Ukushabalala kwama-dinosaur kwenzeka eminyakeni eyizigidi ezingu-66 edlule lapho i-asteroid eyaziwa ngokuthi "Chicxulub" ishayisana noMhlaba, okwabangela ukuqedwa kwezinhlobo eziningi zezinto eziphilayo. Nokho, indawo enembile yomthelela kanye nesiphetho sezinsalela zale nto enkulukazi yasezulwini kuseyimpicabadala. Abantu abaningi bayazibuza lapho kwawa khona i-meteorite eyaqothula ama-dinosaur.
Kulesi sihloko sizokutshela ukuthi i-meteorite eyashabalala ama-dinosaur yawa kuphi kanye nezici zayo.
Chicxulub asteroid
Ngokusho kweNyuvesi yaseChile, umthelela we-asteroid wadala inhlekelele yokucekelwa phansi komhlaba, amandla alingana nezingu-50.000 zezikhali zenuzi ezikhona. Ubukhulu bomthelela bebumangalisa ngempela, ngezilinganiso ezibeka ububanzi bawo phakathi kwamakhilomitha ayi-12 kanye ne-15, futhi olunye ucwaningo lwaze lwahlawumbisela ukuthi kungenzeka ukuthi lufinyelele kumakhilomitha angama-80. Ijubane eshayisane ngalo noMhlaba lalimangaza ngokufanayo. ehamba ngesivinini esingamakhilomitha angu-20 ngomzuzwana, okulingana nesivinini esimangalisayo esiphindwe izikhathi ezingu-59 kunesivinini somsindo.
Ukufika kwalesi sigameko esiyinhlekelele kuholele ekuqothulweni kwezidalwa zasendulo ezingaba ngu-75%, kungashiyi lutho ngaphandle kwezinsalela zazo ezizinsalela ezigqitshwe ngaphansi kwemfucumfucu. Babunjalo ubukhulu balo mthelela kangangokuthi kwawushintsha unomphela umkhondo wokuphila emhlabeni wethu.
I-meteorite eyaqothula ama-dinosaur iwe kuphi?
Lapho befunda lesi sigameko, abacwaningi baphethe ngokuthi indawo yomthelela itholakala edolobheni lase-Chicxulub, eliseNhlonhlweni yase-Yucatan e-Mexico, yingakho igama layo. Ngokusho kweNational Geographic, igama elithi "Chicxulub" livela olimini lwesiMayan futhi, ngokumangalisayo, Ingahunyushwa ngokuthi "umsila kadeveli", "izeze likadeveli" noma "indawo yophondo oluvuthayo."
Ngokwemibono yesayensi, kukholakala ukuthi leli dolobha, elihlalwa abantu abambalwa abangaphezulu nje kuka-4.000, laliyisizinda somthelela we-asteroid. Izilinganiso ze-NASA zibonisa ukuthi umthelela ubangele i-crater eyayikala cishe amakhilomitha angu-180 ububanzi futhi yafinyelela ekujuleni okungaba ngamamitha angu-900.
Ezigidini zeminyaka, ubukhulu balesi simo buye bancipha, okwenza singabonakali namuhla. Kwaze kwaba ngawo-1980 lapho kwavela khona umbono owawuhlongozwe ososayensi uLuis Álvarez noWalter Álvarez. Kamuva, abanye ochwepheshe baqinisekisa futhi ekugcineni bavuma ukuthi lena yindawo eqondile yomcimbi obalulekile. Nakuba kungase kungabi khona i-crater ebonakalayo, kunemikhondo ebonakalayo eMhlabeni esebenza njengobufakazi bokubukeka kwayo.
UDkt. Gary Kinsland, uprofesa wesayensi yokwakheka komhlaba eNyuvesi yaseLouisiana, ubefunda iChicxulub kusukela ngo-1994. Lapho ekhuluma ngalesi sihloko nezingane ezifunda isikole, usebenzisa isifaniso esilula: Ake sithi ubeka indishi embhedeni wakho futhi amboze ngamashidi nezingubo zokulala. Isitsha sizobonakala njengokuhlehlisa kancane. Nakuba umgodi omkhulu ungase ungasekho, uma uhlola i-indent embhedeni wakho, uzobona ukuthi isahambisana nomkhawulo wesitsha esingaphansi kwayo. "Lokhu kubheka kusivumela ukuthi sithole ulwazi mayelana nesakhiwo esingaphansi," kuchaza umcwaningi. Ngeshwa, Azikho izinsalela ze-meteorite ezitholakele.
