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Zawartość minerałów FeNi w chondrytach H jako wskaźnik zasobności pozaziemskich skał rudonośnych w wybrane metale

Blutstein K., Przylibski T. A., Łuszczek K.

Przegląd Geologiczny

2018

Vol. 66, nr 12

776--784

Extraterrestrial resources should be the basic sources of materials for the development of humankind civilization in space as well as they could replace the Earth’s resources when they would be exhausted. They can be obtained from the planets, their moons or asteroids, primarily NEOs but also from the asteroid belt. This article presents the results of petrographic research on the content of FeNi minerals whose may be a source of iron and nickel, in H type ordinary chondrites: Pułtusk, Cher- gach, Tamdakht, Gao-Guenie andNWA 4555, which parent body is probably the 6Hebe. The results confirm that the volumetric abundance of FeNi minerals in H type chondrites is ca. 8%. Moreover, this study shows the reliability of the reflected-light optical microscopy for determination of ore mineral concentrations in extraterrestrial rocks with weathering grade W0. Taking into account the homogenous spatial distribution of metallic grains (proved by author’s microscopic observations) and knowing the amount of FeNi minerals in rocks with Hchondrite composition, the amount of potential FeNi resources on Hparent bodies can be calculated. It was estimated that the iron resources from Hebe’s FeNi minerals would cover 1.3 million years of terrestrial mining production whereas nickel resources would last for approx. 100 milion years. A small NEO asteroid like (143624) 2003 HM16 (2 km in diameter) has resources comparable with 15 months of mining iron production and over 100 years of nickel production at present rate.

Thermal metamorphic evolution of the Pułtusk H chondrite breccia – compositional and textural properties not included in petrological classification

Krzesinska A. M.

Geological Quarterly

2016

Vol. 60, No. 1

211--224

The thermal history that chondrites experienced on their parent body is an aspect of their petrological classification. However, in the classification scheme, metamorphic conditions are generally limited to the peak metamorphic temperature attained, while it is known that reconstruction of the genuine thermal evolution of any rock requires identification of various metamorphic factors, definition of the temperature-time path during metamorphism and characterization of the processes responsible for heating. Study of the brecciated Pułtusk H chondrite shows that the meteorite comprises both low and high petrologic type material and should be classified as a H3.8–6 chondrite. Based on the textures and mineral and chemical composition, the thermal metamorphic history of the breccia is reconstructed and it is shown to be inconsistent with the petrologic classification; the textural maturation and degree of compositional equilibrium in the meteorite do not correspond to the temperatures attained. The metamorphic conditions are shown to be a function of the primary composition of the accreted minerals and of two metamorphic phases, progressive and retrogressive. First, a prograde phase led to textural maturation and equilibration of the chemical composition of silicates and oxides. The peak metamorphic temperatures were at least ~700ºC for the type 3.8. and 4 material, and up to ~1000ºC in H6 clasts i.e., sufficient to locally give rise to partial melting. The following retrograde metamorphism led to compositional re-equilibration of minerals and textural re-equilibration of minerals with partial melts. The cooling rate during retrograde metamorphism down to at least ~700ºC was low, which allowed potassium feldspar to form patches in Na-plagioclase and pseudobrookite-armalcolite breakdown to form an association of ilmenite and rutile. The two-phase metamorphic evolution of the Pułtusk breccia was the most likely the result of impact heating, which affected the parent body in its very early history.