Banded hlau formations yog xav tias tau tsim nyob rau hauv hiav txwv dejvim qhov tshwm sim ntawm oxygen tsim los ntawm photosynthetic cyanobacteria. Cov pa oxygen ua ke nrog cov hlau yaj hauv lub ntiaj teb dej hiav txwv los tsim cov hlau tsis huv, uas tau los nag, tsim ib txheej nyias ntawm cov dej hiav txwv.
qhov twg cov hlau txuas tau tshwm sim hauv Australia?
Cov pob zeb uas muaj hlau ntawm lub xeev Hamersley hauv thaj av Pilbara ntawm Western Australia, yog cov pob zeb tuab tshaj plaws thiab dav tshaj plaws ntawm hom no hauv ntiaj teb.
Thaum twg cov kab hlau txuas tau tshwm sim?
Banded Iron formations tshwm sim hauv cov pob zeb Proterozoic, xws li hnub nyoog ntawm 1.8 txog 2.5 billion xyoo. Lawv yog tsim los ntawm alternating txheej ntawm hlau-nplua nuj khoom (feem ntau magnetite) thiab silica (chert).
Banded hlau formations yog dab tsi?
Banded hlau-formations yog sedimentary pob zeb formations nrog alternating silica-nplua txheej txheej thiab hlau-nplua nuj txheej uas feem ntau muaj li ntawm hlau oxides (hematite thiab magnetite), hlau-nplua nuj carbonates (siderite thiab ankerite), thiab/los yog hlau-nplua nuj silicates (piv txwv li, minnesotaite thiab greenalite).
Dab tsi yog banded hlau formations pov thawj ntawm?
Nyob rau xyoo 1960, Preston Cloud, tus kws tshaj lij geology ntawm University of California, Santa Barbara, tau nyiam ib hom pob zeb hu ua Banded Iron Formation (lossis BIF). Lawv muab ib qho tseem ceeb ntawm cov hlau rau kev tsim tsheb, thiab muab pov thawj rau qhov tsis muaj pa oxygen nyob rau lub ntiaj teb thaum ntxov
