Ukudaleka koMhlaba wo Mzantsi Afrika

© David Fleminger

I-Dominion Group

Kucingelwa ukuba iintsalela ze Dominion group zashiyeka malunga neminyaka ezi 3.07 billion eyadlulayo, kumngxuma owombeka ngethuba icrust ephantsi kwe craton yaqala ukwanda. Olu xinzelelo lwaze lwadama i-igneous intrusion esuka kwi mantle.

Ezinye iilayers zeDominion Group zine golide, nethe yombiwa ngempumelelo encinci. Akukho okunye okwaziwayo nge Dominion Group, konke oku kwenzeka kudala kakhulu. Zimbalwa iindawo apho amatye asagcineke kakuhle khona. Kwingingqi yase Vredefort umzekelo, iDominion Group ibonwa nge
thin layer ye lava evele kwindawo enye okanye ezimbini kuphela.

Emva kokuba iDominion group yondlalekile, iingxenye ze Kaapvaal craton zathomalala kwaye eziseleyo emazantsi zatshatyalaliswa ngamanzi. Oku kwadala, ulwandle olukhulu, olungekho nzulu. Olu lwandle lwathi tshitshilili kubukhulu bomhlaba welizwekazi kwaye lwaya lusanda ngakumbi. Kulendawo, kuluncedo ukunika ingqwalasela kwindima edlalwa ngamanzi kwi
sedimentation process.

I-Witwatersrand Supergroup

Lilonke,amanzi ahambayo akhukhulisa iingceba kwilitye. Isantya samanzi sivamise ukubonakalisa umgama ozakuhanjwa zezingceba. Xa imilambo ifika kumanzi amaninzi (afana namadama okanye ulwandle), ukunkcenkceza kuthoba isantya. Iingceba ezisindayo/ezinkulwana ziyazika ziyokuhlala emazantsi. Iintsalela ezincinci, ezifana nesanti kunye nodaka, zihlala zibhabha phezu kwamanzi ixesha elide kwaye zithanda ukuyokulahlelwa kude nenyele. Isizathu sokuba ndikuxelele elibali linika umdla, sizakucaca ethubeni.

Malunga neminyaka ezii 2.97 billion eyadlulayo, iqela lee layer ze sedimentary rock zondlaleka kulwandle olungekho nzulu, olwalugquma ubuninzi bomhlaba ophakathi eMzantsi Afrika wanamahlanje. Oku kubizwa nge West Rand Group kwaye yadala iqela le topographical features ezinikisa umdla, ezifana ne eponymous Witwatersrand ridge ehamba phakathi kwe Germiston kunye neKrugersdorp.

Kwithutyana elingephi, icraton yonyukela ngaphezulu nje kancinci waze umhlaba wajikeka wabanee ridges kunye nee basins eziliqela. Imilambo yahamba ukusuka kwimihlaba ephezulu emantla kunye nase ntshona yabangama chibi kunye nee depressions, nalapho ukongezeleleka kwakukhawuleza ngamandla. Lamatye adaleka ngelithuba abizwa ngokuba yi Central Rand Group. Ewonke , iWest Rand Group kunye ne Central Rand Group abizwa ngokuba yiWitwatersrand Supergroup.

Intsoma-ntsomane yokudaleka koMhlaba

I-Central Rand Group yayikhethekile keyona, kuba amahlalutye amakhulu egolide akhukhulisekela ecaleni komlambo kunye nagrabile. Oku kwadala owona mhlaba uzele yigolide eMhlabeni, uqulathe phantse isiqingatha yegolide yomhlaba wonke. Ethubeni, lamatye azele yigolide (abizwa nge reefs) zathi zombiwa ngenkulu yona impumelelo. Owona mthombo walegolide useyintsomantsomane yokudaleka komhlaba.

Kwizithuba zeminyana ezi 2.7 billion eyadlulayo, iKaapvaal Craton yangquzulana kunye ne craton ye Zimbambe ukuya emantla. Oku kwadala intabakazi eyathi yanyuka yayokuma kwindawo ebizwa nge Limpopo Mobile Belt. Oku kwakhokelela kwizikhukhula ze lava nezathi zaphuphumala ngapha kweentanda zecraton, neyathi yagquma amatye eWitwatersrand Supergroup. Ezi lava zenza umandlalo ongaphantsi kwe Ventersdorp Supergroup.

I-Transvaal Supergroup

Ukugqithelana phambilana, malunga nee2.5 billion zeminyaka eyadlulayo, iKaapvaal yancipha kwakhona yaze yaphantse ukudibana nengxenye enkulu yolwandle oluphakathi emhlabeni. Oku kwadala omnye umjikelo we heavy sedimentation kwaye iphawula ukuqala kwe Transvaal Supergroup. Oku kungaxeshanye nokuphela kwe Archaean kunye nesiqalo lexesha le Proterozoic, neyathi yahlala de kwabayiminyaka ezii 570 million eyadlulayo.

