Impacts – The Key to Understand Earth

Abstract

A significant factor, where are the major elements e.g. Mg, Fe, Si, Al, Ca, P, Ni that make up the asteroid or comet after the impact, has been ignored since the proposal of the impact events. In a striking contrast, there are many remaining unanswered or poorly answered questions regarding the formation and nature of banded iron formation (BIF), iron stone, phosphorite, bedded manganese ore, dolomite and carbonaceous black shales. The appearance of Lake Superior type banded ion formation associated with dolomite, quartzite, and black shale, the deposition of manganese ore and the occurrence of large phosphate repository during the Plaeoproterozoic; the onset of BIF with phosphate deposition and sedimentary manganese deposits and cap dolomite during the Neoproterozoic; the penecontemporary formation of oolitic iron stone taking place of the BIF, bedded manganese deposit, phosphorite, dolomite, and black shale during the Phanerozoic, which suggest a genetic link among them from the perspective of chemical elements. Actually, during hypervelocity impact cratering events, the main part of the asteroid or comet and target material are vaporizing, which forms a mushroom cloud of vapor in the atmosphere.The previous study shows that the calcite, magnetite, clay minerals and organic compounds condense from a solar gas at 10−4 atm with temperature less than 400 K, which provides an analog for the generation of the chemical sedimentary ore deposits. This also supported by table isotopes fractionation at small sacle (grain size, cm scale), all stable isotopes fractionation e.g. (Cr, Fe, S, Si, O,C) and mass-independent fractionation of sulphur isotopes following the rule of isotope fractionation during impacts: the earlier the condensed material, the more enriched in lighter isotopes. Thus, the impact of the asteroid or comet provides not only the elements source of chemical sedimentary ore deposits and the mechanism for their formation. The enrichment in iridium in BIFs and their associated impact spherule units are the other evidence to demonstrate that BIFs are the products of impacts. Impacts produce black shale, banded iron formation, limestone and dolomite. Based on the coeval sub-continental lithosphere mantle (SCLM) formation, juvenile crust generation, banded iron formations, mantle plumes and black shale, it seems that impacts maybe the driving force for Earth.