Isikhathi seCretaceous

Kuyo yonke inkathi ye- Mesozoic sithola izinkathi ezi-3: the I-Triassic, the I-Jurassic futhi i Okuhle kakhulu. Namuhla sizogxila ekukhulumeni ngesikhathi seCretaceous. Kuyisigaba sesilinganiso sesikhathi esihambelana ne- isikhathi sokuma komhlaba ukuba yisikhathi sesithathu nesokugcina seMesozoic. Kwaqala cishe eminyakeni eyizigidi eziyi-145 edlule futhi kwaphela cishe eminyakeni eyizigidi ezingama-65 edlule. Lesi sikhathi sihlukaniswe izingxenye ezimbili ezaziwa njengeLower Cretaceous ne-Upper Cretaceous. Lesi ngesinye sezikhathi ezinde kakhulu ngaphakathi kwe-Phonerozoic eon.

Kulesi sihloko sizokutshela konke odinga ukukwazi mayelana nesikhathi seCretaceous.

Izici eziyinhloko Izici ze-Cretaceous

Lesi sikhathi sinegama laso elivela esiLatini ngesi- eta okusho ukuthi ushoki. Leli gama lisuselwa kumucu otholakala e-Parisian Basin eFrance. Kule nkathi impilo olwandle nasemhlabeni yavela njengenhlanganisela yamafomu wesimanje kanye namafomu asendulo. Ihlala cishe iminyaka eyizigidi ezingama-80 cishe, yisikhathi eside kakhulu se-Phonerozoic eon.

Njengasezikhathini eziningi zokuma komhlaba esizifundile, ukuqala kwalesi sikhathi akuqinisekile ngeminyaka eyizigidi ezimbalwa ngaphezulu noma ngaphansi. Konke ukuqala nokuphela kwezikhathi zokwakheka komhlaba kunqunywa ngomcimbi othile obalulekile emhlabeni jikelele, kungaba ngokushintsha kwesimo sezulu, izimbali, izilwane noma i-geology. Ukutholakala kokuphela kwalesi sikhathi kunembile maqondana nesiqalo. Lokhu kungenxa yokuthi uma uqondanisa nolunye lwezendlalelo ze-geologic ezinobukhona obuqinile be-iridium futhi obubonakala buhambisana ukuwa kwe-meteorite kulokho manje okuhambisana neNhlonhlo Yucatan neGulf of Mexico.

Le yi-meteorite edumile engagcina idale ukuqothulwa okukhulu okwenzeke ekupheleni kwalesi sikhathi lapho iningi lezilwane lanyamalala khona, kufaka phakathi ama-dinosaurs. Lo ngumcimbi obaluleke kakhulu omemezela ukuphela kwenkathi yeMesozoic. Kungemva kweJurassic nangaphambi kwe- I-Paleocene.

I-geology e-Cretaceous

Amatshe aseCretaceous

Maphakathi nesikhathi seCretaceous, ngaphezu kwengxenye yemithombo kawoyela yomhlaba esinayo namuhla yakhiwa. Ukugxila okuningi okudume kakhulu kutholakala ePersian Gulf nasendaweni ephakathi kweGulf of Mexico kanye nogu lwaseVenezuela.

Sonke lesi sikhathi, izinga lolwandle lalikhuphuka ngokuqhubekayo ngenxa yokwanda kwamazinga okushisa omhlaba. Lokhu kukhula kwaletha amazinga olwandle emazingeni aphakeme kakhulu ake abhalwa emlandweni weplanethi yethu. Izindawo eziningi ezazingugwadule ngaphambili zaba ngamathafa agcwala amanzi. Izinga lolwandle lafika ezingeni lokuthi yi-18% kuphela yomhlaba ebingaphezu kwezinga lamanzi. Namuhla sine-29% yendawo yomhlaba evelile.

I-supercontinent eyaziwa ngokuthi yiPangea yahlukaniswa phakathi nayo yonke inkathi yeMesozoic ukunikeza amazwekazi esiwaziyo namuhla. Izikhundla ababeziphethe emuva ngaleso sikhathi zazihluke kakhulu. Ekuqaleni kweCretaceous kwase kunama-supercontinents amabili abaziwa ngeLaurasia neGondwana. Lezi zindimbane zomhlaba ezinkulu zahlukaniswa uLwandle lwaseThetis. Ekupheleni kwalesi sikhathi amazwekazi aqala ukuthola amafomu acishe afane nawamanje. Ukwehlukaniswa okuqhubekayo kwamazwekazi kubangelwe isenzo se- Ukukhukhuleka kwezwekazi futhi kuhambisane nokwakhiwa kwamapulatifomu abanzi nemifula.

