Szaniszló B é rczi , associate professor,

1. Evolution of a Chondritic Parent Body Studies on the Antarctic MeteoritesCollected by the NIPRJapanese Antarctic Expeditions Szaniszló Bérczi, associate professor, Department of Materials Physics,Institute of Physics, Eötvös Loránd University, Budapest, Hungary bercziszani@ludens.elte.hu Lecture on Okayama University

2. 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. Lecture on Okayama University

3. 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. Lecture on Okayama University

4. Main minerals of the Lewis-Barshay model Lecture on Okayama University

5. 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. Lecture on Okayama University

6. 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. Lecture on Okayama University

7. Meteorites 1 • The main groups of the meteorites follow the main mineral groups of the condensation model of the Solar System. Lecture on Okayama University

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

9. 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. Lecture on Okayama University

10. Iron meteorite on the Antarctic snowfield 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. New source of meteorites: Antarctica Lecture on Okayama University

11. 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. Lecture on Okayama University

12. 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. Lecture on Okayama University

13. Radial – and – porphyritic Lecture on Okayama University

14. Cratered – and – composite Lecture on Okayama University

15. 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. Lecture on Okayama University

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

17. Chondritic textures, metamorphism • Chondruletypes • Alterations • Thermal • Aqueous • Impact brecciation • Other processes. Lecture on Okayama University

18. 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. Lecture on Okayama University

19. 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. Lecture on Okayama University

20. 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. Lecture on Okayama University

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

22. Eukritok: bazaltok a felszínről Lecture on Okayama University

23. 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. Lecture on Okayama University

24. Differentiation Lecture on Okayama University

25. 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). Lecture on Okayama University

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

27. The Urey-Craig field Lecture on Okayama University

28. 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. Lecture on Okayama University

29. Summary of the H, L, LL metamorphic sequences in the NIPR set Lecture on Okayama University

30. 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) Evolutionary paths of chondriter groups in the UCF Lecture on Okayama University

31. Cross section of a chondritic body • Meta-morphous steps during evolution of a chondritic body, form concentric belts. Lecture on Okayama University

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

33. Fragmentation of the Chondritic Parent Body by Collision • Final events before mete-orites reach Earth: collisions in the asteroid belt Lecture on Okayama University

34. Oxigene isotopic ratios Lecture on Okayama University

35. Summary • Thefragments of various asteroidalbodies 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. Lecture on Okayama University

36. 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/ Lecture on Okayama University