Chinese Journal of Polar Research ›› 2025, Vol. 37 ›› Issue (3): 510-521.DOI: 10.13679/j.jdyj.20240044

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Comparison of the thermal metamorphic history between two types of chondrules in GRV 13100 and NWA 13632 enstatite chondrites

GAO Xukai1, 2, XIE Lanfang1, 2, CHEN Hongyi1, 3, YANG Shanshan4, XIA Zhipeng1, 2, YIN Yiman1, 2, ZHAO Yanfei1, 2   

  1. 1Institute of Meteorite and Planetary Material Research, Key Laboratory of Planetary Geological Evolution of Guangxi Provincial Universities, Guilin University of Technology, Guilin 541006, China;
    2Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration, Guilin University of Technology, Guilin 541006, China;
    3Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources in Guangxi, Guilin University of Technology, Guilin 541004, China;
    4State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, China
  • Received:2024-04-23 Revised:2024-09-29 Online:2025-09-30 Published:2025-09-25

Abstract: The characteristics of petrology and mineralogy for porphyritic olivine pyroxene chondrule and barred pyroxene chondrule in GRV 13100 (EH4) and the whole rock in NWA 13632 (EH6) enstatite chondrite are reported in this paper, and the comparative study of their thermal metamorphic history are carried out. Two different cathodolumine-scence olivine, thermometers of oldhamite of porphyritic olivine pyroxene chondrule in GRV 13100 show that the chondrule have undergone incomplete melting of 800~900 ℃ and rapid cooling crystallization. The barred pyroxene chondrule in GRV 13100 underwent complete high-temperature melting higher than 1315 ℃, and the cooling rate was greater than 1 000 ℃·h-1. Their thermal metamorphic characteristics conform to the “rubble pile model”, and the metamorphic heat source comes from the impact energy. NWA 13632 enstatite chondrite has a high degree of thermal metamorphism (type 6) and weathering (W3), a blurred boundary between chondrule and matrix, a low impact metamorphism (S2), no impact melting phenomenon; The olivine and silica phases are absent in the residual spherules and matrix. Compared with GRV 13100, the Mn content of enstatite and troilite in NWA 13632 is low, and the secondary plagioclase and pyroxene form an equigranular texture in some areas. So, its thermal metamorphism characteristics are consistent with the “onion model”. NWA13632 meteorite may have formed deep within its parent body and was heated by the decay of radioactive elements.

Key words: enstatite chondrite, petrology, mineralogy, thermal metamorphism, GRV 13100, NWA 13632