Ukwenziwa Kwezemvelo eNingizimu Afrika

© David Fleminger

Uhlobo lokubusa(Dominion group)

Kucatshangwa ukuthi inzika zenhlobo yokubusa zafakwa eminyakeni engaba ngu-3.07 izigidi zezigidi ezedlule, esigodini sesigodi esakhiwe lapho isikhala ngaphansi komhlaba saqala ukwelula. Lo mgodi wabe ushukunyiswa idwala elishisayo. Ezinye izingxenye zenhlobo yokubusa ziqukethe idiphozi zegolide, ziye zasetshenziselwa izimayini ngenempumelelo encane. Akukho okunye mayelana nenhlobo yokubusa eyaziwa, ngoba konke kwenzeka esikhathini esidlule futhi kunezindawo ezimbalwa lapho amadwala agcinwa khona kahle.

Endaweni yaseVredefort, isibonelo, inhlobo yokubusa iboniswe ngehla encane ye-lava evezwa kuphela endaweni eyodwa noma ezimbili. Ngemuva kokuthi inhlobo yokubusa ihlelwe phansi, izingxenye ze-craton kaKaapvaal zashona phansi futhi zonke izimbiza eziphansi zazingcoliswa ngamanzi. Lokhu kwakha ulwandle olukhulu, olungajulile kulo lonke leli zwekazi futhi kwaqala inzika eziningi. Kuleli qophelo, kuyasiza ukuhlolisisa indima edlalwa ngamanzi ohlelweni lwesihlabathi.

Uhlobo lweWitwatersrand

Ngokuyinhloko, amanzi athatha izingcezu ezilahlekile kude nedwala lomthombo. Ijubane lamanzi nivame ukucacisa ibanga lalezi zingxenye ezizohamba. Lapho imifula ihlasela izitho ezinkulu zamanzi (njengezibi noma ulwandle), ukugeleza kwehlisa izinga elikhulu futhi iningi lezinhlayiya ezinzima liyehla futhi liye phansi. Izinhlayiya ezicoliweyo, ezifana nesihlabathi nodaka, zihlala zimisiwe emanzini isikhathi eside futhi zivame ukufakwa kude kakhulu ogwini. Isizathu sokuthi ngikutshela konke lokhu okuthakazelisayo kuzobonakala kamuva.

Ngakho-ke, eminyakeni engaba ngu-2.97 izigidi zezigidi edlule, izingqimba eziningana zedwala zafakwa olwandle olungajulile oluhlanganisa indawo engaphakathi yeNingizimu Afrika yamanje. Lokhu kubizwa ngokuthi i-West Rand Group futhi yakha izici eziningi ezithakazelisayo zezobuciko, ezifana ne-Witwatersrand igwadule eliqhamukayo eliphakathi kweGermiston neKrugersdorp.

Esikhathini esithile kamuva, ungqimba ngaphakathi komhlaba yavuka kancane futhi umhlaba waqhuma waba uchungechunge lwamagquma
nezitsha. Imifula manje yayigijimela eziqhingini ezisenyakatho nasentshonalanga ibe uchungechunge lwamachibi nokuthungatha, lapho ukuthunyelwa khona kwakusheshe khona. Amadwala akhiwe phakathi nalesi sikhathi abizwa ngokuthi iCentral Rand Group. Kanye, i-West Rand Group neCentral Rand Group kuthiwa yiWitwatersrand Supergroup.

Imfihlakalo yomhlaba

I-Central Rand Group yayihlukile, kodwa, ngoba izinhlamvu ezinzima zegolide zazifakwa ngezikhathi ezithile emibhedeni yomfula, kanye nohlalwane. Lokhu kwakha insimu yegolide ecebile kakhulu emhlabeni, equkethe isigamu segolide lomhlaba. Kamuva, lezi zingxenye zamatshe ezinamahlombe ezithwala igolide (ezibizwa ngokuthi imifula) ziyobe zenziwa ngempumelelo emangalisayo. Umthombo wokuqala walezi zinhlayiya zegolide, noma kunjalo, uhlala ungumfihlakalo wezwe.

Eminyakeni eyizigidi zezigidi eziyizinkulungwane ezimbili ezidlule, ingaphakathi yomhlaba yaseKaapvaal yahlangana ne yaseZimbabwe enyakatho.

Lokhu kwakha uhla lwezintaba ezinkulu eziphakama kulokho manje okuthiwa iLimpopo Mobile Belt. Kwaphumela ekukhuphukeni kwamatshe ancibilikileyo aphuma njengomfula entabeni amaningi, avala amatshe eWitwatersrand Supergroup. Lezi zakha ingxenye engezansi ye-Ventersdorp Supergroup.

I-Transvaal Supergroup

Ukuhamba phambili ngokushesha, cishe eminyakeni eyizigidi zezigidi ezingu 2.5 ezedlule, ingaphakathi yomhlaba yaseKaapvaal yabuye yaxhaswa futhi yaguqulwa cishe olwandle olubanzi. Lokhu kwaqala esinye isisindo somswakama osindayo futhi sibonisa ukuqala kwe-Transvaal Supergroup. Lokhu kuhambisana nokuphela kwezinsuku ezindala ngaphambi kokuba kube khona ukuphila emhlabeni kanye nokuqala kwenkathi yeumoya ohlanzekile(Proterozo), eyaqhubeka kwaze kwaba yizigidi eziyi-570 eminyakeni edlule.