I-Transvaal Supergroup yimbumba yamatye enza umdla. Eyona layer ingaphantsi, nebizwa nge Black Reef Formation, iqulathe amasuntswana egolide. Ngaphezu kwayo kubekho iChuniespoort Group. Le layer iqulathe ubungqina bobunye ubomi obabuphila kuqala eMhlabeni- photosynthesising cyanobacteria. Kulungile, ayivakali impressive, kodwa ezi microbial critters zakhupha i-oxijini njengokungcola kwaye kusenokwenzeka ukuba zizo ezabangela ukwenyuka kwamaqondo e-oxijini emoyeni-atmosphere. Le oxijini isuka kule cyanobacteria yadibana nolwandle yaze yadala isixa esininzi see-iron oxides, nezaphela zisenza iron kunye nee manganese eninzi, nesiyombayo namhlanje.

I-Malmani Dolomites

Iintsholongwane zakhula kumanzi angekho nzulu, afana nee coral reefs, zaze zafunxa icarbon dioxide emanzini. Oku kwadala icalcium carbonate ikhawuleze, neyathi yagquma ilayer enyeke-nyeke-goey ye ntsholongwane. Lentsholongwane yaqhubekeka nokukhula ngaphezu kwe layer ye calcium kweze oku kwaphinda phindana amatyeli amaninzi. Oku kwenza
iintsholongwane ezimile okwe dome, nezathi zahamba zaba fossilised zabayinto esiyibiza ngokuba yi stromatolites. Imizekelo yezi petrified stromatolites iyafumaneka kwinginqi ye
Vredefort kwaye icalulwa njenge ndawo ye World Heritage Site.

Le calcium carbonate yadala ne layer yamatye ebizwa nge Malmani Dolomites. Ezi zibalulekile ngoba le dolomite yahamba yatyiwa ngamanzi angaphantsi komhlaba nawangena kwimingxunya yelitye, ukuze kwenzeka imiqolomba eliqela. Ethubeni, lemiqolommba yaba likhaya lokugqibela lokuphumla abantu bokuqala, abafana no Nkskz. Ples kunye no Little Foot. Ifossil ezidumileyo ezafunyanwa e Craddle of Humankind, Sterkfontein, Makapansgat kunye nase Taung zonke zaphuma kule layer ye limestone. Kukholeleka ekubeni Vredefort impact kusenikuba yabaesandla ekudaleni iintanda ezathi zajika zayimiqolomba, nto eyo eyathi yasincesa sasombulula iriddle yokuqaleka kwabantu- human evolution.

I-Bushveld Igneous Complex

Emva kokudaleka kwe Transvaal Supergroup, kwabakho ukugquma okusuka ngaphantsi komhlaba. Malunga neminyaka ezii 2.06 billion yeminyaka eyadlulayo,kwamane kuqhubakho uqhushumbo olwaphazamisa uxolo lwe cyanobacteria yaze yagquma iKaapvaal Craton ngomandlalo wamatye kunye nothuthu. Emva koko, enye iplume esuka kwi mantle yatshovela ngaphezulu isixa esikhulu se igneous material neyathi yadudula iilateral planes kwi sedimentary Transvaal rocks, kodwa ayade yafikelela ngaphezu komhlaba. Le subterranean magma chamber yathi chuu ukuphola yaze yadala ukwalekana okumangalisayo kwamatye abizwa nge Bushveld Igneous Complex.

Inwenwela phantse wonke umphakathi waMazantsi eAfrika, kwaye ingewona mzekelo mkhulu wohlobo lwayo kwihlabathi liphela. Le Complex ikwaqulathe ezinye platinum, chromium, copper, vanadium, titanium kunye nickel zehlabathi.

I-Vredefort Bolide

Emva koluntlitheko, amatye amatsha aqhubeka ukubumbeka ku Mazantsi Afrika, nazo zonke ii geological processes ezichazwe ngentla zisaqhubeka nanamhlanje. Nangona kunjalo, ukutshintsha-tshintsha kokumila komhlaba kusaqhubeka nanamhlanje inkcazelo epheleleyo ye geology yengenye yeli lizwekazi ingapha kwalencwadi. Endaweni yoko, masikhe siwushiye umhlaba sijonge ezinkwekwezini, ukuze sifumane ingxelo ngobunjalo bayo ye ‘single energy release event’ eyakhe yabonwa leli hlabathi.