Further illite crystallinity data from Bowers Terrane, Millen Schists and Robertson Bay Terrane (northern Victoria Land, Antarctica)

This paper provides new data on the regional relationships between Bowers and Robertson Bay terranes, two main units of Ross age in the northern Victoria Land sector of the Transantarctic Mountains. This contribution aims to complete the regional investigation by surveying areas never or only partly visited and sampled during the scientific expeditions in the last fifteen years. The analysed samples were collected from the Bowers Mountains and the Robinson Heights. The data deal with the illite crystallinity index (IC) values of very low- to low-grade metamorphic rocks from both the Bowers and Robertson Bay terranes, and the intervening Millen Schist belt. The obtained results confirm the already known regional setting. All the IC data are comparable and may be related to the epizone; anyway, the IC average values from the three tectonic complexes show slight differences. Comparison of these differences with petrographic observations (original on the same samples or retrieved from literature) points to a slightly higher metamorphic imprinting (coeval with more severe deformation) of the Millen Schist with respect to the Bowers and Robertson Bay rocks.