Esikhathini se-Paleozoic sinezikhathi eziningana lapho i- isikhathi sokuma komhlaba. Isigaba sokuqala ngesika- ICambrian. Iwukuhlukaniswa kwesikali sesikhathi sokuma kwezwe kanye nenkathi yokuqala kweziyisithupha zenkathi ye-Paleozoic. Yaqala cishe eminyakeni eyizigidi ezingama-541 edlule futhi yaphela cishe eminyakeni eyizigidi ezingama-485 edlule. Isikhathi esilandelayo yi- I-Ordovician.
Kulesi sihloko sizogxila kuzo zonke izici, i-geology, isimo sezulu, izitshalo nezilwane zenkathi yeCambrian.
Izici eziyinhloko
Lesi sikhathi somqondo wePaleozoic sihamba phambili ngokuba umthelela omkhulu ezingeni lokwakheka komhlaba kuyo yonke iplanethi. ICambrian kubhekwe ukuthi ithathe iminyaka eyizigidi ezingama-70 kuphela, kepha isayensi ikwazile ukuyilungisa ngenxa yolwazi oluqoshwe embikweni wezinsalela. Igatsha le-geology eligxile kulezi zinguquko ezitholwa yiplanethi yomhlaba selokhu yakhiwa yi i-geology yomlando.
Sonke lesi sikhathi sithola igama leCambrian egameni elivela eCambria. Leli gama liyindlela yesiLatin yeCymru okusho ukuthi iWales. I-Wales namuhla lapho kutholakala khona izinsalela zokuqala zokwakheka komhlaba kule nkathi. Ngalesi sigaba sokuma komhlaba kukhona ukuqhuma okukhulu kokuphila okokuqala okurekhodwe kumafosili. Izakhi zokuqala ezinamaseli amaningi zingahlukaniswa eziyinkimbinkimbi kunezipanji noma i-jellyfish.
Phakathi kwezidalwa ezibaluleke kakhulu kulesi sikhathi kukhona ulwelwe oluhlaza olungamamilimitha ambalwa nje ububanzi ngenxa yama-trilobites. Lawa ma-trilobite ayiqembu elidumile lama-arthropods abekwazi ukusinda ekuqothulweni okukhulu okukhulu. Lokhu kuvela kwempilo kubizwa ngokuthi ukuqhuma kweCambrian futhi kwakungesinye sezehlakalo ezinkulu ezaziphawula umngcele phakathi kweNeoproterozoic kanye nezikhathi zeCambrian. Ukuze ufunde kabanzi mayelana nalokhu kuguquguquka kwemvelo, ungabheka isihloko esithi izilwane zaseCambrian nezinye ezihlukile izikhathi ze-geological.
Isikhathi seCambrian geology
Ngalesi sikhathi kucatshangwa ukuthi amazwekazi awumphumela wokuhlukaniswa kwe-supercontinent enkulu eyayivele ikhona ku-Neoproterozoic futhi yayibizwa ngokuthi i-Pannotia. Ingxenye enkulu yezwekazi elikhulu iGondwana futhi iseningizimu kanye namazwekazi amathathu amancane abizwa ngokuthi iLaurentia, iSiberia neBaltica. Lawa mazwekazi ayehambela enyakatho ngenxa yokuhamba kwe Amapuleti eTectonic eziqhutshwa imibukiso ye-convection yengubo yomhlaba.
Kwaqala kanjena ukukhukhuleka kwezwekazi, kwakha izikhundla esizaziyo namuhla. Amazinga okukhukhuleka ezwekazini esikhathini se-Cambrian alinganiselwa ukuthi abephezulu ngokungavamile uma kuqhathaniswa nezikhathi zangaphambili. Lokhu kusho ukuthi bekunomsebenzi omkhulu wamapuleti e-tectonic. Ngenxa yalokhu kunyakaza kwezwekazi, ukuhlukahluka kwemvelo kuye kwanda emhlabeni wonke, njengoba izinhlobonhlobo zemvelo ezinezici ezihlukahlukene zadalwa. Ukuze ujule kulezi zinguquko ze-geological, kuyathakazelisa ukubukeza i-athikili ethi kanye I-Proterozoic.
Ulwandle iPanthalassa yilo olumboze iningi lomhlaba wonke, ngenkathi ezinye izilwandle ezincane ezinjenge-proto-Tethys nolwandle lwaseKhanty zitholakala phakathi kwamanzi wamazwekazi amancane abizwa ngeLaurentia neBaltic.
