ngokushesha yavumela ukuvela kwezinto eziphilayo ezihlukene, ezingashintsha zibe izinhlobo zezilwane nezitshalo eziyinkimbinkimbi.. I-ozone layer (O) nayo yakhiwa3), evikela ubuso bomhlaba emisebeni ye-ultraviolet, yenza kube lula ukuhlangana kwezindawo zasemhlabeni.
Ukuqhathanisa phakathi komkhathi wakudala nowamanje
| Gas | I-Primitive Atmosphere | Umkhathi wamanje |
|---|---|---|
| I-nitrogen (N2) | Yethula ngamanani amancane | ~ 78% |
| I-Oxygen (O2) | Indlala noma ayikho | ~ 21% |
| I-carbon dioxide (CO2) | Kuchichima kakhulu | ~ 0.04% |
| I-Metano (CH4) | Yethula ngobuningi | Landelela |
| Umhwamuko wamanzi (H2O) | Okuguquguqukayo kakhulu, kodwa kuningi | Iyaguquguquka ngokuya ngesimo sezulu |
Umkhathi njengendlela yokuhlola ukutadisha amanye amaplanethi
Ulwazi mayelana nokuziphendukela kwemvelo komkhathi woMhlaba luphinde lusetshenziswe ukuhlaziya umkhathi kwezinye izindikimba zasezulwini., njengeMars, Venus noma ama-exoplanets. Ukutadisha izici zabo kusiza ukuthola ukuthi bangakwazi yini ukusekela ukuphila noma ukuthi bake bakwenza.
Ngokufanayo, ukuqonda ukuthi ukuhluka okuncane kwamagesi kungaqala kanjani izinguquko ezinkulu esimweni sezulu kanye ne-biosphere kuyisihluthulelo sokuqonda ubuthakathaka bebhalansi yamanje.. Lokhu kunezinhlelo zokusebenza eziqondile ekuhlaziyeni ukuguquka kwesimo sezulu samanje eMhlabeni.
Kusukela kumusi we-silicate we-Hadean kuya ebukhoneni be-ozone ku-stratosphere yesimanje, umkhathi woMhlaba ube umkhiqizo wenqubo esebenzisanayo neguqukayo.. I-geology, i-biology, ne-astronomy kuyahlangana ukuze kwakhiwe le ndaba enikeza incazelo emsuka wethu nekusasa lethu.