Minerals in Iron and Titanium Skeletal Textures in Nakhlites MIL 090030, MIL 090136, MIL 090032, and MIL 03346: Comparative Analysis With Terrestrial Analogues From Canary Islands, Spain

Abstract

The presence of minor minerals is a key factor distinguishing meteorite types, as they provide valuable insights into the formation processes, surface conditions, and evolutionary history of their parent bodies. In Martian nakhlites, one of the most distinctive minor phases is iron-titanium oxides forming characteristic skeletal textures. However, their mineralogical nature remains debated, with most studies identifying them as titanomagnetite, whereas others suggest ilmenite skeletal textures. This study uses Raman imaging to investigate the mineralogical distribution of these skeletal textures. Additionally, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) was used to assess titanium concentration gradients from the exterior to the core of the structures. Chemometric methods were applied to differentiate and represent the mineralogical distribution. Furthermore, similar skeletal textures observed in terrestrial analogs from the Timanfaya and Maciot volcanoes (Lanzarote, Canary Islands, Spain) were analyzed using Raman imaging to evaluate potential similarities or differences in composition and formation processes with those found in the paired meteorites studied. The results show that the skeletal textures in the MIL nakhlites consist of ilmenite surrounded by titanomagnetite and magnetite. In contrast, in the analogs, two types of skeletal textures were identified: some composed of ilmenite and others of magnetite. These findings indicate that skeletal oxide textures in Martian and terrestrial samples from two field sites formed through distinct processes and constitute sensitive recorders of the evolution of mafic magmatic systems. These differences reflect restricted redox conditions and limited subsolidus re-equilibration in the MIL nakhlites, versus oxidation and faster cooling histories in the terrestrial analogs.