Gems shine light on an­cient Earth

CityPress - - News - ATHANDIWE SABA athandiwe.saba@city­

Di­a­monds are not only a girl’s best friend; sci­en­tists are fond of them too.

Three of th­ese gem­stones, dug up in Jo­han­nes­burg be­tween 1890 and 1930, have re­vealed se­crets of how the Earth worked more than 3.5 bil­lion years ago.

Th­ese green di­a­monds – ex­tracted from the 3 bil­lion-year-old Wit­wa­ter­srand Su­per­group, the rock for­ma­tion that is host to the fa­mous Jo­han­nes­burg gold mines – were in­ves­ti­gated by sci­en­tists in­clud­ing Dr Katie Smart and pro­fes­sors Su­san Webb and Lewis Ash­wal from Wits Univer­sity. Their re­search was pub­lished in the jour­nal Na­ture Geo­science this month.

The di­a­monds were found in the Wit­wa­ter­srand con­glom­er­ate, where the gold that led to the es­tab­lish­ment of the city of Jo­han­nes­burg was found.

“Be­cause di­a­monds are some of the hard­est, most ro­bust ma­te­ri­als on Earth, they are per­fect lit­tle time cap­sules and have the ca­pac­ity to tell us what pro­cesses were oc­cur­ring ex­tremely early in Earth’s his­tory,” said Smart.

“We are not the first re­search group to study di­a­monds in or­der to tell when plate tec­ton­ics [the the­ory deal­ing with the plates that make up the Earth’s outer shell] be­gan, but our study of con­firmed Ar­chaean [the aeon from 4 bil­lion to 2.5 bil­lion years ago] di­a­monds sug­gests that plate tec­ton­ics was in op­er­a­tion by as early as 3.5 bil­lion years ago.”

The re­search team say the plate tec­tonic process is vi­tal for shap­ing the Earth as we know it, be­cause it is the ac­tiv­ity of plate tec­ton­ics that causes earth­quakes and volcanic erup­tions, and that is re­spon­si­ble for con­struct­ing Earth’s land­scapes, such as deep-sea trenches and the de­vel­op­ment of moun­tains on the con­ti­nents.

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