Phakathi kohlu lwezindawo ezishisa kakhulu Emhlabeni, ugwadule lwaseSahara e-Mauritania, i-Afrika ibalwa nakanjani ohlwini, lapho amazinga okushisa angafinyelela phezulu aze afike ku-57.7 degrees Celsius. Imimoya enamandla neshisayo ibhidliza indawo ebanzi unyaka wonke kodwa kukhona nendawo eyimfihlakalo ogwadule; futhi emhlabeni wonke, yaziwa ngokuthi 'Iso LeSahara.'
'Iso LeSahara' - Isakhiwo seRichat
Isakhiwo se-Richat, noma esaziwa kakhulu ngokuthi 'Iso Le-Sahara', i-geologic dome - nakuba kuseyimpikiswano - equkethe amatshe angaphambi kokuvela kokuphila eMhlabeni. Iso lifana noluhlaza okwesibhakabhaka inkunzi futhi itholakala eNtshonalanga yeSahara. Iningi lezazi zokuma komhlaba likholelwa ukuthi ukwakheka kwe-Eye kwaqala lapho i-supercontinent Pangea iqala ukuhlukana.
Ukutholwa 'kweso Le-Sahara'
Emakhulwini eminyaka, yizizwe ezimbalwa zendawo eziyimizulane ezazikwazi lokhu kwakheka okumangalisayo. Yaqala ukuthwebula izithombe ngawo-1960 ngu Iphrojekthi Gemini osomkhathi, abayisebenzise njengophawu lomlando ukulandela inqubekela phambili yokulandelana kwabo kokwehla. Kamuva, isathelayithi iLandsat yathatha izithombe ezingeziwe futhi yanikeza imininingwane ngosayizi, ukuphakama, nobukhulu bokwakheka.
Izazi ze-Geologists ekuqaleni zazikholelwa ukuthi 'Iso Le-Sahara' kwakuyi-crater yomthelela eyadalwa lapho into evela emkhathini ishaya phezu komhlaba. Kodwa-ke, ucwaningo olude lwamadwala ngaphakathi kwesakhiwo lubonisa ukuthi imvelaphi yawo isekelwe eMhlabeni ngokuphelele.
Imininingwane yesakhiwo 'yeso Le-Sahara'
I-'Eye of the Sahara', noma eyaziwa ngokusemthethweni ngokuthi i-Richat Structure, i-dome elinganayo kakhulu, eyi-elliptical, eguguleke ngokujulile enobubanzi obungamamayela angu-25. Itshe le-sedimentary elivezwe kule dome lisukela ngeminyaka yobudala I-Proterozoic esedlule maphakathi nendawo yedome kuya e-Ordovician sandstone nxazonke zayo. Ukwehla kokuguguleka okwehlukene kwezingqimba ezingamelana ne-quartzite kudale ama-cuestas ayindilinga ephezulu. Isikhungo sakhona siqukethe i-siliceous breccia emboza indawo okungenani eyi-19 miles ububanzi.
Okuvezwe ngaphakathi kwengaphakathi leSakhiwo seRichat kunezinhlobonhlobo zamatshe angenalutho futhi athintekayo. Kubandakanya amatshe entaba-mlilo angama-rhyolitic, ama-gabbros, ama-carbonatites nama-kimberlites. Amadwala e-rhyolitic aqukethe ukugeleza kodaka lwentaba-mlilo kanye namadwala e-tuffaceous aguqulwe yi-hydrothermally ayingxenye yezikhungo ezimbili ezihlukene zokuqhuma, okuhunyushwa ngokuthi izinsalela eziguguliwe ezimbili maar.
Ngokuya ngemephu yasensimini kanye nedatha ye-aeromagnetic, amadwala e-gabbroic akha izindonga ezimbili zamasongo. I-ring dike yangaphakathi icishe ibe ngamamitha angama-20 ububanzi futhi ilele cishe ngamakhilomitha ama-3 ukusuka maphakathi noRichat Structure. I-ring dike yangaphandle icishe ibe ngamamitha angama-50 ububanzi futhi ilele cishe ngamakhilomitha ayi-7 kuye kwayi-8 ukusuka maphakathi nalesi sakhiwo.
Imigwaqo engamatshumi amathathu nambili ye-carbonatite kanye ne-sills yenziwe imephu ngaphakathi kweRichat Structure. Izindunduma ngokuvamile zingamamitha angama-300 ubude futhi imitha eli-1 kuye kwayi-4 ububanzi. Ziqukethe ama-carbonatite amakhulu kakhulu angenawo ama-vesicles. Amatshe e-carbonatite abhalwe ukuthi apholile phakathi kweminyaka engama-94 no-104 million edlule.
