Positive europium anomaly at the Permo‐Triassic Boundary, Spiti, India

Abstract

A limonitic layer at the base of the Otoceras‐Ophiceras zone in the Lalung section in Spiti valley shows a significant positive europium anomaly with maximum Eu/Eu * = 1.9. This layer defines the contact between the earliest Griesbachian and the Permian Productus shale sequence. The layer shows a small cerium anomaly having the maximum value of (Ce/La) N = 1.4. The iridium concentration in this layer, at 73 pg/g, is only marginally above the levels found in the adjacent shales although higher than that found in the overlying limestones. Another horizon having 114 pg/g of Ir occurs 70 cm below this limonitic layer in the shale sequence. These observations have important implications, both for the terrestrial (mainly volcanic) and extra‐terrestrial impact hypotheses for the Permo‐Triassic transition which are discussed.