Ukwengeza, i-NASA ithwebule izakhi ezengeziwe ezicashile ezivela emkhathini eziveze indawo yomthelela: ukwakheka kwe-semicircular eyachazwa ngokuthi "cishe iphelele." Lokhu kuqashelwa kwenziwa iqembu labacwaningi abangobhongoza ababephakathi kwabokuqala ukuphakamisa i-Chicxulub njengendawo yomthelela.
Ngesikhathi sokuhlola, ososayensi bamangala ngedatha kazibuthe kanye namandla adonsela phansi inkampani kawoyela yaseMexico eyayiqoqwe ngaphambili lapho ifuna uwoyela. Le datha yembula ukwakheka okukhulu, okuyindilinga ngokuphelele, ababekubone njenge- impact crater. U-Kevin Pope, usosayensi we-NASA obambe iqhaza ocwaningweni lwemivubukulo yamaMayan, unikeze imininingwane eyengeziwe ngalokhu okutholakele okumangalisayo.
Isiphetho sezinsalela ze-asteroid akwaziwa
Ingxenye encane kuphela yento enkulu yasezulwini ekwazile ukusinda. Abacwaningi baqokomisa ukuthi izingcezu eziningi zakhishwa ngendluzula emhlabeni wethu, kodwa zimbalwa kuphela eziye zalondolozwa noma okunzima ukuzithola.
Ngokombono wabo, ingxenye yempahla yashiswa ngesikhathi kushayisana, kuyilapho izingcezu ezisele. Kancane kancane bangcwatshwa amamitha angamakhulu ambalwa ngaphansi komhlaba phakathi nezigidi zeminyaka.. Nokho, izinsalela ze-asteroid zisengatholakala eYucatán, nakuba ngamanani amancane. Ucwaningo lwakamuva olushicilelwe kumagazini ohlonishwayo iSayensi ngo-2021 lwembula ukuthi abacwaningi bathola iminonjana yothuli lwe-asteroid endaweni yomthelela. Leli qiniso lingabangelwa ukuba khona kwe-iridium, i-metallic element evame ukutholakala kuma-asteroids, ekhona ku-crater.
Ngokusho kwe-athikili, idatha ecutshungulwayo yembule ukungaqondakali kwe-iridium okuphawulekayo ngaphakathi kokulandelana kwendandatho ephezulu yesakhiwo somthelela we-Chicxulub, Itholwe ku-drill core etholwe ngesikhathi se-IODP-ICDP Expedition 364. Inyuvesi yase-Austin yahola uhambo lwasolwandle lapho yavubukula khona amatshe enkabeni ye-Yucatan seafloor crater core. Lokhu kutholakala okudabukisayo kwakuhilela ukukhonjwa kwezikhonkwane ze-iridium ezinikeze ubufakazi obubambekayo obuvuna imfundiso ye-Chicxulub asteroid.
Okutholakele okwengeziwe
Okutholakele okwengeziwe kuye kwavela phakathi neminyaka okukholakala ukuthi kungenzeka kusuka kumthelela we-Chicxulub. Muva nje, ngo-2022, i-New York Times ishicilele i-athikili ememezela ukuvubukulwa kwezinsalela zamathambo ediphozithi etholakala eNyakatho Dakota, e-United States. Lokhu okutholakele kuphakamisa ukuthi kungenzeka ukuthi lezi zingcezu zingase zixhunywe nesibhakabhaka esinesibopho somcimbi we-Chicxulub.
Ngesikhathi ekhuluma ne-NASA, uRobert DePalma, isazi se-paleontology esihola ucwaningo, wathi izinsalela ezitholakele zinganikeza ulwazi olubalulekile ngohlobo lwale nto. Nakuba kukholakala ukuthi i-asteroid, kukhona okungenzeka ukuthi kungase kube inkanyezi enomsila.
Phakathi naleso sikhathi, wabonisa ukuqiniseka ngenqubo eqhubekayo yokuhlonza into engaqondakali, ethi: "Uma sesikwazi ukuhlonza ubunjalo bayo, ngokungangabazeki sizomangala ngokuthola kwethu." Ithiyori ka-DePalma isuka emuva kuzinsalela zamatshe ancibilikisiwe akhishwa ngamandla ngesikhathi somthelela., ezishintsha zibe ama-spherules engilazi njengoba ephola kancane kancane. Lama-spherules, ngokusho kochwepheshe, "ahlala ngaphakathi kwe-resin yesihlahla, eyayisebenza njengemvilophu ye-amber evikelayo, igcina isimo sayo sokuqala." Lokho uDePalma akuthola kwakungamadwala angashintshiwe avaleleke ngaphakathi kwalezi zakhiwo zezingilazi.