Szaniszló Bérczi, associate professor, Evolution of a Chondritic Parent Body Studies on the Antarctic Meteorites Collected by the NIPR Japanese Antarctic Expeditions Szaniszló Bérczi, associate professor, Department of Materials Physics, Institute of Physics, Eötvös Loránd University, Budapest, Hungary bercziszani@ludens.elte.hu 16/01/2019 Lecture on Okayama University

Lecture on Okayama University Introduction 1 Meteorites are fragments of different asteroidal sized bodies. Mineralogical and textural characteristics of various meteorites reveal processes, which help to arrange them into types and calsses. Many important processes can be fitted into a global evolutionary picture if we assume, that larger bodies suffered thermal transformation during their early lifetime, when radioctive heating warmed up them. This way main chondritic processes of early classifications to types of Prior, then Urey and Craig, further developments by Wiik, Keil and Fredriksson, and to petrologic class definition of Van Schmus and Wood serve as parallel partial processes in this global picture. 16/01/2019 Lecture on Okayama University

Heritage: Solar abundance of nuclei Around Sun the solar nebula contains the nuclei of elements in solar abundance, near to the cosmic abundance Of this composition minerals precipitate or keep balance with the solar nebula Their composition changes with the solar distance, determining p and T od the solar nebula. 16/01/2019 Lecture on Okayama University

Main minerals of the Lewis-Barshay model 16/01/2019 Lecture on Okayama University

Planetary cross sections in the Lewis-Barshay model From minerals larger blocks and later planetosimals form. Collisions of planetosimals form larger bodies. The largest known bodies are the chondritic asteroids. 16/01/2019 Lecture on Okayama University

Double-crystallisation in the Solar System Two great periods in the formation of the planetary system Precipitation of the minerals Accumulation into planetosimals by collisions. 16/01/2019 Lecture on Okayama University

Lecture on Okayama University Meteorites 1 The main groups of the meteorites follow the main mineral groups of the condensation model of the Solar System. 16/01/2019 Lecture on Okayama University

A well known carbonaceous chondrite: Kaba It fall in Hungary in 1857, April 15. at the village of Kaba. Its type is CV3. 16/01/2019 Lecture on Okayama University

The main type of the meteorites: the chondrites (Mezőmadaras) Of tha falls of meteorites 85 % is chondritic Their main characterising components are the chondrules: grains in English. Their size is bw. Millimeter and some 10 s of micrometers. 16/01/2019 Lecture on Okayama University

New source of meteorites: Antarctica In this study we use the thin section set of the National Institute of Polar Research, Tokyo, Japan. It contains 30 polished thin sections of meteorites. This collection gives a good cross section about the meteorite evolution. Iron meteorite on the Antarctic snowfield 16/01/2019 Lecture on Okayama University

NIPR Antarctic Meteorite Set 30 polished thin sections. 3 chondrite groups form vSW sequences from 3-to 6 types (H, L, LL). 4 carbonaceous chondrites 12 achondrites. Excellent collection for teaching the evolution of a chondritic parent body Lecture note atlas helped students in their studies. Beautiful collection. 16/01/2019 Lecture on Okayama University

Lecture on Okayama University Types of chondrules Once they were in molten state. Droplets were formed by the solar flares. Their textures formed during their cooling the first textural type is. Glassy. 16/01/2019 Lecture on Okayama University

Radial – and – porphyritic 16/01/2019 Lecture on Okayama University

Cratered – and – composite 16/01/2019 Lecture on Okayama University

Lecture on Okayama University CAI: Ca-Al Inclusion During the early inner zone (belt) of the Sun minerals with refractory composition were formed Frequently they have amoeboid shape. Sztrókay Kálmán measured their composition and found it to be mostly composed of spinel. This is a CAI from the Allende meteorite. 16/01/2019 Lecture on Okayama University

Lecture on Okayama University Observations - 1 Chondritic texture consists of two main constituents: chonrules and matrix. They form a breccsa like texture of many other constituents. 16/01/2019 Lecture on Okayama University

Chondritic textures, metamorphism Chondruletypes Alterations Thermal Aqueous Impact brecciation Other processes. 16/01/2019 Lecture on Okayama University

