Both approaches are based on valuable observations and the exact origin of Hatrurim Formation is still a matter of debates. The first points out that the primary materials were bituminous sedimentary marls and chalks adjacent to the Mottled Zone 20, 21 and the second hypothesis is that the high temperature was a result of a firing of hydrocarbons (preferentially methane) from mud volcano explosions initiated by tectonic activity at the Dead Sea transform fault 22. Two popular hypotheses explaining the source of the fired substance have been proposed. pyrometamorphism caused by the spontaneous or stimulated burning of carbonaceous matter. The sediments were subject to a combustion metamorphism, i.e. The Mottled Zone has attracted scientific interest as a suite of chalky-marly sediments which underwent extensive and repetitive high-temperature (500–1500☌) and low-pressure (down to one bar) metamorphic events 20, 21. The thickness of the formation reaches several hundred meters.
#BRUKER APEX II DUO CCD DIFFRACTOMETER SERIES#
The Mottled Zone is exposed in a series of outcrops with a total area of ~600 km 2. This unique geological complex is located in the vicinity of the Dead Sea, Levant, covering large areas in Israel and Jordan ( Fig. Phosphide mineralization described herein occurs in the pyrometamorphic rocks related to the Hatrurim Formation, also known as a “Mottled Zone”. The almost complete absence of phosphides in the Earth's crust resulted in the conventional view on the extraterrestrial origin of these minerals, hence meteoritic bombardment of the Earth's surface is considered as a likely source of phosphides and therefore of the reactive prebiotic phosphorus in the Archean era 1, 2, 3, 4, 5. Contrary to meteorites, phosphides have never been found in terrestrial rocks, with the exception of schreibersite found as trace inclusions in native iron from the Disko Island, Greenland 16, the single find of barringerite in garnet peridotite from China 17 and a few grains of phosphides found in fulgurites – silicate glasses formed by cloud-to-ground lightning events 18, 19. Knowledge of the phase relations in the Fe-Ni-P system substantially contribute to the understanding of the origin of planetesimals in the Solar System 6, 7, 14 and to the prediction of phase transitions in planetary interiors 12, 14, 15. 6, 9), barringerite and its high-pressure polymorph allabogdanite, (Fe,Ni) 2P (refs. Among eight known natural phosphides, five related to the ternary Fe-Ni-P system are particularly significant from the cosmochemical viewpoint: schreibersite - nickelphosphide, (Fe,Ni) 3P - (Ni,Fe) 3P (refs. Phosphide minerals are common accessory phases in meteorites and, to a lesser extent, in lunar rocks, interplanetary dust particles and comets 6, 7, 8. The plausible hypothesis assumes that the phosphite ions could be generated by the oxidation of phosphides, oxygen-free minerals containing phosphorus in a redox state lower than zero 4, 5.
It was suggested that the phosphorus(III) served as a precursor of prebiotic organophosphorus compounds 2, 3, which raises an important question on the origin of reduced phosphorus in the Archean era. However, at the times of the early Earth the situation might be very different: recently, phosphite species, (HP 3+O 3) 2−, containing reduced trivalent phosphorus, have been identified in marine sediments related to the Archean era 1.
Phosphorus, one of life essential elements, exists under current geochemical conditions in the pentavalent state as orthophosphate ion (P 5+O 4) 3−.
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