Phosphorus is one of the key elements,which determined the emergence of primordial life on our planet.The source of prebiotic phosphorus was most likely to be easily soluble compounds containing phosphorus in the nega...Phosphorus is one of the key elements,which determined the emergence of primordial life on our planet.The source of prebiotic phosphorus was most likely to be easily soluble compounds containing phosphorus in the negative form of oxidation(e.g.,phosphides).The present paper is the first thorough investigation of phosphide-bearing mineral assemblages confined to telluric(terrestrial)native iron from volcanic rocks of Disko Island,Greenland.Phosphorus speciation in given assemblages varies from the solid solution in native iron(up to 0.3 wt.%P),different phosphides–schreibersite Fe_(3)P,nickelphosphide Ni_(3)P,barringerite Fe_(2)P,and phosphates,including fluorapatite,anhydrous Fe-Na phosphates,phosphoran olivine and pyroxene(up to 1 wt.%P).The diversity of observed phosphorus speciation can be explained by the steep changes of redox conditions during subsurface crystallization of iron-phosphide-bearing lavas.Based on the available data on likely redox conditions on the early Earth,we hypothesize that reactive prebiotic phosphorus may have originated from shallow crustal rocks.展开更多
Plagioclase is the major rock-forming mineral constituting the Earth's crust,whereas anorthite(CaAl_(2)Si_(2)O_(8))is a common minerals in lunar highlands crust,meteorites,possibly in some comets and on Mercury.Be...Plagioclase is the major rock-forming mineral constituting the Earth's crust,whereas anorthite(CaAl_(2)Si_(2)O_(8))is a common minerals in lunar highlands crust,meteorites,possibly in some comets and on Mercury.Besides anorthite,two high-temperature polymorphs of CaAl_(2)Si_(2)O_(8)are known:dmisteinbergite and svyatoslavite,which are found in burnt coal dumps,meteorites and pseudotachylytes.Here we present the results of detailed studies(quenching experiments,elemental analysis,Raman spectroscopy and in situ high temperature single crystal X-ray diffraction(up to 1000℃))on naturally co-occurring CaAl_(2)Si_(2)O_(8)polymorphs(anorthite,dmisteinbergite and svyatoslavite)from a burnt coal dump in Kopeisk,Russia.New polymorphs were found in all natural samples and obtained upon heating of dmisteinbergite(unquenchableβ-dmisteinbergite and quenchable y-dmisteinbergite).It was shown that Ca coordination differs significantly in CaAl_(2)Si_(2)O_(8)polymorphs,resulting in a different capacity to host Ba and possibly other large ion lithophile elements.Combining our data on natural samples with the previously published data on natural and synthetic compounds,we propose a new scheme of CaAl_(2)Si_(2)O_(8)polymorphs stability.Our results indicate that CaAl_(2)Si_(2)O_(8)polymorphs could be used for temperature estimations for both Earth and planetary sciences.展开更多
基金supported by the Russian Science Foundation(grant 23-77-10025).
文摘Phosphorus is one of the key elements,which determined the emergence of primordial life on our planet.The source of prebiotic phosphorus was most likely to be easily soluble compounds containing phosphorus in the negative form of oxidation(e.g.,phosphides).The present paper is the first thorough investigation of phosphide-bearing mineral assemblages confined to telluric(terrestrial)native iron from volcanic rocks of Disko Island,Greenland.Phosphorus speciation in given assemblages varies from the solid solution in native iron(up to 0.3 wt.%P),different phosphides–schreibersite Fe_(3)P,nickelphosphide Ni_(3)P,barringerite Fe_(2)P,and phosphates,including fluorapatite,anhydrous Fe-Na phosphates,phosphoran olivine and pyroxene(up to 1 wt.%P).The diversity of observed phosphorus speciation can be explained by the steep changes of redox conditions during subsurface crystallization of iron-phosphide-bearing lavas.Based on the available data on likely redox conditions on the early Earth,we hypothesize that reactive prebiotic phosphorus may have originated from shallow crustal rocks.
基金the Grant of the President of Russian Federation(MK-2831.2021.1.5)
文摘Plagioclase is the major rock-forming mineral constituting the Earth's crust,whereas anorthite(CaAl_(2)Si_(2)O_(8))is a common minerals in lunar highlands crust,meteorites,possibly in some comets and on Mercury.Besides anorthite,two high-temperature polymorphs of CaAl_(2)Si_(2)O_(8)are known:dmisteinbergite and svyatoslavite,which are found in burnt coal dumps,meteorites and pseudotachylytes.Here we present the results of detailed studies(quenching experiments,elemental analysis,Raman spectroscopy and in situ high temperature single crystal X-ray diffraction(up to 1000℃))on naturally co-occurring CaAl_(2)Si_(2)O_(8)polymorphs(anorthite,dmisteinbergite and svyatoslavite)from a burnt coal dump in Kopeisk,Russia.New polymorphs were found in all natural samples and obtained upon heating of dmisteinbergite(unquenchableβ-dmisteinbergite and quenchable y-dmisteinbergite).It was shown that Ca coordination differs significantly in CaAl_(2)Si_(2)O_(8)polymorphs,resulting in a different capacity to host Ba and possibly other large ion lithophile elements.Combining our data on natural samples with the previously published data on natural and synthetic compounds,we propose a new scheme of CaAl_(2)Si_(2)O_(8)polymorphs stability.Our results indicate that CaAl_(2)Si_(2)O_(8)polymorphs could be used for temperature estimations for both Earth and planetary sciences.
