Musi hu Saathu dzhena Vredefort

© David Fleminger

The Geological Sequence

Lwa minwaha ya dzi million dzo fhelaho, shango ḽo thoma u dzika ḽa ima fhethu ho dzikaho fhedzi ha dzulela na u sokou vha hu tshi khou ṱhaselwa zwa vha zwi tshi khou ita uri hu dzule hu huṱuku, khamusi ngauri vhunzhi ha zwithuthubisi zwire kha solar zwo vha zwo no thuthuba zwo no vha zwithu zwine zwo no shuma. Water vapour, carbon dioxide na dzinwe dzi gasse dza mbo ḓi thoma u shuma kha shango dza thoma u sika tshikhala. Ha thoma una mvula ha thoma zwa u dzula kha matombo. Maḓi a mvula ovha ahone lwa minwaha ya 3.9 billion yo fhelaho.

Tshifhinga tsha Archaean

Hetshi ndi tshifhinga tsha u thoma Archaean (zwine zwa amba zwithu zwa kale) nahone zwo fhedza minwaha yo no swika 2.5 billion yo fhelaho. Nga hetsho tshifhinga,mabannda a vhane vha ḓi vhidza uri Granite-Greenstone dzi ḽeyara dza matombo dzo mbo ḓi sikiwa. Tsumbo yo no vhonala ya tshifhinga tsha Archaean ikha ḓi vha hone kha shango na ṋamusi i wanala kha ḽa Mpumalanga, kha ḓorobo ya Barberton, hune havha na matombo a kale a Granite-Greenstone ane o rembuluswa ubva fhasi.

Haya matombo a lurofhe lwa volacano ane avhidzwa komatiities, o sikiwa kha seabed zwa kale vhukati ha minwaha ya 3.6 na 3.2 billion. Hu na zwine zwa sumbedza uri hezwi zwithu zwo sikiwa musi mufhiso wo vha u nnṱha vhukuma u fhirisia zwine wa vha zwone ṋamusi. Zwine zwa sumbedza uri kha shango hu khou ḓiisa phanḓa na u rothola nga tshifhinga tsha zwino.

Musi hu tshi khou ḓiisa phanḓa na u ṱukufhala, havha na zwishumiswa zwa, silica-rich (zwine zwo vha zwi songo tou tsitsikana nga maanḓa u fhira Molten ya fhasi) ya mbo ḓi gonyela nnṱha ya hwala i nnṱha ha mantle. Ngauri yo vha ina muvhala wo thanyaho ufhira dzoṱhe Mantle na u tshimbila ha lwanzhe, heḽi tombo ḽa silica ḽo vha ḽi songo subducted ḽa dzulela u bva fhasi, ḽa vha ḽi tshi khou khwaṱha la fhira maḓi sa tshiṱangadzime.

Cratons

Nga murahu ha tshifhinga, tshiṱangadzime tshine tsho sikiwa, tsha isa phanḓa na u fhanduwa nnṱha kha dzi plate, zwi tshi khou wela nnṱha ha dzinwe dzi tshi khou sika zwinwe, u sikwa hu tshi tou sikwa zwine ra zwi vhidza uri shango fhethu ho fhambanaho. Hezwi zwoṱhe zwi vhidzwa upfi ‘micro-continents’. Nga inwe nḓila, matombo aya bva nnḓa ha maḓi, mitalo ya isa phanḓa i tshi khou fhiswa nga maḓi, ha kona uvha na zwinwe zwine nazwo zwo ḓiswa kha shango na lwanzhe zwine ra zwi vhidza uri bada ya mavu, hune havha huna muṱavha na matombo.

Shango ḽa u thoma ḽo vha ḽi tshi khou dzhia tshivhumbeo. U fhungudza mafhungo, shango ḽa u thoma ḽa mbo ḓi thoma u hula ngauri vho vha vha songo tsitsikana ufana na u tshimbila ha lwanzhe, zwo konadzea uri hu dzulee. Hunwe fhethu ha dzula ho tou ralo lwa minwaha ya 3 billion. Vha nga vha vho ita vha tshi lwa, vha tshi pfumbedzana, fhedzi avha ngo tshinyadziwa kana u dovhololwa. Ṋamusi hafha fhethu ri hu vhidza uri ndi fhethu ha vha kale. ‘cratons’.

The Kaapvaal Craton

Dzinwe dzi zwithu zwa kale dza zwa shango ndi Kaapvaal Craton, hune ha kha ḓi vha ho dzula kha tshivhindi tsha Southern Africa. Tshivhumbeo tsha vhukuma tsha tsiko atshi ḓivhei, fhedzi dzi ngudo dzo sumbedza uri devhula ha tshipiḓa tsha Australia, India na Madagascar zwo vha zwo ṱangana zwoṱhe nga tshifhinga tsha zwa kale. Lwa minwaha, ho vha hu tshi ḓa dzi leyara nntswa dza matombo nnṱha ha dzi craton’s Granite-Greenstone, khathihi na zwine zwa mangadza zwa mineral. Kaapvaal Craton yo vha I tshi ḓo dovha ya vha vhukati ha Vredefort.

Leyara ya u tou thoma ya tombo yo sikiwa Kaapvaal craton vhidzwa upfi tshigwada tsha Dominion. Ivha ina dzi ḽeyara tsekene dza matombo a u khwaṱha nga nnṱha ane avha a vhubvo. Matombo a Sedimentary a sikwa musi munukhelelo wa manwe matombo atshi ḓiswa fhethu huswa a kona u shanduka avha matombo, zwo itwa nga nḓila ine ya vhidzwa upfi lithification. Matombo a mvelo, nga inwe nḓila a sikwa nga mishumo ya volacano nnṱha nṱha kha mantle na crust, hune magma ṱhavhiwa nga mitwe i tshi ya kha crust u swika i tshi fhola. Lava I tshimbila kha shango iya kona u sika matombo a mvelo.

Translated by Khalirendwe Nekhavhambe