The gradual shift from forearc basalt-like to boninite-like magmatism during intra-oceanic subduction-initiation recorded by ophiolitic chromite deposits from Cuba Domínguez Carretero, Diego Proenza Fernández, Joaquín Antonio Pujol Solà, Núria Gervilla Linares, Fernando Villanova-de-Benavent, Cristina Colás, V. Núñez-Cambra, K. Piñero-Pérez, E. García Casco, Antonio Ophiolitic chromitites Platinum-group elements (PGE) Subduction-initiation Forearc basalts Boninites This research was financially supported by Spanish grant PID 2019-105625RB-C21 funded by MCIN/AEI/10.13039/501100011033 and by a “Ayudas predoctorales 2020” number PRE 2020–092140 PhD grant to DD-C by the Spanish Ministry of Science and Innovation. The help extended by the Empresa Geominera de Camagüey and Instituto de Geología y Paleontología / Servicio Geológico de Cuba during fieldwork are also gratefully acknowledged, as well as the technical support in EMPA sessions by Dr. Xavier Llovet. This paper has been produced within the framework of the MinResET (Mineral Resources for the Energy Transition) research group (2021-SGR-00239, Agència de Gestió d’Ajuts Universitaris i de Recerca de Catalunya). https://static-content.springer.com/esm/art%3A10.1007%2Fs00126-025-01355-x/MediaObjects/126_2025_1355_MOESM1_ESM.pdf https://static-content.springer.com/esm/art%3A10.1007%2Fs00126-025-01355-x/MediaObjects/126_2025_1355_MOESM2_ESM.xlsx https://static-content.springer.com/esm/art%3A10.1007%2Fs00126-025-01355-x/MediaObjects/126_2025_1355_MOESM3_ESM.xlsx https://static-content.springer.com/esm/art%3A10.1007%2Fs00126-025-01355-x/MediaObjects/126_2025_1355_MOESM4_ESM.xlsx https://static-content.springer.com/esm/art%3A10.1007%2Fs00126-025-01355-x/MediaObjects/126_2025_1355_MOESM5_ESM.xlsx Cuba contains the largest number of ophiolitic chromite deposits throughout the Americas. Most of these deposits are found within the mantle section of the Eastern Cuba and Camagüey ophiolitic massifs, which contain four different chromite mining districts (Camagüey, Mayarí, Sagua de Tánamo, and Moa-Baracoa). In addition to their potential as economic resources, chromite deposits are also excellent petrogenetic indicators to interpret the nature of ancient upper mantle, processes of melt formation in the mantle, and large-scale geodynamic processes. In this sense, major and trace elements of unaltered Cr-spinel cores together with chromitite whole-rock PGE composition reveal that high-Al Camagüey and Moa-Baracoa chromite districts were formed in equilibrium with forearc basalts (FAB)-like magmas during the incipient intra-oceanic subduction of the proto-Caribbean lithosphere underneath the Caribbean lithosphere, in a subduction-initiation process. Conversely, the high-Cr Mayarí chromite district was formed in equilibrium with more hydrated melts of boninitic affinity, typical of a more advanced stage of the subduction-initiation process. Nonetheless, the shift from FAB-like to boninite-like magmatism in an intra-oceanic subduction is gradual. This progressive change is well-recorded in the Sagua de Tánamo district that contains both high-Al and high-Cr chromitites. Thus, the studied ophiolitic chromitites allow tracing the complete magmatic evolution of an intra-oceanic subduction-initiation process. Furthermore, our data exhibits that accessory Cr-spinel composition of peridotites surrounding chromitites can be used as a prospecting indicator to anticipate the composition of ophiolitic chromitite bodies. Systematically, Cr-spinel from dunites associated with high-Al chromite deposits have lower Cr# values compared to the accessory Cr-spinel from the associated harzburgites. On the contrary, Cr-spinel from dunites of high-Cr chromite deposits show higher Cr# compared to the accessory Cr-spinel from the host harzburgites. 2025-04-30T07:02:10Z 2025-04-30T07:02:10Z 2025-03-07 journal article Domínguez-Carretero, D., Proenza, J.A., Pujol-Solà, N. et al. The gradual shift from forearc basalt-like to boninite-like magmatism during intra-oceanic subduction-initiation recorded by ophiolitic chromite deposits from Cuba. Miner Deposita (2025). https://doi.org/10.1007/s00126-025-01355-x https://hdl.handle.net/10481/103851 10.1007/s00126-025-01355-x eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional Springer Nature