Imfihlakalo ngemuva kwemvelaphi 'yeso Le-Sahara'
Isakhiwo seRichat saqala ukuchazwa phakathi kweminyaka yama-1930s kanye nama-1940s, njenge-Richât Crater noma i-Richât buttonhole. Ngo-1948, uRichard-Molard wakubheka njengomphumela we- i-laccolithic thrust. Kamuva imvelaphi yayo yabhekwa kafushane njengesakhiwo somthelela. Kodwa ucwaningo oluseduze phakathi kwawo-1950 no-1960 lwaphakamisa ukuthi lwakhiwa izinqubo zasemhlabeni.
Kodwa-ke, ngemuva kocwaningo olunzulu lwensimu kanye nelabhorethri ngasekupheleni kwawo-1960, abukho ubufakazi obuphathekayo obutholakele ukushaqeka metamorphism noma yiluphi uhlobo lokukhubazeka okubonisa i-hypervelocity ngaphandle umthelela.
Ngenkathi i-coesite, uhlobo lwe-silicon dioxide oluthathwa njengenkomba ye-shock metamorphism, ekuqaleni kwakubikwe ukuthi lwalukhona kumasampula amadwala aqoqwe kuRichat Structure, ukuhlaziywa okuqhubekayo kwamasampula edwala kwaphetha ngokuthi i-barite yayingaziwa njenge-coesite.
Umsebenzi wokuqomisana nesakhiwo wenziwa ngeminyaka yawo-1990. Ucwaningo oluvuselelwe lokubunjwa kwe-Richat Structure ngu-Matton et Al kusukela ku-2005 kuya ku-2008 kuqinisekisile isiphetho sokuthi empeleni akusona isakhiwo somthelela.
Ucwaningo lokuhlaziya okuningi ngo-Richat megabreccias lwaphetha ngokuthi ama-carbonates ngaphakathi kwama-megabreccias acebile nge-silica adalwe ngamanzi aphansi okushisa aphansi, nokuthi isakhiwo sidinga ukuvikelwa okukhethekile kanye nophenyo olwengeziwe ngemvelaphi yalo.
Ithiyori ekholisayo yemvelaphi 'yeso Le-Sahara'
Ososayensi basenemibuzo mayelana ne-Eye yeSahara, kepha izazi zokuma komhlaba ezimbili zaseCanada zinomqondo osebenzayo ngemvelaphi yazo.
Bacabanga ukuthi ukwakheka kwe-Eye kwaqala eminyakeni engaphezu kwezigidi eziyi-100 eyedlule, njengoba iPangea yezwekazi eliphakeme yahlakazwa ngama-plate tectonics futhi manje okuyi-Afrika neNingizimu Melika kwakudatshulwa komunye nomunye.
Idwala elicibilikile laqhubekela phezulu kodwa alizange lenze yonke indlela, lakha i-dome yezingqimba zamatshe, njengenduna enkulu kakhulu. Lokhu futhi kudale imigqa yamaphutha ejikeleza futhi ewela i-Eye. Idwala elincibilikisiwe laphinde lachitha i-limestone eduzane nendawo maphakathi ne-Eye, elawa lakha uhlobo oluthile lwedwala elibizwa nge-breccia.
Ngemuva nje kweminyaka eyizigidi eziyi-100 edlule, i-Eye yaqhuma kakhulu. Lokho kwawa ingxenye eyodwa yebhola, futhi ukuguguleka komhlabathi kwenza wonke umsebenzi wokwenza i-Eye yeSahara esiyaziyo namuhla. Amasongo enziwe ngezinhlobo ezahlukahlukene zedwala eliguguleka ngejubane elihlukile. Umbuthano omude oseduze nendawo maphakathi neso yidwala lentaba-mlilo elenziwa ngesikhathi sokuqhuma.
'Iso Le-Sahara' - ingqophamlando evela emkhathini
Osomkhathi banamuhla bayalithanda i-Eye ngoba ingxenye enkulu yoGwadule iSahara ilulwandle lwesihlabathi olungabhidliki. I-Eye eluhlaza okwesibhakabhaka ingelinye lamakhefu ambalwa e-monotony abonakala emkhathini, futhi manje sekuwuphawu olubalulekile kubo.
I-'Eye of the Sahara' iyindawo enhle ongayivakashela
I-Western Sahara ayisenazo izimo ezipholile ezazikhona ngesikhathi kwakhiwa i-Eye. Kodwa-ke, kusengenzeka ukuvakashela ugwadule olomile nolunesihlabathi i-Eye of the Sahara olubiza ngokuthi yikhaya — kepha akusilo uhambo lukanokusho. Abahambi kumele baqale bathole ukufinyelela kwi-visa yaseMauritania bese bethola umxhasi wendawo.
Uma sezamukelwe, izivakashi ziyelulekwa ukuba zenze amalungiselelo okuhamba endawo. Abanye osomabhizinisi banikela ngokugibela izindiza noma ibhaluni lomoya oshisayo phezu kwe-Eye, banikeze izivakashi umbono wezinyoni. I-Eye iseduze kwedolobha i-Ouadane, okuyindawo yokugibela imoto iqhele esakhiweni, futhi kunehhotela ngisho ngaphakathi kweso.