Isimo sezulu seCambrian
Isimo sezulu senkathi yeCambrian kukholakala ukuthi besishisa kakhulu kunasezikhathini zangaphambili. Ngalesi sikhathi kwakungekho glaciation ye-polar. Okusho ukuthi, akukho gxolo lendawo eMhlabeni elalimbozwe yiqhwa. Ngokulandelayo, inkathi ye-Cambrian ihlukaniswe izinkathi ezintathu: i-Lower Cambrian, i-Middle Cambrian ne-Upper Cambrian. Ake sihlaziye kafushane isimo sezulu kanye ne-geology yenkathi ngayinye kule nkathi.
- I-Lower Cambrian: Ngalesi sikhathi izwekazi laseGondwana kanye nabanye abantu abancane bahlala kuzo zonke izindawo ezisenkabazwe. Lokhu kwaziwa ngenxa yamarekhodi amadiphozithi e-limestone olwandle oluningi nase-epicontinental eshisayo. Ngaleso sikhathi, i-orogeny yeCadomian yiyo eyaholela ezinkathini zokuvela kwenqwaba yomhlaba omkhulu ekuqaleni kweCambrian.
- I-Middle Cambrian: ngalesi sikhathi kwakukhona umjikelezo oweqisayo owaphazanyiswa yimidumba emibili ehlehlayo.
- I-Cambrian Ephezulu: ingxenye enkulu yezwekazi laseGondwana, elalinezikhundla ezingaphezulu kwezinkabazwe, lalibhekisa ezindaweni ezingamakhaza kakhulu. Bebebuyiselwa ezikhundleni njengoba izixuku ezincane zamazwekazi ezinjengeLaurentia, iSiberia ne-Australia bebezikhundleni ze-equatorial.
Ukuqhuma kwempilo
Njengoba kushiwo ngaphambili, le nkathi yaziwa njengokuhlukaniswa kwesikhathi lapho kwaba khona ukuqhuma okukhulu kwempilo kunanini ngaphambili. Kuyaziwa ngokuthi ukuqhuma kweCambrian. Lokhu kuqhuma kwaholela ekuveleni kwezinhlobonhlobo zezinto eziphilayo ezimangalisayo emhlabeni, okuhlanganisa namaqembu amaningi ezilwane esiwaziyo namuhla, njengama-chordate, ayingxenye yezilwane ezinomgogodla futhi ahlanganisa abantu. Akwaziwa ngokuqinisekile ukuthi kwenzeka kanjani inhlansi enjalo yokuqhuma kwezinto eziphilayo. Kukholakala ukuthi kungenzeka ukuthi kwakuwumoya-mpilo owawukhona ngaleso sikhathi emkhathini nokuthi, ngenxa yokukhishwa kwe-cyanobacteria kanye nolwelwe olwenziwe i-photosynthesis, ukwazile ukufinyelela emazingeni adingekayo ukuze zonke izinto eziphilayo zikhule izakhiwo zazo eziyinkimbinkimbi kakhulu, okubangela izinhlobo ezihlukahlukene zokuphila.
Esinye isici okufanele usicabangele imvelo eyenza kwaba nokwamukela izihambi kancane njengoba isimo sezulu sifudumala futhi nolwandle lukhuphuka. Ngale ndlela, kwadalwa izindawo ezihlala olwandle ezingajulile, ezazilungele ukukhiqiza izinhlobo ezintsha zokuphila ngoba zaziqukethe inani elikhulu lemisoco. Ubudlelwano nezinye izikhathi, njenge I-Ordovician, kubalulekile futhi ukuqonda ukuvela kwempilo ezinkathini ezahlukene kanye nobudlelwano bayo ne izilwane zangaphambilini.
Kodwa-ke, kucatshangwa ukuthi ososayensi abaningi benze ihaba ngobukhulu bokuqhuma kweCambrian ngenxa yokwanda kwezilwane ezinezakhiwo ezilukhuni ezatholwa kalula ngokushesha futhi kalula kunangaphambi kwazo. Njengakho konke lokhu ungaba namarekhodi ezinsalela kuncike esakhiweni somzimba. Uma umzimba uthambile awunakwenziwa ifossilized ngendlela efanayo. Isibonelo, okuningi kwaziwa ngama-brachiopods ayehlala kumagobolondo afana ne-clam- kanye ne-cockle-like nezinye izilwane ezinamathambo angaphandle abizwa namuhla njenge-arthropods.
Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi mayelana nesikhathi seCambrian.
