La "firma" di un antico supercontinente — chiamato Pannotia, più antico della Pangea — è conservata in catene montuose oltre che negli oceani e risale a 600 milioni di anni fa, nel periodo Precambriano. La conferma della sua esistenza arriva da uno studio pubblicato sulla rivista Geological Society of London, di cui uno dei due autori, il geologo Damian Nance dell'Università statunitense dell'Ohio, ne ha sempre sostenuto l'esistenza.
Una rappresentazione della Pannotia
Insieme a Brendan Murphy, dell'Università canadese St. Francis Xavier, ha stabilito che i segni dei profondi sconvolgimenti avvenuti della superficie terrestre, come la formazione di catene montuose, l'apertura di spaccature della crosta terrestre, i mutamenti del clima e della chimica degli oceani, sarebbero compatibili con la formazione e la successiva frammentazione di Pannotia.
"Questo supercontinente ha avuto una profonda influenza sulla storia della Terra e sull'evoluzione di oceani, atmosfera e biosfera", ha osservato Nance. "I cicli di formazione e frattura dei continenti - ha aggiunto - hanno influenzato anche il campo magnetico del pianeta".
Ansa/px
Per saperne di più:
- L'articolo pubblicato sulla rivista Geological Society of London
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