Assimilation of Crustal Xenoliths in a Basaltic Magma Chamber: Sr and Nd Isotopic Constraints from the Hasvik Layered Intrusion, Norway

Abstract

contaminated layered intrusions known. Thousands of recrystallized Strontium and neodymium isotopic data for mafic cumulates, chilled tabular xenoliths of metasedimentary origin enclosed in the cumulates margins, and adjacent crustal rocks of the Hasvik Layered Intrusion, are thought to represent the remnants of the assimilated material. North Norwegian Caledonides, are reported together with new The xenoliths spalled off the roof during magma emplacement, and, mineralogical and whole-rock analytical data to constrain the extent together with the elevated temperatures (400–600°C) of the midand effect of the assimilation of crustal xenoliths in a basaltic crustal country rocks, led to a high degree of assimilation in the magma chamber. Initial Sr/Sr (700 Ma) of 0·7045 and eNd Hasvik magma chamber. (700 Ma) of+3·03 for the chilled margin, which has a tholeiitic composition akin to the chilled rocks of the Skaergaard intrusion, demonstrate that the parental magma was derived from a depleted mantle source. The basal cumulates (0–335 m) show an up-section decrease in Sr/Sr from 0·7045 to 0·7038 and a correlative