Petrochemistry and Oxygen Isotope of Karimati (L5) Chondrite, a 2009 Fall in Uttar Pradesh, India

Abstract

Karimati, a single stone, weighing ~1 kg, fell on the mid-day of May 28, 2009, in Karimati village, Tahsil Hamirpur, Uttar Pradesh, India. Based on textures and mineralogy, Karimati is classified as brecciated, L5 (S2), ordinary chondrite. Petrologically, the chemical group, L has been assigned based on the typical mean compositions of olivine (Fa:25.5) and low-Ca pyroxene (Fs:21.6). The bulk chemical composition also resembles L chondrite as Mg/Si ratio ~0.82. Finally, the oxygen isotopic ratios of bulk meteorite sample yielded δ17O (+3.78%o and +4.07%o) and δ18O (+4.95%o and +5.52%o), respectively further confirmed Karimati as L-chondrite. The Karimati appears to have been subjected to single fragmentation in the atmospheric flight and it is evident from similar characters of all the lateral faces except the base of the pyramid in terms of its uniform colour, homogeneous fusion crust and shallow regmaglypts. The metamorphic equilibration temperature for Karimati chondrite using two different thermometers (olivine-chromite and two pyroxene thermometry) has been estimated and ranges 655°C and 770°C, respectively with a mean value of ~710°C and corresponds to the Type 5 thermal equilibration event.