Alok Kumar Tripathi

Bar-Ilan University

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Chandan Upadhyay

Indian Institute of Technology BHU

R. S. Loyal

Panjab University

N. Bhandari

Graphic Era University

M. S. Sisodia

Physical Research Laboratory

R. P. Tripathi

National Institute of Immunology

S. C. Mathur

Jai Narain Vyas University

H. C. Verma

Teerthanker Mahaveer University

S.D. Gour

Jai Narain Vyas University

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Jai Narain Vyas University

Jodhpur National University

Physical Research Laboratory

Indian Institute of Technology BHU

Banaras Hindu University

Lovely Professional University

Indian Institute of Science Education and Research, Bhopal

National Institute of Technology Rourkela

Institute of Medical Sciences

Kathmandu University

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Thermal decomposition pattern and particle size estimation of iron minerals associated with the Cretaceous‐Tertiary boundary at Gubbio

Meteoritics and Planetary Science (2002)

H. C. Verma Chandan Upadhyay Alok Kumar Tripathi R. P. Tripathi N. Bhandari

Abstract— Mössbauer studies of the samples from the Cretaceous‐Tertiary (K‐T) boundary layer at Gubbio, Italy show that iron appears mainly in two phases, magnetically ordered hematite and a paramagnetic silicate phase. The average particle size of hematite is estimated to be in the range of 16 to 27 nm from transmission electron micrographs and lack of a Morin transition. The hyperfine magnetic field at the iron nucleus is observed to be somewhat less than that of bulk hematite, which may be explained by collective magnetic excitation. Stepwise heating up to 1000°C shows a decomposition pattern of the paramagnetic phase, which suggests it to be a tri‐octahedral layer silicate. The iron‐bearing phases found in the bulk sedimentary K‐T boundary material are different from those found in the spherules separated from this material indicating that the redox conditions changed rapidly after the impact, becoming more oxidizing during the period these bulk phases were formed.

10.1111/j.1945-5100.2002.tb00866.x

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Spherules from the Late Cretaceous Phosphorite of the Fatehgarh Formation, Barmer Basin, India

Gondwana Research (2005)

S. C. Mathur S.D. Gour R. S. Loyal Alok Kumar Tripathi M. S. Sisodia

10.1016/s1342-937x(05)71157-6

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Citations (16)