Uhlelo lwamaphutha olwalukhona kwiJurassic yangaphakathi lwaluhlukanise iYurophu, i-Afrika nezwekazi laseNyakatho Melika. Kodwa-ke, lawa mhlaba ahlala esondelene. I-India neMadagascar babehamba besuka ogwini lwaseMpumalanga Afrika. Esinye seziqephu ezibaluleke kakhulu zokuqhuma kwentaba-mlilo okukhulu kwenzeka phakathi kokuphela kweCretaceous nokuqala kwePaleocene eNdiya. Ngakolunye uhlangothi, i-Antarctica ne-Australia zazisahlangene futhi zazisuka eNingizimu Melika, zikhukhuleka zibheke empumalanga.

Konke lokhu kunyakaza kudale imizila emisha yasolwandle njengeNyakatho yasendulo neNingizimu Atlantic futhi, uLwandle lweCaribbean nolwandle i-Indian. Ngenkathi i-Atlantic Ocean yayisanda, ama-orogenies ayesekhule ngesikhathi seJurassic aqhubeka esuka ezintabeni zaseNyakatho Melika ngenkathi i-orogeny yeNevada ilandelwa ngamanye ama-orogenies afana neLaramide.

Isimo sezulu seCretaceous

i-geology e-cretaceous

Amazinga okushisa ngalesi sikhathi akhuphukele ezingeni eliphezulu eminyakeni eyi-100 yezigidi edlule. Ngaleso sikhathi kwakungekho iqhwa emapalini. Izidumbu ezitholakale kusukela kulesi sikhathi zibonisa ukuthi amazinga okushisa ebusweni bolwandle olushisayo kufanele abe phakathi kuka-9 no-12 degrees, afudumele kunamanje. Amazinga okushisa olwandle olujulile kufanele ukuthi abe ngisho nangama-degree angama-15 nangu-20 ngaphezulu.

Iplanethi bekungafanele ifudumale kakhulu kunangesikhathi se-Triassic noma i-Jurassic, kodwa kuyiqiniso ukuthi i-gradient lokushisa phakathi kwezigxobo ne-Equator bekufanele libe bushelelezi. Le gradient ebushelelezi yokushisa ibangele ukuthi imisinga yomoya weplanethi inciphe futhi yaba nomthelela ekwehliseni imisinga yolwandle. Ngalesi sizathu, bekukhona izilwandle eziningi ebezime kakhulu kunanamuhla.

Lapho isikhathi seCretaceous sesiphelile, amazinga okushisa aphakathi nendawo aqala ukwehla okuhamba kancane okwakusheshisa ngokuqhubekayo futhi ezigidini zeminyaka zokugcina isilinganiso sonyaka sehle sisuka kuma-20 degrees saya kuma-10 degrees.

Izimbali nezilwane

Isikhathi seCretaceous

Umphumela odale ukuthi uMhlaba uhlukane ube ngamasimu womhlaba ayi-12 noma ngaphezulu kukhethwe ukuthuthukiswa kwezilwane nezitshalo. Kulezi zizwe, bazakhela ezabo iziqhingana zamazwekazi eziqhingini zase-Upper Cretaceous futhi bavela ukuze bakhiqize okunhlobonhlobo okuningi kokuphila kwasemhlabeni nokwasolwandle esikwaziyo namuhla.

Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana nesikhathi seCretaceous.


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  1. Ubhekele imininingwane: Miguel Ángel Gatón
  2. Inhloso yedatha: Lawula Ugaxekile, ukuphathwa kwamazwana.
  3. Ukusemthethweni: Imvume yakho
  4. Ukuxhumana kwemininingwane: Imininingwane ngeke idluliselwe kubantu besithathu ngaphandle kwesibopho esisemthethweni.
  5. Isitoreji sedatha: Idatabase ebanjwe yi-Occentus Networks (EU)
  6. Amalungelo: Nganoma yisiphi isikhathi ungakhawulela, uthole futhi ususe imininingwane yakho.

  1.   UJorge Gomez Godoy kusho

    Umbiko omuhle kepha unamaphutha amaningi wokubhala nokubhala.