I-Transvaal Supergroup iyisigaba esithakazelisayo samatshe.Isendlalelo esincane kunazo zonke, esibizwa ngokuthi uthunge lwamatshe amnyama ahambayo ngaphansi komhlaba(Black Reef Formation), siqukethe imifanekiso yegolide. Ngenhla yilokho uhlobo lweChuniespoort.

Lo ungqimba uqukethe ubufakazi bokunye kokuqala kokuphila emhlabeni - ukuphila kwamabhakthiriya . Kulungile, akuzwakala kumangalisa, kepha laba bahlaziyi bamabhakthiriya amancane bakhipha i-oksijeni njengomkhiqizo futhi babelokhu benomthwalo wokwandisa amazinga e-oksijeni mahhala emkhathini.

oksijeni evela kobhakthiriya nayo yasabela ngamanzi olwandle ukuze kutholakale inqwaba yomoya wezinsimbi esizthola emgodini namuhla.

I-Malmani Dolomites

Ibhakhtheriya ikhule emanzini angajulile, afana nemifula yamakhorali, futhi amunya amanzi e-carbon dioxide. Lokhu kwakwenza ukuba i-calcium carbonate ibe yinkimbinkimbi, eyabe isigcwele uketshezi olunamathela njalo luthambile.

Amabhaktheriya aqala ukukhula ngaphezulu kwezingqimba zekhalisiyamu futhi inqubo iphindwe kaningi. Lokhu kwakhiwa amabhakhtheriya, okwakhiwa kamuva ekugcineni kwalokho sikubiza ngokuthi ama-stromatolites. Izibonelo zalawa ma-stromatolite atholakalayo zikhonjisiwe endaweni yaseVredefort futhi ziye zachazwa njengengxenye evelele endaweni yaMagugu omhlaba.

Ikhalusiyamu carbonate nayo yakha izingqimba zamadwala okuthiwa i-Malmani dolomites. Lezi zibalulekile ngoba i-dolomite yayidliwa ngamanzi asemhlabathini aguqulwa emifantwini edwaleni, ukuze enze uchungechunge lwamapulangwe. Kamuva, le mihume yayizoba yindawo yokugcina yokhokho bokuqala, unkosazana Ples no Little Foot. Indulu edumile itholakala ku Mbeleko Yabantu (Cradle of Humankind), eSterkfontein, Makapansgat naseTaung sonke siphuma kulolu luhlu lwamatshe aluhlaza.
Kuye kwaphakanyiswa ukuthi umthelela weVredefort kungenzeka ukuthi ube nesandla ekwakheni ukuphazamiseka okwakhuphula Umhume, futhi ngaleyo ndlela wasisiza ukuba sixazulule lo mkhuba wokuziphendukela kwabantu.

Idwala lasehlathini (Bushveld Igneous Complex)

Ngemuva kokufakwa kwe-Transvaal Supergroup, kwakukhona ukuqhuma okuvela phansi ngezansi. Eminyakeni eyizigidi zezigidi ezi ngu 2.06 ezedlule, inqwaba yeziqhumane eziqhumayo zaphazamisa ukuthula kwamabhakhtheriya futhi zavala amadwala eKaapvaal ngezingqimba zamatshe nomlotha. Ngemva kwalokho, intuthu evela esihlokweni yaphakamisa inani elikhulu lamadwala aphoqelela ukuya phezulu , kepha azange afinyelele phezulu.

Leli gumbi lamagagasi eliphansi lancipha kancane kancane futhi lakha uchungechunge oluphawulekayo lwamadwala aqoshiwe okuthiwa i-Bushveld Igneous Complex. Lendlulela ngaphakathi eNingizimu Afrika futhi liyisibonelo esikhulu kunabo bonke emhlabeni. Idwala lasehlathini niqukethe, insimbi engathombi-c, ithusi, i-vanadium, i-titanium nensimbi emhlophe.

Umlilo we Vredefort (Vredefort Bolide)

Kwabe sekufika isimanga esikhulu. Eminyakeni eyizigidigidi ezidlule, i-Vredefort Bolide yafika ihamba ngesivinini esisheshayo eMhlabeni. Kwakungamakhilomitha amaningana ububanzi futhi bahamba ngesivinini esikhulu kakhulu ukuya enkabeni yamadwala eKaapvaal.
Umthelela wawungeke ucatshangelwe. Amadwala apheuka uthuli ,uqweqwe lwaphendulwa ngaphakathi, okwakhombisa izazi zamadwala zanamuhla ukungaqondakali okungavamile esikhathini esidlule. I-Vredefort bolide yaveza umbono omkhulu. Ngemuva komthelela, amatshe amasha azoqhubeka ewakhiwa eNingizimu ye-Afrika, futhi zonke izinqubo amadwala ezichazwe ngenhla ziyoqhubeka nanamuhla.

Kodwa-ke, i-akhawunti ephelele yesayensi ephathelene nomumo wamatshe yezwekazi ingaphezu kwamandla ale ncwadi. Esikhundleni salokho, kumele manje siphenduke emhlabathini bese sibheka esibhakabhakeni,ukuze sithole imininingwane egcwele mayelana nesehlakalo esikhulu kunazo zonke sokushicilelwa kwamandla emhlabeni.