First chondritic evolution period (metamorphism) Samples: A) Samples of first chondritic evolution period (metamorphism) in the set: Carbonaceous Chondrites: - C1 - NIPR 27, CM2 - NIPR 28, CO3 - NIPR 29, CV3 - NIPR 30. Unequilibrated Chondrites: EH3 - NIPR 14, H3 - NIPR 15, L3 - NIPR 19, LL3 - NIPR 23. Equilibrated Chondrites: H4 - NIPR 16, H5 - NIPR 17, H6 - NIPR 18, L4 - NIPR 20, H5 - NIPR 21, H6 - NIPR 22, LL4 - NIPR 24, LL5 - NIPR 25, LL6 - NIPR 26. Primitive Achondrite: PA - NIPR 13. 16/01/2019 Lecture on Okayama University

Observations/interpretations - 3 Over vS-W stage 6 chondritic mineral assemblage begins to melt partially. This stage is represented by primitive achondrites, like the lodranites. 16/01/2019 Lecture on Okayama University

Observations/interpretations - 4 Two main partial melts appear: - first the metallic sulphide/metal FeNi melts migrate downward, this mineral assemblage can be seen in pallasites. 16/01/2019 Lecture on Okayama University

Observations/interpretations - 5 - second the basaltic liquids migrate upward to produce basaltic achondrites: eucrites, howardites and diogenites. 16/01/2019 Lecture on Okayama University

Eukritok: bazaltok a felszínről 16/01/2019 Lecture on Okayama University

Observations/interpretations - 6 The final remnant of these partial melting processes is a peridotitic rock, similar to ureilites. This mineral assemblage preserve many characteristics of the original chondritic composition. 16/01/2019 Lecture on Okayama University

Lecture on Okayama University Differentiation 16/01/2019 Lecture on Okayama University

Urey-Craig-Field (UCF) of iron compounds In 1953 Urey and Craig compiled all good chondritic compositional data and made a metal+sulphide versus oxidized iron compounds compositional field. They could distinguish two main groups of chondrites - those with High (H) total iron content - those with Low (L) total iron content. Later 3 other groups were defined by Wiik, Friderickson and Keil (E, LL, C). 16/01/2019 Lecture on Okayama University

Chemistry of chondrites The chond-rites groups of E, H, L, LL, C are arranged in the Urey-Craig Field (UCF). 16/01/2019 Lecture on Okayama University

Lecture on Okayama University The Urey-Craig field 16/01/2019 Lecture on Okayama University

Projections of Fe-compound data on the UCF UCF is similar to HRD in astronomy. We may follow on it the evolutionary trends of various regions in a chondritic body. We used NIPR Dataset of chondrites (444 chondrites) and projected them to the UCF. As an example: H3, H4, H5, H6 sequences were projected on the UCF. 16/01/2019 Lecture on Okayama University

Summary of the H, L, LL metamorphic sequences in the NIPR set 16/01/2019 Lecture on Okayama University

Evolutionary paths of chondriter groups in the UCF In the first period most chondrites are reduced from 3-to-4 vS-W stages Second they become oxidized At L and LL iron loss is beginning at stage 6 (and 7) 16/01/2019 Lecture on Okayama University

Cross section of a chondritic body Meta-morphous steps during evolution of a chondritic body, form concentric belts. 16/01/2019 Lecture on Okayama University

Asteroidal cross section The stratification of the main achondrite types in the initially chondritic asteroidal body, which later differentiated by migration of melts. 16/01/2019 Lecture on Okayama University

Fragmentation of the Chondritic Parent Body by Collision Final events before mete-orites reach Earth: collisions in the asteroid belt 16/01/2019 Lecture on Okayama University

Oxigene isotopic ratios 16/01/2019 Lecture on Okayama University

Lecture on Okayama University Summary The fragments of various asteroidal bodies are the meteorites. Their mineralogical and textural characteristics revealed processes. On the basis of these processes studies arranged them into types, classes; formed transformational sequences from them. The processes are in accord with a global evolutionary picture. This thermal transformation occurred during the early life time of the parent body, when radioctive heating warmed up them. There were two main periods in chondritic evolution: - thermal metamorphism, - differentiation into layers of the chondritic body. This global picture can be deciphered in more details by further studies on meteorites. 16/01/2019 Lecture on Okayama University

Acknowledgments and references Thanks to NIPR Antarctic Meteorite Research Center, Tokyo, for loan of the Antarctic set. Thanks for invitation to the university and kind hospitality here. Some more details can be shown on our homepage: http://planetologia.elte.hu/ 16/01/2019 Lecture on Okayama University