Comprehensive Paleo- and Rock-Magnetic Study of the Moa-Baracoa Massif, Northeastern Cuban Ophiolite: Serpentinization, Magnetite Source and Tectonics

Characterization of paleo- and rock-magnetism, oxide microscopy and AMS of Upper Jurassic to Eocene age ophiolites and related rocks from the Moa-Baracoa massif are reported. Diabase and tuff show low magnetic susceptibility and low natural remanent magnetization while gabbro and serpentinites show instead higher values, regardless of serpentinization degree. Bulk rock magnetic measurements show comparable iron concentration at specific serpentinization degree. Hysteresis parameters and FORC analysis suggest magnetic grains with predominantly vortex state. Low- to high-temperature dependence of magnetic susceptibility indicate magnetite as main magnetic carrier controlling variation and hematite and pyrrhotite contributions. Serpentinites show maghemite probably of hydrothermal origin. The magnetite growth is related to high values of magnetic anomalies, which could be used as exploration guide for mineral deposits. The AMS results show different magnetic fabric for gabbro, peridotite and diabase, dominating foliated subvertical fabrics with some triaxial for gabbro and peridotite and poorly organized fabric in diabase. The paleomagnetic results show dispersion in the declination data, between NNW and NE, due to vertical axis rotations and related regional strain-partitioning by collision with Bahamas platform for Early Eocene.